Drowning is the third leading cause of accidental deaths worldwide, accounting for 359 000 deaths annually according to estimates from World Health Organization (WHO). It is the leading cause of unintentional injury among children between ages 1 and 4 years, and ranks second among children between the ages of 5 and 14 years.
There has been much confusion regarding the terminology used to describe persons who have drowned. Previously, it was divided as salt versus fresh water drowning, dry versus wet drowning, and also as near drowning. Nonetheless, this lack of uniformity lead to confusion and underreporting of drowning cases, and as a result a new definition of drowning and the drowning process was created. Drowning is the process of experiencing respiratory impairment from submersion/immersion in liquid, resulting in primary respiratory impairment.
More than 50% of drowning victims treated in emergency departments (EDs) require hospitalization or transfer for further care. These nonfatal drowning injuries can cause severe brain damage that may result in long-term disabilities. Research has identified racial disparities with higher drowning rates among American Indians/Alaskan Natives followed by African Americans. Multiple factors can contribute and predispose a victim; the following have been identified as risk factors for drowning:
No two cases of drowning are the same. The type, temperature, and quantity of water aspirated may differ. Very cold water may result in rapid hypothermia which will decrease the victims requirements for oxygen, thereby prolonging the period of time they may be submerged and still completely recover. The process of drowning typically begins with a period of panic, loss of the normal breathing pattern, breath holding, and a struggle by the victim to stay above the water. With the development of hypercapnia, reflex inspiratory efforts eventually occur, leading to hypoxemia by means of aspiration or laryngospasm (secondary to the presence of liquid in the oropharynx or larynx). In cases where laryngospasm ensues first, as the victim becomes hypoxemic, the laryngospasm abates and liquid is aspirated. This in turn will lead to surfactant washout, pulmonary hypertension, and shunting, further aggravating the hypoxemia. If the victim is not ventilated soon enough, circulatory arrest occurs and multiple organ dysfunction and death results.
The mechanism of drowning starts with aspiration of water of any type which immediately affects alveolar ventilation, gas exchange, and the mechanical characteristics of the lungs. Hypoxemia is the hallmark of the pulmonary pathophysiology during submersion. Volumes as little as 1–3 mL/kg are sufficient to cause disruption in alveolar gas exchange and hypoxemia. Whether the drowning event occurs in fresh water or sea water, the end result is pulmonary edema, decrease in compliance, and increase in VQ mismatch. In severe cases of submersion, patients present with acute respiratory distress syndrome (ARDS), profound hypoxemia, and noncardiogenic pulmonary edema; in these patients, ...