In vitro absorption of atmospheric carbon monoxide and hydrogen cyanide in undisturbed pooled blood.

Blood samples from aircraft accident victims are analyzed for carboxyhemoglobin (COHb) and cyanide ion (CN(-)). Such victims often suffer open wounds near the autopsy blood collection sites. Many aircraft crashes result in fires that fill the victim's atmosphere with smoke that is rich in carbon monoxide (CO) and hydrogen cyanide (HCN). It is important to determine whether pooled blood in those wounds may have absorbed these gases after death, which could lead one to erroneously conclude that the presence of COHb and CN(-) in blood was the result of breathing in these gases. A laboratory desiccator was used as a chamber to establish whether CO or HCN may be absorbed in undisturbed, pooled blood. COHb levels were 4.3-11.0% after exposure to CO (5,532, 8,298, 11,064, 22,129 and 33,193 ppm) for 30 and 60 min. Blood CN(-) concentrations (1.43-5.01 µg/mL) increased with exposure to HCN at 100 and 200 ppm, each at 15, 30, 45 and 60 min. The observed COHb increases do not exclude the possibility for higher COHb levels in blood exposed to highly CO-rich atmospheres, but there is a strong potential for CN(-) levels to increase by the absorption of atmospheric HCN. Thus, postmortem COHb and CN(-) levels should be carefully interpreted.