tv Day 9 of Trial for Derek Chauvin Accused in Death of George Floyd CSPAN April 8, 2021 11:52am-1:10pm EDT
has been accredited. >> we have been accredited since the '90s, since 1994 pretty. >> overtime, different accrediting boards rated. >> yes, that is correct. >> and have you gone through the accreditation process. >> yes. i have been employed but we have gone through any accreditation cycles. >> from 19. [inaudible]. >> doctor, turning your attention back to exhibit 943. and focusing on the restraint on the ground. you are focused on the first five minutes and three seconds in particular that mr. derek chauvin was applying his weight to mr. george floyd's neck. >> hi why was the time.
after the five minutes and seconds afterwards pretty. >> because at that point, where he extended his leg, that we see happening at the point that we see that happening, is at 2421. that's when he suffered brain injury, and we can tell from the movement is of his legs the level of oxygen in his brain is caused we call a seizure type of activity. their medical terms but it basically means that he has kicked out his legs and an extension form, that he has straightened out his legs and that is something that we see as physicians and patients they suffer brain injury as a result of a low level of oxygen. >> will talk about that more in
a moment. dr. tobin but is a significant whether mr. derek chauvin moved his leg off of george floyd after george floyd is unconscious pretty. >> no. the movement happened around a different time but obviously, the key thing is everything up to the time that we see the hypopharynx, that is occurring. with the officer derek chauvin moved his knee after that really is not quite have any material impact on the case. >> we can help ladies and gentlemen of the jury understand that if esther derek chauvin is applying pressure on the side of the neck as we see here in exhibit 943, does it translate into narrowing of the hypopharynx. >> is going to depend on what is the orientation of officer derek chauvin body and is orientation
of his leg and then also in particular into what is the orientation of mr. george floyd and where exactly is the orientation of george floyd. because it is the ligaments, and is underneath officer derek chauvin's knee, there's going to be various compression of the hypopharynx in this region and then if it moves to the side, and officer derek chauvin weight is coming down on the side of mr. george floyd's neck, then you get a huge compression of the hypopharynx. >> again looking at exhibit 943 and focusing on the first five minutes. it was his knee overarching really on the side or on the back. >> for the first five minutes, the left knee is on the neck virtually all of the time in the right knee by my calculations,
the right knee is on his back 6. in the reasons that i can say that is not a hundred percent is because most of that of the time, i don't get a good view of the camera, they move around. the body camera so i cannot see it but for that period of time, the crucial period of time, that the five minutes and three seconds, i can see the officer derek chauvin knee on his back for over 57 percent of the time. >> let's talk about the third mechanism of the prone position. with george floyd being placed in his prone position and also have an impact on the narrowing of the hypopharynx. >> yes facing him on the prone position has several different effects but particularly, it also causes narrowing of the hypopharynx among other things that the prone position does.
>> is there concept of physiology referred to as long files pretty. >> yes there are. >> what is that, what is not referred to. >> is just the way we long specialist, we measure how the size of long indifferent patients. and we quantify out in different areas, what level of the long there is, whether it is different segments of the long behave in different ways. >> do you have an illustration that you brought to help us better understand the concept pretty. >> yes. >> i'm going to show you exhibit 929 have you first identify it. >> i am identifying this pretty this is well it shows you loan functions and it shows you. [inaudible]. >> is an inaccurate illustration of lung function and title -
>> yes it is. >> i offered exhibit 929 pretty. >> is there any objection. >> 929 is received. >> so we can get started again. do i go ahead and describe this. yes. [inaudible]. we are getting into a bad habit pretty could you ask the question again please. i forgot it pretty. >> thank you your honor, i'm just going to ask you dr. tobin if you would explain to us what we see in exhibit 929 pretty. >> we are looking here the lungs inside of the chest of the chest is great and we see the long inside and around the space. and we are saying that as we were looking at this going in and out it generates volume and it showed as a waveform down at the bottom.
and so that is what happens in somebody with what would regular people. >> let me see if we can get our title volume. >> so here you can see that the chest is expanding like right in the front here, the actions of the chest. then with each breath you can see air going into the lungs that produces the size of breath. so this is the title volume. an inner exhalation is going backup. that was the tidal volume. >> standard for normal size of breath pretty. >> yes there is an virtually all adults, people, it is about 400 cc, the size of the tidal printed the same for men and women and for teenagers and grandparents.
>> so can lung volumes be calculated that pretty. >> yes then you can calculate further additions. >> did you actually do a calculation for mr. george floyd lung volume pretty. >> is a calculated how does lung volume precisely based on his age, his and his height. ... ... >> so with using this be helpful to explain her testimony? >> yes what. >> your honor, i want to offer exhibit 930. >> any objection? >> none, your honor. >> 930 is received.
>> these are the lung volumes in mr. floyd while he is sitting on the sidewalk, and the volume will be focusing on is the elv, the in expiratory lung volume. that becomes crucially important in understanding what happened to mr. floyd. i calculate out his elv to be 3840 and that's what it is shown there by the horizontal -- [inaudible] sitting on top of that it is the size of each breath and then underneath is the residual volume. the residual volume is when you blow all the out of your long and that's your finished blowing, you can't looking out. that's the area that is still left inside your chest is the residual volume. that in mr. floyd is to leaders and 300 cc.
