[background noises] [laughter] ♪♪ >> c-span, unfiltered view of government. ♪♪ >> broadband is a force for empowerment, invested billions, building infrastructure, upgrading technology, empowering opportunity in communities big and small. charter is connecting us. >> c-span as a public service along with other television providers. a front row seat to democracy. up next, on c-span2, testimony in the trier trial of

minneapolis police officer derek chauvin charged in the death of george floyd. the jury heard from critical care specialist doctor martin tobin. lack of oxygen that led to mr. floyd death. [silence] [background noises] >> we are on the record. mr. nelson, do you wish to make the record? yes, i have either. >> yes, very briefly for purposes of, it is my understanding calls medical expert this morning, all of the experts ultimately rely on some

degree doctor baker's autopsies and findings and the information, i don't have a problem calling doctor baker of for purposes of foundation. however, understand the record reflects calling doctor baker. >> liable for any foundation based on the representation. >> correct. >> your honor, we have seen. >> thank you. anything else for the record? all right. [silence]

[silence] [silence] [silence] [silence]

[silence] [background noises] >> good morning, everybody. >> good morning, counsel, ladies and gentlemen. we call our first witness this morning. doctor martin tobin. [background noises] [background noises] >> raise your right hand. you swear or affirm. [inaudible]] >> ies do.

[background noises] >> remove your mask for your testimony. sure the microphone is properly placed. state your full name. >> martin tobin. >> good morning, doctor tobin. would you tell us -- [inaudible] >> i am a physician and critical care medicine. >> whereabouts? >> in chicago at the university medical school.

>> is the va hospital a large facility? >> it used to be the largest va hospital in the country, i think it now superseded by one or two others. >> you specialize in pulmonology? >> i specialize in pulmonology and critical care. >> would you tell the jury what pulmonology is? >> the study of the lungs that deals with all diseases that affect the respiratory system of the lungs, test will. >> what are the various elements components of the respiratoryha system other than lungs and chest walls? >> respiratory system begins at the nose and mouth that goes down through the back of the throat, down through the windpipe down to the air sac, the small rape like structures

at the bottom where oxygen gets in and carbon dioxide is removed. >> this is the system for getting oxygen into the body? >> correct that is the primary purpose to get oxygen and. >> at the hospital you work in the intensive care unit? >> yes, the medical care unit. >> that's considered critical care?ge >> these words all have the same meaning. >> is critical care different from emergency medicine. >> very different than emergency medicine. emergency medicine is the front door of the hospital, the triage area where you separate where people need to go, the critical care you take the very sickest to. >> what kind of patients you see

in the icu? >> in the icu, probably more than half patients require mechanical ventilation, on a respirator. another substantial number are not on a respiratory but the primary problem relates to the lungs, 70% of the remaining patients have drug overdoses, alcohol withdrawals, diabetic sepsis, things of that nature. >> do you only see patients in need of respiratory care? >> no, once they come into the icu, i p am the primary care physician for everybody who comes in. >> how long have you been a physician? >> three months short of 45 years where did youen go to school? >> medical school in dublin,

ireland. >> anybody noticed the accident but are you from dublin? >> no rushford, a small village in rural ireland. >> what degrees do you hold? >> the degree i hold is megabyte, irish prevalent of the american empty and subsequently from an md research. >> are you currently licensed? >> yes and state of illinois and ireland and england and a number of u.s. states but i let them all go because the only place i practice is in illinois. >> are you board-certified? >> yes, i am board certified in internal medicine pulmonary medicine. >> so you arere still actively caring for patients?

>> yes taking care of patients in the icu, monday i go straight back to icu again. >> how long have you held the position of the university? >> thirty-two years almost. >> before going, are you practicing medicine somewhere else? >> iic spent seven years at the university of texas and houston. >> did you also set up a sleep? >> yes, it would have been the early 80s i set up the very first lab in the united states for evaluating patients with obstructive sleep apnea. >> how do sleep disorders fit within your expertise? >> it's related to breathing problems with sleep,

particularly people who snore and people who snore during the nighttime to the upper airway and they can stop breathing 500, 600 times a night and the level of oxygen in the blood goes very low the basic problem sleep apnea is because the soft palate, the roof of your mouth is your hard palate and then you look in the mirror the peace hanging down at the back, that's your soft palate and uvula that janzen your throat. >> does that kind of research or science or medicine relate to your work in this case?e? >> just, the case of mr. floyd, obviously sleep apnea, the problem is the back of the throat, as we would see in mr.

floyd, a problem of where the obstruction is occurring is the hypo fair next in the back, and has an overlap to patients with sleep apnea. >> will come back to that in a little bit, are you also engaged in medical research. >> what that? >> are you engaged in medical research? >> i've been doing medical research since 1981. >> what kind of research have you been doing? >> all my research is related tb breathing so either looking at breathing in patients with lung disease, people who have lung disease who will in the doorse d patient in the icu and particularly patients requiring ventilation but i do a lot of research that has nothing to do

with medicine just to know how people breathe. >> heavy offer on this subject? >> yes, i have authored a large textbook on mechanical ventilation in ventilation. >> by showing the cover of your textbook here on the camera, is this the book you are referring to? >> correct. >> 1500 pages? >> correct. >> are youar familiar with l.a. mct medical journal? >> yes, it's one of the top medical journalism. >> does that refer to this book as the mechanical ventilation? >> yes. >> heavy offered other books?

>> yes. >> other books all related to respiratory failure? >> correct. the lungs. >> after you published articles, approximately how many? >> i lose count but i think more than 750 probably or something like that. >> have you published in the journal of medicine? >> this, several articles in the new england. >> are they thehe most effective medical journals? >> they are, yes. >> heavyes also held editor positions? >> yes, i was editor in chief, the american journal of repair medicine so it is the world on

lung disease and the world for intensive care medicine, the official journal of the american line. >> have you taught and lectured outside of illinois or texas? >> yes. >> generally where? >> all around the world. i've lectured in more than 13 different countries around the world, probably vast majority are in the united states. >> how aboutis minnesota? >> i've lectured in minnesota, i've been inli the mayo clinic several times. >> were you given an award for the mayo clinic? >> yes, the lecture in the mayo clinic and give it out to one doctor every ten years it's only one doctor, it doesn't't matter what specialty. it could be neurosurgery,

whatever, it's just one person every ten years. >> was there anything in particular you are recognized for? >> just my work as a researcher in clinical medicine. >> have you published basic science journalists such as journal of applied science? >> yes, i've published a lot of work on base science that wouldn't necessarily be related to medicine. >> the jurors may not be familiar with what physiologist is, could you generally explain it? >> it's basically how the body works, noly science of how it works, a deeper understanding of what really the mechanisms that make the body does what it does. >> within the field of physiology, is there a particular focus for interest you have? >> primarily interested in breathing in the bigger area so

with breathing, that would mean how the brain regulates your breathing, the brain sends signals down to the models that control your reading breathing, rib cage and how you expand your chest and overcome forces within your chest like resistance within your chest and other ways to get air moving and in-and-out of your lungs. the particular forces you generate in terms of pressures within your chest to enable breathing to occur with ultimate purpose of getting oxygen in getting rid of carbong dioxide. >> you consider this a study of that is in? >> is not quite the part of the study of medicine, and separately coast more basic physiology so more in the realm of math and physics but then you slide over because to be a good doctor, you need a good knowledge of science, the

sciencege part is really separae from the medical part and you try to home down on the science as best as possible. >> how long have you p been working in respiratory physiology? >> since 1981, 40 years. >> what drew you to the physiology of breathing? >> because i was going into pulmonary, at that stage, i was already directed spent five years during lung disease and i just wanted to really know how you brief and i wanted to come up with new knowledge because everybody thinks they knew everything about breathing. >> you know others in your field who have been studying respiratory physiology for 46 years? >> no, i know enough along the way but i would know no more

than a handful worthless of people still doing physiology at the patient's bedside. >> change subject and talk about your experience working as an expert. have you been with us before? >> yes, i have. >> what types of cases? >> practically all have been in medical malpractice so both the plaintiff, the patient side and forth the defense, the physician side. >> have you ever been involved in a criminal case before? >> no, never a criminal case. >> have you testified in court before? >> i've testified in court, i don't keep track of the numbers but i suspect about 50 times. >> would you tell ladies and gentlemen if you're getting paid

for your time inhe this case? >> no, i am not getting paid. >> why is that? >> when i was asked to do the case, i thought i might have some knowledge that's helpful to explain how mr. floyd died and since i've never done this type of work, i decided i shouldn't be paid for. >> so did you volunteer in the state of minnesota or to the state of minnesota call you? >> the state of minnesota contacted me. >> what were you asked to do? >> i was asked to review medical records related to theie case, e records from the county and a number of interviews, i've given a long list of these and primarily related to looking at a large number of different videos and the big part was i needed to lead on the scientific

background of all the variance it was related to. >> let's talk about your t opinn in respect to this case. have you formed an opinion for medical certainty on the cost of mr. floyd death? >> i have. >> would you please tell the jury what your opinion is. >> yes, mr. floyd died from low level of oxygen and it caused damage to his brain and pea arrhythmia that caused his heart to stop. >> you mean pulseless electrical activity? >> correct, a particular form of abnormal t2 the heart and arrhythmia. >> is this what some might refer to as asphyxia? >> yes, it has been called

asphyxia. to me, it's not terribly helpful, it's just low level of oxygen. others talk about hypoxia but it's just a latin term meaning low level of oxygen so all of this is just really other words for the snowman that low level of oxygen. >> have you formed an opinion as to what the cause is or was of the low level of oxygen in mr. floyd? >> yes, i have. >> would you tell us what that is? >> the cause of the low level of oxygen was shallow breathing, small breasts. it stopped the air through his lungs down to the essential areas of the long get oxygen into the blood andod get rid of

the carbon dioxide at the bottom of the lung. >> using a short video you prepared would explain to the jury how oxygen gets into the lungs of the body. >> we are looking at the lungs in the body and we see, we can see the windpipe and the bronchial tubes and you can see the diaphragm at the bottom. what contracts, get the hair moving. >> i'm sorry. i apologize. >> received.

>> we will display so the jurors can see it. >> now can see the contraction and diaphragm, the area at the bottom t which is pulling down o the windpipe proceeding down to the bronchialou tubes and it wil continue down the bronchial to and reach out to the air sac and now we are seeing we are moving down here in the gridlike bottom andof the this is where the action occurs the action close across the air sacs and the co2 goes across. let's everything in very rapid video. >> so what happened in the case of mr. floyd that relates to

shallow breathing that resulted in his low oxygen? >> there are a number of forces that led to the size of his breath became so small so a series of forces higher up leading to that and the forces are going to need the shallow breath will be he is prone on the street he has to handcuff, combined with the street and the money on his neck and a knee on his back and side, all of these forces are ultimately going to result in low volume, which gives you shallow breath as we saw here so the air cannot reach air sacs that was on the video where the oxygen is exchanged and carbon dioxide is removed. >> is there a concept respiratory medicine is known as dead space? >> how does that relate.

think of the video back all the way until you saw the blood vessels around below, everything, as you are breathing through your nose, your windpipe, down through your bronchial, grading out to the air sacsti up to the air sacs, it's all dead space because the reason we call it that is because no oxygen can get across the bronchial tubes. no carbon dioxide can get across. the only place that gets across his those structures so everything in the lungs before that. >> you mentioned several reasons for mr. floyd low oxygen and i want to capture that for the jury and then we'll talk about

it. he mentioned the street, right? >> correct. >> you mentioned knee on the neck. >> yes. >> i didn't get an a in school. the prone position? >> yes. >> then the knee on the back, arm inside. talk about each of these but before we do that, might it be helpful in explaining this the jury, to see the relative positioning of the

officers on mr. floyd's body when he was on the ground? >> i think that would be very helpful. >> did you prepare an illustration to show the officers on the ground? >> yes, i did. >> let me show you what's been marked as exhibit 949. could you describe what is? >> i watched the videos and segments hundreds of times, it's difficult to get an overall view of where everybody is positioned because you see different videos from differented angles so it's taken all the different videos here and he combined them into one moment in time you can see here and remove, you get a better view so you are looking at a birds eye view of where mr.

floyd is and where the officers are positioned in relationship to this. >> the purpose is to show relative positions of officers? >> correct. >> exhibit 949. >> any objection? 949 is received. >> so what time have you told u- >> a particular time, i don't remember the exact minute and second at the topct of my head. >> 821 and 44 seconds? >> sounds about right. [background noises]

[background noises] >> let's walk through exhibit 949. tell us what we are seeing. >> you can see the rotation, officer chauvin, officer kueng and officer lane. you see under mr. floyd, rotated and the car has been removed so you are able to see how they are positioned in terms of officer chauvin with his knee on the neck his right knee on mr. floyd's arm and chest and then you can see officer lane holding his legs and you can see officer

talking with his knee on his torso. >> a snapshot in time as you told us, did the officers positions change over time asn they were on the ground? >> yes, the officers positions changed over time and also the position of mr. floyd himself changed over time and these become relevant and how we evaluate everything. >> was it something you factored into your analysis? >> yes. >> did you consider where mr. chauvin's left knee was during the account?e >> yes. for officer chauvin left knee, virtually on thene neck for the vast majority of the time. >> when you say vastnd majority, are you able --

>> more than 93% of the time, there are certain times where it's difficult because you don't get a good view. for example, i know officer chauvin's right knee is on his back 57% of the time. the reason i am not able to say 43% is i don't get a good view. i don't have a good view of exactly where it is. >> did you focus on the first five minutes and few seconds? >> yes, the first five minutes and three seconds because it's up to the time we see evidence of brain injury. >> it to mr. chauvin's rightim knee was on his back time to time and other times it was a place where in your observationt >> on his arm and ran into mr.

floyd's left chest so whether you make a distinction of whether the knee is on the chest or left arm and rand in against the left chest, from the view of breathing, the effects are extremely similar. >> let's turn to number one . i want to turn back, written down for the reasons you told us floyd's low oxygen, handcuffs and the street, talk about the first -- >> yes., >> did you tell us how the

various mechanisms, handcuffs industry, knee on the neck, prone position, knee on the b neck, knee on the back, arm inside, how to the mechanisms fall into your work of respiratory physiology or clinical medicine. >> they don't have an awful lot to do with clinical medicine but directly related to my work in physiology so understanding the forces the body has to cope with, these are crucial in terms of the various forces that are involved in physiology. >> 's attorney to the first one in handcuffs the street, the very first one, what is the effect of the handcuffs and context of what happened to mr. floyd? >> the handcuffs are extremely important, the handcuffs on their own, just handcuffed are

not that important, it must be handcuffs combined with the street because the positioning of the handcuffs at the back and how he is manipulated with the handcuffs by officer chauvin ana officer came, how they minute it the handcuffs and they pushed the handcuffs into his back and push them behind. then on the other side you have the street so the street played a crucial part because he against hard asphalt street so the way they push down on the handcuffs combined with the street, his left side we see that, it's like the left side totally being pushed and f squeezed in from each side from the street at the bottom and then the way handcuffs are many related. it's not just the handcuffs, it's how the handcuffs are being

held and pushed, where they are being pushed that totally interferes with features how we breathe. >> mr. floyd is pancake to between the pavement and forced on top of him. >> precisely. >> could you help us explain how this mechanism, handcuffs and the street, how does that explain shallow breathing you're describing? >> is get back to how we breathe and it's fairly simple. the way we breathe, we have two big muscles that help us with breathing. we have the diaphragm and the rib cage muscles. the c diaphragm is 72% of what e need for breathing and 30% from the rib cage.

our rib cage contracts, expand the chest and when you expand then air flows in from outside coming in, to expand the chest, there's two crucial actions that have to happen and we referred to these by the terms pump handle so simple. if you have a regular bucket to carry water with you lift up the handle, the handle goes up. when you contract your diaphragm, your performing bucket handle movement on the rib cage. you contract your diaphragm and each time as c you inspire, you can see yourt size. you see the rib cage goes out like that, that's the bucket handle. the second movement is called

the pump handle and it reflects the water pump in the yard, pumping out water so you have to handle at the top of the pump in the the handle and the water comes out of the start at the bottom you get your container of water. with that action, you lift up your, this refers to the front to back movement of the chest wall so with the pump handle, your chest goes out with each breath so you can do it yourself, as you take a deep breath, you can see front to back, you expand your chest, front to back expansion of your chest is with your pump handle. the front at the same time, your book doing both at the same time at the same time you do that, your chest is expanding side to side and that's with your bucket

handle so both of these are occurring without these, you can't breathe. if you don't have the t bucket handle pump handle, there is no air that can get in. >> do you have a photograph you help understand the pump handle and bucket handle? let me show you exhibit 951. you recognize what this photograph depicts? >> yes. >> is it an accurate portrayal of a certain incident. >> yes. >> would help to explain the testimony? >> yes. thisla is an event in england. >> i need -- we offer exhibit 951. >> no objection.

