Evaluation of post-mortem oxymetry with reference to the causes of death.
We examined blood samples of 214 forensic autopsy cases, excluding fire victims, on a CO-oximeter system in order to evaluate post-mortem oxymetric profiles with reference to the causes of death. Oxyhemoglobin (O2-Hb) levels in the left and right heart blood, respectively, ranged from 0 to 97.7% and from 0 to 92.1%, showing no apparent correlation with the post-mortem intervals or rectal temperatures. In nearly 60% of the cases, O2-Hb was lower than 10%. A high O2-Hb level (over 50%) in the left heart blood was most frequently observed in death from cold exposure and occasionally in fatalities from blunt injuries and stab/incised wounds with or without medical care. O2-Hb in the heart blood was usually very low (under 10%) in fatalities from asphyxiation, drowning, poisoning and natural diseases. A greatest oxymetric variation was observed in death from injuries, probably due to varied causal mechanisms of death. In most cases, the differences between blood O2-Hb levels in the heart and iliac vessels were within 15%; whereas O2-Hb in the cerebral venous blood was usually evidently higher than that in the right heart blood. An inverse relation of O2-Hb levels to total hemoglobin contents was observed slightly for the blood in the heart and iliac vessels, and more obviously for the cerebral venous blood. The above post-mortem oxymetric profiles were considered to at least partially reflect the final balance of oxygen uptake and consumption in dying process, possibly also affected by the circulatory status, giving an objective index to the color of cadaveric blood (hypostasis), although it should be assessed in consideration of post-mortem interference and total hemoglobin contents. In any case, however, post-mortem oxymetry seemed to have a limited value owing to severe systemic hypoxia which would be a common final state before death from various fatal traumas and diseases, maybe except for those with extremely short agony.