The derivation of predictive equations to speculate the post-mortem interval using cases with over 20-mL pleural effusion: A preliminary study

Abstract Often, pleural effusion is noted at autopsy when the cause of death is drowning or diseases such as heart, renal and liver failure. Several studies have established a correlation between the concentrations of electrolytes in pleural effusion and the post-mortem interval (PMI) or those concentrations and drowning site. The present study aims to investigate the relationship between the amount of pleural effusion, concentrations of electrolytes and total protein in pleural effusion, by integrated interpretation using various factors such as the deceased's gender, age, cause of death, drowning site, PMI and body temperature. We included 40 cadavers (26 male, 14 female) with >20-mL pleural effusion, which were categorised into four groups as follows: freshwater drowning; brackish water drowning; seawater drowning (drowning group); and not drowning. An equation derived to assess the lung weight revealed that the drowning site affected the lung weight. An equation for the amount of pleural effusion in the drowning group for the first time revealed that the amount of pleural effusion was directly proportional to the PMI. Using an equation to assess the PMI, we could estimate the PMI within 13.0–13.2 h in cases with >20-mL pleural effusion. Despite a small number of cases in the present study, we attained exciting results from the integrated statistical analysis.