Drowning Syndromes: the Mechanism

The drowning syndromes should be viewed as a continuum between the aspiration of a relatively small amount of water, causing symptoms and respiratory-based signs, through near-drowning, in which there is loss of consciousness but with survival, to the fatal cases of drowning. The latter rarely involve the gross haemodynamic and biochemical changes seen in some animal experiments. The behaviour of the victims, animal and human, during the incident is reviewed, as are the experiments conducted on animals, with various types and quantities of aspirate, to model the physiology. These experiments are compared with adult human clinical case series. “Quiet” drownings are described and classified. The clinical features of near drowning are reviewed. Factors which influence survival are noted. The pathological findings are discussed, with a critical approach to the concept of “dry” drowning, and some postulates on the findings of cranial haemorrhages. Lungs are the primary and dominant organ involved and hypoxia is the major physiological abnormality. The salt water aspiration syndrome, including its development, clinical and laboratory findings as seen in scuba divers, is also reviewed. Finally a brief review of the literature specific to scuba drownings is given.