-- two two leaders. that is included in the eelv. eelv is everything below that horizontal purple line. the eelv sitting upright is 3840. we also see -- >> if i could stop you for just one second. to help us understand better the mr. end expiratory lung volume, eelv, would that be, referred to as oxygen reserves? >> that's also where your main oxygen stores are in the body. they are contained within your eelv. this is where you store your oxygen reserves. >> so for the ladies and gentlemen of the jury , it's true that not all the air you breathe it is exhaled out? >> no. i mean, the eelv is basically the volume that is in your lung in between each breath. so when you are breathing in and
out, when you're between the next breath, what is in your lung is your eelv. >> and the residual balls you, rv, is that also residual oxygen the body can you? >> yes. >> so the oxygen reserves you have are included in the eelv and obviously a subset of the eelv is a residual volume. all below the purple horizontal come all below your tidal volume is your oxygen reserves. >> so then can you explain your tax relations for mr. floyd's lungs? >> so here we see based on his age come his sex and his height we are seeing exactly that is eelv sitting upright is 3840, and we see is residual volume is 2300. >> and again if the matter their
he's taking in in tidal volume would be the same as anyone else? >> right and that is the 400 at the top. that is a tidal volume and that's the same as for anybody. >> 400 cc? >> correct. >> cubic centimeters? >> cubic centimeters, or millimeters or oh however you want to put it. >> the oxygen graph is on the side? >> yes. >> what does that depict? >> the level of oxygen with anybody varies with age and this is exactly the level of oxygen you expect in a 46-year-old man. so. so it is a po2, the level of oxygen measured in pressure of oxygen if you do an arterial blood glass were somebody sticks of needle in your risk, took out a sample of arterial blood,, that's a level of oxygen they will find, 89 millimeters of mercury is how come is the units we use when we describe levels of oxygen.
>> you told us that mr. floyd being in the prone position served to narrow the hypopharynx or decrease the vibe of oxygen in the long? >> bright. it had multiple effects including those two. >> why is that? >> because that eelv is very important in terms of obviously it's where we store the oxygen but as well is that it has an effect on the upper airway. so when you breathe then you don't notice it, as you are expanding your lungs you're aware of expanding your lungs but at the same time the size of your hypopharynx also widens out because there's attraction forces that are occurring between. it's just part of normal breathing that as you inhale you expand your lungs but you also expand that little area that you have 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 hypopharynx also get less. it's going to collapse down. as your eelv goes down. >> did you actually calculate the reduction in lung volume for mr. floyd due to the proposition? >> yes, i did. >> could i show dr. tobin exhibit 927? doctor, is exhibit 927 the calculation that i am referring to? >> yes. >> your honor, i offer exhibit 927. >> any objection? [inaudible] ninety-seven? >> yes. >> -- 927?
no objection. >> 927 is received. >> so dr. tobin, tell us what we are seeing here in exhibit 927 as relates to mr. floyd in the prone position. >> you were seeing it smaller when you're placed facedown. and so you're getting a decrease in the volume and that is occurring because in part let's say you're lying flat into bed with your her face in the pillow if you are laying prone facedown. you are no longer going to be able to use your bucket handle action. so your lungs are going to get smaller. you are also going to greater difficulty in using your bucket handle action, less so than the pump handle. and then as well as that as you lay facedown your belly is going to rise up into your chest and
so your diaphragm rises. so the lungs get smaller and that is what we see here. so if anybody who is turned prone you see that the lung volumes on average go down by about 24% by simply turning them prone. so with that when you're getting the small involved into getting less reserves and you're also going to affect the hypopharynx. >> so if the lung size go down 24% come to the oxygen stores also down 24%? >> the oxygen stores will go down by 24% 24% as well. once you have less volume inside your lungs, your oxygen reserves are going to go down proportionately. >> is absolute when a 4%? >> no. i mean, again in physiology the way we do things is look at 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 there's always going to be something like us to do for% variation you are going to see around these numbers, but -- two the 4% we speak of the average change that is occurring. >> so is the 24% reduction significant in the case of mr. floyd? >> yes, it is extremely important because again because of the factors that we are dealing with. we are seeing here that with the reduction in the eelv just from the prone, decreasing the oxygen reserves, we are also affecting the size of the opening of the hypopharynx because as a eelv goes down your getting a proportional reduction in the size of that. and in addition when you are turned prone like this your work of breathing goes up because of stiffness of your lungs changes and the stiffness of your chest wall changes. so the person has to do more
effort to breathe in that position. >> so the hypopharynx is linked to the size of the loan that is the size of the hypopharynx? >> yes your doctor, maybe you can help us understand this. is it true that some person suffering from covid actually treated in the prone position? >> absolutely. >> why is that? >> it's a different scenario but, i mean, in any patients with pneumonia taken with covid but receiving any patients with pneumonia, when you turn them prone it can help. the problem is if the have pneumonia they have bad matching between blood vessels going through the lungs and the air sacs. we saw the movie at the beginning resolve the alveoli and you saw all those blood vessels surrounding the bunch of grapes. in people who have pneumonia,
covid, whatever, that matching is going to be very bad and that's what leads to the worst oxygenation in those patients. if you flip those patients prone, some of them will show no improvement but a substantial number of them, the matching will get better between the blood vessels and the air sacs. you can't predict ahead of time until you turn the patient prone come you will not know which ones would do better but some of them do. and so this is why prone has been very valuable in patients with covid but that is in people with pneumonia, just does not apply to people with normal lungs. it's not happening. >> dr. tobin, also a lot of people sleep in the prone position. >> yes. >> is that dangerous? >> no. because again for the average person you have so much reserves. so, i mean, for a drop of 24%
for you is not going to have any impact because you have a huge amount of reserve it's not going to matter. but if somebody who drops the lung volume by 24% and then that person is going to have to cope with a knee on the neck and is going to have to cope with having the arms pushed up and being unable to move the left lung, then it's a whole different kettle of fish. >> thank you, doctor. so have you covered the third mechanism the prone position? >> yes. >> then let's talk about the fourth. which is the knee on the back arm or side. >> yes. >> now, if we bring to mind mr.
