Influence of antemortem perfusion on autopsy blood ethanol concentration

Abstract

An injured subject receiving transfusions of blood or fluids may present with diluted samples at autopsy. Calculation of blood ethanol concentration at the time of the event can be very challenging, given potential antemortem dilution. From a complete literature survey, it seems that this topic has received little attention. The aim of this study was to investigate a case in which antemortem dilution of blood alcohol had occurred. Before death, the victim (male; 1.70 m, 70 kg) was perfused (left elbow) with a total volume of 3.25 l (1.5 l NaCl 0.9%, 1.5 l Voluven, 0.25 l sodium bicarbonate). He was pronounced dead within minutes after the perfusion. The blood alcohol concentration (right subclavian venous blood) in the autopsy sample was 0.1 g/l. The judge in charge of the case requested us to explain the influence of the perfusion in the final blood alcohol concentration, particularly because the assailant claimed that the victim was drunk, like he was. Because nonalcoholic liquid was added to the body, the subject’s alcohol concentration obviously would be affected to some degree. Intravenous fluids are administered in roughly the same amounts as fluids lost by other paths, in order to maintain blood pressure. An effective approach can be the calculation of the dilution factor. Alcohol is distributed in total body water, rather than in blood. Therefore, if 3.25 l of fluid is given to a 70-kg man, with a volume of distribution of 0.70 l/kg, the total body water, and consequently the blood alcohol, is diluted by less than 10%. The premise presented for estimating the effect of dilution is mostly valid when the ethanol has reached equilibrium in the total body water (time dependent). A higher dilution of the blood alcohol concentration can occur when ethanol distribution to the total body water has not reached equilibrium. Comparisons of autopsy results with blood analysis data for hemoglobin, albumin, or total proteins collected before the incident, can be of great interest to evaluate the dilution factor. If results can be obtained within the same range, this will make allowances for the uncertainty in each calculation. Considering the relatively small amount of fluid added compared with the mean distribution volume of ethanol, the effects of antemortem intravenous fluids were thought to be minimal. The dilution factor was estimated to be in the 7–10% range. The contribution of the sampling and infusion site was considered to be minimal, given the respect by the physician for anatomical right–left separation.