INTRODUCTION — Every year, drowning accounts for at least 500,000 deaths worldwide, including approximately 4000 fatalities in the United States [1,2]. Statistics for nonfatal drowning are more difficult to obtain, but nonfatal drowning events may occur several hundred times as frequently as reported drowning deaths [3,4].

Drowning and its management are reviewed here. The management of specific complications of nonfatal drowning (eg, hypothermia, acute respiratory distress syndrome, and bradycardia), complications of SCUBA diving, and the general management of trauma are discussed separately. (See "Accidental hypothermia in adults" and "Hypothermia in children: Management" and "Complications of SCUBA diving" and "Acute respiratory distress syndrome: Clinical features, diagnosis, and complications in adults" and "Initial management of trauma in adults" and "Trauma management: Approach to the unstable child".)

TERMINOLOGY — Multiple definitions of drowning, nonfatal drowning, and submersion injury have been proposed in the medical literature, creating confusion and underlining the need for a more consistent approach to reporting and studying these incidents [1]. Nonfatal drowning generally is defined as survival, at least temporarily, after suffocation by submersion in a liquid medium [5]. Most authors include the loss of consciousness while submerged as a criterion for the syndrome.

However, some authors have argued that since pulmonary complications may follow the aspiration of water without the loss of consciousness, nonfatal drowning should be defined as survival, at least temporarily, after aspiration of fluid into the lungs ("wet nonfatal drowning") or after a period of asphyxia secondary to laryngospasm ("dry nonfatal drowning") [6].

In its 2010 resuscitation guidelines, the American Heart Association recommends that the Utstein definitions and methods of data reporting for drowning and related events be used to improve consistency in reporting and research [7-9]. According to the Utstein guidelines, drowning refers to: "a process resulting in primary respiratory impairment from submersion or immersion in a liquid medium" [7]. The Utstein guidelines further suggest that ambiguous or confusing terms such as "near-drowning," "secondary drowning," and "wet drowning" should not be used. Revisions of the Utstein guidelines highlighting core data to include in studies of drowning resuscitation were released in 2015 [10].

EPIDEMIOLOGY — Drowning is a common cause of accidental death in the United States and an important cause of childhood fatalities worldwide [11-17]. Low and middle-income countries have the highest rates of drowning, accounting for over 90 percent of such fatalities.

In the United States, drowning is a major cause of accidental death among persons under the age of 45 years and a leading cause in children under five years of age in states where swimming pools or beaches are more accessible, such as California, Arizona, and Florida [11,18,19]. The highest incidence of drowning occurs among males, African-Americans, children between the ages of one and five years, persons with low-socioeconomic status, and among residents of Southern states [12,17,20]. Drowning is much more common during the summer months.

The age distribution of submersion injury is bimodal. The first peak occurs among children less than five years of age who are inadequately supervised in swimming pools, bathtubs, or around other liquid-filled containers; approximately 7 percent of these incidents appear related to child abuse or neglect. The second age peak is seen among males between 15 and 25 years old, and these episodes tend to occur at rivers, lakes, and beaches [21].

RISK FACTORS — The following factors increase the risk of drowning [2,11,21-30]:

●Inadequate adult supervision.

●Inability to swim or overestimation of swimming capabilities.

●Risk-taking behavior.

●Use of alcohol and illicit drugs (more than 50 percent of adult drowning deaths are believed to be alcohol-related).

●Hypothermia, which can lead to rapid exhaustion or cardiac arrhythmias. (See "Accidental hypothermia in adults".)

●Concomitant trauma, stroke, or myocardial infarction.

●Seizure disorder or developmental/behavioral disorders in children [31,32].

●Undetected primary cardiac arrhythmia (may be a more common cause of drowning than generally appreciated) [33]. As an example, cold water immersion and exercise can cause fatal arrhythmias in patients with the congenital long QT syndrome type 1. Similarly, mutations in the cardiac ryanodine receptor (RyR)-2 gene, which is associated with familial polymorphic VT in the absence of structural heart disease or QT prolongation, have been identified in some individuals with unexplained drowning [26]. (See "Congenital long QT syndrome: Epidemiology and clinical manifestations", section on 'Triggers of arrhythmia' and "Catecholaminergic polymorphic ventricular tachycardia".)

