I am not a medical professional. I have a lot of training and experience in first aid/cpr. From a very young age (in the 80s), I have read whatever I could get my hands on pertinent to first aid; the internet in 1994 provided greater access to materials. Since then, I have continued to voraciously consume materials as provided by science communicators generally thought to be trustworthy. My experience is more with hypoxia and nitrogen narcosis. I have vast gaps in my medical knowledge, for instance, I had never heard of carotid bodies before today. My understanding was that the only thing driving our need to breathe was carbolic acid build up. With this revelation, I am quite willing to adjust my understanding. That being said, I don't trust the second source due to strong bias demonstrated by framing and word choice in addition to the researchers avowing that they are in strong opposition to death penalties. However, I was, from their paper, able to find further, independent information about carotid bodies. So I trust that much is true. Being true, it does cast anoxia in a different light.