Hypoxia and Medicine

at what spo2 does hypoxia and tissue death start to occur?

Public Comments

1. Unfortunately, your question does not have a black and white answer. It depends greatly a LOTs of factors, including renal function and cardiac function at the time of desaturation. It would also depend on the position of your patient (Supine? Prone? Semi-Fowler's? High Fowlers?) What really kills tissue (cell death) is more related to acid production (anaerobic glycolysis/lactate production) than just the level of oxygen in one's hemoglobin. HOWEVER, you will see that people will tend to GO bradycardic (and eventual heart failure) with "sustained" SpO2s around 84-88% by starving heart muscle. Decline is even more rapid below 84% SpO2, as that drops your pO2 at or near the venous threshold of 40 mmHg. Now, remember, this is "opinion" based on experience. I can't think of any reference material that will give you a specific window of Oxygen Saturation that equates cell death (as mitochondria vary from individual to individual). Anyway... good luck. I didn't want to attempt to answer your question, but it didn't seem like anyone was offering to help. Do let us know what you discover on your own. You can read this following study to get some incite in the right direction: http://biomed.gerontologyjournals.org/cgi/content/full/55/4/M239