●Hyperventilation prior to a shallow dive. Swimmers commonly hyperventilate in order to prolong the duration of underwater swimming, and by so doing they reduce the arterial partial pressure of carbon dioxide (PaCO₂) while the content of oxygen (CaO₂) does not increase appreciably. As the individual swims, oxygen is consumed and the partial pressure of oxygen (PaO₂) falls to 30 to 40 mmHg before the PaCO₂ rises sufficiently to trigger the urge to breathe. This can lead to cerebral hypoxia, seizures, and loss of consciousness, which can result in drowning. (See "Control of ventilation".)

PATHOPHYSIOLOGY — Fatal and nonfatal drowning typically begins with a period of panic, loss of the normal breathing pattern, breath-holding, air hunger, and a struggle by the victim to stay above the water. Reflex inspiratory efforts eventually occur, leading to hypoxemia by means of either aspiration or reflex laryngospasm that occurs when water contacts the lower respiratory tract [2,3,34-37]. Hypoxemia in turn affects every organ system, with the major component of morbidity and mortality being related to cerebral hypoxia [22]. (See "Hypoxic-ischemic brain injury in adults: Evaluation and prognosis".)

The literature formerly emphasized the distinction between salt water and fresh water drowning [38]. It was believed that the hypertonicity of salt water caused plasma to be drawn into the pulmonary interstitium and alveoli, leading to massive pulmonary edema and hypertonic serum. Drowning in fresh water was thought to create the opposite effect, with aspirated hypotonic fluid rapidly passing through the lungs and into the intravascular compartment, leading to volume overload and dilutional effects on serum electrolytes.

Subsequently, researchers have recognized that this distinction is more apparent among persons who are dead on arrival than among victims who are brought to the hospital alive. Aspiration of more than 11 mL/kg of body weight must occur before blood volume changes occur, and more than 22 mL/kg before electrolyte changes take place [39-41]. Because it is unusual for nonfatal drowning victims to aspirate more than 3 to 4 mL/kg, the distinction between salt water and fresh water drowning is no longer considered important [42-44]. Both types of nonfatal drowning result in decreased lung compliance, ventilation-perfusion mismatching, and intrapulmonary shunting, leading to hypoxemia that causes diffuse organ dysfunction [38]. The temperature of the water and the presence of contaminants may affect patient outcomes [3,21,34].

END ORGAN EFFECTS — Hypoxemia ultimately produces tissue hypoxia, which affects virtually all tissues and organs within the body.

The American Thoracic Society (ATS) consensus conference report for the detection, correction, and prevention of tissue hypoxia, as well as other ATS guidelines, can be accessed through the ATS web site at www.thoracic.org/statements.

Pulmonary — Fluid aspiration results in varying degrees of hypoxemia [22]. Both salt water and fresh water wash out surfactant, often producing noncardiogenic pulmonary edema and the acute respiratory distress syndrome (ARDS) [3,21]. Pulmonary insufficiency can develop insidiously or rapidly; signs and symptoms include shortness of breath, crackles, and wheezing. The chest radiograph or computed tomography at presentation can vary from normal to localized, perihilar, or diffuse pulmonary edema (image 1). (See "Acute respiratory distress syndrome: Clinical features, diagnosis, and complications in adults".)

Neurologic — Hypoxemia and ischemia cause neuronal damage, which can produce cerebral edema and elevations in intracranial pressure [45]. Some authors consider the progressive rise in intracranial pressure that is sometimes observed approximately 24 hours after injury to reflect the severity of the neurologic insult rather than its cause [46]. Approximately 20 percent of nonfatal drowning victims sustain neurologic damage, limiting functional recovery despite successful cardiopulmonary resuscitation [47]. (See "Hypoxic-ischemic brain injury in adults: Evaluation and prognosis".)

Cardiovascular — Arrhythmias secondary to hypothermia and hypoxemia are often observed in nonfatal drowning victims. (See "Accidental hypothermia in adults", section on 'Clinical signs and their progression with worsening hypothermia' and "Accidental hypothermia in adults", section on 'Electrocardiographic changes'.)

The initial arrhythmias described following nonfatal drowning include sinus tachycardia, sinus bradycardia, and atrial fibrillation [48]. In addition, swimming (including diving) can precipitate fatal ventricular arrhythmias in patients with congenital long QT syndrome type 1. (See "Congenital long QT syndrome: Epidemiology and clinical manifestations", section on 'Triggers of arrhythmia'.)

