Carboxyhemoglobin and blood cyanide concentrations in relation to aviation accidents
Canfield, D.V.; Chaturvedi, A.K.; Dubowski, K.M.
Aviation Space and Environmental Medicine 76(10): 978-980
2005
ISSN/ISBN: 0095-6562 PMID: 16235883 Document Number: 594032
Introduction: It is important in aviation accident investigations to determine if a fire occurred during flight or after the crash and to establish the source(s) of the toxic gases. Methods: Bio-specimens from aviation accident fatalities are submitted to CAMI for analyses. In blood, CO is analyzed as carboxyhemoglobin (COHb) and hydrogen cyanide as cyanide (CN-). Analytical data were stored in a database, and this database was searched for the period of 1990-2002 for the presence of COHb and CN- in the submitted cases. Results: Out of 5945 cases, there were 223 (4%) cases wherein COHb was >= 10%. Of the 223 cases, fire was reported with 201, no fire with 21, and undetermined fire status with 1. CN- concentrations were at or above 0.25 mu g (.) ml(-1) in 103 of the 201 fire-related cases. None of the 2 1 non-fire cases had CN-, but nicotine was detected in 9 of the cases. All non-fire cases with COHb > 30% (four cases) were associated with exhaust leaks. Of the 223 cases, COHb-CN- fractional toxic concentration (FTC) was lethal only in 31 cases with elevated CN- levels. Conclusions:The presence of COHb and CN- in elevated concentrations in the blood of victims found by autopsy to have died on impact would indicate an in-flight fire, In the absence of fire and CN-, the elevated COHb concentrations would suggest an exhaust leak, particularly at COHb > 30%. The findings of this study also suggest that, in addition to COHb, CN- plays a detrimental role in fire-associated aviation accident fatalities.