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Prosecution Questions Pulmonology Expert in Chauvin Trial. Aired 11-11:30a ET

Aired April 8, 2021 - 11:00   ET


DR. MARTIN TOBIN, PULMONOLOGIST: In and that's compressing in against his side as well.


So the ability to expand his left side here is enormously impaired. And also, you're seeing that the size of the chain between the two -- the right side and the left side is very short. So he -- his whole left arm is also being pulled over. And so, it's preventing him also from expanding the right side.

I've been focusing on the bucket handle and the pump handle on the left. But you can also see here that these are impaired, his ability to expand his chest.

And, of course, the key factor you must keep that is in kind of a sense seen here in one sense is the street. The street is what is having a huge effect because he's jammed down against the street. And so the street is playing major role in preventing him from expanding his chest.

JUDGE PETER CAHILL, HENNEPIN COUNTY COURTHOUSE: You may use the stylist to draw on the screen.


Now did you select another still image that you observed as Mr. Floyd struggled to breathe?


BLACKWELL: I'm going to show what you is marked as state's exhibit 942. And if you can just identify it.

TOBIN: I identify it.


BLACKWELL: Thank you, Your Honor

So, do you recognize this as the still image that you selected?

TOBIN: Yes, I do.

BLACKWELL: Your Honor, we offer state's exhibit 492.

CAHILL: Any objection?


CAHILL: 942 received.

BLACKWELL: Could you tell us, Dr. Tobin, what is the significance of this image, of what we see here?

TOBIN: What you're seeing is slightly different than the two images. But they marry together. If you look on the left side, you see his finger is pushing against his street -- the street. You also see the hands here of the officers around his left hand. You can see the left handcuffed arm as we discussed. You're seeing a more clear view here, how it is really rammed into the back of his back. There is just no way he's going to be able to expand that.

But with this -- the left image you see the finger on the street. Then over on the right image, you see his knuckle against the tire. And to most people, this doesn't look terribly significant.

But to a physiologist, this is extraordinarily significant, because this tells you that he has used up his resources and he's now literally trying to breathe with his fingers and knuckles, because when you begin to breathe, you begin to breathe with your rib cage and your diaphragm. Then the next thing you recruit after that is your sternum muscle which is the big muscle in your neck. And when those are wasted up, then you're relying on these types of muscles like your fingers to try and stabilize your whole right side, because he's totally dependent on getting air into the right side.

So he's using his fingers and his knuckles against the street to try and crank up the right side of his chest. This is his only way to try and get air to get into the right lung.

BLACKWELL: Doctor, showing what you is marked as state's exhibit 938. Is this related series of photographs and images?


BLACKWELL: Your Honor, we offer state's exhibit 938.

CAHILL: Any objection?

UNIDENTIFIED MALE: No, your honor.

CAHILL: 938 is received.

BLACKWELL: So, Doctor, tell us what do we see in exhibit 938?

TOBIN: The focus with -- the top panel is the same as the bottom one. The bottom is just the blowup of what you're seeing on the top. The focus on the left hand side is his shoulder.

And, again, as I mentioned, when you have difficulty in breathing, you begin with the diaphragm, the rib cage. You go on to the accessory muscles, like the sternum muscle, one of the very last muscles that you will use is your shoulder.

You don't really use your shoulder for breathing. But if you look here on the left hand side, the shoulder is extremely prominent. So, this is what people in the gym call sculpting of the shoulder muscles.


And you're seeing them standing out very prominently.

So, at this point on the left hand side, he is taking a breath in. Using his shoulder to try and get a breath in. And then on the right side, you see between the breath where he's relaxing. He's not -- he's breathing out.

And it's the two of them are shown so as you see the marked effect on the left. But again, you have to realize that the shoulder is a very ineffective way of breathing, because at that stage, the chest is also expanded. So when you contract your shoulder, because the chest underlying it is so expanded, you get very, very little air in.

It's a very poor way of breathing. But it's what you have to do when everything else is failing, with you're in extremis, you will call on the use of the shoulder to try and breathe.

BLACKWELL: So, Dr. Tobin, have we covered the first item, the handcuffs and the street?