Changes in the electrocardiogram of a small number of patients following non-fatal submersion injury that suggest myocardial ischemia may be due to takotsubo cardiomyopathy, coronary artery spasm, or hypothermia, in addition to myocardial ischemia proper [49].

Acid-base and electrolytes — A metabolic and/or respiratory acidosis is often observed. Significant electrolyte imbalances generally do not occur in nonfatal drowning survivors except those submerged in unusual media, such as the Dead Sea, where the extremely concentrated seawater can produce life-threatening hypernatremia, hypermagnesemia, and hypercalcemia due to absorption of swallowed seawater [50]. (See "Simple and mixed acid-base disorders".)

Renal — Renal failure rarely can occur after submersion, and is usually due to acute tubular necrosis resulting from hypoxemia, shock, hemoglobinuria, or myoglobinuria [51,52]. (See "Overview of the management of acute kidney injury (AKI) in adults".)

Coagulation — Hemolysis and coagulopathy are rare potential complications of nonfatal drowning [53].

MANAGEMENT — Management of drowning victims can be divided into three phases: prehospital care, emergency department (ED) care, and inpatient care. Little high-quality evidence is available to guide the management of drowning victims; the guidance provided below is drawn from observational studies and clinical experience [54].

Prehospital care and acute interventions — Rescue and immediate resuscitation by bystanders improves the outcome of drowning victims [16,54-56]. The need for cardiopulmonary resuscitation (CPR) is determined as soon as possible without compromising the safety of the rescuer or delaying the removal of the victim from the water.

Ventilation is generally considered the most important initial treatment for victims of submersion injury. Rescue breathing should begin as soon as the rescuer reaches shallow water or a stable surface. Note that the priorities of CPR in the drowning victim differ from those in the typical adult cardiac arrest patient, which emphasize immediate uninterrupted chest compressions. If the patient does not respond to the delivery of two rescue breaths that make the chest rise, the rescuer should immediately begin performing high-quality chest compressions. CPR, including the application of an automated external defibrillator, is then performed according to standard guidelines. (See "Adult basic life support (BLS) for health care providers" and "Pediatric basic life support (BLS) for health care providers".)

Although guidelines from the American Heart Association and European Resuscitation Council emphasize rescue breathing as a critical part of the CPR for drowning victims, the impact of rescue breathing during transport on neurologic outcome remains uncertain [57,58]. In a large, population-based, observational study using a Japanese government registry, no significant difference in neurologic outcome at one month was found between drowning victims treated initially with compression-only CPR and conventional CPR with rescue breathing [59].

In a review of 2388 drowning victims from a United States database, no airway device was associated with a statistically significant improvement in survival with good neurologic outcome [60]. Bag-mask ventilation remains a reasonable approach during early care and prehospital transport. Particularly in areas with a high risk of respiratory infection from coronavirus disease 2019 (COVID-19) or comparable pathogens, bag-mask ventilation devices should be equipped with a high-efficiency particulate air (HEPA) filter.

Cervical spinal cord injury is uncommon in nonfatal drowning victims, unless there are clinical signs of injury or a concerning mechanism (eg, dive into shallow water). According to the AHA Guidelines for Advanced Cardiac Life Support (ACLS), routine cervical spine immobilization can interfere with essential airway management and is not recommended [7,57]. A cohort study of 2244 submersion victims reported that 11 (0.5 percent) sustained cervical spine injuries and all had obvious signs of injury and a mechanism (eg, diving, motor vehicle crash) suggestive of spinal trauma [61]. Nevertheless, it can be difficult to assess the spine of nonfatal drowning patients with an altered mental status (eg, intoxicated) and clinicians should use caution when deciding to remove spinal immobilization.

Drowning patients can present with life-threatening arrhythmias, and these are treated according to ACLS protocols. Pulses may be very weak and difficult to palpate in the hypothermic patient with sinus bradycardia or atrial fibrillation; a careful search for pulses should be performed for at least one minute before initiating chest compressions in the hypothermic patient because these arrhythmias require no immediate treatment. If the patient does not respond to the delivery of two rescue breaths that make the chest rise, the rescuer should immediately begin performing high-quality chest compressions once the absence of a pulse is established in the hypothermic patient. CPR is then performed according to standard BLS guidelines. (See "Advanced cardiac life support (ACLS) in adults" and "Pediatric advanced life support (PALS)" and "Accidental hypothermia in adults", section on 'Resuscitation' and "Accidental hypothermia in adults", section on 'Arrhythmias not causing cardiac arrest'.)

