Near-drowning and clinical laboratory changes

Opposite to clinical laboratory findings in experimental drowning of animals (erythrocytic lysis, hyperkalemia, and final cardial fibrillation) are the observations in drowned humans (increase of pCO2, hypoxic encephalopathy), which leads to a different pathophysiological interpretation of the drowning process. This process, however, is recently discussed again, therefore an additional study seemed to be recommended. In a retrospective study, 31 cases of near-drowning (23 cases: fresh water; 8 cases: brackish water) clinical laboratory data were analysed. While 21 of the cases were fatal with a delay of up to 180 days, 10 individuals survived the accident, four cases with severe neurological deficits. Data of pH, potassium, sodium, chloride, hemoglobin and total protein were collected during the very early post-drowning period. Nearly all cases (96%) revealed a reduction of pH due to hypoxic acidosis, and only two cases (6.5%) exhibited a slight hyperkalemia. The hemoglobin level was normal in most of the cases (83%) and slightly reduced in the others (17%) while the protein level was slightly reduced in most of the fatalities (80%). As a result of our investigation we have to state the lack of hyperkalemia as well as of an increase of the hemoglobin level indicate that there is no distinct intravascular red cell lysis due to influx of water into the vascular compartment. Therefore the death by drowning in humans in most cases is the result of a hypoxic cerebral process. A comparison with animal experiments obviously is not helpful because the drowning process in humans leads to an aspiration of only 2-4 ml water/kg, while in animal experiments more than 10 ml water/kg will be artificially aspirated leading to red cell lysis as well as to electrolyte disturbances and cardial fibrillation.