chauvin's right knee on mr. floyd back or left side -- let me ask this. forget that question. does it matter whether the right knee was on mr. floyd back or left arm or his site. >> was no. it's really all about into the same. because we talking again back to the bucket handle and the pump handle. so whether it's on the back or rand in against the side and down on the arm, all of these are just going to markedly impair your ability to be able to move your chest with your bucket handle and your pump handle. you just can't do it. it's all rammed in. also the whole time in this case you have to constantly keep in mind that this is taking place on the street. the street is playing a huge part because it's coming in in the front and totally preventing every action happening on the front. >> did that influence mr.
floyd's oxygen reserves? >> yes, they are going down. once the eelv goes down every proportionate decrease you are seeing in the eelv you are seeing the same proportionate decrease in the oxygen stores. >> were you able to calculate what that influence was? >> yes. >> i want to share what is marked as exhibit 932. and ask you, dr. tobin, does this reflect the calculations that he did? >> yes, this does. but now you see -- >> one moment, doctor. your honor, i want to, i offer exhibit 93232. >> any objection? >> no objection. >> 932 is received. >> now doctor please tell us what we see in 932. >> what you were seeing now is that networks no longer just prone. now you have the knee on the
back in addition or the knee on the side. and so it is, this is going to her the compressed down the eelv. so here you are seeing that the eelv is now being really squashed down. so 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 there's 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. and so when you decrease the size of the eelv, that's going to cause it. and an additional effect is 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 come with each breath he has to try and fight against the street. yester try to fight with the small volumes that he has and then he has to try and lift up the officers in the with each breath, and also remember yester try and also lift up the effect of the other officer pumping in his arm with a handcuffed arm. they are pushing it into his chest. so yesterday call these efforts to try and breathe against that. >> so doctor when you tell us about a 43% reduction, 24% of that is just being in the prone position? >> correct. >> the of the 19% is the contribution of the knee on the neck? >> exactly. the other 19% -- so 24% from being prone and another 19% coming from the knee on the back. >> just so we're clear back.
>> just so we're clear for the jury had his this translate into difficulty in breathing? >> 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 effect of nothing else. that's even leaving out the effect of the knee on the neck. just some look at what's happening within the chest. so there's a huge increase in the work that mr. floyd was performing just to try and cope with what was happening below the neck, leaving aside what is happening above the neck. >> doctor, i want to show you exhibit 922-926. and that you have a chance to see them i want you first to identify just what we are seeing in those before we show to the jury. >> yes, i identify. >> tell us please what it is for the record. >> we are looking at the effect
of the lungs on the hypopharynx beginning with mr. floyd sitting on the sidewalk. >> your honor, offer exhibit 922 through 926. >> any objection? [inaudible] [inaudible conversations] >> no objection. >> 920 through through nine it is my sixth inclusive are received. >> doctor, if you walk us through these help us understand a link of the hypopharynx in the case of mr. floyd. >> right. before you look at the hypopharynx just looked down at
the lungs and you see that the lungs as you'd expect their expanding with each breath. you see the type am going to pick you can see the pump handle action, the lungs are getting bigger, the back then you see that exactly as the lungs are expanding, if you focus up in the yellow box and then the yellow box is enlarged over on the right side. and you can see that as you inspire, the size of the hypopharynx is also inspired come is enlarging. so you were seeing both of these happening, so it is the effect of the of the lung volume, how it influences the opening of the hypopharynx. and this is sitting on the sidewalk. >> so looking at exhibit 922 what do we see here now in the prone position? >> so now we see mr. floyd after he is turned prone and now we can see the lungs are smaller than they were because they fall
as we know when you turn prone. and then you also see now that the area, the hypopharynx, is further narrowed because the lungs as they get smaller they have less effect in keeping it t open. and so that gets smaller. >> okay. >> and then we have the knee on the back, and now we with the knee on the back, then the lungs become further reduced like i showed you for the precise calculations of the volumes and now you see here is the size of the hypopharynx further is shrunk as result of it. so the opening through the hypopharynx is impacted by the knee on the back. >> and if we compare them altogether all three -- >> you were seeing than her altogether. on the left is sitting on the sidewalk, then just the effect
of prone and then the effect of prone with the back compression. you can see the arrow is pointing out to you on the first one what is the hypopharynx right, that area, and with -- you can see it is expanding when he is sitting down. and then when he is prone and when he is prone with the back compression. you are seeing that the area of expansion is skating smaller, as exactly as what you would expect to happen. >> going back to mr. floyd salon volumes, dr. tobin, is there a point in time when you determined -- mr. floyd's lung volumes -- where mr. floyd does not have enough oxygen in his stores remain conscious? >> yes, there is. >> and when was that? >> the time in terms of the loss