The Heimlich maneuver or other postural drainage techniques to remove water from the lungs are of no proven value, and rescue breathing should not be delayed in order to perform these maneuvers [16,57,62]. High-flow oxygen-delivery systems should be used to ensure adequate oxygenation of spontaneously breathing patients; apneic patients and those in respiratory distress or unable to protect their airway should be intubated. Attempts at rewarming hypothermic patients with a core temperature <33ºC should be initiated, either by passive or active means as available. (See "Accidental hypothermia in adults".)

Emergency department management — Prehospital resuscitative efforts should be continued and the airway secured as indicated. (See "The decision to intubate" and "Approach to advanced emergency airway management in adults" and "Emergency endotracheal intubation in children".)

In the symptomatic patient, indications for intubation include the following:

●Signs of neurologic deterioration or inability to protect the airway

●Inability to maintain a PaO₂ above 60 mmHg or oxygen saturation (SpO₂) above 90 percent despite use of a high-flow oxygen-delivery system or noninvasive ventilation

If tracheal intubation is performed, an orogastric tube should be placed to relieve gastric distension, which occurs from passive passage of fluid and is common in nonfatal drowning patients.

In symptomatic patients who do not require immediate intubation, supplemental oxygen should be provided to maintain the SpO₂ above 94 percent. In addition, noninvasive positive pressure ventilation via continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BPAP) can improve oxygenation and decrease ventilation-perfusion mismatch [53]. Note that positive airway pressure increases intrathoracic pressure and patients must be carefully monitored for possible hypotension. (See "Noninvasive ventilation in adults with acute respiratory failure: Benefits and contraindications".)

In addition to frequent vital sign measurements and clinical reassessment, monitoring of the symptomatic patient should include continuous oxygen saturation, end-tidal CO₂, and cardiac telemetry. A beside glucose measurement should be obtained soon upon arrival. Empiric administration of naloxone is reasonable in some cases when opioid intoxication may be a factor. (See "Pulse oximetry" and "Carbon dioxide monitoring (capnography)".)

A trauma evaluation should be performed and appropriate imaging studies obtained as indicated. Injury of the cervical spine is not common in patients with submersion injuries, but precautions should be taken if there is a concerning history (eg, dive into shallow water) or signs of injury. (See "Initial management of trauma in adults" and "Trauma management: Approach to the unstable child" and 'Prehospital care and acute interventions' above.)

Wet clothing should be removed and rewarming initiated in hypothermic patients. Methods include passive and active external rewarming (eg, application of warm blankets, plumbed garments, heating pads, radiant heat, forced warm air), and active internal core rewarming (eg, warmed humidified oxygen via tracheal tube, heated irrigation of peritoneal and pleural cavities). In addition, endovascular and several extracorporeal rewarming options are available in some centers. (See "Accidental hypothermia in adults".)

Possibly because of the neuroprotective effects of hypothermia, complete recovery of some patients with accidental hypothermia and cardiac arrest, despite prolonged resuscitation, has been well documented [63]. Therefore, prolonged resuscitative efforts may be effective (in rare instances, even if continued for several hours) and should be continued until the patient's core temperature reaches 32 to 35ºC (90 to 95ºF) [64]. A low-reading thermometer may be necessary. Prolonged resuscitations appear more likely to be effective when drowning occurs in cold water or circumstances suggest that hypothermia preceded asphyxia, although data is limited and the relative benefits of cold water have been questioned [65]. Otherwise, survivors are likely to have a poor neurologic outcome if the return of spontaneous circulation does not occur within 30 minutes of the initiation of advanced life support [66]. (See 'Neurologic injuries' below and 'Outcome' below.)

Patient disposition — Most nonfatal drowning victims are hospitalized because of the severity of illness or concern for clinical deterioration. However, a review of 75 pediatric patients found that all who ultimately developed symptoms did so within seven hours of immersion [67]. Based upon that study and similar analyses in adults and children, the following guidelines may be used to triage nonfatal drowning victims in the emergency unit [68,69]:

●Symptomatic patients should be admitted to a monitored setting until symptoms and physiologic disturbances resolve.