[background noises] [background noises]

[background noises] [background noises] >> in this case, were you able to observe whether this includes reading was important handcuffs on street? >> yes. observe?id you >> particularly the internal, and from the police and particularly on the left side, they were forcing his left wrist into his chest, forcing it tight against his chest, high up and

you have to keep in mind the opposite side is on the was squashed between the two sides to this meant he couldn't exist exert his pump handle. it was no way he could do any front to back movement and the way they were present in on the back, there was no way he could do any front to back movement. in addition because of the knee brandon against the left side of the chest, sometimes the knee was down on theow arm or against the chest so this would have the same effect. so basically on the left side of his long, it was almost like a surgical movement, as if the surgeon had gone in removed the long, not quite but along those

lines. virtually very little opportunity for him to get any air to move in to the left side of his chest. he was totally dependent on what to do with the right side. >> have you selected any footage from body worn cameras you feel depicts his struggles to reach? >> yes. >> i'm going to show you>> exhit 944. would you describe what is first?t? >> what you're seeing here -- >> described for the record. >> they will not see this, i am describing what i am seeing? >> yes, for now. >> okay. what i am seeing is his left hand is being grabbed by the police officers, the handcuffs,

left hand pushed into his chest so he's just not able to expand. in addition what i am seeing -- [inaudible] >> i apologize. >> will hold off. >> exhibit 944. >> now the jurors can see you. >> i apologize. >> tell us what the significance is. >> now you are able to see the officer holding mr. floyd left hand, he is holding firmly, a very firm grasp and mr. floyd hand is being pushed in against his chest. we are also able to see on the side that officer chauvin e is coming in and it's against his

side as well so the ability to expand his left side is enormously impaired and also you see the size between the right side and left side is very short so his left arm is also being pulled over so it's preventing him from expanding the right side, focusing on the pump handle on the left and you can see his ability to expand his chest and the key factor here is the street, the street has a huge effect, he's jammed down against the streets of the street plays a major role in preventing him from expanding

his chest. >> thank you. you can clear the c screen. [inaudible] >> did you select the evidence you observe as mr. floyd struggled to breathe? >> yeser. >> going to show you exhibit 942. if you could just identify it. [inaudible] >> thank you, your honor. >> you recognize this is a still image you selected? >> yes. >> we offer exhibit 942. >> no objection. >> 942 is received.

>> could you tell us, what is the significance of this image? >> is slightly different than the two images but they are married together. if you look on the left side,in you see his finger is pushing against the street. you also see the hands of the officers around his left hand, you can see left handcuffs, a more clear view here how it really brandon to the back, there's just no way to expand. with the left image, you see the finger and over on the right image youou see is knuckle agait the tire this doesn't look terribly significant but for physiology, it's a sick nor

extraordinarily significant because it shows he's used up resources and now is literally trying to breathe with his fingers and knuckles because when you begin to brief with the rib cage and diaphragm, next thing is your sternum muscle, the big muscle in your neck. when those are wasted up, then you rely on these muscles like your fingers to stabilize your whole right side, totally dependent on getting air into the right side so he's using his fingers knuckles against the street to crank up the right side of his chest. way to get into the right lung. >> exhibit 938, is this a

related series of photographs and images? >> yes. >> exhibit 938. >> objection. >> received. >> tell us what we see here in exhibit 938. >> the top is the same as the bottom, the bottom is just a buildup of what you u see on the top. the focus on the left side is his shoulder and again, as mentioned, when you haveme difficulty breathing, you begin the diaphragm, rib cage, the very last muscle you use would be your shoulder. you don't really use your shoulder for breathing but if you look here on the f left sid, the shoulder is extremely prominent so this is what people

at the gym would call sculpting of the shoulder muscle and youp see them standing out prominently so at this time on the left-hand side, he is taking a breath and using his shoulder to try to get a breath and and on the right side between the breath where he is relaxing, he's not breathing out and the effect on the left but you have to realize the shoulder is an ineffective way of breathing because at that stage, the chest has expanded so when you contract your shoulder because the chest underline is so expended, it's very little air, it is a poor way of breathing but it is what you have to do when everything else fails. you will call on the use of the shoulder to try to brief.

>> have we covered the first item, handcuffs on the street? >> yes. >> let's talk about number two, the knee on the neck. explainn why the knee on the nek is so significant. >> extremely important because going to occlude the air through the passageway. >> is a probable demonstrate with an anatomy lesson that may be relevant? >> to understand the knee on the neck, you need to examine yourr own neck, all of you like i am doing now. the first thing if you put your index and palm the top of your neck, the first thing you find is your adam's apple you can

find the adam's apple, it's very sturdy archer, it is surrounded by cartilage and it protects the voice box, larynx which is essential for speech. any amount of compression on the adam's apple will not compress this is an extremely strong sturdy structure. then you go down from your adam's apple you feel the bumps these are rings of cartilage of your trachea so this is your windpipe so again, because of the cartilage there and in the on the front would not cause compression but then bring your finger to the top of your adam's apple and at the top, your directly over the hypo pharynx, the crucial area of mr. floyd

neck and that's where the hypo pharynx is located on your service anatomy. >> why is the hypo pharynx from important for understanding this? >> it's very important to understand this for number of reasons because it's so vulnerable, it has no cartilage around it, it's going to be an area compressed, it is extremely small to breathe through and becomes very important to be able to continue to brief. >> i want to show you exhibit 935937. could you identify for the record, tell us -- >> i'm looking at 937 which is

the hypo pharynx. >> the week of -- >> 935, hypo pharynx. >> do these two images fairly andnd accurately depict the hypo pharynx? >> yes. >> exhibit 93535 and 937. >> 935 and 937 are received. >> show them to the jury. using exhibit 937 and 935, could you help us better understand what the hypo bearings is and what it does? >> what you are looking at -- so here where i have drawn in red is the top and above it is an empty space and above that is

the top. then the tongue comes down and the critical structure in this case, the act of speech and mr. floyd becomes important, how he was able to speak and all the so the structure thatso uses speech are the vocal cords here and the voice box and the larynx and when the epiglottis and that comes back to prevent food from going the wrong way. we use the hypo pharynx both for flock swallowing, eating and the hypo bearings for breathing. when we are breathing, the air is going to come into your nose and mouth, through the hypo pharynx and through the vocal cords and the trachea and go down into the lungs where as when you swalwell, the top door

prevents the food going into the air passages directly into the food tube at the back of the esophagus. the area of the hypo pharynx is exactly the base of the epiglottislo down to the second yellow arrow, that area that is the size of the hypo pharynx so we know the cross section of the hypo pharynx, i have here in 199, it's obviously difficult to remember but in the middle would be the size of a dime, basically the size of what the hypo pharynx is and y it tells you hw small and vulnerable the area is

so it's going to be decreased in size, a very tiny area. >> so why is the hypo pharynx important in the case h of mr. floyd? >> the hypo pharynx is going to be the area that's vulnerable to occlusion from the knee on the neck in addition to hypo pharynx has another aspect, the hypo pharynx is controlled by the size of your long, as lungs expand, you increase the size of hypo pharynx with every breath so there's a regulation of breathing going on. >> was mr. chauvin playing pressure. >> at different times, it varied time to time. >> are you able to tell us, if mr. chauvin put his weight

directly, his whole weight on mr. floyd neck, are you able to tell what impact that would have on mr. floyd? >> if officer chauvin placed his knee directly on the hypo pharynx and it never varied from their and it came in like a bull's-eye on that particular area, he would expect the area would be totally occluded but he carried the position, mr. floyd. the position of his head and officer chauvinn also varied the position of his knee so it varied over time. >> if it had become totally occluded, and what? >> within seconds you're going to drop a level of oxygen that would produce oxygen deprivation

resulting in either a seizure or heart attack, one or the other. >> you have another photograph ivand footage of the scene that would help the jury understand? >> yes. >> i'm going to show you exhibit 941. this is exhibit 15 already in evidence. you recognize photograph in 941? >> yes, i do. >> exhibit 941. >> 941 is received. >> tell the ladies and gentlemen of the jury what is you need to convey here inn exhibit 941. >> if you're looking on the left

and you look at me first before you look atst that, stick your finger in your ear, draw a line down from your finger to your spinal column, look at that access, that's what i have drawn here with the yellow dotted line. ... the whole palm of your hand around it.

sorry? >> [inaudible] [sidebar] [sidebar]

these are not required. you may do them in more frames if you were to do them and if you wish to do it, that is your choice. you are not required but feel free to do it if you wish. >> thank you, your honor. doctor tobin, if we could go back to where you were explaining the anatomy on the back of the base of the skull. >> as i'm putting my hand on the back of my neck and feeling the tip of my skull and then bringing down my hand, i feel an extreme ligament and it's almost as i put the palm of my hand on

my ligament it's almost like would. it's a strong ligament and that is what you are seeing. his me is being placed over on the left-hand side and so with the need directly over the nuchal ligament, it can cause no obstruction because this is sod dense and that's what you are seeing. and as well with the yellow diagonal feared that the bulk of officer chauvin's knee is above the yellow line. the second, you can see mr. floyd has his face rammed into the street because he's using his face to try to crank nkup his chest. he's actually using his four head and his nose and his chin as a way of trying to help him

get air into the right side of his chest. >> how do you contrast that to what we see in the photograph on the right and exhibit -- >> the right-hand side you can see now the orientation of mr. floyd has changed, and also you can see the position of officer chauvin's knee has changed, because it's come down below the yellow diagonal, and this position is going to be far greater compression of the hyper pharynx in this region here compared with what you were seeing on the left side. on the left side, there's no compressionn of the hyper pharynx, but on the right side -- and if you watch the videos over time, you will see that there is a variation over time as to where exactly is the location of mr. floyd's head and where is the location of officer chauvin's knee.

>> and then the photograph on the right, the knee is exerting force on the hyper pharynx. is it possible to calculate the amount of force? >> yes, it is. we can calculate the amount based on the weight of officer chauvin on the bodyweight taking into account how much weight he carries and then also you have to remove out the weight of his shin and boot. c >> can you also calculate the changes when narrowing in the space people have to breathe through? >> yes, you can. separately. >> would this be in any way i can to breathing through a small openinghi like a straw?

>> when you have to breathe through a narrow passageway, it's like breathing through a drinking straw that it's worse than that because breathing through a drinking straw at the end is somewhat unpleasant, but not that unpleasant and then it gets worse than that. >> as the space narrows is it more difficult to breathe through? >> enormously, and we know that through physics. >> is that also something that can be calculated? >> yes. >> and that calculation, would it be specific to george floyd? >> in terms of what we know what happens when you have this level of narrowing it is going to happen to everybody. >> can you explain to the jury what those calculations would show about the effect of the narrowing onbof the airway? >> yes.

i believe there's an exhibit. [inaudible] >> any objection.

