Carbon monoxide poisoning as a cause of death and differential diagnosis in the forensic practice: A retrospective study, 2000–2010

This study presents the epidemiology and the postmortem forensic aspects in cases with a carboxihemoglobin (COHb) analysis, from autopsies performed at the Forensic Pathology Department of the Centre Branch of the National Institute of Legal Medicine and Forensic Sciences of Portugal. Between January 2000 and December 2010, 69 COHb analyses were requested in our institution. In approximately 70% of the situations, circumstantial information included a Carbon Monoxide (CO) source at the death scene. More than half of the cases presented thermal lesions, cherry-red lividity, and cherry-red blood and viscera coloration were found in, approximately, 30% of the cases. Fourteen cases were recorded as CO poisonings. The highest number of poisonings occurred in 2000, with most of the cases in winter (53.8%), in 51–60 years-old male individuals. 69.2% of the poisonings were accidental and the remainder were suicides, being fires the most frequent sources of CO (38.5%). Cherry-red lividity was present in 61.5% of the cases, and all of them presented cherry-red blood and viscera coloration. Older individuals and those with thermal lesions presented lower COHb levels, and politrauma was the most frequent cause of death among the negative cases. It is possible to conclude that the forensic aspects of CO poisonings interact in a complex way, and differential diagnosis is not straightforward. This study also emphasizes the role played by public prevention campaigns and improvement of heating appliances in reducing the number of accidental CO poisonings, and the importance of preventing urban and forest fires, the major source of CO among us.