●Electrocardiography, measurement of serum electrolytes and creatinine, and serum and urine assays for alcohol and illicit drugs are generally recommended in asymptomatic, as well as symptomatic, adolescent and adult patients. Measurement of blood counts and a prothrombin time are reasonable in the symptomatic patient. Additional testing may be useful in specific circumstances (eg, troponin to assess myocardial injury).

●Asymptomatic patients should be closely observed for approximately eight hours and admitted if any deterioration occurs. If vital signs, pulse oximetry, and all studies, including a chest radiograph obtained close to the end of the observation period, are normal and no clinical deterioration develops during this period, the patient may be discharged with appropriate follow-up. Clear verbal and written instructions to return to the emergency department immediately for any respiratory or other problems must be given, and the patient must be accompanied by a responsible adult.

Inpatient management — Symptomatic patients require hospitalization for supportive care and treatment of organ-specific complications.

Neurologic injuries — The major determinants of neurologic outcome are the duration of loss of consciousness and the neurologic state of the patient upon presentation. The goal of hospital management is to prevent secondary neurologic injuries due to ongoing ischemia, cerebral edema, hypoxemia, fluid and electrolyte imbalances, acidosis, and seizure activity. Useful treatments may include the following:

●The head of the bed should be elevated to 30 degrees if potential cervical spine injuries have been excluded. More aggressive measures to reduce elevated intracranial pressure, as well as intracranial pressure monitoring, have not been documented to improve outcomes and are rarely undertaken [46].

●Diuretics can be used to avoid hypervolemia, but care should be taken to avoid volume depletion, which can lower cardiac output and cerebral perfusion.

●For patients in imminent danger of cerebral herniation, hyperventilation may be used acutely as a temporizing measure to reduce intracranial pressure by decreasing intracranial blood volume. Prolonged hyperventilation should be avoided because it can cause vasoconstriction, decreasing cerebral blood flow and worsening cerebral ischemia. (See "Evaluation and management of elevated intracranial pressure in adults".)

●Seizure activity, which increases cerebral oxygen consumption and blood flow, should be aggressively controlled. Non-sedating anticonvulsants (eg, phenytoin) are preferred because they do not depress consciousness and thereby complicate neurologic assessment. (See "Perioperative care of the surgical patient with neurologic disease", section on 'Seizure disorders'.)

●Neuromuscular blocking agents should be avoided, if possible, because they can mask neurologic signs. (See "Neuromuscular blocking agents in critically ill patients: Use, agent selection, administration, and adverse effects".)

●Both hypoglycemia and hyperglycemia may be harmful to the brain, and euglycemia should be meticulously maintained. (See "Glycemic control in critical illness".)

The appropriate use of therapeutic (induced) hypothermia in the postresuscitation period following nonfatal drowning remains unclear, primarily due to the absence of high quality evidence. A number of case series have reported no clear improvement in outcome following the use of therapeutic hypothermia [70,71], and the treatment has been associated with an increased incidence of sepsis, probably secondary to cold-induced immunosuppression [47,71,72]. However, other case reports describe improved outcomes following such treatment [73,74], and several guidelines mention therapeutic hypothermia as a possible intervention [7,58,75]. Given the weak, equivocal data, we believe it is reasonable either to treat or not to treat unconscious nonfatal drowning patients with therapeutic hypothermia. At a minimum, normothermia is desirable. Hyperthermia should be avoided as it increases cerebral metabolic demands and lowers the seizure threshold. The introduction and on-going management of therapeutic hypothermia are discussed separately. (See "Initial assessment and management of the adult post-cardiac arrest patient", section on 'Temperature management'.)

The use of barbiturates and controlled hypothermia in unconscious nonfatal drowning victims was reported in 1979 to decrease mortality and neurologic morbidity in children [76]. However, subsequent studies failed to show any benefit from this therapy [37]. As an example, one study of 31 comatose, drowned children did not show a difference in outcomes between those treated with mild hypothermia alone, and those treated with mild hypothermia plus pentobarbital [77].