>> 959 is received. >> let's start with exhibit 948. this is an experiment and what it's looking at is what is the effort to breathe that is what is shown along the y axis of the plot and then it is without differentro levels of narrowing. the bottom one with the white triangle, the lowest curve, there is no narrowing and so we see as it varies and are shown in red is what would be the normal rate in a 46-year-old man. and we can see what is the work that is done. if you look at the normal one and then you look at the 60% airway narrowing and this is more than just breathing through a straw and you can see there's really no bigger increase in the

effort to breathe. it's hardly different from in terms of normal. but then if you get 85% narrowing, now we see the effort increases 7.5 times compared to what it was with no narrowing. so you see a huge increase in the work that is required. it becomes far more difficult to breathe as the narrowing becomes more narrow. >> let's look at exhibit 939. >> so, this is the science behind that lot. and this is the equation in physics that tells you how that works. and the key thing when you look at anhe equation like this for e it means a physiologist is focused on the square side of the structure. that tellsgn me here when the square sign is on top of it and

when it is below the level on the equation and that you're going to be fine all along for a period of time and then suddenly everything is going to increase enormously into what we call an exponential increase and that is exactlyy what we see on the experiment that was done. what we e see is there is really nothing happening at 60 but at 85% it suddenly takes off and if you had beyond 85% it would be even more and more. so, based on the formula here, you can tell that as you are narrowing and narrowing the effort to breathe is going to become extraordinarily high anda unsustainable. you're just not going to be able to do it. >> so in this case, in the caseo of mr. floyd, the narrowing was of his hyper pharynx. >> it was his hyper pharynx,

yes. >> did mr. chauvin's knee because the narrowing of fiber pharynx? >> yes, it did. >> so, given the changes that you observed in mr. chauvin's knee, were those changes significant from the standpoint of placing pressure on the hyper pharynx? >> yes they are extremely significant. >> what's look at exhibit 947. we would offer exhibit 947, which is taken from exhibit 15. >> 947 is received. >> tell us what we see here on

exhibit 947. >> what you see is the orientation of officer chauvin. his body build is quite direct here, but in particular, what you're seeing is that the toe of his boot is no longer touching the ground. this means that all of his body weight is being directed down on mr. floyd's neck, because in many of the calculations i excluded of the affect of his leg and his shoe, because some of it was touching the ground. but here, you can see none of it is touching the ground. so taking half the bodyweight plus the weight of half the gear and all of that is coming directly down on mr. floyd's neck. exhibit 943 did you assist in

preparing this exhibit? >> yes, i did. >> would it help you in explaining your testimony? >> we offer exhibit 943. >> if your honor can clear the screen. thank you. so, doctor tobin, what do we see here in exhibit 943? >> what we see is half of his body weight plus half of his gear is coming down directly on mr. floyd's neck. >> is that all we see? >> the reason we are seeing that is because the toe is off the ground and there is no bodyweight sitting back. he isn't conquering back on his heel, so everything is directed down on his knee.

in this place, his shin and his toe and his boot is playing no contribution. >> and were there times also when mr. chauvin's left knee was on the back of mr. floyd's neck? >> correct. >> and when was that? >> when he's knee is on the back, that is a separate set of force. it's the same force, but compressing different areas, compressing inside his chest. >> and what about the time when mr. floyd would have had his face smashed directly into their pavement? >> when his face is into the pavement at that time, like one of the ones i showed you, if it is coming down on that nuchal ligament, it's going to be a huge weight to try to breathe but he wouldn't be compressing the hyper pharynx at the time that is happening. so all these different forces are somewhat complex in terms of how they are interacting. but they are all coming to the

same point. >> now, you pay particular attention -- you told us the first five minutes and three seconds on the ground. how would you characterize mr. floyd's oxygen levels during the first five minutes and three minutes that mr. chauvin was on top of him? >> we know that his oxygen levels were enough to keep his brain alive, and the reason we know that is because he continued to speak over that time. we know that he made various spoken sounds for four minutes and 51 seconds from the time that the knee is placed on the neck. that's telling us partly that he's speaking, but the big thing it's telling us -- because you can speak without a brain being active, so we know there's oxygen getting to his brain whenever he is making an attempt to speak. >> [inaudible]

>> [sidebar]

anytime in the next ten minutes [inaudible] >> your honor,, this is probably a good time. >> all right. let's take our 20 minute midmorning break. watch live coverage of the trial on c-span2, online on c-span.org or listen live on the c-span radio app. if you must live coverage watch at 8 p.m. on c-span2 and any anytimeon demand@c-span.org congress returns from their holiday recess. next week the senate returns monday, 3 p.m. eastern to continue work on the nomination of the deputy transportation

secretary. the number two post undersecretary pete. senators later begin working on more nominations including wendy sherman to be the deputy secretary of state and gary gensler the chair of the securities and exchange commission. the house is back tuesday for legislative business. this week, members are expected it to work on equal pay for women legislation, as well as a bill to prevent workplace violence against healthcare and social services workers. president biden's infrastructure and jobs package is not expected on the house floor until later in the spring or early summer. watch live coverage of the house on c-span of the senate on c-span2 and follow our congressional coverage anytime on c-span.org or listen on the free c-span radio app.

back now to the trial of former minneapolis police officer derek chauvin. in this portion, the prosecution continued its questioning of long and critical care specialist doctor martin tobin. >> may i have a seat now? >> you may. >> doctor, turning your attention back to exhibit 943. focusing on the restraint on the ground. you are focused on the first five minutes and three seconds, in particular, that mr. chauvint is applying his weight to mr. floyd's neck.

and why was the time period after the first five minutes and three seconds less significant to you? >> because at that point where he extended his leg that we see happening at the point we see that happening at 24:21, that is when he had suffered brain injury. we see, and we can tell from the movement of his leg that the level of oxygen in his brain has caused what we call a seizure typere activity. just medical terms but basically it means that he has kicked out his leg in an extension form that he's t straightened out his leg. that is something we see in patients when they suffer a brain injury as a result of the

low level of oxygen. >> we will talk about that more in a moment, doctor. but is it significant to you whether mr. chauvin moved his knee off of mr. floyd's neck after mr. floyd was unconscious? >> the movement happens around a different time, but obviously, the key thing is everything up to the time that we see the high proxy, the brain injury that's occurring. and where officer chauvin moved his knee after that really is not going to have material impact on the case. >> would you help the ladies and gentlemen of the jury understand that if mr. chauvin is applying pressure on the side of the neck, as we see here in exhibit 943, how does that translate into a narrowing of the hyper pharynx? >> again, it's going to t depend on what is the orientation of

officer chauvin's body, what is the orientation of his leg. and then also in particular what is the orientation of mr. floyd. where exactly is the orientation of mr. floyd's head, because it is his the nuchal ligament underneath officer chauvin's knee, there's going to be very little compression of the hyper pharynx in this region. then if it moves to the side and officerr chauvin's weight is coming down on the side of mr. floyd's neck, then you're going to get huge compression of the hyper pharynx. >> and again, looking at exhibit 943 and focusing on the first five minutes, was his knee overarching on the side door on or onthe back of the neck? >> for the first five minutes, the left knee is on the neck,

virtually all of the time. the right knee, by my calculation, the right knee is on his back 57% of the time. the reason i can't say that it's 100% is because much of the other time i don't get a good scene. the cameras move around. it's the body cameras, so i can't see it. before that period of time, the crucial time, the five minutes and three seconds i can see officer chauvin's knee on his back for over 57% of the time. >> let's talk about the third mechanism of the prone position. would the fact of mr. floyd being placed in the prone position also have an impact on the narrowing of the hyper pharynx? >> yes, facing him on the prone position has several different affects, but particularly it's also causing narrowing of the hyper pharynx among other things

the prone position does. >> is very concept of physiology referred to as lung vitals? >> yes.. >> what does that refer to? >> that is the way that we measure how big is the size of the long in different patients and we quantify out in different areas what level of the lung whether it is different segments behaving in different ways. >> do you have an illustration you brought to help us better understand this concept? >> yes, i have. >> i'm going to show you what is marked as exhibit 929 and have you identify it. >> identifying 929. >> what is it? >> it shows you lung function and the time volume. >> and is it an accurate

illustration of the function and title volume? >> yes, it is. >> your honor, i offer exhibit 929. >> without objection. 929 is received. >> if we could start at the beginning. >> do i go ahead? >> yes, please. >> [inaudible] >> we are getting into that bad habit. if you could ask the question again, mr. blackwell. i forgot. >> thank you. i'm just going to ask you, doctor tobin, if you could explain what we see an exhibit 929. >> we are looking at the lung inside the chest and then we see it inside andhe around it is the pleural space. and we are seeing that as the, you are looking ats the breath going in and out it generates a tide of the volume.

the title volume is shown as aho waveform down at the bottom. and so, that's what happens in somebody with regular breathing. >> let's see if we can get our title volumes to tide. >> here you can see the chest is expanding like on the front we are seeing the pump handlees action and then with each breath, you can see air going into the lungs and that produces the tidal wave. so this is the volume. and then on the exhale it is going back. >> doctor tobin, is there a standard or normal size of breath?r >> yes, there is. virtually all adult people it is about 400 cc is the size of the tidal volume. >> same for men and women? >> same for men and women and

teenagers and grandparents. >> can these volumes be calculated? >> yes, then you can calculate additional further volumes. >> [inaudible] i'm going to show you what is marked as exhibit 939. it's exhibit 930. would you be able to explain -- ei want to offer exhibit 930. any objection?

>> 930 is received. >> these are the lung volumes of mr. floyd when he is on the sidewalk. the key volume we are going to be focusing on is the ee lv. that is the end expiratory lung volume and that becomes crucially important in understanding what happened to mr. floyd. and i calculate out his eelv to be 8,340, and that is what is a shown there. sitting on top of that then is the size i of each breath. when you can't blow anymore out, that is the air that is still left inside your chest is the residual volume.

it is included in the eeo lv. it is everything below that horizontal purple lines. sittingel upright it is 3840. >> we also see on this side -- >> if i could stop you for one second and help us understand better the end expiratory lung volume, the eeo lv, would that be commonly referred to as oxygen reserves? >> that is where the main oxygen stores are in the body and contained with your eelv.re this is where you store your oxygenen reserves. >> so all the air breathed and is not exhale doubt? >> no because the eeo lv is basically the volume that is in

your lung in between each breath. so, when you are breathing out between the next breath what is inr your lung is your eelv. >> and the residual volume, is that also residual oxygen that the body can use? >> yes. so, the oxygen reserves that you have are included in the eelv, and obviously a subset of the eelv is the residual volume. so, all below the tidal volume is your oxygen reserve. >> so then can you explain the calculations for mr. floyd's lungs? >> we see here based on his age, sex and height, we are seeing that his eelv sitting upright is 3,840. and we see the residual volume

is 2,300. >> and the amount he's taking in would be the same as anyone else. a. >> that is the 400, the pink part going up and down, that is the tidal volume and that is the same for everybody. >> and 400 cc. is that cubic centimeters? >> that is cubic centimeters, correct. >> and the oxygen graph is on the side. >> back. >> what does that depict? >> the level of oxygen with anybody varies in age and this is exactly the level of oxygen you would expect in a 46-year-old man. so it is a pao2, that is the level and pressure measured if you were to do and the arterial blood gas where somebody stuck a needle in your wrist, took out a sample of arterial blood, that is the level of oxygen that they would find, 89. that's the unit we used to

describebe levels of oxygen. >> now you told us that mr. floyd, being in the prone position, served to narrow theas hypo pharynx. >> it had multiple affects including those two. >> why is that? >> because the eelv is very important in terms of its where we store the oxygen and as well as that it has an affect on the upper airwaves. so when you breathe in, you don't notice it as you're expanding your lungs you are aware of expanding your lungs, but at the same time, the size of your hypopharynx also widens out because of the forces that occur between it. it is just part of normal breathing that as you inhale, you expand your lungs, but you also expand that little area that you have that the air has to go down through, so that is

influenced by the size of the eelv. likewise, when the eelv gets less, then the size of the opening of the hyper pharynx -- hypopharynx would get less. it's going to come down as your eelv goes down. >> did you also calculate the reduction and the lung volume for mr. floyd in the prone position? >> yes, i did. >> i show doctor tobin exhibit 927. >> doctor, is exhibit 927 a calculation that i am referring to? >> yes. >> your honor, i will offer exhibit 927.

>> 927 is received. doctor tobin, tell us what we are seeing an exhibit 927 as it relates to mr. floyd in the prone position. >> you see the drop in volume. it's more than the placed face down. and so, you're getting a decrease in the volume and that is occurring because in part say you are flat on the bed with your face into your pillow if you are lying prone to face down. you will no longer be able to use your actions so your lungs are going to get smaller and you will have greater difficulty in using the handle actions less so than the pump. as you lay face down, your belly

is going to rise up into your chest. so the lungs gets smaller and that is what we see here. anybody that is turned prone may see that the lung volumes on average go down by about 24% by simply turning them prone. with that when you get the smaller volumes you get less reserves and it will also affect the hypopharynx. >> so if the lung size goes doww 24%, do the oxygen stores alsore go down 24? >> the oxygen stores would go down as well. once you have less volume inside of your lung, your oxygen t reserves are going to go down proportionately. >> is absolutely 24%? >> no, i mean, its physiology. the way we look at things is what is the average change that happens when we do experiments. but in biology, there's always a

certain amount of biological variation. and so,l there's always going to be something like a two to 4%e variation that you're going to figure out in these numbers. but when we speak about something, we speak in terms of the outreach change that is occurring. >> so, is the 24% reduction significant in the case of mr. floyd? >> it's extremely important because of the factors that we are dealing with. the reduction just from the prone. we are also affecting the size of the opening of the hypopharynx because it goes down and you are getting a proportional reduction into the size of that r and in addition s the work of breathing goes up.

the hypopharynx is linked to the size of the lung? >> yes. >> help us understand is it true a person suffering from covid or actually treated in the prone position. >> absolutely. any patient dealing particularly with covid that we see it in any patient with pneumonia. when you turn them prone if they have pneumonia they have bad matching between the lung vessels going through the lungs and the air sacs. we saw at the beginning all tthose blood vessels around the

botch of grapes. in people that have pneumonia, covid, whatever, that matching is going to be very bad, and that is what leads to the worse oxygenation in those patients. if you flip those patients prone, some of them would show no improvement, but a substantial number of them, the matching will get better between the blood vessels and the air sacs. until you turn the person prone you don't know which ones are going to do better that some of them do. so, this is why prone has been very valuable. in patients with covid but that is with people with pneumonia. this doesn't apply to people witheo normal lungs. >> doctor tobin, a lot of people also sleep in the prone position. is that dangerous? >> no. because again, for the average person you have so much

reserves. so 24% for you is not going to have h any impact because you he a huge amount of reserve. it's not going to matter. but if you have somebody that drops the lung volume by 24% and then that person is going to have to cope with a knee on their neck andnd then have to ce with having arms pushed up and being unable to move, then it is a whole different kettle of fish. >> thank you, doctor. so, the third mechanism, the prone position. >> yes. >> now let's talk about the fourth one. knee on the back, arms or side. >> yes.

>> if we bring to mind mr. chauvin's right knee on mr. floyd's back or left side -- forget that question. does it matter whether the right knee was on mr. floyd's back or left arm over his side? >> it really amounts to the same because again we are talking [inaudible] whether it is on the back, around, against the side, down on the arm, all of these are just going to impair your ability to be able to move your chest. you just can't do it. it's all ramped in. all the whole time in this case you have to constantly keep in mind that this is taking place on the street. it's playing a huge part because it is coming in at the front and totally preventing every action

happening. >> did that influence mr. floyd's oxygen stores or reserves, the eelv? >> yes, they are going down as a result. you see the same decrease in the oxygen stores. >> were you able to calculate what those stores were? >> i want to show exhibit 932. >> and ask you, doctor tobin, does this reflect the calculations that you did? >> now you see with the affect -- [inaudible] >> i offer exhibit 932. >> 932 is received. >> now please tell us what we see on 932. >> what you see now is it is no longer just prone.

now you have the knee on the back in addition, or on the side. so this is going to further compress down the eelv. you can see that it's now really been squashed down. so it's by the combination of turning him prone, and also having the knee on the back. you are seeing a 43% reduction in the eelv, which means that is also a 43% reduction in his oxygen reserves, which means there is also a huge reduction in the size of the hypopharynx, because this is directly linked to the hypopharynx, and you will see how this is linked. so when you decrease the size of the eelv, that's going to cause it. g andd then an additional affect s that your work of breathing goes

up, because when you are turned prone, and with the knee on the back, now the work that mr. floyd has to perform becomes huge, because he has to -- with each breath, he has to try to fight against theag street. he has to try to fight with the small volumes that he has, and then he has to try to lift up the officers knee with each breath. and also remember, he has to also try to lift up in the other officer pumping at his arm with a hand left arm they are pushing it into his chest so they have to make all these efforts to try to breathe against that. >> when you tell us about a 43% reduction, 24% of that is just being in the prone position? >> correct. >> the other 19% is the contribution of the knee on the neck. >> exactly. the other 19% -- 24% from being prone, the other 19% coming from

the knee on the back. >> just so we are clear for the jury, how does this again translate into difficulty in breathing?n >> so again, i did calculations of this, and basically you're looking at more than a threefold increase in the work of breathing. in terms of just from the affect of nothing else that's even leaving out the affect of the knee on the neck. just from looking at what is happening within the chest. so, there's a huge increase in the work that mr. floyd was performing just to try to cope with what was happening below the neck, leaving aside what was happening above. >> doctor, i want to show you exhibit 922 through 926. and after you have a chance to see them, i want you first just to identify just what you are seeing in those before we show it to the jury. >> yes, i've identified.