BLACKWELL: So let's talk about number two, the knee on the neck.

Explain why the knee on the neck is so significant.

TOBIN: The knee on the neck is extremely important because it's going to occlude the air getting in through the passage way.

BLACKWELL: So is it possible, Doctor, to perhaps illustrate with an anatomy lesson?

TOBIN: Yes, so --

BLACKWELL: It may be relevant.

TOBIN: To understand the knee on the neck, you need to examine your own necks, all of you here in the jury, like I'm doing now. And so the first thing is, if you put your index and thumb up here at the top of your neck, the first big thing you're going to find is your Adam's apple. You can find the Adam's apple and it's a very sturdy structure because it is surrounded by cartilage and protects the voice box, the larynx, which is essential to -- for speech.

And so any amount of compression on the Adam's apple is not going to compress it. This is an extremely strong, sturdy structure. It's not going to be compressed by a knee on the neck. Then you go down from your Adam's apple and you feel the little bumps

beneath that. And these are the rings of cartilage of your trachea, or your trachea. So this is your windpipe here.

And so that's, again, because of the cartilage there, a knee on the front part is not going to cause compression. Okay?

But then bring your finger up to the top of your Adam's apple. And up at the top of your Adam's apple, you're now directly over the hypopharynx. And the hypopharynx is the crucial area in Mr. Floyd.

So, this here is where the hypopharynx is located on your surface anatomy.

BLACKWELL: So why is the hypopharynx important for understanding this case, what happened?

TOBIN: It's very important for understanding this case for a number of reasons because it's so vulnerable, because it has no cartilage around it. Its going to be an area that is compressed. It's extremely small to breathe through. And it becomes very important for being able to continue to breathe through.

BLACKWELL: Doctor, I want to show you what's been marked as state's exhibit 935 and 937. Could you identify just for the record tell us what is depicted?

TOBIN: Yeah, I'm looking at 937 which is the hypopharynx.

BLACKWELL: And then 935? Here we go. And 935 --

TOBIN: I'm look being at 935, the hypopharynx with a coin.

BLACKWELL: And do these two images fairly and accurately depict the hypopharynx?

TOBIN: They do.

BLACKWELL: Your Honor, I offer state's exhibit 935 and 937.


CAHILL: 935 and 937 are received.

BLACKWELL: We can show them to the jury.

So, Doctor, using exhibits 937 and 935, could you help us to better understand what the hypopharynx is and what it does.

TOBIN: Right. What you're looking at here -- does this work? Yeah, it does.

So, here where I have drawn in red is the top of your tongue. Okay? And that's the tongue there. And then above it is an empty space and then above that is the top of the hard palate. So, that orientates you there. [11:10:05]

And so, then the tongue comes down along here. And the critical structure in this case, because the act of speech in Mr. Floyd becomes very important -- how he was able to speak and all these different things.

So the structure that gives the speech are the vocal cords right here. And they're in the voice box and in the larynx. And then we have a little area called the epiglottis. It's a little sliver. That comes in to prevent food from going the wrong way when we're swallowing because we use the hypopharynx both for swallowing for eating, and we use the hypopharynx for breathing.

So when we're breathing, the air is going to come in through your nose or your mouth, go on down through the hypopharynx and then through the vocal cords and into the wind pipe, into the trachea, and go on down into the lungs. Whereas when you're swallowing, that trap door of the epiglottis will prevent the food going into the air passages and will direct it into the food tube at the back, the esophagus.

The area of the hypopharynx is exactly from the base of the epiglottis, the first yellow arrow down to the second yellow arrow which is the larynx. It's that little area that is the size of the hypopharynx?

BLACKWELL: Can we see 935?

TOBIN: And so, this -- we know that the cross section of area of the hypopharynx in adult people, I have it here in the millimeters, 199 to 303, which are obviously difficult to remember those type of millimeters, but, in fact, right in the middle of this is would be the size of the dime.

So a dime is basically the size of the hypopharynx and it tells you how small and how vulnerable is this area. So if it's going to be decreased in size. It's a very tiny area.

BLACKWELL: And so why is the hypopharynx important in the case of Mr. Floyd?

