Originally Posted by
DocRohan
@slats.
I am not sure that there would be much value in determining carboxyhaemoglobin or lactate levels in blood from bodies immersed in hypertonic salt water...Likely the hypertonicity would significantly alter biochemistry.
Examination of lungs and detecting diatoms could give an indication of whether people were alive or deceased prior to immersion, although this is still not 100% conclusive at autopsy.
(apologies for graphic content)
Hypertonic or not, salt water is still basically water and electrolytes, I don't think that it would mess with lactate, except through simple diffusion.
I'm skeptical about these tests too but for a different reason.
CO poisoning is one of the less likely things to kill you in a fire, it usually happens during prolonged exposure to gases from a poorly ventilated furnace or an internal combustion engine. CO only forms in the presence of insufficient supply of oxygen. CO poisonings are common in general aviation, and almost invariably occur when piston engine malfunction results in the exhaust gas being pumped into the cabin. The only large jet incident I could find was caused by a malfunctioning air conditioner. A fire that gets to the point where hazardous levels of CO are produced would pose a high risk to structural integrity of the aircraft, and there would be ample direct evidence of that.
CO could be one of the things to look for, but it would indicate a mechanical problem, like the aforementioned air conditioner, rather than a fire.
I don't think that lactate forms in significant quantities during hypoxia if the person is stationary.
In both cases, there should be more obvious physical signs, e.g. soot in the lungs to indicate a fire.