George Floyd died from lack of oxygen after being pinned down, expert tells Chauvin trial

8 April 2021, 21:28 | Updated: 9 April 2021, 13:05

George Floyd died from a lack of oxygen from being pinned facedown on the pavement with his hands cuffed behind him, a medical expert has said.

Dr Martin Tobin, a lung and critical care specialist from Chicago, was speaking at former Minneapolis police officer Derek Chauvin's murder trial.

He said, while being held down by Chauvin and other officers, Mr Floyd's breathing was too shallow to take in enough oxygen, damaging his brain and causing an abnormal heart rhythm that made his heart stop.

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Dr Tobin took the stand as part of an effort by prosecutors to establish that Chauvin's actions - and not Mr Floyd's illegal drug use and underlying health conditions as the defence contends - killed the 46-year-old on May 25 last year.

Analysing a graphic of three officers pinning Mr Floyd for what prosecutors say was almost nine-and-a-half minutes, he said Chauvin's knee was "virtually on the neck for the vast majority of time".

He said it was "more than 90% of the time in my calculations".

It appeared that Mr Floyd was getting enough oxygen for about the first five minutes to keep his brain alive because he was still speaking, Dr Tobin added.

But he explained to jurors what happens as the space in the airway narrows, saying breathing becomes "enormously more difficult" and adding that it would be worse than "breathing through a drinking straw".

Dr Tobin gave evidence that if the hypopharynx, the bottom part of the throat, becomes totally obstructed, it takes just seconds to reduce the level of oxygen to where it would result "in either a seizure or a heart attack".

Prosecutors showed images of Mr Floyd side by side, one with the front of his face smashed against the pavement and another with his head turned.

Dr Tobin said that when Mr Floyd's head was face down, a ligament at the back of his neck would have protected his airway.

But with his head turned, Chauvin's weight would have compressed the hypopharynx.

The expert calculated that at times when Chauvin was in a near-vertical position, with his toes off the ground, half of Chauvin's body weight, 91.5lb, was directly on Mr Floyd's neck.

Dr Tobin said other factors worsened the effect on Mr Floyd. He pointed out that Officer Kueng held Mr Floyd's left hand upward, and Chauvin's right knee compressed Mr Floyd's side, meaning "the ability to expand his left side is enormously impaired."

The handcuffs and the hard surface also interfered with Mr Floyd's ability to breathe, Dr Tobin said.

Chauvin, 45, is charged with murder and manslaughter.

Mr Floyd was arrested outside a neighbourhood market after being accused of trying to pass a counterfeit 20 dollar bill.

He struggled and claimed to be claustrophobic as police tried to put him in a squad car, and they pinned him to the pavement.

Defence lawyer Eric Nelson has argued that Chauvin "did exactly what he had been trained to do over his 19-year career" and disputed that the officer's actions were what killed Mr Floyd.

Fentanyl and methamphetamine were found in Mr Floyd's system.

The trial continues.