TOBIN: Because the hypopharynx is going to be the area that will be vulnerable to occlusion from the knee on the neck, but in addition, the hypopharynx has another aspect. And that is the hypopharynx is also controlled by the size of your lungs. As your lungs expand, you increase the size of the hypopharynx with every breath. And so there is a regulation of that that's going on.

BLACKWELL: Was Mr. Chauvin applying force or pressure to the hypopharynx of Mr. Floyd that you observed?

TOBIN: At different times. It varied from time to time.

BLACKWELL: Now, are you able to tell us if Mr. Chauvin had put his weight directly his full weight on Mr. Floyd's neck, are you able to tell us what impact or effect that would have had on Mr. Floyd? TOBIN: Right. If Mr. Officer Chauvin had placed his knee directly on

the hypopharynx, just that area of the dime and never varied from there and it kind of came in like a bulls-eye on that particular area, then you would expect that this area would be totally occluded. But it did -- it mean he varied the position -- that Mr. Floyd varied the position of his head, and Officer Chauvin also varied the position of his knee. So, it varied over time.

BLACKWELL: And if it had -- it had become totally occluded, then what?

TOBIN: If it had become totally occluded, within seconds, you were going to drop the level of oxygen to a level that will be -- produce oxygen depravation in the body resulting in either a seizure or a heart attack, one or the other.

BLACKWELL: Do you have another photograph taken from footage at the scene that would help the jury understand this point?


BLACKWELL: I'm going to show you what is marked as state's exhibit 941. And this is derive from exhibit 15 already in evidence.

Do you recognize this photograph and 941?

TOBIN: Yes, I do.

BLACKWELL: Your honor, we offer state's exhibit 941.

CAHILL: Any objection?


CAHILL: 941 is received.

BLACKWELL: Dr. Tobin, tell the ladies and gentlemen of the jury what it is you mean to convey here in exhibit 941?

TOBIN: So if you're looking, say, on the one on the left and if you look at me first before you look at that.


So if you stick your finger in your ear and you draw a line from your -- from the finger of your ear going down through the vertical bodies in your spinal column, you can get a line going down and you're looking at that axis. And that's what I've drawn in here with the yellow dotted line.

And so if you look here on the first slide, you see that Mr. Floyd's nose, his face is directly faced down on the street. It's not at any angle.

So next thing is, again, don't look at the slide, feel yourself on your own neck, and now if you put your hand at the back of your neck and you put -- at the -- you feel the bottom of your skull. And so, where the skull, the bone of the skull ends and then you come down from that and you find -- and you put your whole palm of your hand around it. Sorry?


KATE BOLDUAN, CNN HOST: Hi, everyone. I'm Kate Bolduan. We've watching the ninth day of witness testimony in the trial of Derek Chauvin.

Let me bring in our CNN legal analyst Laura Coates as well as Charles Ramsey once again.

Chief, thanks for being here.

Laura, your reaction from what we've learned from Dr. Tobin?

LAURA COATES, CNN SENIOR LEGAL ANALYST: You know, I'm sick to my stomach in his description, Kate, because what he's describing is torturous. I mean, he actually describes not only the physiology behind trying to respirate, he's a pulmonologist, an expert in this field.

But also, he talks about George Floyd being reduced to trying to use his fingers, his knuckle, his shoulder --


COATES: -- trying to lift the chest up. And you combine with not just the idea of the kneeling, but he adds a new element here, the idea of manipulation of handcuffs with the street creating a rock and a hard place. His description of this torturous end for George Floyd is so compelling.

BOLDUAN: Yeah, describing the left side of his body being in a vice and effectively rendering it as if it left lung had been removed. That's how hard it had been.

Chief, stick with me. It looks like we might be getting back into it. Let's listen.

CAHILL: You may do it -- if you were to do it, and if you wish to do it, that is your choice. You are not required to do anything that the witness instructs you to do. But feel free to do it if you wish, Mr. Blackwell.

BLACKWELL: Thank you, Your Honor.

Dr. Tobin, if we could go back to where you are explaining the anatomy in the back, and the base of the skull?