>> tell us please what it is for the record. >> we are looking at the affect of the lungs on the hypopharynx, beginning with mr. floyd is sitting on the sidewalk. >> your honor, we offer exhibits 922 through 926. >> [inaudible] >> 922 through 926 are receivedi >> so, doctor if you will walk us through these to help us understand the narrowing of the hypopharynx in the case of

mr. floyd. >> before you look at the hypopharynx, just look down at the lungs and you will see that the lungs as you would expect our expanding with each breath. you see the diaphragm going down. youck can see the pump handle action. the lungs are getting bigger front to back. but then he that exactly as the lungs are expanding, if you focus on the yellow box there, the yellow box area is enlarged over on the right side, and you can see that as the size is also. you are seeing both ofs these happening. so it is the affect of the volume and how it influences the opening of the hypopharynx. and this is sitting on the sidewalk. >> looking at exhibit 922. what do we see now in the prone position? >> now we see mr. floyd after

he's turned prone and we can see the lungs are smaller than they were, because they fall we know when you turned prone to. and then you also see now that the area, the hypopharynx is further narrowed because the lungs, as they get smaller, they have less affect in keeping that open. so that gets smaller. >> and then we have the knee on the back and now we see with the knee on the back, the lungs become b further reduced like i showed you for the precise calculations of the volumes. and now you see here the size of the hypopharynx further shrunk in as a result of it, so the opening to the hypopharynx is impacted by the knee on the back. >> and if we compare them altogether, all three? >> so here you are seeing them altogether.

on thee left is sitting on the sidewalk. then just the affect of prone and then the affect of prone with the back compression. you can see the arrow is pointing out on the first one, whereas the hypopharynx, that right area you can see that it's expanding when he's sitting down. and then when he's prone with the back compression, you see that the area of expansion is getting smaller as exactly you would expect to happen. >> going back to the lung volume he didn't have enough stores to remain conscious.

when was that? >> the time in terms of the loss of consciousness was 24:53. we can tell it precisely in terms of where the consciousness occurred. this is something as an icu doctor you can tell how conscious somebody is. and we can tell by how you move the muscles in your face, and that you will be able to tell is the person conscious or unconscious. it is a very important sign in patients as we are taking care of them, to be able to monitor that as a primary way that we monitor it is by inspecting it. so, i would have done this millions of times. >> do you know, doctor tobin, but the oxygen level would have been if he went unconscious? >> we know that at the time if

you have somebody that is in the situation who's at risk of trouble with oxygen, the moment that you lose consciousness, the level of oxygen in your blood would be 36. that is the number associated based on very hard scientific [inaudible] >> and the normal level of oxygen was? >> was 89, in a 46-year-old you would expect the normal level is 89. the level at which you would have an absence of consciousness would be 36. >> doctor, i want to show you exhibit 928. if we could clear the screen, your honor. first for the record, can you

identify what is exhibit 928? >> we are looking at the effects on mr. floyd's oxygen as a result of all of the various maneuvers that are being done to him. >> i offer exhibits 928. >> 928 is received. >> tell us what do we see here in exhibit 928? >> we are looking at the level of oxygen when i saw it it began with 89 and then we see that it falls down to 36. the slide is looking a bit different than what i saw before. so heree you see the level of oxygen before hand is 89 and then at the point when we notice the lack of consciousness in his face, the level of oxygen will

drop down to 36. so that tells the loss of consciousness. and then we know that it continues from there, from the time he stops breathing which is 20:25:16 and then i calculated out from then you can calculate based on, again, very rigorous science when the oxygen would have gone down to zero. but this first one we are looking at, the level of the loss of consciousness and that is happening at 20:24:53 and we are able to tell that by looking at his face. >> 20:24:53 is 8:24 p.m. and 53 seconds. >> correct.

>> was there a point in time that he no longer had any oxygen left in his body? >> yes because once again, when he stops breathing at 25:16, it will taken another 25 seconds fr the level of oxygen to go down to zero. at that point he wouldn't have an ounce of oxygen left in his entire body. >> i want to show in exhibit 931. and ask first if you would just tell us what it takes before we show it to the jury. >> what do we see in 931? >> what we see is the level of oxygen has gone all the way down to zero. >> so, we are going to show this to the jury but first let me show exhibit 931.

>> now doctor tobin, can you show us what we see in exhibit 9 931? >> the level of oxygen has gone down to zero that at that point there isn't an ounce of oxygen left in his body and again this is totally you can figure this out with very precise science looking at when somebody stops breathing what will be the rate of decline and how long it will take to reach zero. so, we see here that he reaches a level of zero for oxygen at 20:25:41. at that point, there is not an ounce of oxygen left in his entire body at 20:25:41. >> was the knee lifted off his neck at the point there was no oxygen left in his body? >> it remained on his mac for nr

another three minutes and two seconds after we reached the point there wasn't an ounce of oxygen left in the body. >> thank you, doctor. are you aware of studies suggesting that putting somebody in the prone position and putting weight on the back [inaudible] >> i'm aware of the studies. they largely come out from the group of colleagues. >> are you able to generally characterize the nature of the studies for the jury? >> the bottom line is they are highly misleading. >> are they relevant to the analysis you have just given tol the jury this morning? >> they are not relevant to the analysis this morning. >> the problem is in these particular studies it could be

close to ten of them. first of all they take perfectly healthy volunteers and bring them into the physiology lab and put a mask underneath. then they put weight on top of them and many of them i they use the barbells that you see inha a gym like an olympic wheel that you would see for weightlifting and they placed those on the back of the subjects and they measure various volumes. typically they will measure the capacity. these are specific types of tests you don't need to bother with. but they show a decrease in the abilityd around 35%. that is a substantial decrease in d your volume that you're

finding. and then they conclude virtually all of the studies. that level of decrease doesn't matter because there is no change in the level of oxygen. so therefore it isn't relevant. the problem is in doing a study like that, oxygen is the wrong yardstick to be using in a study like this. what they needed to do is continue to measure out the changes in volume like the eeoc, showing what happens to this. it will only fall at the very end. it is an extremely insensitive measure. it's verys insensitive to know f stuff is going bad inside the body. it's going to be a very late event and so for the concluding of this. >> any other questions?

>> [inaudible] to help us better understand, are these studies measuring the asdecrease in the oxygen reserv? >> no, they are not. i want to show you what is marked as exhibit 948. >> exhibit 948 does it point to one of the studies that you were referring to? >> yes it does. >> would it be helpful to use this to explain in the testimony? >> yes, it would. >> your honor, we would offer exhibit 948. a. >> without objection. >> 948 is received. >> looking at this slide, what does this tell us in terms of,

for example, the service area that is involved on the weight on the back? >> if you look at the subjects back you can see that there are four weights placed on the back of the subject and the big wheel late on an olympic plate is going to have a diameter of 17.n measure the cross section of air is going tocr be 240 square inches. the trouble is that when officers kneel on the back of a suspect, they don't have an olympic wheel on their back. the cross section area is 24 square inches which is one tenth of the area that you are looking at here, so we know from simple physics that pressure is forced over the area so that is 240 divided by 24. that tells you that the pressure

being exerted on the back is ten times more than what the san diego people are training. they are off by a factor of ten. >> so it is ten times greater is what you're saying. >> do any of these studies involving the knee on the neck? >> nobody has done any studies involving a knee on the neck. i suspect you would have major trouble getting that through the ethics committee and the medical school. >> studies go on for nineal minutes and 29 seconds? >> no. they are all very brief studies. >> so, have we now covered the four mechanisms that resulted in the shallow breathing and reduction of the hypopharynx? >> yes, we have.

were you or are you aware mr. floyd had pre-existing health conditions? >> yes, i am. >> how were you aware of that? >> i read parts from the county and i also saw them mentioned in the i autopsy. .. >> a type of the tumor fair in

the pay regularly a. >> is appear again, significant to you? >> no. >> one of the key things it is a 10 percent tumor which means those that secrete adrenaline could be important but 90 percent do not secrete. so nine out of ten times with that. ganglia, there is no increase. >> if somebody were to die from a tumor from the effect of a death would it be sudden? >> yes six reported cases of people whode had these that died suddenly and those that have died have headaches. he complained of a lot of

different pains and regions but not of headaches. >> in terms of reported cases where people have died from paraganglioma all over the world there were six cases. >> . >> did mr. floyd die a sudden-death? >> no. >> we'll talk about a different subject the jurors may have heard one of the officers say if you can speak you can breathe. is that a true statement? >> it is a true statement but the enormous false sense of security. shirley at the moment you are speaking you are breathing but it doesn't tell you you will be breathing five seconds later. blackwell: tell me why this is

significant. >> s for speaking you only speak when you exhale. you have to blow air out and then you vibrate the vocal cordss that's all there is to speech. going across the vocal cords that vibrate and then you speak. but to speak, there are two things that are important. you cannot blow air out if you can take a breath in before hand you have to have inspiration into speak. second you cannot speak if your brain is not alert. so when you see somebody speaking you know they have an inspiration before they are speaking and there is oxygen going to the brain at the time

they are speaking. blackwell: was the time of one - - his speech important to the timing? >> yes. for the time he is speaking and he continues to speak for minutes, 51 seconds from the time they need is placed on the neck. there could not be complete compression. because he is continuing to speak for minutes, 51 seconds. blackwell: doctor tolman is the brain sensitive to oxygen deprivation? >> the brain is the most sensitive to needing oxygen. blackwell: what percentage

does it consume? >> the brain is relatively small. it's only 2 percent of our body weight. but it takes in 20 percent of all the oxygen we are taking in. the brain eats oxygen at ten times the normal level. it sends outds millions of nerve signals every second. so it needs a high supply of oxygen. blackwell: how long can it go without oxygen? >> if you stop the flow of oxygen to the brain you lose consciousness and eight seconds. blackwell: you might recall mr. floyd's last words. i can't breathe.

are those significant to you as a pulmonologist? >> yes. very important in different ways. one is complaining of difficulty with reading but they are also telling me at that time he says please come i can't breathe, we know at that point he has oxygen in his brain. but again it's a perfect example of how it gives you a false sense of security because shortly after that we will see has a major loss of oxygen. so it tells you how dangerous is the concept if he can breathe or speak that he can breathe. yes that is true. on the surface but highly misleading. very very dangerous mantra. blackwell: if i hear you correctly when he says i cannot breathe that shows that his brain is alert.

but immediately thereafter his brain was not. >> correct. blackwell: is there anything in the video you can show the jurors that they can see that would point to the fact his brain was no longer alert? >> yes. blackwell: exhibit number 47 already in evidence. twenty, 24. - - 2024. i will play a clip for you doctor tobin and tell me what you see. >> the key finding that you see here when you see his leg going up. keep in mind hes is prone. he is facing down the leg is coming up backwards.

so that is the extension movement of the leg. that is something we see when somebody suffers major brain lack of oxygen sometimes it is called a hypoxic seizure. there are different terms that are used. but really it amounts to say what you see here is fatal injury to the brain from a lack of oxygen. >> sometimes anoxic seizure. >> all different words there'she a lot of different words that are used. they all come down to the same thing. that at that point the brain is responding to the drastically low level of oxygen that is present.

blackwell: does the anoxic seizure indicates damage to the brain? >> severe damage too the brain. blackwell: the reflex we saw with the legs coming up is that involuntary reaction? >> involuntary. there is a lot of different medical terms that we apply to it. the bottom line is that the leg jumps up like that as a result of the fatally low level of oxygen going to the brain. blackwell: we talked about the brain injury. he told us earlier of the low levels of oxygen have post lists oxygen activity. >> with a low level of oxygen i will show up in the brain and also in the heart. when it shows up in the heart

it will cause the heart to beat abnormally and in a particular way that it happened with mr. floyd was that he developed a particular arrhythmia called pea where we see electricity in the heart not resulting in any mechanical force. pulseless electrical activity. that is why it has that name. the low level of oxygen is producing both. we don't see the pea arrhythmia intel that shows up on the ekg so it is much later we see the evidence in terms of display. but here we see the huge evidence in terms of the leg. the leg is crucial. this isim the time, the first time you see there is major

league oxygen damage. blackwell: so where mr. floyd cannot speak due to low oxygen was there a correlation on - - correlation to thepe narrowing of the airways? >> yes. blackwell: exhibit 934, 936. tell us what are these images? >> s again the same mri but a different view that we looked at before. >> . blackwell: tell us what we see

here. >> this is the same mri that you saw before. the yellow area points to the vocal cords. you must inhale intake air into your lungs and then when you let it out he will vibrate those vocal cords and that makes a sound to speech. >> here we see the signs of the windpipe, the trachea because this becomes important because of speech. our knowledge of the influence of the size of the trachea, the windpipe is from patients have the tracheal

tube in place. and develop scarring after that. as a result we know what is the point out how much scarring in your windpipe would prevent you from speaking. these are just that this is the size of the normal trachea it is between a quarter and a dime in terms of the diameter. and when those coins have been shrunk at 50 percent. even when the trachea has narrowed all the way down at 15 percent you can still speak. even when the whole through your windpipe where i shrunk the size of the coins, you can still speak. it tells you how dangerous it is to think if you can speak he is doing okay. because at this point you can speak.

but again, there is a small increase of the amount of narrowing here, not only will you not be able to speak, you can't breathe, you can't live. it's a very dangerous thing to think because you can speak you are doing okay. blackwell: you're unable to speak or breathe or live once the airway narrows below 15 percent? >> correct. 15 percent you can still speak but as it gets lower from that, it is startling then at a some stage you cannot do anything. blackwell: exhibit 940. >> this is the same experiment i showed you before. it just so happens it is the 85 percent you are looking at the top curve that's the same

number we showed you on the mri. if you can see here. once you are at 85 percent it is seven.five increase. and then the narrowing gets further and further. than their work becomes unbearable. it just emphasizes at the point where you can speak and you are in deep trouble.

blackwell: doctor i wouldor like to transition from talking about the physiology of breathing, to talk about your work as a clinician taking care of patients with respiratory troubles. does that experience factor and hear your opinion also? >> yes. blackwell: did you do anything to try to understand mr. floyd's actual rate of breathing? >> yes i did. blackwell: why was that important? >> a major part of my work as a lung specialist is looking at people's breathing. you get a lot of information by looking at how they breathe how they use their chest wall. this is extremely informative forgot the lowest level the simplest thing to do is to simply count how many breasts somebody takes in like with blood pressure and the respiratory rate that gives a lot of clues to what is happening inside the body. blackwell: is is something you have done before? >> millions of times. blackwell. >> medical students and nurses.

