Drowning
Vasily Perov: The Drowned, 1867
Specialty	Critical care medicine
Symptoms	Event: Often occurs silently with a person found unconscious[1][2] After rescue: Breathing problems, vomiting, confusion, unconsciousness[2][3]
Complications	Hypothermia, aspiration of vomit into lungs, acute respiratory distress syndrome[4]
Usual onset	Rapid[3]
Risk factors	Alcohol use, epilepsy, access to water,[5] cold water shock
Diagnostic method	Based on symptoms[3]
Differential diagnosis	Suicide, seizure, murder, hypoglycemia, heart arrhythmia[2]
Prevention	Fencing pools, teaching children to swim, safe boating practices[6][5]
Treatment	Rescue breathing, CPR, mechanical ventilation[7]
Medication	Oxygen therapy, intravenous fluids, vasopressors[7]
Frequency	4.5 million (2015)[8]
Deaths	324,000 (2016)[6]

Drowning is a type of suffocation induced by the submersion of the mouth and nose in a liquid. Most instances of fatal drowning occur alone or in situations where others present are either unaware of the victim’s situation or unable to offer assistance. After successful resuscitation, drowning victims may experience breathing problems, vomiting, confusion, or unconsciousness. Occasionally, victims may not begin experiencing these symptoms until several hours after they are rescued. An incident of drowning can also cause further complications for victims due to low body temperature, aspiration of vomit, or acute respiratory distress syndrome (respiratory failure from lung inflammation).

Drowning is more likely to happen when spending extended periods of time near large bodies of water.^[4][6] Risk factors for drowning include alcohol use, drug use, epilepsy, minimal swim training or a complete lack of training, and, in the case of children, a lack of supervision.^[6] Common drowning locations include natural and man-made bodies of water, bathtubs, and swimming pools.^[3][7]

Drowning occurs when a person spends too much time with their nose and mouth submerged in a liquid to the point of being unable to breathe. If this is not followed by an exit to the surface, low oxygen levels and excess carbon dioxide in the blood trigger a neurological state of breathing emergency, which results in increased physical distress and occasional contractions of the vocal folds.^[9] Significant amounts of water usually only enter the lungs later in the process.^[4]

While the word “drowning” is commonly associated with fatal results, drowning may be classified into three different types: drowning that results in death, drowning that results in long-lasting health problems, and drowning that results in no health complications.^[10] Sometimes the term “near-drowning” is used in the latter cases. Among children who survive, health problems occur in about 7.5% of cases.^[7]

Steps to prevent drowning include teaching children and adults to swim and to recognise unsafe water conditions, never swimming alone, use of personal flotation devices on boats and when swimming in unfavourable conditions, limiting or removing access to water (such as with fencing of swimming pools), and exercising appropriate supervision.^[6][5] Treatment of victims who are not breathing should begin with opening the airway and providing five breaths of mouth-to-mouth resuscitation.^[7] Cardiopulmonary resuscitation (CPR) is recommended for a person whose heart has stopped beating and has been underwater for less than an hour.^[7]

Causes

A major contributor to drowning is the inability to swim. Other contributing factors include the state of the water itself, distance from a solid footing, physical impairment, or prior loss of consciousness. Anxiety brought on by fear of drowning or water itself can lead to exhaustion, thus increasing the chances of drowning.

Approximately 90% of drownings take place in freshwater (rivers, lakes, and a relatively small number of swimming pools); the remaining 10% take place in seawater.^[11] Drownings in other fluids are rare and often related to industrial accidents.^[12] In New Zealand’s early colonial history, so many settlers died while trying to cross the rivers that drowning was called “the New Zealand death”.^[13]

People have drowned in as little as 30 mm (1.2 in) of water while lying face down.^[14]

Death can occur due to complications following an initial drowning. Inhaled fluid can act as an irritant inside the lungs. Even small quantities can cause the extrusion of liquid into the lungs (pulmonary edema) over the following hours; this reduces the ability to exchange the air and can lead to a person “drowning in their own body fluid”. Vomit and certain poisonous vapors or gases (as in chemical warfare) can have a similar effect. The reaction can take place up to 72 hours after the initial incident and may lead to a serious injury or death.^[15]

Risk factors[edit]

Many behavioral and physical factors are related to drowning:^[16][17]

• Drowning is the most common cause of death for people with seizure disorders, largely in bathtubs. Epileptics are more likely to die due to accidents such as drowning. However, this risk is especially elevated in low and middle-income countries compared to high-income countries.^[18]
• The use of alcohol increases the risk of drowning across developed and developing nations. Alcohol is involved in approximately 50% of fatal drownings, and 35% of non-fatal drownings.^[19]
• Inability to swim can lead to drowning. Participation in formal swimming lessons can reduce this risk. The optimal age to start the lessons is childhood, between one and four years of age.^[20]
• Feeling overly tired reduces swimming performance. This exhaustion can be aggravated by anxious movements motivated by fear during or in anticipation of drowning. An overconfident appraisal of one’s own physical capabilities can lead to “swimming out too far” and exhaustion before returning to solid footing.
• Free access to water can be hazardous, especially to young children. Barriers can prevent young children from gaining access to the water.
• Ineffective supervision, since drowning can occur anywhere there is water, even in the presence of lifeguards.
• Risk can vary with location depending on age. Children between one and four more commonly drown in home swimming pools than elsewhere. Drownings in natural water settings increase with age. More than half of drownings occur among those fifteen years and older occurred in natural water environments.^[20]
• Familial or genetic history of sudden cardiac arrest (SCA) or sudden cardiac death (SCD) can predispose children to drown.^[21] Extensive genetic testing and/or consultation with a cardiologist should be done when there is a high suspicion of familial history and/or clinical evidence of sudden cardiac arrest or sudden cardiac death.
• Individuals with undetected primary cardiac arrhythmias, as cold water immersion or aquatic exercise can induce these arrhythmias to occur.^[22]

Population groups at risk in the US are the old and young.^{[16][dead link][citation needed]}

• Youth: drowning rates are highest for children under five years of age and people fifteen to twenty-four years of age.
• Minorities: the fatal unintentional drowning rate for African Americans above the age of 29 between 1999 and 2010 was significantly higher^[vague] than that of white people above the age of 29.^[23] The fatal drowning rate of African American children of ages from five to fourteen is almost three times that of white children in the same age range and 5.5 times higher in swimming pools. These disparities might be associated with a lack of basic swimming education in some minority populations.