Fentanyl level not fatal
Blood tests conducted as part of Floyd's post-mortem autopsy revealed 11 nanograms per milliliter, or ng/ml, of fentanyl present. According to expert witnesses, this wasn't enough to be considered fatal
Dr. Daniel Isenschmid, a toxicologist at NMS Labs in Pennsylvania, presented data at trial from more than 2,300 blood samples in fentanyl DUI cases from the last year. He showed that while the average fentanyl blood level was close to 9.6 ng/ml, a quarter of people tested had 11 ng/ml or higher. (Important to note: Blood samples were taken from drivers who tested positive for fentanyl and were alive at the time of collection.)
Isenschmid also showed that Floyd's blood ratio of fentanyl to norfentanyl, the molecule fentanyl is broken down to once in the body, was lower than the average ratio both for people who died of overdoses and those arrested for DUI who lived.
Overdose victims who die rarely have norfentanyl in their blood, since death often occurs before the body can break the drug down, he said.
Isenschmid's testimony was supported by pulmonologist and critical care specialist Dr. Martin Tobin of Loyola University Medical Center.
"Mr. Floyd died from a low level of oxygen, and this caused damage to his brain that we see. And it also caused a PEA (pulseless electrical activity) arrhythmia that caused his heart to stop," he told the court. He explained Floyd's body position on the street, handcuffs pulling his arms back and a knee on his neck, back and sides, led to his low oxygen levels.
"All of these four forces are ultimately going to result in the low tidal volume, which gives you the shallow breaths" that can't effectively bring oxygen into the lungs, Tobin said.
He stated because fentanyl typically slows down a person's breathing, the drug was not a contributing factor based on his calculations of Floyd's breathing rate based on witness video, which at the time appeared about the same as a healthy individual.