blackwell: you are counting the breath the observe the muscles? >> separately you look at w the different muscles whether the sternum you are looking at all of this was somebody as old as me i can see all this very rapidly. blackwell: did you take this clinical experience and apply it to mr. floyd's video? >> yes i did. blackwell: could you take measurements on video evidence? >> yes there is. blackwell: exhibit 43 already in evidence. i want to play this and afterward tell us what we are seeing. >> if you focus the handcuff

that is the best place to see and you can count out those rates then another. so we need to play it back so to focus down there. >> we will play it once more so we can see what you are referring to. >> one, two, three, four, five, si.

blackwell: that was a 172nd clips. >> between seven and eight. blackwell: did uses to calculate the rate of respiration? >> it is simple once you have 19 seconds you count the number of breaths you have. you count seven breaths that would come out a rate of 22 respiratory rate. blackwell: is that number significant in this case? >> it is extremely significant because one of the things in this case is a question of fentanyl if it is causing depression than that will have a decrease in the respiratory rate and is shown with fentanyl you expect a

40 percent reduction in the respiratory rate. so with fentanyl the rate should be down at around ten instead it is rate in the middle of normal at 22. blackwell: you did not see a depressed rate of respiration in mr. floyd. >> it is normal. blackwell: so what does that tell you bottom line fentanyl? >> in terms of fentanyl one of the major changes you see is the slowing of the respiratory rate. again, we would be expecting a 40 percent reduction with fentanyl. the normal respiratory rate is 17 best per minute plus or minus five. that means a normal rate between 12 and 22. that is the normal range of

respiratory rate. so with fentanyl you would expect a respiratory rate of ten. which you counted hear yourself the respiratory rate is 22. so basically it tells you there is not fentanyl that is affecting his respiratory rates what is not having an effect. blackwell: mr. floyd respiratory rate was normal at 22 just before he lost consciousness. >> correct. blackwell: the jury may have heard other information in the case about the fentanyl related to an elevated carbon dioxide level in the emergency room. was at significant to you? >> yes that is very significant as well. because he i is reported a

carbon dioxide level in the emergency room of 89. that's a very high level of carbon oxide. you have to take into account the factors that might w have led to that. the particularly important factors for mr. floyd to explain why his carbon dioxide was found at 89 in the emergency room. blackwell: doctor, what normal would has been carbon dioxide level? >> in you or me is between 35 and 45. there are units that are given in the hospital chart. blackwell: you said there were significant factors in the case of mr. floyd. help the jury understand whatth those are. >> the important factors are

we know he made his own last spontaneous effort to breathe at 2025, 16. after that, if you look at the videos he makes no effort. no breath. the last breath he took was at 2025, 16. then we know after that he stayed on the street for another three minutes and then he is placed into the ambulance and we know when the ambulance they attempted to put inn the airway. you can see that on officer lanes body camera. you can see that happening. then you can see the time at which they successfully inserted the airway and when they gave him the first breath. that is a gap of nine minutes, 50 seconds from when he last took a breath.

blackwell: why is that significant? >> because we can calculate the rate of increaseom of the carbon dioxide in somebody who doesn't breathe. if somebody doesn't take a breath, carbon dioxide increases at a a predictable rate. that rate is up four.nine parts of mercury for a minute. so he has not taken a breath for nine minutes 50 seconds. see you would expect, just on the basis that his carbon dioxide level so you add 49 to the normal values between 35 and 45 so you will get a value

between 89 and above. it comes virtually identical on - - identical to the value they found in the emergency room of 89. blackwell: what is the punchline? what does that tell us? >> the significant is it the second reason why you know fentanyl is not causing the depression of his respiration. you see the increase in his carbon dioxide, found in the emergencyy room is solely explained by what you expect to happen in somebody that doesn't have anything for nine minutes and 50 seconds. that is completely explained by that. blackwell: when a person is not breathing carbon dioxidet' would continue to build up in the body. >> yes. blackwell: that matches in? the or and mr. floyd. >> precisely. blackwell: you said there were

other things that were related to the rate of respiration. we talked about fentanyl. snything else? >> yes. two other things that are very important to the respiratory rate. exactly his respiratory rate. if you have somebody with underlying heart disease. it is so severe that it is said it causes shortness of breath, causes difficulty with breathing, but virtually all of those patients would have very high respiratory rates. they would have a respiratory rate over 30 or even 40 if you have heart disease. instead we find the respiratory rate is normal at 22. >> the second thing that is

important, about the respiratory rate of 22 if you have somebody the primary problem in the body is airway narrowing, the airways are being compressed, there is narrowing in the neck are in the chest. what the response, the physiological response is a normal respiratory rate. that is what he has. the respiratory rate that he sees is normall is the expected physiological response with somebody who has airway narrowing. blackwell: so we covered the mechanisms of how low oxygen occurs. as a clinician did you observe low oxygen in a video of the

last minute of george floyd's life? what did you observe? >> in terms of what we are seeing is the changes of his facial appearance becomes crucially important. to see the effects of the low oxygen. blackwell: have you seen this in other patients? >> yes i work in the ico where 40 percent of the patients die. i'mex extremely familiar seeing people die unfortunately. when you seee these changes, you see the changes in the face. that is the key way of noticing something by looking at the effects on the face. blackwell: exhibit number 15.

i want to play a clip and have you tell us what it shows. >> at the beginning you can see he is conscious. then it disappears. one second he is alive. one second he is no longer. blackwell: that went pretty fast. can we do that again so the jurors can see that? one second. 2024, 53 in the composite.

>> the speed is slow down by one third. you can see his eyes. he is conscious. then you can see he isn't. that is the moment the life goes out of his body. blackwell: i will show you a clip from another body worn camera. exhibit 43. 2022, 22. blackwell: i want to play this for you and tell us what this

informs us. >> no he is on his right side. he is moving his hip to get air. you can see him again pushing down on the street to get air in. there is movement of his hip. but he has to use his entire spine just try to get air into the right side of the body. keep in mind the left side is nonfunctional the way he is pushed into the street. he is cracking up the right side of his body. you can see it right there to get some air into the right side ofre his chest. he is make it one - - making repeated movements again with

the hips because he is using hisir spine. he is using those muscles to move air into the right side of his chest. again he tries to use his right arm and is unable because of the chain linking it to the left side. he's trying to push that right arm down into the street but he can't because of the handcuffs. blackwell: at what point mr. floyd stopped speaking what does that tell us about his oxygen supply? >> where he is not speaking it tells us the airway narrowing in his upper airway is more than 85 percent. it is separate in terms of the oxygen level. that we can see by the face. so once we see how much narrowing there is but they are all coming in together.

blackwell: did the restraint stop? at the time of the brain injury and the pea arrhythmia? >> know the restraints continued with the cessation when he cannot take a breath then he remains on the neck for another three minutes 27 secondss after he takes his last breath. then he remains. there is no pulse then he remains on the neck for another two minutes 44bu seconds after the officersth have found themselves no pulse then he remains on the another two minutes 44 seconds. blackwell: no further questions.

>> we will take the lunch break until 1:30 p.m. underneat-

>> >> as a a reminder you are still under oath.

>> good afternoon doctor tobin. i will take a set. cheers we are in ireland. [laughter] i just want to review a few things with you. i don't think we will take too long. you are ultimately approached by the state of minnesota to assist them in the review of the medical issues in this case. >> correct. nelson: you volunteered to do this work at no cost. >> correct. nelson: normally you are not involved in criminal cases of this nature. >> correct. nelson: this the first time you've been involved in a criminal case. >> correct. nelson: for that reason you decided not to charge a fee. >> correct. nelson: other cases what fee

do you charge? >> i charge per hour. my hourly rate 500 per hour. nelson: you a grade to waive your hourly weight. - - rate. no in preparation for the testimony today you met with the state numerous times. >> correct. >> you have the opportunity to review all of the medical information obtained in this case. that would include mr. floyd's previous medical history, the autopsy and the toxicology reports prepared in this case. >> yes. nelson: as well as investigative materials and police reports. >> correct. nelson: correct me if i am wrong you are not a pathologist. >> correct. nelson: your specialty is

pulmonology, critical care. >> correct. nelson: you also have an interest and impressive resume to applied physiology as well. >> you have been honored quite extensively for your work in that regard. correct. nelson: you're not a minneapolis police officer. >> correct. nelson: the training provided by the mpd in terms of medical care comes nowhere close to your level of expertise. >> correct. nelson: you understand minneapolis police officers are not even emt. >> correct. nelson: they have a basic lifesaving certificate with tourniquets inn cpr and gunshots. >> yes.

>> you also have the opportunity to review the body camera footage. correct? >> i thank youed testified you have watch these videos hundreds of times. >> correct. >> and from all different angles. >> correct. >> you have the luxury of slowing things down going into slow-motion at various times. so your analysis of this case comes after hundreds if not thousands of hours of time spent looking at this information. >> so you prepare a report and you provide that to the state of minnesota january of this year. >> generate 27. after that you have numerous meetings with the prosecution team in this case. >> by zoom. >> including january 30 of

this year? >> i don't know the date but that sounds correct. >> ifch i told you the date was january 30th, march 3rd, mar chl 7, he would not have any reason to dispute you? >> no reason. nelson: you understand notes are made of the meetings to provide to the defense. >> i understand. >> you could spend a substantial amount of time preparing the exhibits the jury could see earlier today. >> correct. nelson: those were prepared by you are somebody in your team. >> prepared by me. nelson: you provided those to the prosecution in advance of today's testimony. >> correct. >> those were provided to me last night. >> i have no idea when. nelson: you had a lot of time to prepare both yourself and the prosecution team in connection with this case. fair to say? >> correct.

nelson: you talked a lot about physics in your direct testimony. >> yes. nelson: you would agree that physics, or the application of physical forces is a constantly changing set of circumstances. would you agree if you look at the concept of physics, these are constantly changing. >> all the time. >> constant in milliseconds and nanoseconds. so if i put this much weight all the formulas and variations will change from second to second, millisecond to nanosecond. >> i agree. similarly biology works the same way. >> my heartbeats, my lungs brief, my brain is sending millions of signals to my body at all times.

>> correct. >> faster than the e speed of light. >> millions of signals every nanosecond. >> yes. in your report you even discuss when you talk about these instances, the physics or the biology, what you are really talking about is a single nanosecond there are working in concert at all times. >> the way we calculate this , it is into one instant. >> you have taken this case and literally boiled it down to one nanosecond. >> i would not say that. obviously in my report as you can see it is sequential there's a whole chronology beginning at the time than he is placed on the neck and

until what is happening through the er. nelson: so talk about sequential nature but when we talk about the biology and physics. they are working simultaneously, contemporaneousy altogether. in the incredibly rapid fashion. >> yes. nelson: you would agree with me that as this incident was occurring, there was nobody measuring the units of force placed with any particular position of any particular person at any particular moment. >> there was nobody there measuring at the time. i agree but it is all calculable. nelson: when you calculate them what you have to do is boil it down to the mean or

the average. >> correct if we look at the concept of the average they are things happening before or after. >> yes. nelson: forces will increase or decrease relativend to the nanosecond of time. >> yes and ultimately when we talk about the biology of things the pathologist will look at the intersection of all the things that occur in a particular death investigation. >> it has nothing to do with physiology. >> but they are also looking at how other factors may contribute to the death of an individual. >> yes, partly. nelson: looking beyond the

nanosecond. agreed? >> no. i think in terms of a pathologist they are looking at the nanosecond of death. nelson: but taking into consideration simply what extends beyond physiology. >> they are looking primarily at the pathology. nelson: what causes the heart to stop where what stops the lungs to function. >> they are making the inference based on the pathological time point. nelson: a multitude of biological factors involved in the death of a person. >> any physician is looking at a multitude of factors.

nelson: in terms of your review, you would agree that the amount of time that you spent looking at videos and analyzing the's videos from perspectives and angles is far greater in this incident. >> probably times 1000. >> it is substantially. >> ultimately you conclude mr. floyd died a hypoxic death. >> low level of oxygen. nelson: low level of oxygen causing damage to the brain which resulted in the pulseless electrical activity. >> not quite. he had a low level of oxygen causing damage to the brain. the brain did not cause the dea the low level of oxygen

caused the damage to the brain usit separately called the pea. nelson: so an example how multiple processes are occurring simultaneously. >> not really. one process low level of oxygen. nelson: it has an effect on the heart and the brain and the lungs. >> it is just to. the brain and the heart. nelson. nelson: the new goal ligament? is that correct? that space at the back of the neck that is very very hard. >> roughly the palm of your hand at the back of your neck. nelson: a very hard surface

could withstand a great amount ofof pressure. talk about the placement of the knee there are periods of time when mr. chauvin was placed on that ligament. >> yes. nelson: you had an opportunity to review the autopsy. >> yes. nelson: there was no bruising either on top the skinner under the skin surfaces noted by doctor baker. >> i am aware. nelson: you talked about the hypopharynx you are aware it is photographed and no injury was noted. >> i am aware. nelson: i find it very interesting in your testimony akand in your report when you

talk about the notion if you can speak that doesn't mean you can breathe. i'm so sorry. if you can speak you can breathe. you describe this is a very dangerous proposition. you describe this as causing a false sense of security to people. >> yes. nelson: you actually write a paragraph how physicians oftentimes have trouble with it. >> yes. nelson: so people similar to yourself in medical school. >> yes. nelson: intelligent men and women graduating from college going on to medical school are engaged in the practice of medicine.

sometimes have problems with this notion. >> an patient comes in and they say they have trouble breathing. often times a physician will not believe them, essentially. >> it's important mr. nelson we are talking about speech or difficulty in breathing? they are different. nelson: when they say they are hysterical. >> may i approach, your honor. >> it is hearsay. >> overruled. nelson: some doctors incorrectly consider patients hysterical and they arelt imaginary in nature which for early on - - further aggravates patient distress.