of consciousness was 24:53. we can have precise in terms of where the absence of consciousness occurs. >> and can you tell bifacial features? >> i mean, this is something i do not as a physiologist but as an icu doctor. we are always looking at facial features to be able to tell how conscious somebody is. and we can tell how your eyes for how you move with the n your face, and that you will be able to tell is the person conscious or unconscious. it's a very important sign in patience as we are taking care of them, to be able to monitor that and in the primary way we monitor it is by speculates i would've done this millions of times. >> do you know, dr. tobin, what is oxygen level would've been at the time he went unconscious? >> yes, we also know that at the time you get somebody who is in the situation who is at risk, we
know that the moment at which you lose consciousness the level of oxygen in your blood will be 36 here at the number that is associated based on very hard scientific data telling us that. >> and against the normal level of oxygen was -- >> in mr. floyd was 89, and a 46-year-old man you man you expect the normal level of oxygen is 89. the level at which you would have an absence of consciousness then would be 36. >> doctor, i want to shoot exhibit 928. -- show you. if we could clear the screen, your honor. first for the record before we show this to the jury can you just identify what is exhibit 928? >> we look at the effects on mr.
floyd's oxygen as result of all the various maneuvers that are being done to him. >> your honor, i i offer exhit 928. >> any objection? >> none your honor. >> 928 is received. >> so tell us, dr. tobin, what we see here in exhibit nine under 28? >> we are looking at, i mean whitney kent the level of oxygen when i saw it, begin with a level of oxygen of 89, and then we see that it falls down to 36. the slide is looking a bit different than what i saw before. so here you see that the level of oxygen forehand is 89 and then at the point when we notice the lack of consciousness in his face that the level of oxygen dropped down to 36.
so that tells you, that tells you for the time of the loss of consciousness. and we know it continues from their, from the time that he stopped breathing, which is 20:25:16 and then i calculated out that from there on that you can calculate based on a given very rigorous science when the level of oxygen would have gone down to zero. but this first one we are looking at the level, the loss of consciousness at 36, and that's happening at 20:24:53 and we are able to tell that by looking at his face. >> and 20:24:53 is 8:24 p.m. and 53 seconds? >> correct. >> was a point in time when mr. floyd no longer had any oxygen left in his body?
>> there is because once again when he stops breathing at 20:25:16 then it would take another 25 seconds for the level of oxygen to go down to zero. at that point he would have enough oxygen left in his entire body. >> doctor doctor, i want tt exhibit 931. >> okay. >> and ask you first if you adjust tell us what it depicts before we show it to the jury. >> yes, that is it showing exactly. >> what you receipt in 931? >> so what we are seeing in 9:30 one is that his level of oxygen has got all the way down to zero. >> so we will show this to the jury but first let me move to admit exhibit 931. >> any objection? >> none, your honor. >> 931 is received.
>> dr. tobin would you explain what we see in exhibit 931? >> we are seeing the love of oxygen has gone down to zero, that there is at that point does not an ounce of oxygen left in his body. and again this is totally calm you can figure this out with very precise science looking at once somebody stops breathing what would be the level of decline oxygen how long it will take to reach zero. so we see here that he reaches a level of zero of oxygen at 20:25:41 ansell at that point does not an ounce of oxygen left in his body in his entire body at 20:25:41. >> so was the knees and lifted off his neck at the point there was no oxygen in his body? >> no. than need be made on the neck for another three minutes and
two seconds after we reached the point where there's not an ounce of oxygen left in the body. >> thank you, doctor. are you aware of a study suggesting that putting someone in the prone position and putting a weight on the back is not dangerous pgh yes i am aware of these studies. they largely come out from san diego from the group of dr. chan and his colleagues. >> are you able to generally characterize the nature of the study for the jury? >> the bottom line is they are highly misleading. >> are they relevant to the analysis you have just given to the jury this morning? >> no, they are not relevant to the analysis we have gone through this might. >> help us understand why. >> okay. the problem is in these particular studies, i mean i don't know how many and total but could be close to ten of
them, and where they take people -- first of all that take perfectly healthy volunteers here if they bring them into the physiology lab and they lay thin flat input of matt on them which is different from the street and they put weight on top of them so the weights could be led weight in bags or in many of them they use kind of the barbells that you see in the gym like an olympic wheel that you see in the gym for weightlifting, and they place those on the back of the subjects and a measure various lung volumes it's a typically they will measure what we call maximum ventilation. these are specific types of lung function tests that you don't need to bother with but they are showing a decrease in lung availability of around 35%. that's a substantial decrease in your lung volumes that you are finding.
