Three medical experts testified today about why they believe George Floyd died and what was found in his system in May 2020.
Here's what they said today during the trial of former officer Derek Chauvin:
Dr. Martin Tobin, a physician in pulmonary and critical care medicine, testified after having reviewed the medical records in the Floyd case.
"Mr. Floyd died from a low level of oxygen," Tobin testified. "And this caused damage to his brain that we see and it also caused a PEA arrhythmia, that caused his heart to stop."
PEA means pulseless electrical activity, "which is a particular form of abnormal beat of heart — an arrhythmia," he explained.
He also shared his opinion on the cause for the low level of oxygen in Floyd. "The cause of the low level of oxygen was shallow breathing. Small breaths. Small tidal volumes. Shallow breaths that weren't able to carry the air through his lungs down to the essential areas of the lungs that get oxygen into the blood and get rid of the carbon dioxide."
Tobin also testified that fentanyl did not have an effect in "causing depression of the respiratory centers" in Floyd. Tobin said that with fentanyl, Floyd's respiratory rate should have been 10, instead the rate was at 22, which is normal.
"Basically it tells you that there isn't fentanyl on board that is affecting his respiratory centers. It's not having an effect on his respiratory centers," Tobin told the prosecution.
Tobin noted that the normal range for a respiratory rate is between 12 and 22. Tobin testified that Floyd's respiratory rate was 22 just before he lost consciousness.
Dr. William "Bill" Smock, emergency medicine physician with specialized training in forensic medicine, testified that Floyd died because of a lack of oxygen in his body.
"Mr. Floyd died from positional asphyxia. It is a fancy way of saying he died because he had no oxygen left in his body," Smock said. "When the body is deprived of oxygen, in this case from his chest pressure and back, he gradually succumbed to lower and lower levels of oxygen until it was gone and he died."
Smock also discussed the nature of strangulation and whether bruising is something that always occurs. "You can be fatally strangled, die of asphyxia, and have no bruising. The presence or absence of a bruise on a human body, is dependent upon a multiple different variables. How much pressure is applied? How is that pressure applied? How frequently is that pressure applied?" Smock said.
Dr. Daniel Isenschmid testified that fentanyl and methamphetamine were found in the blood taken from Floyd at the hospital. Floyd’s fentanyl concentration was 11 nanograms per milliliter, Isenschmid said. Norfentanyl, a drug that it breaks down into, was recorded at a level of 5.6, he said.
The norfentanyl concentration could indicate fentanyl was taken and then some of it had already broken down, or it could indicate someone took a dose of the drug, then later took another dose, Isenschmid explained.
The impact of fentanyl on someone can vary person to person, due to tolerance, he said.