>> yes. nelson: this represents a a physician's failure to understand the fundamental cause of the clinical disorder. >> but i'm talking about a different thing that is hyperventilation syndrome that is very different than the difficulty of speech. it is apples and oranges. nelson: but as a physician, someone comes in hyperventilating and they articulate i can't breathe. it is hyperventilation syndrome. and physicians as you indicate confuse this issue. >> correct. nelson: they blame the patient. >> they certainly miss the diagnosis. i don't know if they blame the patient. nelson: talking about speaking and breathing simultaneously it is a consideration of a minneapolis police lieutenant who trains police officers stestified that is a common statement in the course of training they may take exception with that

statement. >> i do not follow your question. it's hard to hear it up plexiglas. nelson: and i'm losing my voice. if a minneapolis police officer or a lieutenant who trains police officers testified it is frequently said that a person can talk it means they can breathe. you have a problem with that? >> yes. they can breathe at that moment in time that ten seconds later they may be dead. nelson: dealing with any person is a rapidly evolving situation that can change from second to second. >> yes.

nelson: in terms of the calculations that you made you would agree they are generally theoretical. >> they are not theoretical. they are based on direct measurements. they are based on extensive research. nelson: you're making assumptions in the application. >> very few assumptions. nelson: you are with assuming his weight. >> i am aware there are two different weights given. nelson: and the equipment the officer wears. >> yes. nelson: you have not physically measure the weight of the equipment. >> no. i took the measurements that are reported. nelson: you're actually weighing what mr. chauvin wade on may 25, 2020. and in your measurements for my understanding, that your

measurements assumed the equal weight distribution. >> yes. that is correct. nelson: as we know as things change and evolve inflow it is frequently redistributed. >> that is correct. >> in terms of the ee lv. nelson: you are basing those calculations on the presumption a person is a healthy individual.

>> that will not change. nelson: but in terms of the normal respiratory rate, excuse me the other factors you put into your analysis it is premised upon a healthy individual. >> based on a 46 -year-old person of a particular height and sex. nelson: who was healthy. >> correct. nelson: you would agree if biology can change rapidly that the specific biological conditions of mr. chauvin or mr. floyd come into play. >> correct those figures that you put into this case they are conditioned upon him being a healthy individual. >> it varies in terms of the lungs. compliance would very but ee

lv is robust. nelson: the other factors. >> it varies. different segments they are not all monolithic. nelson: you talk about one thing. and this is the aside, in terms of the prone position and pushing the stomach into the lungs. the size of a person stomach has some bearing. >> it does. nelson: somebody who has a few extra inches if i am prone it would push further or harder into my lung. >> yes. nelson: a person who is healthy muscular, would have less of an impact. >> that is correct.

nelson: in terms of what we have learned with mr. floyd from his autopsy medical records we understand mr. floyd had heart disease. >> that is correct. nelson: i believe in his arteries between 75 and 90 percent occlusion of the ventricular artery. >> correct. nelson: that would affect blood flow in a person. make the body work a little harder. >> not really. it would not do that. nelson: how does that affect a person's respiratory? >> the coronary artery is affecting it if it was contributing to shortness of breath you would expect he would be complaining of chest pain andem that he would be demonstrating a very rapid respiratory rate we don't see either. nelson: we will come back to

the respiration. i am taken by her accent. i cannot say it. respiratory rate. [laughter]om i will say it like you his respiratory rate. >> there you go. nelson: based on his medical records with hypertension or high blood pressure. >> yes . . . .

>> not the elasticity. if it's having any effect it would be within the trachea and bronchial three. so it wouldn't have anything to do with the elasticity. >> but we also learned quite a bit about the toxicology, excuse me, on covid-19 you testified treatment of people with covid-19 includes leaving them in the prone position. >> correct. >> so those people treated for covid-19 in the prone position, basedas on your calculations, yu would have a 24% decrease in the eelv. >> right. this is people with covid. where during the time that they have covid. >> that same decrease in the eelv. >> no, it's going to be very

different in somebody that has, say pneumonia. what's going to happen in the prone position would be very different from one person to another as a result of the pneumonia. it's different than normal. >> okay. so, in essence every person is different. >> for certain. >> now, you calculated his respiratory rate to be 22. >> right.ha >> and you said that was within the normal respiratory rate? >> yes. >> and you wouldn't describe him as hyperventilating? >> the word hyperventilation is open to an awful lot of misinterpretation. that is certainly not hyperventilation. >> hyperventilation assists in the removal of carbon dioxide from o the body? >> it's confusing. it's not that simple. >> in its simplest terms.er >> in the simple terms, yes it

gets rid of carbon dioxide. >> alright -- >> but it can be frequently misleading. >> in terms of the toxicology of mr. floyd, we did learn that there were some controlled substances in his system, right? >> yes. >> we know for example, there was nicotine. mr. floyd was a smoker. >> correct. >> antismoking changes lung function, agreed? >> some, yes. >> we also learned -- i'm not suggesting all people that smoke have lung problems. >> [inaudible] >> speak into the microphone. >> so, we focused in your direct examination quite a bit in terms

of fentanyl and its effect on the respiration rate. >> yes. >> and you would agree generally that fentanyl is a respiratory depressant. >> it can be. >> and it's used in operating rooms, right? >> yes. >> and it's also used in the management of chronic pain. a. >> yes. >> and medically speaking, those are the only two reasons fentanyl would be prescribed. >> yes, probably. >> you understand that fentanyl has become far more prolific and street drugs, right? >> yes, i know where. >> and you would agree that there is a significant difference between fentanyl that's manufactured according to the united states, you know, whatever rules apply, right? the pharmaceutical companies

make it much differently than the street dealers do. >> i imagine so, right. >> so, when a person is ingesting illicit street purchased fentanyl, every time they take a fentanyl does, it is a different experience for that person. >> right, but it's going to activate the receptors. there ise' no way around it. fentanyl isn't going to have an effect on respiration by another mechanism. >> understood. but the end result of fentanyl did include respiratory depression. >> right. >> and we also learned that there was methamphetamine in a low dose and mr. floyd system. >> correct. >> fentanyl and methamphetamine, they can kind of counteract each other, right? >> they are uppers and downers, but in terms of receptors, there

isn't going to be. >> so the methamphetamine is going to increase the heart rate, right? >> that is a different thing -- >> methamphetamine would increase a person's heart rate? >> yes. >> that's one of the side effects. >> yes. >> and there are a few lawfully, there are a few conditions where a physician can lawfully prescribe methamphetamine but it is extremely rare that it is done? >> i can't say. [inaudible] commonly for appetite suppressant. >> and i think adhd? >> yes. >> we also know that adrenaline will increase the heart rate,

right? >> yes. >> and adrenaline can be put into the body in multiple ways, right? >> let me -- there are many things that can cause a surge in adrenaline. >> yes. >> one of those things would be getting into a fight with someone or being afraid. >> difficult to know in terms of being afraid, but getting into a fight. >> and [inaudible] that was found i understand you call that a 10% tumor but in 10% of the tumor cases it can cause an adrenaline surgery? >> yes. >> in terms of the use of fentanyl in the hospital setting, surgical setting, had you becometi familiar with whats called wooden chest syndrome? >> yes. >> can you explain for the jury what that is?

>> some patients with fentanyl you get an increase chest wall -- >> so the lungs become less elastic? >> the chest wall. >> so, that would -- a chest wall rigidity will also decrease the performance of the lungs? >> it would impede the ability of the lungs to expand. >> in your report, you wrote that you would expect the peak respiratory depression to occur from fentanyl within fivee minutes of ingestion. >> right. >> have you come to learn tablets were found or controlled substances were found in the backseat of the squad 320? >> i've heard reports to that effect. i don't know what the status of

it is. >> so, you were not -- you've not been provided with any additional information since the time you've prepared your remarks? >> i -- no, i'm sure that's wrong. i've been provided with a lot of information. i don't p necessarily recall tht at the front of my brain. >> well, yesterday we heard testimony from the state crime lab that they were in the backseat of the squadad car. two of the partially consumed pills found in the back of squad 320. >> objection, your honor. [inaudible] >> characterization of -- >> overruled. if it is foundational. >> it is. you understand? >> no. kind of, but not fully. >> yesterday a chemist from the

state crime lab testified in this case -- >> [inaudible] >> if sustained [inaudible] >> sidebar. [sidebar]

let me ask you in the form of a hypothetical question. if partially ingested pills, that were determined to contain both fentanyl and methamphetamine were found partially ingested in the backseat of a squad car, and that those pills had been -- had the dna of the deceased individual on them, meaning that they took them, and those pills would have been in his mouth at about 20:18, is it fair to say that you would expect the peak fentanyl respiratory depression within about five minutes? >> obviously it would depend on

how much of it was ingested. just finding the pills won't tell you anything about whether he suggested -- ingested some of it. if there was any amount ingested, yes. >> and so, if it happened at 20:18 or there about, when the individual was in the back of the car, you would expect the peak respiratory depression to be around 20:13, right? >> 20:23, sorry. 20:18 to 20:23. >> you're about to really confuse me. [laughter] >> i'm sorry.ll i think i can say it's been a really wild week. so, 20:18 is the ingestion point and you would expect to the peak by 20:23. >> correct. >> that means it could continue afterwards. >> right.

>> you also described in your direct testimony what you have interpreted to be an anoxic seizure at 20:24. >> 4:21. >> 20:24. >> :21. >> and that is what you saw and what the jury was played wasff reflected from officers lane's body camera, and it was the kick of the legs, right? >> yes. point, you canat see officer lane hold the leg down. and you can see l it kick up again. >> right. >> [inaudible] >> please don't talk over each other. >> a tendency to go fast. >> that's what you are recognized based on your 46 years of being a pulmonologist and intensivist in your

experience. >> i mean,, obviously there was additional information fromad that, but the leg was the key. >> and it would be reasonable for a police officer to interpret the same behavior as s resistance? >> objection, your honor, foundational [inaudible] >> sustained. >> now, you testified that the last breath of mr. floyd was at 20:25:16, right? >> correct. >> prior to that point, all people who were there and monitoring him, he would appeared to have been breathing, right? >> it's hard for me to hear. >> sorry. prior too that point, it would e reasonable that he would appear to be breathing, right? >> yes. >> and in fact, you showed a segment where you were able to count his respiratory rate.

and then you said that 20:35:06 is when the first air was pumped back into him. >> correct. >> and you understand that paramedics arrived at 20:27:45. >> yes. >> and so, the time between when the paramedics arrived and mr. floyd got his first air was roughly eight minutes, almost nine minutes. >> yes. >> and according to the timeline, the drive to the hospital was about five minutes. >> i'm sorry? >> were you aware that the drive to the hospital was about five minutes? >> i wasn't aware, but i have no reason to dispute. >> and so, between 20:27:47 when

the emts first arrived, and the time they got him to having air in his lungs, it was a crucial nine minutes. >> yes. >> your honor, i have nothing further. >> mr. blackwell. >> doctor tobin, just a few questions. just for clarification sake, you were just asked a lot of questions about science and medicine, constantly changing, evolving. you heard all of this. i want to go to the period of time when mr. chauvin was on the back and neck of mr. floyd.

>> yes. >> did you see him get all of the back of mr. floyd by the nano second, millisecond, by any second in the nine minutes and 29 seconds that you saw him on? >> no i did not. >> if you look at the five minutes and three seconds that you focused on, where where you consider all of the nano seconds and milliseconds in the five minutes and three seconds, where was mr. chauvin the vast majority of that time? >> he was on mr. floyd's neck and on his back. >> not constantly changing? >> no. >> now, you were asked questions about what injuries were noted on autopsy. >> yes. >> and i think reference was there was no injury on the hypo- pharynx. does that make any difference to you? >> none whatsoever. i wouldn't expect them from the autopsy. >> why not? >> the affect on the hypopharynx

isn't something that is going to remain at the time of an autopsy. the type of changes that we see saying somebody with sleep apnea, that isn't something you will see the following morning when you look at somebody. it's just not there. >> there was also a reference made it to the absence of bruising on the neck during autopsy. does that make a difference to you whatsoever? >> no, because obviously whenever i go to church i sit on a hard bench. i don't get a bruising when i leave. so i wouldn't expect anything in terms of that. so if you have somebody -- this was a static force. it's not as if somebody is jabbing against it. so you wouldn't expect anything in the way of bruising. >> and scientifically, do you know of any correlation between the presence and absence of bruising on the autopsy and the forces necessary to restrict breathing? >> no, they are totally different because it's in terms of static forces and dynamics.

>> what about low oxygen? if somebody has low oxygen, does that show up on the autopsy? >> no it doesn't. >> does that mean anything whatsoever? >> it has no meaning because low oxygen is a function just like an arrhythmia is a functional thing. it doesn't leave a fingerprint on the autopsy. it's just there. it's something that happened. but it won't leave any fingerprint afterwards. you don't seeve it. >> that doesn't mean that the person did not have low oxygen. >> no, absolutely not. if you take somebody and suffocate them with a pillow and it's very clear to you after you've suffocated the person that he's dead from the pillow, you are not going to see the affects of thego low oxygen. >> now, you are asked quite a feww questions about mr. floyd's epre-existing health conditions. >> correct. >> and recited a number of

those. do any of those have anything to do with the cause of mr. floyd's death, in your professional opinion whatsoever? >> none, whatsoever. >> and again, what was the cause such that those conditions don't matter? >> the cause of death is a low level of oxygen that caused the brain damage and caused the heart to stop. >> you were also asked questions about substances in mr. floyd's system. i think you were asked questions about nicotine. he didn't die from nicotine. >> no. >> you were asked questions about fentanyl and methamphetamine. any evidence he died from thoset >> no, none. >> you were asked questions about whether he had ingested any fentanyl within five minutes of the time of death. >> yes. >> now i think you explained to us that if somebody is suffering from a fentanyl overdose, you would see a depression in the

respiratory -- >> yes. >> and depression means some reduction in the rate or ability to read. >> correct. >> did you see any depression and the ability to breathe whatsoever before he went unconscious? >> absolutely not. it was normal. >> any evidence then that any fentanyl in the system depressed his breathing in any way whatsoever?? >> no, and [inaudible] >> nothing further. >> two very quick questions. in terms of the carbon dioxide level, you testified that it was at a 96? >> i'm sorry? >> you testified to the carbon dioxide was out and 96. >> i think it was 89. >> and it was also measured at 102. >> the altar here is the one you

need to look at. >> and in terms of the ingestion or just generally speaking, fentanyl can also cause death as a result of low oxygen to the brain. >> but it would have to be -- >> the question is fentanyl can also cause death as a result of low oxygen. >> [inaudible] >> fair enough. thanks. >> mr. nelson brought up fentanyl again as a cause of death. doctor, you're familiar with the way people die from fentanyl. >> yes, very. >> do they or do they not go into a coma before they die as a fentanyl overdose? >> yes, they will. >> was mr. floyd ever in a coma?