and then they conclude in virtually all of their studies that that level of decrease in lung volume doesn't matter because there's no change in the level of oxygen. and so, therefore, it's not clinically relevant. the problem is in doing a study like that oxygen is the exact wrong arctic to be using in a study like this. what they needed to do is continue to measure out the changes in lung volume like the eelv showing what happens to this. oxygen will only fall at the very end. it's an extremely insensitive measure your it's very important but it's very insensitive to know that stuff is going back inside the body. that's going to be a very late event. and so for their concluding of this -- >> do have another question? [inaudible] >> so to help us better
understand, dr. tobin, are these studies measuring the diminution or decrease in the oxygen reserve, the eelv? >> no, they are not. >> i want to show you what is marked as exhibit 948. and does exhibit 948-point to one of the studies that you were referring to? >> yes, it does. >> would it be helpful to use this like to explain your testimony? >> yes, it would. >> your honor, we would offer exhibit 948. >> any objection? >> none, your honor. >> 948 is received. >> so look at the slide, dr. tobin, what does this tell us in terms of, for example, the surface area that is involved of the weight on the back.
>> so if you look at the subjects back you can see here that there are four weights out of the gym that a place on the back of the subject. and the big wheel out at, and olympic plate come is going to have a diameter of 17.5 inches. see you can measure the cross-section of very of that is going to be 240 square inches. the trouble is that when officers kneel on the back of a suspect they don't place and olympic wheel on their back. they place their knee and so the sectional area of the knee is 24 square inches, which is one-tenth of the area of the big bells you are looking at here. and so we know from simple physics that pressure is forced over area and 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 can. >> so the pressure being exerted by an knee is ten times greater is what you're saying? >> ten times greater than come is going to be affected by the bell here that is shown out of the gym, the bar that you're looking. >> do any of these studies involve an knee on the neck? >> nobody has been any studies involving the knee on the neck. i suspect it would have major trouble getting that through the ethics committee in any medical school. >> do any of the studies go on for nine minutes and 29 seconds? >> no. they are all very brief studies. >> said doctor come have we now covered the four mechanisms that resulted in mr. floyd schaller breathing and reduction of the hypopharynx? >> yes, we have. >> -- shallow. >> were you or are you aware
that mr. floyd had some pre-existing health conditions? >> yes, i am. >> and how are you aware that? >> i read them in the records from hennepin county and obviously also saw been mentioned in the autopsy. >> do you have an opinion to a reasonable degree of medical certainty as to whether a person who had none of this pre-existing health conditions, a healthy person, would have died under the same circumstances as mr. floyd? >> yes. a healthy person subjected to what mr. floyd was subjected to would have died as a result of what he was subjected to. >> are you also aware that mr. floyd was found to have type of tumor known as i picking glioma? >> yes, i yam. >> and for the ladies and gentlemen of the jury , what is a pair glioma? >> it is a type of a tumor that is found in the parable indians come sometimes in the pelvis.
>> is the finding of this significant to you as relates to mr. floyd and his death? >> no. because one of the key things about it is it is called a 10% tumor which means 10% of people secrete adrenal but that could be important but 90% of them don't secrete adrenaline. so you don't -- nine out of ten of the time you have no increase in the amount of adrenaline. >> so if somebody were to die from a tumor, from some effect would be a sudden death? >> yes. there's been six reported cases of people who have had those who died suddenly but that's the total in the literature, six. those people who died have headaches. mr. floyd complained of a lot of pain and a lot of different regions in the street but he did
not complain of headaches. >> so in terms of reported cases where people have died from paragangliomas over the entire world there are six reported cases? >> yes. >> on all those sudden death? >> yes. >> did mr. floyd died of sudden death? >> no. >> i want to talk you about the different subject that the jurors may have heard one of the officers say if you can speak you can breathe. >> yes. >> is that a true statement? >> it's the true statement but it gives you an enormous false sense of security. certainly at the moment that you are speaking you are breathing, but it doesn't tell you that you're going to be breathing five seconds later. >> so let's talk about kind of why this is significant. so could you tell us about something that may seem obvious, that is, what is required for
speaking? >> right. for speaking you only speak when you're exhaling. you have to blow air out and then you vibrate the vocal cords and that's all there is to speech. so it is air going across the vocal cords, fenofibrate and you speak. but to speak there are two things important. one is you cannot blow air out if you didn't take a breath in before hand. so you must have had an inspiration in to speak. second thing is you cannot speak if your brain is not alert. so when you see somebody speaking, you know that have had an inspiration momentarily before they are speaking, and that there is oxygen going to the brain at the time that they are speaking. >> and by inspiration you mean they haven't taken a breath in?
