MINNEAPOLIS — The civil rights trial of three former Minneapolis police officers resumed Monday with a Harvard pulmonologist testifying that George Floyd died of asphyxia from the pressure on his neck and restrictions to the movement of his midsection.
"This was an eminently reversible respiratory failure event right up until the time he lost consciousness," Dr. David Systrom testified, adding that the situation was "quickly reversible if the impediments to breathing were removed."
Instead, Floyd died under the pressure of Derek Chauvin's knee on his neck for 9 minutes and 30 seconds with two other officers holding him prone against the hard asphalt, unable to expand his diaphragm and draw deep breaths, Systrom said.
He described the fatal combination as "obstruction and restriction" of Floyd's breathing that ultimately caused him to lose consciousness and his heart to stop.
Systrom, who is on staff at Brigham and Women's Hospital in Boston and has published more than 120 peer-reviewed papers, walked through a detailed explanation of heart-lung function. He was the first witness after court was paused last Wednesday due to a positive COVID-19 test by a defendant.
Judge Paul Magnuson never said which defendant had the virus; both Tou Thao and J. Alexander Kueng were in court Wednesday but Thomas Lane was not. All three were back Monday.
Systrom was paid $600 an hour for his testimony and said he worked about 20 hours to prepare. He is critical to the prosecution's case, which seeks to show that Floyd died directly as a result of the actions of the former officers. The defense is working to instill doubt on that by claiming that Floyd went into cardiac arrest due to a combination of an enlarged heart, arterial disease and illegal drug use.
During their cross examination of Systrom, the defense attorneys highlighted that his cause of death determination differed from that of Andrew Baker, Hennepin County's chief medical examiner. They also sought to show that unlike the officers on the scene, Systrom had the benefit of hindsight without pressure from angry bystanders outside Cup Foods.
Systrom, who has a calm, assured manner, testified that he has worked as a pulmonologist and in critical care for decades, studying how the heart and lungs work together.
Under questioning all morning by assistant U.S. Attorney Amanda Sertich, Systrom explained that Floyd's position on the ground with his arms cuffed behind his back and officers on top of him was especially problematic. The arms and shoulders work as "adjunct respiratory muscles" to help create space for full diaphragmatic breathing, Systrom said.
To support his assertion that Floyd died of asphyxia, not a heart attack, Systrom pointed to a medical measurement, end-tidal carbon dioxide level. The measurement reflects how well the body is processing carbon dioxide.
A normal level is 35 to 45 milliliters of mercury, Systrom said. Floyd's end-tidal carbon dioxide level was 73 milliliters of mercury, a "life threatening" level, Systrom said.
Systrom said given that measurement, the chances Floyd died of a cardiac event would be "very low." In cardiac events, he said the end-tidal level is as low as 10 milliliters of mercury.
He also testified that Floyd's death was slow, not sudden like cardiac arrest. He said Floyd went from intelligible speech to an inability to speak over minutes.
The prosecutor asked, "In your opinion ... would Floyd have died from his heart disease without the officer restraint?"
Systrom said, "Definitive no."
He also said that neither methamphetamine nor fentanyl played a role in Floyd's death even though both were found in Floyd's body. Systrom said the reasons Floyd couldn't breathe were "evident in the videos."
Paule noted Baker's divergent determination that Floyd died from cardiac arrest caused by the restraint and underlying health conditions. Systrom agreed that his opinion differed from Baker's but that the medical examiner notably deferred to pulmonologists at various points in his testimony at two trials.
Turning to Kueng's role, Sertich asked Systrom specifically about his restraint of Floyd's midsection. Systrom noted how Kueng was holding Floyd's left wrist and leaning against his chest wall with a knee, both of which could restrict his breathing.
Regarding Lane's role, Systrom said that holding Floyd's legs wouldn't restrict his breathing but would have prohibited his "self-rescuing because he could not get up on his knees."
During cross examination, Kueng's attorney Thomas Plunkett tried to elicit that Systrom would be unable to determine from videos how much pressure Kueng was applying to Floyd's body.
Systrom said regardless of the pressure, Kueng's actions would have restricted Floyd's movement.
But Plunkett noted that Systrom had the benefit of reviewing the video and records in the comfort of hindsight with a cup of coffee. "Your opinion is based on a lot of things that Mr. Kueng didn't know about," Plunkett said.
Systrom responded, "From my review, Mr. Kueng had a front row seat to what was going on."
Plunkett countered that Kueng couldn't see Floyd's face — as Systrom could in bystander video.
Systrom responded that Kueng knew when Floyd lost his pulse, could hear Lane asking to roll him on his side and the pleading of bystanders. "I could hear it loud and clear on the video," Systrom said, adding, "To a degree with respect to the very important things, Mr. Kueng had very similar information in real time. I realize this was not a comfortable situation. I respect that."
During direct questioning, Systrom said that allowing Floyd to sit up — even while handcuffed — would have allowed him to return to normal breathing. He also said that after Floyd's heart stopped, there was still a chance to save him if CPR had been started immediately. Instead, the officers stayed on top of him for another three minutes while he was in cardiac arrest, the doctor said.
The prosecutor asked Systrom what Floyd's chances of survival would have been "if he had been repositioned before he lost consciousness."
Systrom responded, "close to 100%."
Late Monday, Officer Nicole Mackenzie, medical support coordinator for the MPD, began testifying. She said officers learn that when someone becomes unresponsive, they should be put in the recovery position — on their side, so they can breathe.
The three officers are accused of violating Floyd's right by failing to render aid while detaining him. Thao and Kueng are also charged with failing to intervene in Chauvin's illegal restraint of Floyd.
Chauvin was convicted of Floyd's murder in state court last year and was sentenced to more than 22 years in prison. He also pleaded guilty in federal court to civil rights violations in December.
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