Analysis of postmortem biochemical findings with regard to the lung weight in drowning

To clarify drowning death, positive evidence for aspiration of the immersion medium and the subsequent fatal mechanism is necessary. This study investigated biochemical findings with regard to lung weight in drowning cases of adults (n = 56, >18 years of age, <48 h postmortem: salt water, n = 19; fresh water, n = 21; brackish water, n = 16), using acute cardiac death cases (n = 240) as controls. The biochemical markers used in this study were urea nitrogen (UN), sodium (Na), chloride (Cl), calcium (Ca) and magnesium (Mg) in the blood and pericardial fluid (PCF). The left-to-right ratio of cardiac blood UN levels was lower for drowning, showing an inverse correlation to the total lung weight. There was a mild postmortem decrease in serum and PCF Na and Cl levels; however, left cardiac serum and PCF Na, Cl, Ca and Mg levels were higher for saltwater drowning, and left cardiac serum Na and Cl levels were lower for fresh water drowning. Correlation of the left cardiac serum level with lung weight was positive for Na, Cl and Mg in saltwater and brackish water drowning, and was also positive for Ca in saltwater drowning. There was an inverse correlation with lung weight for PCF Na and Cl levels in freshwater drowning. These findings suggest that analyses of serum and pericardial markers in relation to lung weight are useful for evaluating the composition and amount of aspirated medium when investigating drowning death.