>> right. >> was a time of mr. floyd's speech during the restraint import your analysis? >> yes, it was. >> why so? >> because it tells us for the time that he speaking and he continues to speak for four minutes 51 seconds from the time thing is placed on his neck, it tells us that there could not have been complete compression, not the been total inclusion of the neck at that time for that time because he's continuing to speak for four minutes 51 seconds. >> is a brain sensitive to oxygen deprivation? >> the brain do so sensitive to needing oxygen. >> what percentage is a body weight and how much oxygen doesn't does it consume? >> the brain is relatively small. it is only 2% of our bodyweight
but it takes in 20% of all the oxygen that we take in. so the brain eats up oxygen at ten times the normal level. it needs a huge amount of oxygen because it's in the out millions of nerve signals every second. so it needs very high supply of oxygen. >> how long can the brain go without oxygen? >> that is well worked out. if you stop the flow of oxygen to the brain, you lose consciousness in eight seconds. >> if you might recall mr. floyd's last words, i can't breathe, i those words significantly as a pulmonologist? >> yes. obviously they are important different ways. one is complaining to you of difficulty with reading but they are also telling me that at that time when he is saying please i
can't breathe, we know at that point he has oxygen in his brain, but and again is the perfect example of how it gives you a huge false sense of security because very shortly after that we are going to see that he has a major loss of oxygen in the way that he moves his leg. and so it tells you how dangerous is a concept, if he can breathe or if he can speak he can breathe. yes, that is true on the surface but highly misleading. very dangerous matchup to have out there. >> so if i'm hearing you correctly when he says i can't breathe that shows his brain is a? >> yes. >> i did meet them there wasn't? >> correct. >> and did you see or is anything in the video that you could show the jurors that they can see also that would point to
the fact that his brain was a longer alert? >> yes. >> let me pull up exhibit 47 already in evidence. at 20:24. i'm going to play a a clip for you, dr. tobin, and then tell the jurors what they see afterwards. >> so this key finding that you are seeing here, and that is when you see his leg going up come here to keep in mind he is prone so he is facing down. this is his leg coming up backwards. so that is what we call as clinicians, that is an extension
of the of the leg and that is something we see when somebody suffers major brain, lack of oxygen. and it tells us at that point he is having what are sometimes called myotonic seizure, sometimes called hypoxic seizure. there are different terms that are used to really all about to say that you are seeing here fatal injury to the brain from a lack of oxygen. >> it sometimes also called anoxic seizure? >> it has all of the step of words. there's lot of different words that are used but they all come down to the same thing, that it is that at that point the brain is responding to be drastically low level of oxygen at present. >> and does the fact when an anoxic seizure reflect damage to the brain? >> it indicates severe damage to the brain.
>> and the reflex that we saw with the likes coming up, , is that an involuntary reaction? >> it is an involuntary reaction. there are a lot of different medical terms we apply but the bottom line is that you are seeing that the leg jumps out like that as a result of fatally low level of oxygen going to the brain. >> we talked about the brain injury. we also told us earlier about low levels of oxygen potentially causing pulseless electric activity. >> yes. >> is a also then evidence of low oxygen? >> right. so, i mean, we have low level of oxygen that's going to show up in the brain and is also going to show up in the heart. and when it shows up in the heart it's going to cause the heart to beat abnormally.
and the particular way that it happened in mr. floyd was you develop a particular arrhythmia called p.e.a., which is pulseless electrical activity where we are seeing their electricity in the heart but it is not resulting in any mechanical force. that is why it is asked that name. so it's the low level of oxygen is producing both. we don't see that dea and tell that is shown up on the ekg in the angeles. so it's much later that we see the evidence of it in terms of display. but here we are seeing huge evidence in terms of the leg. the lake is crucial here because this is the time, the first time you are seeing there is major oxygen damage. >> so we reach the point where mr. floyd couldn't speak due to
low oxygen. was it any correlation also to a narrowing of the airwaves that present his being able to speak? >> yes, as well. >> i want to show what is marked as exhibit 934, 936 and 933. and just tell us what are these images, in general? >> we are seeing again the same mri but as a different view of it that we looked at before. >> i offer exhibit 934, 936 and 933. >> any objection? >> no, your honor. >> exhibit 934, 936 and 933 our received. >> is a doctor, tell us what we see here starting with the first -- >> this is the same mri you saw before, but what you are being,
your attention is drawn to by the yellow arrow is the vocal cords. and the vocal cords is simply how you speak. so to speak you must inhale. you must take care into your lungs and then when you let the air out of your going to vibrate those little vocal cords and that's what makes the sound of speech. so here we see the size of the windpipe, the trachea, and this becomes important in terms of speech. because our knowledge about the influence of the size of the trachea, the windpipe for speech, is from patients who have had an intubation to in place and it is to develop scarring after that pixel as a result of the scarring we know what is the point of how much scarring in your windpipe will prevent you from speaking.
