Drowning occurs when submersion in liquid causes suffocation or interferes with breathing.
Drowning may be nonfatal (previously described as near drowning) or fatal. Drowning is a leading cause of accidental death in the United States and the second leading cause in children ages 1 to 14 years. About four times as many people are hospitalized for nonfatal drowning as die from drowning. Drowning rates are higher for all of the following:
Drowning is common in pools, hot tubs, and natural water settings. Children and toddlers are also at risk from even small amounts of water, such as in toilets, bathtubs, and buckets of water or other fluids, because they may be unable to escape after falling in.
Diving, particularly into shallow water, may cause spinal injuries and paralysis that increase the chances of drowning. People who intentionally hold their breath under water for extended periods may pass out and sometimes drown.
People swimming near an exhaust vent of a boat may develop carbon monoxide poisoning, which may cause unconsciousness and drowning.
When people are submerged under water, water enters the lungs. The vocal cords may go into severe spasm, temporarily preventing water from reaching the lungs but also preventing breathing. In either case, the lungs cannot transfer oxygen to the blood. The decrease in the level of oxygen in the blood that results may lead to brain damage and death. Water in the lungs, particularly water that is contaminated by bacteria, algae, sand, dirt, chemicals, or vomit, can cause lung injury. Lung injury tends to cause continuing oxygen deprivation. Fresh water in the lungs is absorbed into the bloodstream. Absorbing large amounts of fresh water sometimes causes electrolyte abnormalities, such as a low sodium level in the blood.
Effects of Cold:
Submersion in cold water has both good and bad effects. Cooling of the muscles makes swimming difficult, and dangerously low body temperature (hypothermia) can impair judgment. Cold, however, protects tissues from the ill effects of oxygen deprivation. In addition, cold water may stimulate the mammalian diving reflex, which may prolong survival in cold water. The diving reflex slows the heartbeat and redirects the flow of blood from the hands, feet, and intestines to the heart and brain, thus helping to preserve these vital organs. The diving reflex is more pronounced in children than in adults, so children have a greater chance of surviving prolonged submersion in cold water than do adults.
People who are drowning and struggling to breathe are usually unable to call for help. Children who are unable to swim may submerge in less than 1 minute. Adults may struggle longer.
People who are rescued may have a wide range of symptoms and findings. Some are only mildly anxious, whereas others are near death. They may be alert, drowsy, or comatose. Some people may not be breathing. People who are breathing may gasp for breath or vomit, cough, or wheeze. The skin may appear blue (cyanosis), indicating insufficient oxygen in the blood. In some cases, respiratory problems may not become evident for several hours after submersion.
Some people who are revived after prolonged submersion have permanent brain damage because of the lack of oxygen. People who inhale foreign particles may develop pneumonia or acute respiratory distress syndrome, causing prolonged difficulty breathing. People who drown in cold water often have hypothermia.
Doctors diagnose drowning based on the events and the symptoms. Measurement of the level of oxygen in the blood and chest x-rays help reveal the extent of lung damage. Other tests, such as x-rays and computed tomography (CT), may be done to diagnose head or spinal injuries. An electrocardiogram (ECG) and sometimes blood tests may be done to diganose disorders that may have contributed to drowning. For example, certain previously unrecognized heart arrhythmias can cause unconsciousness while swimming.
Swimming pools should be adequately fenced, because they are one of the most common sites of drowning accidents. In addition, all doors and gates leading to the pool area should be locked. Children in or near any body of water, including pools and bathtubs, need constant supervision, regardless of whether flotation devices are used. Because infants and young children can drown in only a few inches of water, even water-filled containers, such as buckets or ice chests are hazardous. Small children should wear life jackets when playing near bodies of water.
People should not engage in swimming or boating when under the influence of alcohol or sedatives. Swimming should be curtailed if people feel or look very cold. People who have seizures that are well controlled need not avoid swimming, but they should be careful near water, whether boating, showering, or bathing.
To decrease the risk of drowning, people should not swim alone and should swim only in areas patrolled by lifeguards. Ocean swimmers should learn to escape rip currents (strong currents that pull away from the shore) by swimming parallel to the beach rather than by swimming toward the beach. Also, swimming near boat exhaust ports should be avoided.
Wearing life jackets when in boats is encouraged for everyone and is required for nonswimmers and for small children. Spinal injuries can be prevented by not diving into shallow water.
Community swimming areas need to be supervised by trained lifeguards. Comprehensive community prevention programs should
However, even young children who have taken swimming lessons should be watched closely around water. Programs that teach infants and young children to swim have not been proven to decrease the risk of drowning.
The factors that most increase the chances of survival without permanent brain and lung damage are the following:
Survival is possible after submersion for as long as 40 minutes. Many people who need CPR can also recover fully, and almost all people who are alert and conscious upon their arrival at the hospital recover fully. People who have consumed alcoholic beverages before submersion are more likely to die or develop brain or lung damage.
Out of the Hospital:
Immediate on-site resuscitation is the key to increasing the chance of survival without brain damage. Attempts should be made to revive people even when the time under water is prolonged. Artificial respiration and CPR should be provided as necessary (see First Aid: First-Aid Treatment). The neck should be moved as little as possible if there is a chance of spinal injury. People who were submerged involuntarily or have any symptoms must be transported to a hospital, by ambulance if possible. People who were submerged but have only mild symptoms may be discharged to their home after several hours of observation in the emergency department. If symptoms persist for a few hours, or if the level of oxygen in the blood is low, people need to be admitted to the hospital.
In the Hospital:
Most people need supplemental oxygen, sometimes in high concentrations or given via a ventilator at high pressures. If wheezing develops, bronchodilators can help. If an infection develops, antibiotics are given.
If the water was cold, people may have a dangerously low body temperature (hypothermia) and may need warming (see Cold Injuries: Treatment). Spinal injury requires special treatment (see Spinal Cord Disorders: Treatment).
Last full review/revision January 2009 by Norman L. Dean, MD