A novel diagnostic method for carbon monoxide poisoning using body cavity fluids other than blood

Abstract Purpose Carboxyhemoglobin saturation (COHb%) in blood is essential for diagnosing carbon monoxide (CO) poisoning; however, postmortem blood is not always available. Few previous studies have investigated substitutes for blood. We determined whether body cavity fluids could substitute for blood using a simple method to concentrate low-Hb samples. Methods We selected autopsy cases with measurable COHb% in blood and body cavity fluids (pleural fluid, pericardial fluid, ascites, and bile). They were classified based on the presence of CO poisoning and decomposition, and where they were discovered. COHb% was measured using a CO-oximeter, and correlations between COHb% in blood and the corresponding body cavity fluids were examined. Low-Hb samples were concentrated using ultrafiltration filters. Results COHb% was measured in 55 cases for pleural fluid, 43 cases for pericardial fluid, 4 cases for ascites, and 1 case for bile. In non-putrefied cases, COHb% in pleural and pericardial fluid showed significant correlations with those in blood. Ascites exhibited a similar trend. In putrefied cases with CO poisoning, correlations were unclear because of emergence outliers and the limited sample size. In putrefied non-CO poisoning cases, COHb% was rather higher, reaching 12% in bodies recovered on land and 48% in those recovered from water. Conclusion The concentration method was useful for analyzing low-Hb samples. COHb% in pleural and pericardial fluids may serve supportive information for estimating CO inhalation, with careful consideration of analytical characteristics of CO oximeters, putrefaction, and sample conditions. In decomposed cases found in water, body cavity fluids were not suitable for diagnosis.