Determination of central-to-peripheral blood diazepam concentration ratio (C/P ratio) in Thai postmortem cases: a postmortem redistribution study

Abstract

Background: Interpretation of postmortem blood diazepam concentrations is important in establishing the cause of death. However, this may be complicated by postmortem redistribution (PMR). Currently, there is limited information regarding PMR of diazepam in the Thai people.

Objective: To compare cardiac and femoral blood diazepam concentrations to examine PMR in Thai postmortem cases.

Methods: A prospective study was performed on medico-legal cases sent for autopsy at the Department of Forensic Medicine, Siriraj Hospital. Thai individuals who were 18 years of age or older and had received diazepam during hospitalization were recruited. Cardiac and femoral blood samples were obtained during autopsy. Blood diazepam concentrations were analyzed, and the cardiac-to-femoral blood ratio (C/P ratio) was calculated. Statistical analysis was performed using the Wilcoxon signed-rank test, and the Mann–Whitney U test.

Results: Forty two subjects were recruited for this study. The median/mean diazepam concentrations in cardiac and femoral blood were 52.0/83.1 ng/mL and 53.6/69.9 ng/mL, respectively. The median/mean C/P ratio of diazepam was 1.0/1.2. Diazepam concentrations in cardiac blood were not significantly different from those in femoral blood (P = 0.385). Although no significant correlation between the C/P ratio and body mass index, postmortem interval, or hospitalization time was observed, the C/P ratio was significantly higher in cases with chest injury than in cases without chest injury (P = 0.007).

Conclusion: The median/mean C/P ratio of diazepam in Thai postmortem cases was 1.0/1.2. Chest injury was the only factor that had an impact on the C/P ratio of diazepam.