Respiratory failure or infection — Repeat chest radiographs may not reflect the severity of the pulmonary involvement and should be performed on inpatients only when indicated by signs and symptoms of increased respiratory distress, declining pulse oximetry, or hypercarbia. Bronchospasm is often seen in nonfatal drowning victims, and management is treated similarly to acute asthma; most cases rapidly improve with inhaled beta-adrenergic agonists. (See "Acute exacerbations of asthma in adults: Home and office management" and "Acute asthma exacerbations in children younger than 12 years: Inpatient management".)

There is no good evidence to support the routine use of glucocorticoids or prophylactic antibiotics in nonfatal drowning victims [34,42,53]. Antibiotics should be used only in cases of clinical pulmonary infection or if the victim was submerged in grossly contaminated water. If pneumonia follows nonfatal drowning, a high suspicion for water-borne pathogens, such as Aeromonas, Pseudomonas, and Proteus, must be maintained [78]. (See "Aeromonas infections", section on 'Therapy' and "Pseudomonas aeruginosa pneumonia", section on 'Management'.)

Mechanical ventilatory strategies are similar to those employed in other types of acute lung injury. Case series and case reports describe the successful use of extracorporeal membrane oxygenation (ECMO) to treat drowning victims, but high-quality evidence supporting this approach is lacking [73,79,80]. (See "Ventilator management strategies for adults with acute respiratory distress syndrome" and "Extracorporeal membrane oxygenation (ECMO) in adults".)

Researchers have investigated the use of exogenous surfactant to treat submersion injury with respiratory failure, with the rationale of replacing surfactant that has been washed out [81,82]. Although there are case reports of surfactant treatment [83], no trials have been performed in nonfatal drowning victims, and there is no high-quality evidence that pulmonary function improves with surfactant therapy in this setting. (See "Acute respiratory distress syndrome: Investigational or ineffective therapies in adults", section on 'Ineffective or harmful therapies'.)

Hypotension — Persons with hypothermia can have significant hypovolemia and hypotension due to a "cold diuresis." This occurs because during the early phase of vasoconstriction, blood moves to the core, causing central volume receptors to sense fluid overload and resulting in decreased antidiuretic hormone production. (See "Treatment of severe hypovolemia or hypovolemic shock in adults" and "Initial management of shock in children".)

Hypoxic cardiomyopathy may develop in nonfatal drowning victims [84]. Pulmonary artery catheterization may be useful in cases in which the etiology of hypotension is unclear, as the data obtained can assist in optimal fluid replacement and inotropic support.

OUTCOME — Evidence pertaining to survival following a submersion injury is limited to a large case-control study and other case series. The following factors at presentation have been associated with a poor prognosis [4,65,75,85-94]:

●Duration of submersion >5 minutes (most critical factor)

●Time to effective basic life support >10 minutes

●Resuscitation duration >25 minutes

●Age >14 years

●Glasgow coma scale <5 (ie, comatose)

●Persistent apnea and requirement of cardiopulmonary resuscitation in the emergency department

●Arterial blood pH <7.1 upon presentation

Traditionally, cold water was thought to benefit drowning victims by decreasing metabolic demands and activating the diving reflex, a primitive reflex of bradycardia and breath-holding often seen in children that also shunts blood to the vital organs. However, the largest assessment of drowning to date, a case-control study of 1094 open water drownings recorded between 1975 and 1996, many of which occurred in colder water, found no association between water temperature and survival with a "good outcome" (defined as no, mild, or moderate neurologic sequelae) [65]. The study did find statistically significant associations between survival with a good outcome and the duration of submersion (88.2 percent were submerged <6 minutes) as well as with patient age (children younger than 5 years did best). Suspected drug or alcohol abuse preceding the drowning was associated with a bad outcome (defined as death or survival with severe neurologic sequelae). Resuscitation standards have changed over the intervening decades since this data was collected, which is among the reasons why it is difficult to draw firm conclusions from this retrospective study, but it represents the best evidence available about prognosis.

Reported survival rates for drowning victims vary widely [65,95,96]. Earlier studies reported survival rates as high as 75 percent, with approximately 6 percent suffering a residual neurologic deficit, although the number of neurologically impaired survivors appears to be increasing as the care of non-neurologic complications improves. The case-control study described above reported a mortality rate of 74 percent, with 4 percent of victims surviving with severe neurologic disability. Of those patients who survive to hospital discharge neurologically intact, long-term survival appears to be similar to the general population [97,98].

