Centre of Forensic Sciences, Toxicology Section, 25 Grosvenor St., Toronto, Ontario, Canada, M7A 2G8, and Department of Pharmacology, University of Toronto, Canada

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.