Carbon monoxide poisoning might not be found by a test for O2 saturation unless they drew from an artery. The test with the finger thing at the doctor's office looks for bound hemoglobin and CO binds hemoglobin even more tightly than O2. That's why it's deadly, actually. It literally takes up all the space. If Mr. Floyd got killed by CO, though, one has to wonder why no one else at the scene developed symptoms and also wonder if he would have been exposed to this lethal gas if officers hadn't been sitting on him until he went unresponsive.Voronwë the Faithful wrote:They were able to rebut the claim with actual facts; they just needed to use the right actual facts. They were able to have their rebuttal witness testify to that Mr. Floyd's oxygen saturation was 98% when he died, thus proving categorically that the defense expert witness's claim that Mr. Floyd's carbon monoxide levels in his blood could have increased by 10% to 15% was categorically impossible. What the judge ruled that the prosecution could not use was test results of carbon dioxide in Mr. Floyd's blood that had not been previously revealed to the defense. It was absolutely the right call by the judge. I don't even have a niggling doubt about that.
Or are you talking about lethal amounts of carbon dioxide? Not being able to blow off CO2 is a sign of diminished respiratory function and I'm not sure how that would help the defense given the findings that Floyd was asphyxiated. But if you can't blow off CO2, your O2 sat will drop because you aren't moving air. You'll also feel like you can't breathe because it's CO2 that drives respiratory function in anyone who isn't in the late stages of COPD. That's why, even though they're able to talk to you, people in respiratory distress will say they can't breathe or can't get in enough air or can't catch their breath. You have to take it seriously when someone is gasping for air and saying they can't breathe because this can progress to respiratory arrest.
ETA: Okay, found some more information about the defense witness's claims vs. the evidence in hand. The O2 sat was from a blood draw, so they could determine if Mr. Floyd got poisoned by CO and yeah, the witness was more than a little off base there.
Also, it appears that Chauvin is invoking his 5th Amendment rights and not taking the stand.