TOBIN: So as I am putting my hand here at the back of my neck and then feeling the tip of my skull and then I am bringing down my hand, I'm feeling an extremely thick ligament. That's called the nuchal ligament. It's almost as if -- if I put the full palm of my hand on my nuchal ligament, it's almost like wood. It's so strong a ligament. And that ligament is what you are seeing the knee is being placed over

on the left hand slide.

And so, with a knee direct will he over the nuchal ligament, it can cause no obstruction, because this is such a dense ligament. That's what you are seeing.

And you are seeing as well with the yellow triangle -- sorry -- the yellow diagonal here, that the bulk of Officer Chauvin's knee is above that yellow line. The second thing, separate from -- on this slide, you can see that Mr. Floyd has his face rammed into the street because he's using his face here to try and crank up his chest. He's actually using his forehead and his nose and his chin as a way to help him get air into the right side of his chest as another way to crank up his chest.

BLACKWELL: How do you contrast to what we see in the photograph on the right in exhibit 941?

TOBIN: On 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 has come down below the yellow diagonal.

And in this position, there is going to be far greater compression of the hypopharynx in this region here compared with what you were seeing on the left side. On the left side, there is no compression of the hypopharynx. 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.


BLACKWELL: And in the photograph on the right, the knee is exerting, Dr. Tobin, greater force on the hypopharynx?

TOBIN: Correct.

BLACKWELL: Is it possible to calculate the amount of force?

TOBIN: Yes, it is. So we can calculate the amount of force based on the weight of Officer Chauvin, on his body weight, taking into account how much gear weight, the gear that he carries. And then also, you have to remove out the weight of his shin bone and his boot, and so subtracting out of all of these, and then you can calculate the weight.

BLACKWELL: Can you also calculate the changes or narrowing in the space that people have to breathe through?

TOBIN: Yes, you can, separately.

BLACKWELL: Would this be in any way akin the breathing through a small opening like a straw? TOBIN: Yes, it would. So I mean, when you have to breathe through a

narrow passageway, it is like breathing through a drinking straw. But it is much worse than that, because breathing through a drinking straw -- I mean, is somewhat unpleasant, but not that unpleasant. And then it gets much worse than that.

BLACKWELL: So, as the space narrows, is it more difficult to breathe through it?

TOBIN: Enormously more difficult. And we know that from physics.

BLACKWELL: And through physics, then, is that something that can also be calculated?

TOBIN: Yes, that can also be calculated.

BLACKWELL: In that type of a calculation, though, would it be specific per see to George Floyd?

TOBIN: No, it wouldn't. This would be for anybody. We know what happens physiologically when you have this level of narrowing, this is going to happen to everybody.

BLACKWELL: Can you please explain to the jury what those calculations would show about the effect of the narrowing on the airway on breathing.

TOBIN: Yes, I believe inside a exhibit that relates to that.

BLACKWELL: Let me show you what's marked as state's exhibit 940 and 939.

CAHILL: Can we have a sidebar?

BLACKWELL: Yes, your honor.

BOLDUAN: All right. It looks like they are taking a quick sidebar once again. Let me try to bring in Chief Ramsey on this, see if we can get your take before we have got jump back in, Chief.

What is the impact, do you think of Dr. Tobin's testimony, and honestly the images that he's using, the exhibits that he is using to talk to the jury and talk us through, just the impact on you?

CHARLES RAMSEY, CNN LAW ENFORCEMENT ANALYST: This is having an unbelievable impact. It is going to have an on believable impact on the jury. He's so simple in his explanation, I mean, even I can understand what it is he's saying.

But I have been thinking about how a copy of the tape and portions of his testimony could be used for future police training, because the manipulation of the cuffs -- I mean, we talk about positional asphyxia. But when you think about all of the other things going on on top of it, that's not what you really think about. And I can see where this could actually help policing in general in terms of training.

BOLDUAN: Chief, stick with me. Let's jump back in.

TOBIN: What it's looking at is what is the effort to breathe, that's what's shown along the y-axis of the plot. And then it is with different levels of narrowing. So the very bottom one, with the white triangle is the lowest curve. That's normal. There is no narrowing.