answer these are just the dimensions. so as you know what is the size of the normal trachea. it is between a quarter and a time, as you can see here in terms of the diameters. >> next slide. >> and here is when those coins have been shrunk to 15%. and even when the trachea has narrowed all the way down to 15% you are still able to speak. even when the whole 30 windpipe is just the size as i shown here i have shrunk the size of the coins you are still able to speak. so it tells you how dangerous it is to think, well, if you can speak, he's doing okay. because at this point you will be able to speak, but again if there is a small increase in the amount of narrowing here, not only will you not be able to speak, you won't be able to
breathe. you won't be able to live. so it is a very dangerous thing to think that because you able to speak you are doing okay. >> and so, doctor, you're not able to speak, briefed or live once the airway narrows to below 50%? >> correct. you go from 15% you will still be able to speak and then as it gets lower from that, initially you'll be struggling and then at some stage you just won't be able to do anything. >> if we could show exhibit 940. it's already admitted. >> so again this is exactly -- this is the same experiment i showed you before. and it just so happens this is pure coincidence. it's at 85%. you look at the top curve and that's the same number that we showed you on the mri. this is pure coincidence but you
can see here once you're up at 85% that the work of breathing is enormous at seven and a half fold increase. and then as as a narrowing wd get further and further, then the work will become unbearable. so again it just emphasizes at the point where you can't speak and you are in deep trouble. >> on doctor, i would like to transition now 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 to your opinions they also? >> yes. >> did you do anything to try to understand mr. floyd's actual rate of breathing? >> yes, i did. >> why was at important to do? >> because a major part of my work as a lung specialist is
looking at people's breathing. you get an awful lot of information by looking at how the breeze, by looking at how they use her chest wall. all of this is extremely informative. and at the lowest level, one of the simplest things to do that is a station informative is simply to count how many breaths somebody takes in. it's one of the five sites like blood pulse, temperature, , it's one of the signs that tells and gives us a lot of clues as to what is happening inside the body. >> is a something you have done before? >> i have done it millions of times. >> do you train others in -- >> therapist, medical students, doctors in how to do it. >> and so you are counting the breaths. do you observe the muscles and things also? >> separately from counting the breaths you're going to look at the different muscles there you think of whether using their student mastoid, what type of
bucket handle, what type of pump handle action, looking at all this, with some as old as me i can see all of this very rapidly. >> so did you take this clinical experience and apply it to your observations of mr. floyd's breathing in this case on the videos? >> yes, i did. >> was their video evidence from which you could take measurements? >> yes, there is. >> i want to show exhibit 43 that's already in evidence. i want to play this, doctor, and afterwards tell us what we are seeing. in one moment it will start. >> so if you focus down here
where the handcuff, where his arm is close to his black shirt is best placed place to u can count out his respiratory rate. you are seeing that is making respiratory rate here. then another. and so we need to play it back so i need to tell you first where to focus. if you focus down there you will be able to count out the rates. >> we will play it once more so that you can count the rates to see what you are referring to. >> one, two, three, four, five, six, seven, eight. >> so that was roughly a
17-second clip? >> right. >> and you can to seven or eight? >> between seven and eight. >> did you use this to calculate a rate of respiration? >> yes, because i mean it's simple once you have 19 seconds and you count out the number of breaths you have here and if it, said you count out to seven, that will come out at a respiratory rate of 22. >> is that number the respiratory rate of 22 significant to this case? >> extremely significant. >> why is that? >> because one of the things in this case is the question of fit no. and if fentanyl is having an effect and is causing depression of sedges, the stench of that control breathing, that's going to result in a decrease in the respiratory rate and it is shown that with fentanyl you expect a 40% reduction in the respiratory rate. so with fentanyl his respiratory
rate should be down at around ten instead of that it is right in the middle at normal at 22. >> so you didn't see a depressed rate of respiration or breathing rate in mr. floyd's? >> no. it's normal. >> and so what does that tell you bottom line with respect to -- >> exactly come in terms of fentanyl, the major, one of the major changes you see in fentanyl is a slowing of the respiratory rate. and again we would be expecting a 40% reduction in the respiratory rate with fentanyl. the normal respiratory rate is 17 breaths per minute, plus or -5. so that that would be a normal respiratory rate of between 12 and 22. that's the the normal range of respiratory rate. and so it was with fentanyl you would be expecting a respiratory
rate of ten instead, you can't get yourself and you can see when you counted yourself the respiratory rate is 22. so basically tells you that there isn't fentanyl on board. that is affecting his respiratory rate senses, not having effect on his respiratory sensors. >> so mr. floyd's respiratory rate was normal at 22 just before he lost consciousness? >> correct. >> so the jury may have heard some other information in the case about the fentanyl related to an elevated carbon dioxide level in mr. floyd's body in the emergency room. was that significant to? >> yes, that is very significant as well. >> also? >> because he is reported to have -- i take it back. he's reported to have a carbon dioxide level in the arterial blood in the emergency room of
89 that's a very high level of carbon dioxide, and so you have to take into account what are the factors that might have led to that. and there's particularly important factors in mr. floyd to explain why his carbon dioxide was found at 89 in the emergency room. >> would you first tell us what would normal have been for carbon dioxide level? >> the normal carbon dioxide level in you army is 35- 35-45 millimeters of mercury. that's the normal. you don't need the millimeters of mercury stuff, but they are the units that are given in the hospital chart. >> so you said there were significant factors in case of mr. floyd. would you help the jury understand what those were? >> yes. the important factors are that we know that he made his own last spontaneous effort to breathe at 20:25:16.
