RELATIONSHIP BETWEEN ETHANOL, CARBON MONOXIDE AND METAHEMOGLOBIN IN BLOOD SAMPLES IN FORENSIC CASES.

JOSEFINA DOMÍNGUEZ-CABRERA M. J., FERRARI L. A. AND GIANNUZZI L.

Florencia

Congreso; The International Association of Forensic Toxicologists, TIAFT, Florencia, Italia, setiembre, 2015.; 2015

The International Association of Forensic Toxicologists, TIAFT

Introduction: Many reports have been published about the role of carbon monoxide (CO), actually Carboxyhemoglobin (COHb) and Ethanol (EtOH) in fire fatalities, but possible physiological interaction between these toxic agents is still under discussion. Furthermore, Methemoglobin (MetHb) is not widely considered in fire episodes. MetHb is an oxidized form of Hemoglobin (Hb), which could be generated by redox imbalance induced by the exposure to several chemical agents. The simultaneous relationship of MetHb and other substances with death is under debate.Aims: The aim of the present study was to investigate the combined effect of EtOH, COHb and MetHb poisoning in forensic cases (n=45) from different judicial regions and to establish the relationship of these three parameters in determining the cause of death.Methods: Blood samples from 45 victims were obtained and tested for: a) EtOH by Head-Space Gas Chromatography with FID detector (HS-GC/FID), b) COHb and c) MetHB. For these latter determinations a co-oximeter was used. A Systematic Toxicological Analysis was also performed in order to detect toxic organic compounds, psychotropic and drugs of abuse, using Liquid-Liquid extraction or Solid-Phase extraction. GC-MS was employed to identify these compounds. Results: Toxic compounds routinely measured (methanol, aldehydes and other volatile compounds), gave negative results on the 45 cases. Neither drugs of abuse, nor psychotropic were detected.According to their COHb levels cases were divided into 4 groups: COHb: 1 ? 12 % (n=10), 12 ? 30 % (n=14), 30 - 50 % (n=13) and > 50 % (n=8). EtOH levels were analyzed according to intoxication criterions: lower 2 g/L (n=35) or higher 2 g/L (n=10). Considering a beginning of intoxication with values above 10%, the MetHb results obtained were divided in: cases with MetHb 10 (n = 34). The results were analyzed linking the three parameters. Statistical analysis showed that %COHb and %MetHb blood concentration were not independent variables with 2: 10.87 (theoretic 2: 2.09, df: 9, α: 0.05). A relationship between COHb/MetHb > 1 was indicate of a possible predominance of CO poisoning by incomplete combustion of carbon compounds. A relationship COHb/MetHb < 1 was indicate of an intoxication by combustion of compounds which mainly release nitrogen oxides, which cause the oxidation of Hb to MetHb. We found no correlation between EtOH and COHb, and no correlation between EtOH and MetHb. Tridimensional graphics, COHb/MetHb vs ETOH, allowed us to infer the type of poisoning predominating in each group.Conclusions: The proposed relationship will help to infer the prevailing type of intoxication in forensic cases, and the atmosphere in which the person was at the time of his death.