And so, we see that as the flow varies, and shown in red is what would be the normal flow 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 lock at 60 percent airway narrowing -- and this is much more narrow than breathing through a straw -- and you can see there is really no bigger increase in the effort to breathe. It's hardly different from what -- in terms of normal.

But then if you get 85 percent narrowing, now you see that the effort to breathe increases 7-1/2 times compared with what it was with no narrowing. And so you are seeing a huge increase in the work that is required. It becomes far more difficult to breathe as the narrowing becomes more narrow.

BLACKWELL: And, Doctor, let's look at exhibit 939.

TOBIN: So, this is the science behind that plot, behind -- before I showed you. And this is just the equation in physics that tells you how that works. And the key thing, when you look at an equation like this, for me, as a physiologist is I focus on the square sign of the stricture that tells me in a when I see a square sign on top of it and it is below the level on the equation.


It is the denominator. I know with that, that you are going to be fine all along for a period of time, and then suddenly, everything is going to increase enormously. You are going into what we call an exponential increase.

And that's exactly what we see on the experiment that was done, where we are seeing there is really nothing happening at 60. It's nothing much. But then at 85 percent, it suddenly takes off. And if you have beyond 85 percent, it would be even more and more.

And 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, and at some stage unsustainable. You're just not going to be able to do it.

BLACKWELL: So, in this case, in the case of Mr. Floyd, the narrowing was of his hypopharynx?

TOBIN: It was in the hypopharynx, yes.

BLACKWELL: Did Mr. Chauvin's knee on the neck then cause the narrowing of the hypopharynx?

TOBIN: Yes, it did. BLACKWELL: So given the changes that you observed in Mr. Chauvin's

knee on Mr. Floyd over time, were any of those changes significant from the standpoint of placing pressure on the hypopharynx?

TOBIN: Yes, they are extremely significant.

BLACKWELL: Let's look at exhibit 947.

And, Your Honor, we would offer exhibit 947, which is taken from exhibit 15.

CAHILL: Any objection?


CAHILL: 947 is received.

BLACKWELL: Now tell us what we see here in exhibit 947.

TOBIN: What you are seeing is the orientation of Officer Chauvin. His body build is quite erect here. But in particular what you are 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 at Mr. Floyd's neck.

Because in many of the calculations, I excluded the effect 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 we are taking half his body weight, plus the weight of his -- half the gear. And all of that is coming directly down on Mr. Floyd's neck.

BLACKWELL: I want to show you what's market as exhibit 943. Did you assist in preparing this exhibit?

TOBIN: Yes, I did.

BLACKWELL: Would it help you in explaining your testimony?


BLACKWELL: Your honor, we offer exhibit 943.

CAHILL: Any objection?

UNIDENTIFIED MALE: No, your honor.

CAHILL: 943 is received.

BLACKWELL: And if Your Honor could clear the screen.

Thank you.

So, Dr. Tobin, what do we see here in exhibit 943?

TOBIN: What we are seeing is that half of his body weight, plus half his gear weight, is coming down. That's 91.5 pounds, is coming down directly on Mr. Floyd's neck.

BLACKWELL: Is that all we see?

TOBIN: And the reason we are seeing that is because the toe is off the ground and there is no body weight sitting back. He is not hunkering back on his heels. So everything is directed down on his knee.

In this place, his shin and his toe and his boot is playing no contribution.

BLACKWELL: And were there times also when Mr. Chauvin's left knee was on the back of Mr. Floyd's neck?

TOBIN: Correct.

BLACKWELL: And when was that?

TOBIN: When his knee is on the back, that's a separate set of forces. It's the same force, but it is compressing a different area. It is compressing inside his chest.

BLACKWELL: And what about the time when Mr. Floyd would have had his face smashed directly into the pavement?

TOBIN: When his face is into the pavement, at that time, like one of the ones I showed you, if it's coming down on the nuchal ligament, it is going to be a huge weight for Mr. Floyd to try and breathe but he won't be compressing the hypopharynx at the time when that's happening.

So all of these different forces, they are somewhat complex in terms of how they are interacting, but they are all coming to the same point.

BLACKWELL: Now, you paid particular attention, you told us, to the first five minutes and three second of the subdual on the ground?