(CNN) — A renowned pulmonary intensive care physician stated Thursday morning that George Floyd died from a “low oxygen level” when former police officer Derek Chauvin pinned him on the street and restricted his ability to breathe.
“This caused her brain damage that we see, and it also caused a PEA arrhythmia that made her heart stop,” stated Dr. Martin Tobin of Chicago, referring to pulseless electrical activity, a type of cardiac arrest.
“The cause of the low oxygen level was shallow breathing,” he added. Small breaths. Small tidal volumes. Shallow breaths that were not able to bring air through their lungs to the essential areas of the lungs that carry oxygen to the blood and remove carbon dioxide, “he explained.
Floyd’s pre-existing health conditions and drug use were not relevant to the cause of his death, Tobin said.
“A healthy person subjected to what Mr. Floyd was subjected to would have died,” he said.
The expert identified four main reasons why Floyd died: the handcuffs and the street acting as a ‘vise’, Chauvin’s left knee on his neck, Floyd’s prone position, and Chauvin’s right knee on the back. Floyd’s back, arm and side. These factors combined limited Floyd’s ability to expand his lungs and narrowed his hypopharynx, a part of the throat that air passes through.
Images show George Floyd trying to “breathe with his fingers and knuckles”
During the testimony, Tobin was shown a series of still images that came from the body camera images of the scene he had reviewed earlier. At one point, Tobin pointed out the significance of an image in which Floyd is seen pressing his knuckles against the patrol car’s tires while Chauvin is on top of him.
“For most people, this doesn’t seem very significant. But for a physiologist, this is extraordinarily significant, ”Tobin said.
“This tells you that he exhausted his resources and is now literally trying to breathe with his fingers and knuckles,” he added.
He then explained: “Because when you start to breathe, you start to breathe with your rib cage and your diaphragm. Then the next thing you recruit is the sternum muscle, which is the large muscle in the neck. When those are exhausted, then you rely on these types of muscles, like your fingers, to try to stabilize your entire right side. Because it totally depends on the air inlet on the right side.
Tobin said he concluded that Floyd was “using his fingers and knuckles against the street to try to lift the right side of his chest.”
“This is his only way of trying to get air into his right lung,” he said.
On his left side, Tobin said, Floyd was trying to use his shoulder to breathe in a similar way. The expert dI say that “because the chest below is so expanded, very, very little air enters.”
“It is a very poor way of breathing. But it’s the thing to do when all else fails, “he said.
George Floyd’s last moment alive
Prosecutors also played disturbing slow-motion video of what Tobin said was Floyd’s last moment alive. His eyes were seen to blink and then close.
“They can see his eyes, he is conscious, and then they see that he is not (conscious). That’s the moment when life leaves your body, ”Tobin said.
Tobin spoke directly toHe jury and urged them to feel parts of the neck and chest while describing how breathing works. Almost all of the jurors did as the doctor asked and engaged with the testimony, according to a report by journalists from inside the courtroom.
Tobin’s testimony came on the ninth day of the trial. Prosecutors moved on to the third phase of their case, which focuses on the medical analysis of Floyd’s cause of death.
The most important medical testimony could happen this Friday, when Hennepin County Chief Coroner Dr. Andrew Baker is expected to testify. Baker performed an autopsy on Floyd and determined that his death was a homicide.
However, Tobin noted that the autopsy may not be of much use in this case. Deaths from lack of oxygen “leave no trace” at autopsy, he said.
Chauvin, 45, has pleaded not guilty to charges of willful manslaughter, second degree manslaughter and aggravated manslaughter in an act eminently dangerous to others.
The medical analysis is important to the prosecution’s case, which argues that Floyd died because Chauvin put the weight of his body on Floyd’s neck and back for more than nine minutes, causing death by “positional asphyxia.” Chauvin’s defense attorney, Eric Nelson, has argued that Floyd died of a drug overdose and pre-existing health problems.
Chauvin remained kneeling for more than 3 minutes after Floyd no longer had oxygen.
Chauvin’s knee was on Floyd’s neck for more than 90% of the time, Tobin said. The doctor calculated that this constituted about 41.5 kg on Floyd’s neck when his feet were lifted off the ground.
By observing Floyd on the video and calculating the rate of decrease in his blood oxygen level, Tobin deduced that Floyd eventually had no oxygen left in his body. Chauvin knelt over him for another three minutes and two seconds after that point, he said.
The expert highlighted a moment from the body camera footage when Floyd’s legs are seen lifting into the air. This involuntary movement, also known as an anoxic seizure, is evidence of fatal brain injury due to lack of oxygen, Tobin said.
Additionally, Tobin explained that fentanyl played no role in Floyd’s death.