In the final moments of his life, George Floyd was so desperate for air that he resorted to trying to use his fingers, knuckles, and shoulder muscles to position himself to breathe while being pinned down by former Minneapolis police officer Derek Chauvin, a medical expert testified Thursday.
Dr. Martin Tobin, a pulmonary and critical medicine doctor with 45 years of experience, was called on by the prosecution as an outside expert witness to testify about Floyd's cause of death, which is at the center of Chauvin's murder trial in Minneapolis.
Prosecutors say that Chauvin's knee on Floyd's neck contributed to his death. The defense argues that Floyd's use of illicit drugs and underlying medical conditions were the key factors.
Tobin testified that Floyd died due to a low level of oxygen caused by the combination of being handcuffed in the prone position on the ground and Chauvin's left knee on his neck and right knee on his back, compromising his ability to breathe.
The jury was shown an image from an officer's body camera video in which Floyd's knuckles are seen pressed against the tire of the squad car while Chauvin's knees are on his neck and back.
Tobin said that while this gesture would not seem important to most people, it was "extraordinarily significant" to a physiologist.
"This tells you that [Floyd] has used up his resources, and he's now literally trying to breathe with his fingers and knuckles," Tobin said.
Tobin said that people first use their diaphragm and rib cage to breathe, but if these become unavailable then they will try to use the sternum muscle in their neck.
"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," Tobin said, "because [Floyd's] totally dependent on getting air into the right side."
Tobin said that Floyd's left side was squeezed in a "vise" between the officers on top of him pushing his handcuffs against his back and the "hard asphalt" of the street.
"He was being squashed between the two sides," Tobin said, adding that his ability to expand his left side to breathe was "enormously impaired."
He testified that Floyd was "using his fingers and his knuckles against the street to try and crank up the right side of his chest" as it was "his only way to try and get air to get into the right lung."
Floyd also tried to use his shoulder to breathe on his left side, which is "one of the very last muscles" people use to breathe, Tobin said.
Tobin said that video showed Floyd contracting his shoulder to try to get oxygen but that it was "ineffective."
"It's a very poor way of breathing," Tobin told the jury, "but it's what you have to do when everything else is failing."
The jury was also shown an image where Chauvin's toe was seen lifted off the ground while his knee was on Floyd's neck. This meant 91.5 pounds, half of Chauvin's weight, was directly compressing Floyd's neck at that point, Tobin said.
Tobin testified that his review of the video footage in the case showed that Chauvin had his left knee on Floyd's neck more than 90% of the time; his right knee moved between Floyd's back and arm and was "rammed" into the left side of his chest.
Even a healthy person who did not have Floyd's preexisting medical conditions would have died, Tobin said, had they been subjected to what he had experienced.
During the incident, Tobin said, Floyd's airway passage narrowed so much that it was "like breathing through a drinking straw but much worse than that."
Dr. Andrew Baker, the Hennepin County medical examiner who conducted Floyd's autopsy and concluded that the manner of death was a homicide, will also be called to testify for the prosecution.
The defense is expected to call its own medical experts to counter the state's arguments.