>> no. >> thank you, doctor tobin. >> anything else? thank you. >> doctor, thank you so much. you are excused. >> okay, thank you. >> let's take a five minute break. we can all get our voices back.

back now today number nine of the trial for the former minneapolis police officer derek chauvin. this portion includes witness testimony from a forensic toxicologist. >> next witness, please. >> the state calls daniel isenschmid. >> raise your right hand please. do you swear or affirm the testimony you are about to give will be the truth and nothing

but the truth? >> and if you wouldn't mind removing your mask for the testimony if you feel comfortable doing so. let's begin by having you state your full name, spelling each of your names. >> my name is daniel isenschmid. >> thank you, your honor. good afternoon, sir. >> good afternoon. >> where do you work? >> i work at nms in pennsylvania. >> how long have you been with nms? >> since 2011. >> what do you do at nms? >> i miss forensic toxicologist. >> and did you have any other lab experience before joining nms? >> yes, i did. prior to joining from 1994 to

2011, i was the chief toxicologist for the wayne county office and before that at the medical lab, director of toxicology. prior to that, from 1982-1991, i was at maryland medical lab in baltimore, maryland. also during that period working for some time from 84 to 86 of the medical examiner's office in baltimore as well. >> rewinding a bit as well to your educational background, can you describe for the jury what your educational background is? have a bachelor's degree in biology from the delphi university of new york, and that was obtained in 1982. then i have a masters degree in forensic pathology with a concentration in forensics toxicology from the university of maryland baltimore. that was in 1986.

and then my phd the university of maryland baltimore in forensics toxicology in 1991. >> do you have any special certifications related to your work? >> i'm board certified as a fellow in the american board of forensic toxicology. >> and what are the requirements for that? >> the requirements, they changed over the years, but for the requirements you can apply to the board after three years after you have your phd. they examine your credentials to see that you're active in the field of forensic toxicology. if you have the right references and your active in the field,ea they will allow you to sit for an examination. and if you pass the examination, the board votes on your final certification. after that, you have to continue education each year and obtain a minimum number of education credits. and then every five years, you have to reapply to the board for

a brief accreditation. >> and have you gone through all of those requirements and satisfied them successfully? >> yes, i have. >> are you up-to-date on those continuing education requirements? >> i am. >> i'm going back to your role as a forensic toxicologist. can you describe your day-to-day job duties as a forensic toxicologist at nms labs? >> my primary responsibility at nns labs is to do case review. and what that means is when toxicology tests are performed at nms labs, particularly ones that require different kinds of tests to be done, they wind up being reviewed by a toxicologist or certified scientist to look at them in the context of all of the testing that was done. so, individual tests are reviewed by analysts in the laboratory and secondarily reviewed as well. but the final review comes to either a toxicologist that is certified and looks at everything in the context of the entire case.

>> and then is this part of your job duty to offer reports and a sign offou on all that testing? >> yes, it is. >> approximately howow many cass have you reviewed in that capacity as a forensic toxicologist? >> i review about seven to 8,000 cases per year. >> and in terms of the work that comes in to nms labs, are they e a variety of agencies that submit samples to nms labs for testing? >> yes, we get testing from medical examiners and coroners and samples from police agencies for dui cases, and we also get a lot of clinical samples from hospitals and referral laboratories. >> so, in that capacity does nms receive both postmortem or death related samples as well as samples from living patients? >> yes it does. >> and nms as a lab approximately how many tests or samples does nms receive for dtesting each day?

>> about 12 to 1300 each day. >> and when you say requisitions -- >> it would mean requests for testing. >> so thousands of tests a year. >> thousands of tests a day. >> tens of thousands of tests a year. >> all right. is nms a licensed and accredited lab? >> it is. >> does that include national accreditations as well? >> national and state accreditations. >> turning to your work on this particular case, did nms labs receive some samples for testing from the hennepin county office related to george floyd? >> we did. >> and were there a number of different samples that were received? >> correct. >> what were the samples that were ultimately tested>> by nms labs?

>> we tested the samples that were requested by t the hennepin medical county examiner to be tested. so we tested samples that were labeled as hospital blood, and we also tested urine that was collected at the autopsy. >> and in terms of the testing that was performed at nms labs, were those tests pursuant to standard operating procedures at thein lab? >> yes, they were. >> and that was followed for all the tests? >> yes. >> going to the results of the testing, what were the notable findings from the testing? t >> so, the most notable findingi in the hospital blood was the presence of fentanyl at 11 nanograms per milliliter. and then the metabolite of fentanyl the breakdown of north fentanyl had a concentration of 5.6 per milliliter. and in this position we found methamphetamine at 19. >> i'm going to talk about each of those substances one by one.

you indicated these were the results from the hospital blood in this case, f right? >> that's right. >> let's start with methamphetamine. what is methamphetamine? >> it is a central nervous system stimulant. it can actually be prescribed. it rarely is, but it can be prescribed undersc the brand nae as oxen and it is used for attention deficit hyperactivity disorder and obesity. it was also experimentally used for the treatmentnt of narcolep. and between 2016-2018, there were about 10,000 prescriptionss in the u.s. written for oxen each year. >> can methamphetamine be a street-level recreational drug and also prescription drug? >> it can. >> with results that you found of methamphetamine, what significance if any is there to that amount? >> that is actually approximately the amount that you would find in the blood and

somebody that was given a single dose of methamphetamine as prescribed. >> so, when you say -- you described the prescription drug form in which methamphetamine can be available. the results would be consistent with the prescription dose, is that right? >> yes, it could be. >> would that be a low level of methamphetamine? >> yes. >> and you also talked about the results of 11 nanograms per milliliter. first what is fentanyl? >> it is used similar to morphine.. it's much more potent than morphine. it can be used to treat pain and also an adjunct use in surgery for anastasia. >> and you talked about opioids. maybe you can describe what an opioid is.

>> so, opioids actually include both natural semi synthetic and synthetic drugs that act on the receptor which is where opioids act. opiates are a natural product that are found in plants, morphine and codeine. so, opiates are opioids but not all opioids are opiates. >> what are some examples of opioids? >> fentanyl would be an example. >> what oxycodone also be an opioid? >> yes, it blood. >> and you talked about similarities between opioids and opiates. and you mentioned morphine as an opiate? >> yes. >> is that heroin? >> so, heroin is actually made from morphine, but when heroin it breaks down into a metabolite and then eventually to morphine. >> so heroin would break down

into morphine, right? >> yes. >> do opioids and opiates have seller affects? >> yes. >> getting back to the fentanyl level in this case, you mentioned it was 11 nanograms per milliliter. can fentanyl levels vary widely depending upon the individual? >> yes, they can. >> and why would that be? >> because of the tolerance. >> and couldn't you just explain how an individual's drug tolerance might affect the impact of the particular drug like an opioid or fentanyl might have on them? >> if a person becomes tolerant to a drug, you need to have more and more to get the desired effect. so, with chronic use, to get the same feeling as you would at a given concentration, you would need to take more to get that effect. >> so if someone is regularly using opiates or opioids, would that individual then develop a

tolerance? >> yes. >> now you also talked about more fentanyl. could you just describe what that is? body gradually eliminates fentanyl, it breaks it down from fentanyl. it's a gradual process that occurs over time and it's one of the ways that the body eliminates fentanyl. >> and you indicated that the amount of norfentanyl found in the hospital blood in this case was 5.6 nanograms per milliliter. >> right. >> what is significant about that amount of norfentanyl? >> it shows that some of the fentanyl was metabolized into norfentanyl. it also could mean that it was pre-existing-e norfentanyl with additional fentanyl given on top of that. but basically, it showed that when wet see -- when we see very recent deaths with fentanyl, we basically see it with no norfentanyl whatsoever, because after a very acute fentanyl

intoxication, the body doesn't have time to breakot it down. >> and you describe when you see a fentanyl overdose, typically you may not see any norfentanyl or very low levels. >> correct. >> in addition to those findings from the hospital blood, were there some other findings as well that were included in your reports? >> there were. there were some incidental findings. i believe there was codeine, which is from smoking, there was caffeine, therefe was evidence f prior marijuana use, but the presence of cannabinoids. i would have to look at the report. >> would that refresh your recollection? >> yes. >> if we could put on the screen just for the witness, exhibit 24, please. >> and then if we could zoom in on the positive findings portion. all right. referring to your reports now,

can you describe the other findings with respect to this case? >> the additional finding was a compound called for a npp, and that is a precursor to fentanyl manufacturing but it is also a metabolite of fentanyl. it is an pharmacologically significant and it's mostly inactive but it was measured as a part of additional testing thatas was requested by the hennepin county medical examiner. and then the year and findings we had a presumptive positive findings not confirmed for cannabinoids and with fentanyl, those were not confirmed because they were present in the blood that followed that and then had findings for opiates in the urine and we were asked to confirm those and we found the concentration of morphine in the urine of 86 nanograms per milliliter. >> you were saying that he found morphine in the urine,

86 nanograms per milliliter. right? >> correct. >> and was the morphine found in the blood? >> no, it was not. >> can a finding of morphine in the year and be indicative of a prior use in advance? >> yes it can. you can see morphine in urine for several days depending on the dose and prior use pattern. >> is that because it shows up in urine longer than blood? >> yes. >> you tested hospital blood as well as the urine. you describe the findings in the urine with respect to morphine. you were also discussing the finding in the hospital blood. with respect to the other findings in your report, can you say what they were and whether they were significant? >> i think i mentioned caffeine which was present and a

metabolite of nicotine from smoking. and then cannabinoids it was 2.d the breakdown product and then the inactive at 42 per milliliter. >> and when it comes to these findings relating to the cannabinoids, what if any impact wdoes that have? >> it's very hard to interpret those, given the nature of the samples and also what happens with cannabinoids, because they go into the fat, so they can be released slowly with time, and certainly anything like cpr or something like that is going to potentially release thc from the fat, so it doesn't mean a whole lot. >> they can remain in the system and be extended for an --

released for an extended period of time? >> yes. >> we can take that down. >> as a part of your testing process, were there also some metabolites or other substances that were detected as a part of the testing but below the last reporting limit? >> we did find substances that were below the threshold and that's why they are not on the report but it's part of the data package that was requested, and one can see those there. >> and you keep those litigation packages part of your standard operating procedures. >> all of the data is a part of the package. it's actually pulled from the data on the request, but yes. >> as part of the testing in the last case i would like to ask about the process for methamphetamine, and whether

there were findings of amphetamine. >> sure. so, when we had a positive -- when it was positive for methamphetamine [inaudible] and anything that is positive abovee a certain threshold in te procedure is then confirmed by an alternate procedure. in this case, methamphetamineha was positive on the screen, and we ran the confirmation test for amphetamines. the amphetamines confirmation test actually consists of ten compounds, but we are only interested in the target count compound is that we are confirming in this case. so in this case, we did detect methamphetamine, and because ofd the metabolite of methamphetamine, there was evidence of amphetamine, but it was below the reporting limit, so it wasn't recorded. >> and you indicated amphetamine as a metabolite of methamphetamine. >> right. >> does that mean the body breaks down methamphetamine into

amphetamine over time? >> yes it does. >> in addition to confirming the presence of amphetamine, was there also an indication on initial testing of morphine? >> because it was below the limits it wasn't confirmed so it wasn't an indication. >> and when you say indication, that means it didn't go through the second step of the process? >> what his view but morphine? >> it is a drug>> that is prescribed and its prescribed for therapy for people that are going through opiate treatment. >> are the components both [inaudible] bupomorphine and it's essentiallyer generic narcan? getting back to the blood that was in this case, you indicated that it was hospital blood,

right? >> that's correct. >> what's significant about using hospital blood for testing? >> hospital blood is -- if it is antemortem blood it's more representative of what is circulating in the body prior to the time of death. after death, there are changes that occur with the drug drug concentrations, particularly in blood collected from the heart. a phenomenon known as postmortem distribution where the blood goes from a higher concentration to a lesser. it's less of an issue with blood samples but it can still occur. ideally, you would want to try to get a sample is close to the time of death as possible. >> and if a blood sample is taken after death or after extensive edr on a patient, can they be postmortem redistribution?

>> i thinkst that's possible. there's a lot we don't know, but it certainly as possible. and if it does, it attempts to increase concentration. >> when you say increase concentration, does that mean the little might show higher than it was at the time of death? >> correct. >> what about how analysis? >> the breakdown of the red blood cells. >> did that have any impact on the testing of this case? >> it would on certain chemistry tests like potassium but when you analyze a blood sample for drugs, you are analyzing a whole sample so it would have no effect. >> so, you mentioned that nms labs receives thousands of tests a day and -- did you review and compile some data from the year 2020, with respect to nms labs'

fentanyl cases and methamphetamine cases? >> i did. >> what does help you to contextualize the cases? >> sure. >> i would offer for demonstrative purposes exhibit 920. >> any objection? >> [inaudible] >> 920. it will be received for the witness testimony.

>> and if we could publish -- thank you. doctor isenschmid, i'm going to have you describe what is shown on the screen. >> as of right now, we are looking at what happens when fentanyl metabolizes over time, so gradually the amount starts to decrease into norfentanyl. >> and that's what happens as the body metabolizes fentanyl. next slide, please. >> could you describe what is shown here. >> this is data from nms labs from the year 2000. and we looked at the fentanyl concentrations in postmortem cases, specifically in those and

only those that were collected in nonpolitical blood. again, i mentioned before blood like cardiac blood could have significant postmortem redistribution so we want to look at samples -- >> you indicated from 2020? >> we had 19,100 cases that we logged in and the peripheral blood in this cases main the fentanyl concentration rate was 16.8 nanograms per milliliter. and the median concentration was ten, being 50% above and 50% below. >> with respect to peripheral blood, you indicated you chose the samples that would have minimal postmortem redistribution. >> correct. >> why is that in comparison to

this case? >> because the sample in the hospital blood is going to have less issues than hadn't been postmortem blood. >> and in these cases that are represented as postmortem cases, are these that you would be getting from offices or coroners offices? >> correct. >> would the individual be deceased or dead? >> correct. >> the norfentanyl concentratioe was 6.0 and the median down to 2.2 nanograms per milliliter. >> just to clarify with respect to the postmortem cases, the ctaverage level of fentanyl was 16.8 nanograms per milliliter and the average level of norfentanyl was 6.1. >> right. >> next slide, please. >> what's shown here? >> this shows postmortem cases

for the year 2020. so, 19,185. we had 15,455 that included fentanyl and norfentanyl, but there were 3,724 cases with no norfentanyl. there are exceptions to that for reasons of testing purposes. but, those are the ones where only fentanyl but no norfentanyl. >> so you would indicate that. there was a significant number, 3,724 cases where there was fentanyl found, but no norfentanyl at all. >> correct. >> next slide, please. >> what is shown here? >> switching years, we are looking at the dui, driving under the influence fentanyl concentrations that we t found n 2020. so, these are blood samples that are sent into nms labs for people that were suspected of driving on the influence of

drugs or potentially other reasons for the way they were driving. and in this case, we tested -- we had 2,345 cases of individuals that were alive that had fentanyl on board. of course other drugs may be present, but this is specifically looking at fentanyl. and we had a main concentration of 9.5 nanograms per milliliter and a median of 5.3. and then for norfentanyl the mean of 5.42. >> just to clarify, for these cases, those individuals were alive. >> correct. >> and you indicated the average level of 9.59 nanograms per milliliter. >> yes. >> and the average norfentanyl was 5.42 nanograms per milliliter. >> right. >> next slide, please. >> and what is shown here?

