In 2002, the World Congress on Drowning published expert consensus recommendations regarding the terminology, evaluation, and management of drowning. For decades, lack of uniformity in terminology has resulted in confusion among clinicians, leading to difficulty in comparing and interpreting data. “Drowning” was defined by the 2002 World Congress as the process resulting in primary respiratory impairment from submersion/immersion in a liquid medium regardless of whether the ultimate outcome is survival or death. Previously used descriptive terminology, such as “near-drowning,” leads to confusion and should be abandoned. In the past, there has also been an attempt to distinguish drowning with aspiration from drowning without aspiration. It is also the consensus that drowning without aspiration does not occur.

The literature formerly emphasized the distinction between salt water and fresh water drowning, believing that the effects from the hypertonicity of salt water were very different than the effects from the hypotonicity of fresh water. It is thought now that rarely enough water is aspirated to cause these varying effects. After voluntary breath-holding takes place, small amounts of water initially are aspirated from the oropharynx, which triggers involuntary laryngospasm, resulting in hypoxia. Larger amounts of water are subsequently swallowed as laryngospasm abates from prolonged hypoxia. Aspiration of water leads to destruction of surfactant, impaired alveolar capillary gas exchange, intrapulmonary shunting, and pulmonary edema. These events lead to progressive hypoxia, hypercarbia, and acidosis. Vomiting and aspiration of gastric contents can contribute to acute lung injury. Prolonged hypoxia leads to intense peripheral vasoconstriction, and decreased cardiac output and arterial blood pressure. If the hypoxic drowning process is not reversed, the brain and the heart can become permanently injured. Ultimately, profound bradycardia and circulatory arrest can occur. The extent of hypoxic insult will ultimately determine outcome.