after that you can look at the videos and you see he makes no effort. he makes no breath the last breath he took was at 20:25:16. then we know after that he stayed on the street for another three minutes or so, then he is placed into the ambulance cot and we know that in the ambulance they attempted to put in an airway, and i jill, and you can see that on officer lane's bodycare. you can see all of that happening. and then you can see the time at which it actually successfully insert the airway and when they gave him the first breath. and that is a gap of nine minutes and 50 seconds from when he last took a breath. >> why is that significant? >> that very significant because we can calculate what is the rate of increase in the carbon
dioxide in somebody who doesn't believe. if somebody doesn't take a breath, carbon dioxide increases at a predictable rate. and that rate is up to 4.9 millimeters of mercury per minute. that it increases. and so he is not taken a breath for nine minutes and 50 seconds, so you would expect just on that basis that his carbon dioxide level would go up by 49. so you add 49 to the normal values of 35-45, and then you add that and you get a value of between 89-and above so it comes out virtually identical to the value that they found in the emergency room of 89. >> so doctor, what is a punchline with respect to that?
what does it tell us? >> the significance of all that is it's the second reason why you know fentanyl is not causing the depression of his respiration. what you are seeing is that the increase in his carbon dioxide that is found in the emergency room is solely explained by what you expect to happen in somebody who doesn't have any ventilation given to them for nine minutes and 50 seconds. it is completely explained by the. >> so when a person is not breathing then carbon dioxide which naturally continue to build up in the body? >> yes. >> that's what matches what was seen in the o.r. for mr. floyd? >> precisely. >> you said there were other things that were significant that were related to the rate of respiration that we talked
about, fentanyl. >> right. >> was or anything else? >> yes. the other things, there are two other things that are very important because you saw with your own eyes exactly his respiratory rate. and the first thing is that these you have somebody who is underlying heart disease and heart disease is so severe that it is been set that it is causing shortness of breath, that it is causing you difficulty with reading, if somebody has heart disease that is causing shortness of breath, virtually all of those patients are going to have very high respiratory rates. ..
the physiological response, where we are narrowing is a normal respiratory rate and that is what he has. the respiratory rate you see is normal, it's the expected physiological response in somebody who has their airway narrowed. >> so doctor, we covered the mechanisms of how low oxygen occurs . as a clinician did you observe low oxygen in the videoshowing the last minutes of george floyd's life ? >> yes.
>> what did you observe? >> in terms of what we are seeing is the changes in his facial appearance . thisbecomes crucially important .you see the effects of the low oxygen. >> have you seen thiseffect in other patients as a clinician ? >> yes, because i work in an icu where 40 percent of our patients die i am extremely familiar with seeing people dieunfortunately. when you see these changes, you see the changes in the face . is the key way of noticing something happening is by looking at the effects on the face. >> doctor, i want to showyou exhibit 15 already admitted into evidence . 4:04. i want to play a clip and have you tell us what itshows
. >> at the beginning you can seehe is conscious . you can see slight from pickering. and then it disappears. so one second he's alive and one second he is nolonger . >> could we just one more play it back so jurors can see it. just one second. it is 20:24:53. and the speed is slow down after just so we can see.
>> you can see he's conscious and then you see that he hasn't. that's the moment the light goes out of his body . >> i want to also show you a from another body worn camera exhibit , 43 . from mister nelson. 20:22. and i want to play this for you also doctor and you can tell the ladies and gentlemen of the jury what this is. >> now he's blocking his
right side. you can see how he's using his hips to try to rock the right sideof his body to get air . you can see him again pushing down to getair in . these movements of his head you may miss but he's having to use all his entire body to just try to get airinto that right side of the body . keep in mind the left side is nonfunctional from the way they have manipulated him and pushed him into the street so he's constantly cracking up the right side of his body, you can see it right there to get some air into his right side of his chest. he's making repeated struggling movements. he's moving again the hips because he's using his spine to try and get them, those muscles to move air into the right side.
and he's again trying to use his right arm and he's not able because of the chain, the small chain linking it over to the left side. he's pushing down that right arm into the street he's unable and he's unable to do it because of the chain and handcuffs. >> and at some pointmister floyd stops speaking and what does that tell us about his oxygen supply ? >> where he is not speaking it tells us the airway narrowing into his upper airway is more than any five percent. and then it's separate in terms of the oxygen level. that we're seeing my face but they're all happening together. one is seeing how much narrowing there is in the airway but they're all coming in together. >> and then did the restraint stop at the time of the brain injury that he a arrhythmia.
>> yes. >> the constraints stopped at that time? >> know, restraint continues after he seizes the respiratory efforts. when he's taking his last breath the knee remains for another six minutes 27 seconds after he takes his last breath. the knee remains. after there is no pulse, the knee remains on the neck for another two minutes and 44 seconds after the officers found themselves there's no burst. then he remains on the another two minutes 44 seconds. >> thank you doctor tobin,no further questions .
>> at the hennepin county courthouse in minneapolis day nine of the trial derek chobani charged in the death of george floyd. they're taking a lunch break until about two: eastern. 1:30 essential or so we will be back with live coverage, hearing from doctor mark bowman, a knowledge is of the events, to begin their cross-examination so our live coverage will resume a reminder to showing the entire trial of the night, the entire day's proceedings in eastern europe on c-span2 and if you miss any of the previous day is available at c-span.org. at the lunch break is underway we willshow you testimony from earlier today . >> good morning everybody.