There is no high quality evidence to identify early predictors of poor neurologic outcomes that can assist in the decision to discontinue resuscitative efforts, and substantial neurologic recovery has been reported following prolonged submersion and anoxia [37,99-101]. However, the absence of spontaneous, purposeful movements at 24 hours is an ominous sign; one study of 44 children with drowning found that all patients in whom such recovery of function did not occur, died or suffered severe neurologic sequelae [102].

PREVENTION — Drowning is preventable in most cases [2,11]. As an example, secure (four-sided) fencing and gating of swimming pools can exclude virtually all children under the age of four and potentially decrease swimming pool drowning by 80 percent [11,103]. The importance of adequate adult supervision, swimming with a partner, appropriate use of personal flotation devices, and avoidance of alcohol and illicit drugs while swimming or boating should be stressed by physicians and public health authorities [11,37,103,104]. Parents must also be warned that toddlers can drown in shallow areas, including toilets and buckets of water, if not adequately supervised [105,106].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Management of environmental emergencies".)

SUMMARY AND RECOMMENDATIONS

●Drowning is a common cause of accidental death in the United States and an important cause of childhood fatalities worldwide. Risk factors for drowning include: inadequate supervision by an adult with a primary responsibility for water safety, inability to swim or overestimation of swimming capabilities, risk-taking behavior, use of alcohol and illicit drugs, hypothermia, seizures, and developmental disorders in children. Drowning ultimately produces tissue hypoxia, which affects virtually all tissues and organs within the body. The distinction between salt water and fresh water drowning is no longer considered important. (See 'Terminology' above and 'Epidemiology' above and 'Risk factors' above and 'Pathophysiology' above and 'End organ effects' above.)

●Ventilation is generally considered the most important initial treatment for victims of submersion injury and rescue breathing should begin as soon as the rescuer reaches shallow water or a stable surface. If the patient does not respond to the delivery of two rescue breaths that make the chest rise, the rescuer should immediately begin performing cardiopulmonary resuscitation (CPR). The Heimlich maneuver or other postural drainage techniques to remove water from the lungs are of no proven value, and rescue breathing should not be delayed in order to perform these maneuvers. (See 'Prehospital care and acute interventions' above.)

●Cervical spinal cord injury is uncommon in nonfatal drowning victims, unless there are clinical signs of injury or a concerning mechanism (eg, dive into shallow water).

●Pulses may be difficult to palpate in the hypothermic patient with sinus bradycardia or atrial fibrillation; a careful search for pulses should be performed for at least one minute before initiating chest compressions in the hypothermic patient because these arrhythmias require no immediate treatment. Because of the neuroprotective effects of hypothermia, complete recovery of patients with hypothermia and cardiac arrest has been well documented despite prolonged resuscitation (sometimes up to several hours).

●In critically ill patients, standard practices are employed to reduce the risk of brain injury and other morbidities. Common interventions are described in the text. The role of therapeutic hypothermia remains unclear. There is no good evidence to support the routine use of glucocorticoids or prophylactic antibiotics in nonfatal drowning victims. Mechanical ventilatory strategies are similar to those employed in other types of acute lung injury. (See 'Neurologic injuries' above and 'Respiratory failure or infection' above and "Ventilator management strategies for adults with acute respiratory distress syndrome".)

●In the symptomatic patient, indications for intubation include the following:

•Signs of neurologic deterioration or inability to protect the airway

•Inability to maintain a PaO₂ above 60 mmHg or oxygen saturation (SpO₂) above 90 percent despite use of a high-flow oxygen-delivery system or noninvasive ventilation

●In symptomatic patients who do not require immediate intubation, supplemental oxygen should be provided to maintain the SpO₂ above 94 percent. In addition, noninvasive positive pressure ventilation via continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BPAP) can improve oxygenation and decrease ventilation-perfusion mismatch. (See 'Emergency department management' above.)

●Wet clothing should be removed and rewarming initiated in hypothermic patients. Rewarming techniques are discussed separately. (See "Accidental hypothermia in adults".)

●Guidelines for patient disposition are provided in the text; symptomatic patients should be admitted. (See 'Patient disposition' above.)