>> this is just a breakdown of fentanyl concentration that we found in drivers that were alive. so, almost the majority were under 5 nanograms per milliliter and then we had another 26.3% that were between 5.1 to 10 nanograms per milliliter. and then the next set of data was between 11 to 15 nanograms per milliliter so that would be in the same area of mr. floyd's level of 11 nanograms per milliliter. we had several cases greater than that. 109 that were between 16 and 20, 81 that were between 21-26. 133 between 26-50 and then we actually had 53 cases in living subjects were fentanyl was greater than 50 nanograms per milliliter. >> so, comparing mr. floyd's level to the driving population, where individuals were alive,

his level was within a quarter of the dui cases that nms labs received. >> it would be right in there with the percentile. >> and you indicated that those levels for drivers were founded 53 cases higher than 50 per milliliter. so those individuals were alive and essentially driving at that time. >> yes. pretty amazing. >> all right. next slide, please. >> and what is shown here? >> so, this is basically a postmortem concentration, samples that were submitted from mr. floyd. we found fentanyl at 11 nanograms per milliliter and norfentanyl at 5.6 nanograms per milliliter. >> next slide, please.

>> so, this slide shows with the ratioti of the drug to metabolie is, so 11 nanograms per milliliter divided by 5.6 of the norfentanyl would give mr. floyd a ratio of fentanyl into norfentanyl 1.96. >> and essentially, does this slide show the way in which you would calculate the fentanyl to the norfentanyl ratio? >> yes. >> next slide, please. >> what is shown on this slide? >> this shows the ratio of the fentanyl levels between nine and 13 nanograms per milliliter. so, that range was chosen because mr. floyd's fentanyl concentration was 11 nanograms per milliliter. and when we do driving under the influence work, we actually assign an uncertainty of measurement to that result. so if a driver had 11 nanograms per milliliter of fentanyl present, we would report that as

11 plus or minus 2 nanograms per milliliter. so, i did this to see what kindf of ratio do we see between postmortem and the dui cases in the fentanyl level is between nine and 13 nanograms. what kind of ratio do we see. and we can see in the postmortem cases the mean ratio was 9.05 with a median of 5.88. versus the dui population where the means was 3.2 and median 2.24. >> and then just to clarify, in the bar that shows the postmortem cases where there are 3,088 cases that you looked at between the ranges of nine to 1. >> yes, between nine and 13. >> and the ratio in the postmortem cases was 9.05 on average, right? >> correct. >> with respect to the dui cases, looking at 275 cases

between nine and 13 nanograms per milliliter. >> that's correct. >> so the average was 3.20, is that correct? >> yes. >> how did mr. floyd's ratio compared to that data set? >> mr. floyd's ratio is roughly a little bit below the median ratio in dui. so, postmortem cases we know fentanyl concentration can be much higher than norfentanyl concentration because frequently these are deaths due tota fentanyl. other drugs may be present, and there can be other reason for the death. it doesn't say these are all fentanyl intoxications, but just looking at it as a whole and largely on the amount of data this is what we observed. we knowwe with the dui populati, they are alive but other drugs may be present as well. so, it is really just sort of looking at how things look differently in the living and postmortem population. >> and in this slide i will show mr. floyd's ratio was below the

average, and even below the median for that found in dui cases. >> yes. >> next slide, please. >> so, this slide is actually just sort of a summary of the previous slide. but it basically shows the relationship between fentanyl and norfentanyl, between the postmortem dui cases and mr. floyd's. >> and again, doesn't show how norfentanyl levels essentially increase over time in relation to the fentanyl level? >> how it metabolizes fentanyl, yes. >> next slide, please. >> did you also look at data with respect to methamphetamine for 2020 and nms labs? >> we did. >> what is shown on the slide up right now? >> this shows the concentration of the methamphetamine found mr. it was 19 nanograms per milliliter. and then as we talkedil about

earlier, amphetamine was below reporting limits, so it wasn't reported. >> not reported but detected as a part of the confirmation process. >> we could see it in the confirmation data, yes. >> next slide, please. what is shown here? >> this slide shows dui and methamphetamine cases. with amphetamine and without, those metabolites. so, we had 3,271 cases that had methamphetamine and driving under the influence population. 2,975 of these included amphetamine. and then 296 were just methamphetamine with no amphetamine. >> and again when we talk about the dui population, these are individuals, the 3,271 number of individuals that are alive. >> correct. >> next slide, please. >> what's shown here?

>> this is a further breakdown of what we see in our methamphetamine and dui cases. the main concentration of all of the dui casesat was 378 nanogras per milliliter of inmethamphetamine. the median was 240 nanograms per milliliter. and in the five to 20 range with five being the lowest level of quantitation, we had cases between five to 20 nanograms per milliliter and that range that mr. floyd's methamphetamine was. >> does this graphic also show p mr. floyd's level of 19 grams per milliliter? >> yes. on the bottom and again the 94% of the dui cases that we tested had methamphetamine concentrations in excess of 20 nanograms per milliliter. >> mr. floyd's level was at the bottom. >> correct. >> next slide, please. >> what is shown here?

>> this is a further breakdown of what kind of methamphetamine concentrations we have observed in drivers in the last 2020.ru and again other drugs may be present. but in this case, we had 196 cases between five to 20. 306 between 201 and 50. 571 between 101 to 200. 1,010 between 200 to 500. and then an additional 250 cases that methamphetamine [inaudible] >> so you had a 215 cases where the number was greater than a thousand nanograms per milliliter. >> correct. >> the biggest piece of the pie, the 30.9% were between 201-500 nanograms per milliliter. >> yes.

>> mr. floyd's level of 19 nanograms per milliliter was exceptionally low. >> in relation to the dui driving population, yes. >> nothing further, your honor. >> good afternoon, sir. it's a little unusual for you to be testifying in a death case, isn't it? >> not terribly. i do work with medical examiners a lot. but they are the ones that testify on the matter of death.

usually if i'm involved in a death case, it's usually a drug resulting in death. >> and so, you work in a laboratory that works with medical examiners from around the country, right?he >> correct. >> and you perform these services in a variety of different contexts, agreed? >> yes. >> so you testified some areur clinical in nature and some are law enforcement in nature, and some are death related, right? >> correct. >> and you, at the time, you became involved in this case, you were obviously aware of the significance of the case, right? >> yes. >> and your laboratory goes through an accreditation process, correct? >> we do. >> part of the accreditation process is to have, to establish standards and reporting

thresholds, right? >> yes. >> so, the reason a laboratory will have those thresholds is to be consistent in how toxicology is reported to various individuals. >> correct. >> so, one of those accreditation standards is actually to have and set this threshold that if a particular chemical component is below that threshold, you would suggest not reporting it, right? or you would say it's not reported. >> so, there are instances where a medical examiner mightre ask s if something was present below the threshold. and depending on what the situation is, it could be potentially reported as such. it isn't common practice. in this case, we didn't do that. >> it isn't common practice to report things that are below, chemical components below the

threshold because it is contrary to the accreditation standard, agreed? >> it does depend on the situation, but by and large, there is a reason that we have cutoffs and if we go below those, basically it's not something we would typically do. >> and so, and analyst who comes in, hypothetically, and may see certain markers that have an indication that something is present or refuses to acknowledge its presence, that would be because of those accreditations and accreditation standards, right? >> not quite sure i understand the question. >> hypothetically speaking, if an analyst from say the state crime lab comes in, and a question is presented to her about the presence of a particular substance, but the substance was below the

reporting threshold -- >> i object, your honor. [inaudible] >> it is a hypothetical. >> overruled. >> the analyst refuses to acknowledge -- refuses to acknowledge the possibility of the presence, that would theoretically or hypothetically be because of those thresholds rules? >> i really can't speak to what is done in a crime lab, because i don't work in that area.rk for me it is really limited to toxicology and the analysis of the biological samples like blood or urine. >> so, in, other words, the reason we have these thresholds is so that we set the rules, right? >> the reasons thresholds are

established it hasee to do with the original validation of the method. the thresholds are notds set because of any standard that says this is what you have to use as a threshold. the laboratory establishes those and then writes it out in accordance with the validation procedures. >> that is the standard operating procedures. and so, if the laboratory sets the standard and says here's the standard and then does something in contravention or reports something that is against that standard, that would be a violation of the standard operating practice, right? >> if it were reported without any explanation, yes. >> so, just a few kind of follow-up questions to your testimony. you've met with or spoken with members of the prosecution team several times. >> yes.

>> including february 26, march 5, march 12th, april 5th? >> that sounds right. >> you w wouldn't disagree if i told you those were the dates? >> yes. >> i was provided with meeting notes and summaries of the conversations. so i just want to make sure that i understand and the jury understands the difference between fentanyl and norfentanyl. >> okay. >> you would agree that fentanyl is the active ingredient for when you report the fentanyl concentration to the active ingredient. >> when the person ingests any controlled substance, doesn't have to be an illegal drug, the body metabolizes it. >> right. >> and then the body eliminates g,it through the natural process of the body. >> right. >> and the elimination of the substance results in what is called a metabolite, agreed?

>> yes. >> so, fentanyl being the active ingredient, norfentanyl is the metabolite or the breakdown. >> correct. >> and included in this particular case, you discovered a fentanyl concentration of 11 nanograms per milliliter, right? >> yes. >> and a norfentanyl level of 5.6. >> yes. on directu testified examination that that could be one of two scenarios occurring. >> yes. >> one scenario was that a person took a certain amount of a controlled substance, of fentanyl, and enough time had passed to eliminate that. or to break it down and have that metabolite. >> iright. >> that's one scenario. >> the other scenario as i understand is someone took some, that initial dose began to break

down and then the person took more. so the active ingredient is there, but it hadn't yet broken down. >> correct. >> so it sort of either -- you describe it i think as an acute ingestion, or a non- acute ingestion. >> when you have fentanyl it will break down into norfentanyl. but if you still take norfentanyl could take fentanyl while the first fentanyl was breaking down. >> correct. so, to put it into a context for people who consume alcohol. if i have a beer and my concentration is going to rise to a certain level, right, whatever based on the alcohol concentration is. >> right. >> and my body will essentially begin to immediately decrease and eliminate the alcohol, right? >> right. >> but if i have a second beer,

i'm adding more alcohol to my blood concentration. >> correct. >> and that is similar with all substances including fentanyl. >> in general, yes. so, alcohol is eliminated at a fixed rate over time. it is only so much you can eliminate over time, but for some drugs it is different. >> some are faster and take longer. when you describe the results of this particular case, you're talking about sorry, strike that. so, there's based on the strict interpretation of the test results, there's no way to esdetermine at what point any particular amount of fentanyl was ingested, agreed? >> i would agree with that. now, fentanyl, again, being a toxicologist is a lawfully manufactured, controlled substance in the united states,

right? >> it can i be prescribed as a fentanyl patch, a lollipop, it can be used in surgery. >> and the fentanyl that is contained in the patch or lollipop or that an anesthesiologist may administer is in a very controlled and known manner, right? >> yes. >> when we are talking about the illicit street drugs that involve or include fentanyl, you really have no way of knowing what the particular fentanyl concentration is literally from pill to pill. >> agreed. >> every pill t you take becomea unique experience for the person. >> that's true. >> so regardless if you have a tolerance or intolerance, every single incident could cause an adverse reaction. >> sure. if you have a pill that is the same amount of and another one, yes.

>> and you have no idea, right? you don't know until -- >> because they are not manufactured in a controlled environment. now, in terms of -- you understand that there were some pills found on the floor of the squad car? >> that's my understanding, yes. >> and those pills were tested and contained the dna of george floyd, right? >> i heard that, yes. >> and presumably, those pills were not in their prior to mr. floyd being in the squad car, right? >> i would assume not, yes. >> and so, you understand that as those pills were tested, those pills were at least partially ingested or partially

dissolved. >> okay. >> so there would be evidence of an acute ingestion of fentanyl and or methamphetamine at the time mr. floyd was in the backseat of the squad car. >> objection, your honor. [inaudible] speculation. >> [inaudible] >> sustained. >> are you familiar with the term hooping -- >> objection. >> answer if you know. >> i don't. >> now, in terms of your slideshow, and i don't have an electronic copy -- some follow-up questions on some of

the slides. you reviewed in 2020 a total of 19,185 fatal overdose cases, correct? >> no, not necessarily fatal overdoses. they were cases that were from medical w examiners that we foud fentanyl in a sample, but they could have been homicides, they could have been other drugs oinvolved. they just were basically concentrations. >> so, someone may have been shot and killed as a result of a gunshot, but as a result of the autopsy process, you collect the blood and analyze the lead as a part of a normal autopsy process. >> correct. >> so the cause or the manner of death being gunshot wound, homicide, but we still look at the blood? >> right.

>> okay. and with a total of 19,185. >> correct. of peripheralco blood samples. >> when the slide says 19,185 fatal overdose cases, you're not suggesting -- it's a little misleading because you're suggesting it's a fatal overdose case. >> i didn't think it said that. >> that's something i corrected the other day. i said that's not correct. >> okay. >> i apologize for the record where it says fatal overdose cases [inaudible]

>> objection. [sidebar] [sidebar] we are going to take a 20 minute recess. we will give you 20 minutes.

i received 49606 and apparently int started working on my preparation and at some point i received an updated copy of this and it is 49623. it's like 17 pages later and i'm just trying to verify when i received that because i was siusing this as preparation, and this was all last night. >> there enough. >> this would have all been provided in the same batch that went out [inaudible] slides were updated and shown to the jury.

>> so i understand there was an earlier version but it was updated [inaudible] you showed the updated version to the jury? >> that's right. >> when was the updated version sent to mr. nelson? >> [inaudible] my best guess april 6. >> so tuesday. >> this would have been the same day as [inaudible] >> let's take our break and nail this down specifically. there's a lot of moving parts. i think we can just acknowledge without showing it again that you received an earlier version

but it's been updated. >> and that's fine, your honor. part of the problem we are experiencing here, i'm getting these things, many of these items in pdf format. some of them i'm getting electronically. there are so many people involved here. i'm getting things in different formats. may i have a second to speak with ms. moss? >> nobody should be criticized. let's just tell the jury this is the latest one and this is what it is. >> i'm happy to provide an extra copy and republish the slides that were presented but i want to make sure we are not showing the jury inaccurate information.

>> it is my fault because apparently we received it on april 6 but i assumed it was a second copy of the same thing. >> we will tell the jury you were relying on an earlier version [inaudible] and leave it at that. >> perhaps it would h help if i just get the copy of that. >> okay. let's reconvene -- where are we at now? 2:40, 3:40. >> the trial for derek chauvin, the former minneapolis police officer charged in the death of george floyd continues friday at 10 a.m. eastern. watch live coverage on c-span2,

online on c-span.org or listen live on the c-span radio app. if you missed the live coverage, watch at 8 p.m. eastern on c-span2 and any time on demand on c-span.org. booktv on c-span2 has taught nonfiction books and authors every weekend.

the ninth day of testimony of the trial of the former minneapolis police officer derek chauvin charged in the death of george floyd. the jury heard from critical care specialist doctor martin who by his own analysis determined it was a lack of oxygen that led to mr. floyd's death