Drowning, as defined by the World Health Organization, is any “process resulting in primary respiratory impairment from submersion in a liquid medium.” A panel of experts reached consensus that this definition be universally used to describe all such incidents, regardless of whether the outcome was fatal. The panel recommended previously used terms such as near-drowning, wet-drowning, dry-drowning, and silent drowning be eliminated from use. Drowning may result in asphyxiation (from fluid aspiration or laryngospasm), hypoxemia, hypothermia, and acidemia. Outcomes from drowning range from life without morbidity to death. Morbidity may be immediate or delayed. The asphyxia of drowning is usually due to aspiration of fluid (previously known as “wet drowning”), but it may result from airway obstruction caused by laryngeal spasm while the victim is gasping under water (previously known as “dry drowning”). The rapid sequence of events after submersion—hypoxemia, laryngospasm, fluid aspiration, ineffective circulation, brain injury, and brain death—may take place within 5–10 minutes. This sequence may be delayed for longer periods if the victim, especially a child, has been submerged in very cold water or if the victim has ingested significant amounts of sedative medications. Laryngospasm develops in about 10% of victims after the first gulp and water is never aspirated. Immersion in cold water can also cause a rapid fall in the victim's core body temperature, so that systemic hypothermia and death may occur before actual drowning. The primary effect is hypoxemia due to perfusion of poorly ventilated alveoli, intrapulmonary shunting, and decreased compliance. A patient may be deceptively asymptomatic during the initial recovery period only to deteriorate or die as a result of acute respiratory failure within the following 12–24 hours. Disseminated intravascular coagulation may also lead to bleeding after asphyxiation from drowning.
Spontaneous return of consciousness often occurs in otherwise healthy individuals when submersion is very brief. Many patients respond promptly to immediate ventilation. Others, with more severe degrees of drowning, may have frank respiratory failure, pulmonary edema, shock, anoxic encephalopathy, cerebral edema, and cardiac arrest.
Drowning is a leading cause of death in children and highly preventable in all ages with implementation of educational and safety measures. Clinicians must provide patient education and guidance about drowning prevention.