Interpretation of Ethanol Concentration Changes in Postmortem Blood and Vitreous Samples During Six Months of Refrigerated Storage

Miljen Maletin, Dusan Vapa, Radosav Radosavkic, Anita Maletin, Maja Djurendic-Brenesel, Niksa Ajdukovic, Dragana Ratkovic and Goran Stojiljkovic

Background and Objective: Blood alcohol concentration (BAC) may rise during storage, or it may decrease. Femoral vein is the best place for taking postmortem blood samples. Urine and vitreous humour (VH) should be obtained. The aims of the study was to determine if there were significant changes in BAC and VH during storage; in which sample is less susceptible to changes and if could VH be used to estimate BAC in postmortem specimens. Materials and Methods: Samples obtained during autopsy of 60 deceased persons were kept at -80°C for six months. Headspace Gas Chromatography with Flame Ionization Detection (HS-GC-FID) was used for quantitative analyses. Samples were analysed immediately (C₁) and after 180 days (C₁₈₀). The level of marginal statistical significance of p<0.05 was used. Results: There was a significant decrease in BAC between C₁ and C₁₈₀ ( = 0.139, SD = 0.097, t = 11.09 and p<0.001), as well as in VH ( = 0.07, SD = 0.063, t = 8.61 and p<0.001). Mean changes in BAC and VH show significant differences (t = 4.635 and p<0.001). Calculated VH/BAC ratio in initial analysis ( = 1.161) and after 180 days ( = 1.244) show a significant difference (t =-2.296 and p<0.05). There is a high linear correlation between VH and BAC values (y = 0.8622x+0.0099, R² = 0.9537, y = 0.7948x+0.0323 and R² = 0.9427). Conclusion: The BAC and VH ethanol levels significantly decreased during six months. Mean VH/BAC ratio corresponds to previous studies, as well as linear regression equations which propose calculating BAC when VH is known. Individual variations in VH/BAC ratio suggest that it is not recommended to use any of these values to predict the other one.

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