Warning: Distressing images
COMMENT: The competing medical reports will be used to argue the case for the prosecution and the defence, writes Dr Gary Payinda
George Floyd's private medical examiners concluded he was a healthy
man asphyxiated by police. The public medical examiner's autopsy revealed he had critical narrowing of his coronary arteries, an enlarged heart, sickle cell trait, methamphetamine and fentanyl use, and a recent coronavirus infection. The autopsies have already been weaponised by both the defence and the prosecution.
How do we make sense of such contradictions, and how might the actual medical findings impact his accused killer's trial?
The government autopsy, done by the Hennepin County Medical Examiner, was performed first. It was far more comprehensive than the later private autopsy, as it included toxicologic examinations of the blood and urine, microscopic analysis of organs and tissues, and examination of parts of the body that the later private medical examiners, Doctors Michael Baden and Allecia M. Wilson, would not have access to.
These limitations would not deter Dr Baden from later saying, during a TV interview on Fox News, "if [George Floyd] had heart disease it was minimal, and didn't cause or contribute to his death". He was also quoted in the New York Times as saying Floyd "was in good health."
There's no gentler way to put it than to say Dr Baden was overstating his case and ignoring the limitations of his exam.
The reality is that he hadn't even examined the third of the heart that was kept by the Hennepin County Medical Examiner, which showed enlargement of the pumping chambers, likely due to chronic hypertension, as well as critical lesions of the LAD, RCA, and first diagonal coronary arteries.
These important blood vessels, which deliver oxygen and glucose to the main pumping chamber of the heart, were severely narrowed: 75-90 per cent blocked.
In most hospitals, findings like these would have resulted in the patient being referred for a cardiac catheterisation with stents, or even a cardiac bypass, to restore adequate blood flow to the heart muscle.
George Floyd's heart was, in any reasonable sense, a ticking timebomb. The police officers' defence attorneys will not have any difficulty proving that Floyd was not a healthy man.
Beyond the issues of an ailing heart, the medical examiner also discovered Floyd had sickle cell trait, which in some patients can limit the oxygen-carrying capacity of the blood.
The lack of oxygen delivery to critical tissues like the heart and brain, especially during times of physical exertion or stress, can cause them to fail. Unstable heart rhythms, irregular breathing, and loss of consciousness can occur under the tremendous stress of restraint and asphyxiation.
Methamphetamine was also found in Mr Floyd's blood at levels suggesting recent use. Methamphetamine can, all by itself, cause heart rhythm irregularities, narrowing and spasm of blood vessels, and reduced oxygen delivery to the heart and other tissues, none of which would show up on an autopsy, but all of which could contribute to a cardiac arrest.
The 20-page Hennepin County Medical Examiner's report also details a couple of interesting, but clinically irrelevant, details. These include a blood level of fentanyl of 19ng/ml - high enough to cause sedation, anaesthesia, and fatal overdose. But numbers don't always tell the whole story.
While the level is high, this is a clinically irrelevant finding, as fentanyl kills through oversedation - a slumber so deep that the stuporous patient eventually stops breathing. In a man who is awake and alert, walking and later fighting for his life against several police officers kneeling on his neck and back, oversedation is not a concern.
The fentanyl levels, like the cannabis levels, can be safely ignored as contributors to George Floyd's death. The knees on his neck and back cannot.
Another interesting but likely irrelevant autopsy finding was the Covid-positive nasal swab, with lungs that showed no evidence of fluid, inflammation or microscopic clotting - no sign of Covid disease. He did have SARS-CoV-2 viral RNA in his nose, but this could have been from a recent infection. We know that 80 per cent of Covid-positive patients will have no symptoms, or only mild symptoms. Again, not a contributing factor to his death.
What the video shows is a process to which autopsies are largely blind: progressive respiratory failure leading to death, played out in numerous other in-custody deaths worldwide, where it is often lumped under the non-medical, ill-defined, catch-all term: 'excited delirium'.
What these cases have in common is often drug use, pre-existing health conditions, and police restraint. Any emergency doctor sees patients with drug use and pre-existing health conditions. The key ingredient in most of these deaths is ongoing police restraint of patients in respiratory failure. In layman's terms, they can't breathe.
With a weighted knee on his neck partially obstructing his airway, and knees on his back impeding his chest expansion and preventing his diaphragm from moving up and down, George Floyd's ventilation would have gradually failed.
During those 8 minutes and 46 seconds, a lack of sufficient oxygen getting in and carbon dioxide getting out would have turned the blood acidic and oxygen-poor. This would have taxed Floyd's diseased heart, likely to the point of heart failure and cardiac arrest.
With blood flow and oxygen delivery to the brain halted, he would have stopped moving, stopped breathing, and become unresponsive.
Neck and torso pressure continued to be applied for minutes after this.
We can safely assume how the rest played out, as it is a common final pathway for most so-called 'secondary' cardiac arrests: a heart which would have been racing under the adrenaline surge of a life-or-death situation quickly burns up all its oxygen and glucose, eventually slowing down, or going into an unstable rhythm.
It often fibrillates for a while, not beating, just quivering as it fails. Then even these movements stop. At that point, resuscitation is virtually always ineffective. The patient is dead.
An autopsy, interestingly, would have shown none of this. Arrhythmias are fleeting and gone without leaving a trace. Oxygen and carbon dioxide levels measured at autopsy are so inaccurate as to be useless.
Dr Gary Payinda practices as a prehospital, retrieval, and emergency medicine specialist in New Zealand.