title: Investigation of oxyhemoglobin and carboxyhemoglobin ratios in right and left cardiac blood for diagnosis of fatal hypothermia and death by fire.
abstract: Few large-scale investigations have looked at the oxyhemoglobin ratio (%O2-Hb) or the carboxyhemoglobin ratio (%CO-Hb) in fatal hypothermia and death by fire as applicable to forensic medicine. We therefore retrospectively examined right and left cardiac blood samples for both %O2-Hb and %CO-Hb in 690 forensic autopsy cases. We therefore sought to establish reference values for the above forensic diagnoses, to compare %O2-Hb in fatal hypothermia with or without cardiopulmonary resuscitation (CPR), and to compare the relationship between %CO-Hb and smoking history. All %O2-Hb and %CO-Hb data were obtained during or immediately after autopsies using a portable CO-oximeter. Death by carbon monoxide (CO) intoxication and death by fire were excluded from the analysis involving smoking history. In fatal hypothermia, %O2-Hb in the left cardiac blood was significantly higher than that in the right cardiac blood, providing important evidence for fatal hypothermia. Furthermore, %O2-Hb in the left cardiac blood increases with CPR but that in the right cardiac blood increases in parallel. No correlation was observed between rectal temperature and %O2-Hb in the right and left cardiac blood, indicating that it is unlikely that postmortem cooling increases %O2-Hb in cardiac blood. %CO-Hb in smokers was significantly higher than that in non-smokers, although the number of cigarettes smoked did not appear to be significant. When assessing death by fire, we identified that %CO-Hb of >10% was a reliable marker of antemortem CO inhalation, regardless of smoking history.
authors.affiliation: Department of Forensic Medicine, The Jikei University School of Medicine, Tokyo, Japan. Electronic address: kanto@jikei.ac.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kanto-Nishimaki
authors.affiliation: Department of Forensic Medicine, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Saito
authors.affiliation: Department of Forensic Medicine, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Miwako
authors.initials: M
authors.lastname: Watanabe-Aoyagi
authors.affiliation: Department of Forensic Medicine, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Toda
authors.affiliation: Department of Forensic Medicine, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Kimiharu
authors.initials: K
authors.lastname: Iwadate
mesh_terms: D001344:Autopsy; D002263:Carboxyhemoglobin / Q000032:analysis*; D002423:Cause of Death; D005390:Fires; D005554:Forensic Medicine; D006801:Humans; D007035:Hypothermia / Q000097:blood*; D010108:Oxyhemoglobins / Q000032:analysis*; D012189:Retrospective Studies; D012907:Smoking / Q000097:blood
chemical_list: D010108:Oxyhemoglobins; D002263:Carboxyhemoglobin
keywords: Carboxyhemoglobin ratio; Death by fire; Fatal hypothermia; Oxyhemoglobin ratio