|SOFT - TIAFT 1998||Poster Session 3||Thursday October 8, 1998|
COMPARISON OF POST-MORTEM BLOOD AND LIVER CARBON MONOXIDE CONCENTRATIONS|
David A. Riley and Joel M. Mayer
Centre of Forensic Sciences, Toxicology Section, 25 Grosvenor St., Toronto, Ontario, Canada, M7A 2G8, and Department of Pharmacology, University of Toronto, Canada
|Since suitable blood samples are not always available from badly burned fire victims, a well protected, highly perfused tissue would be useful as an alternative for the determination of percent hemoglobin saturation with carbon monoxide (%COHB). This study compared the %COHB of heart blood to that of femoral blood, liver tissue and liver fluid. The value of the different matrices to predict a potential carbon monoxide fatality was assessed.
Carbon monoxide was quantitated by gas chromatography (GC) using a wide bore open tubular molesieve column and thermal conductivity detector.
Femoral blood was a good predictor of heart blood %COHB (n = 13, r2= 0.883,) at saturations below 55%. Above that, there was greater but equal dispersion both above and below the regression line. Using 35% as a threshold to predict a potentially fatal COHB following exposure to fire, the femoral blood results did not result in a false prediction of a potentially fatal COHB saturation or a nonfatal saturation. Liver fluid was a good predictor of heart blood %COHB (n = 13, r2= 0.804) at saturations below 55%, above which there was greater dispersion about the regression line. In the 13 cases, one resulted in a false positive and one a false negative, thus resulting in an accurate prediction 85% of the time. Comparing homogenized liver to heart blood (n = 18, r2= 0.582), resulted in extreme variation about the regression line at saturations in excess of 55%. There were no false positive predictions, but 4 false negatives resulting in an accurate prediction 78% of the time.
This study indicates that for the purpose of predicting a potentially fatal carbon monoxide exposure, femoral blood is as useful as heart blood, liver fluid is a good but less reliable predictor, and homogenized liver may be useful in assessing carbon monoxide toxicity, but some fatal exposures may be missed.