Drowning

Drowning is respiratory impairment and/or the sensation of respiratory distress caused by submersion or immersion in a liquid. It is a leading cause of death in children. Risk factors for drowning include age below 14 years, male sex, alcohol use, risky behavior, and seizure disorder. Clinical features of drowning vary based on the duration of respiratory impairment, the core body temperature, and the effectiveness of initial resuscitation, but may include respiratory distress, neurologic compromise, cardiac instability, and/or hypothermia. Prehospital management begins with the removal of the patient from the water and the initiation of basic life support, if necessary. Further management in the emergency department may include advanced cardiac life support (ACLS), oxygen therapy, advanced airway management, mechanical ventilation, and efforts to treat hypothermia. Complications of drowning include acute lung injury, pulmonary edema, cardiac arrhythmia, and anoxic-ischemic brain injury.

• Drowning: respiratory impairment and/or the sensation of respiratory distress caused by submersion or immersion in a liquid ^[1][2]
• Immersion syndrome: the autonomic and respiratory responses caused by sudden immersion in cold water ^[3]
• Shallow water blackout: unconsciousness occurring during submersion that is caused by hypoxia after intentional hyperventilation ^[4]

• Incidence highest in children < 5 years of age ^[5]
• Leading cause of unintentional injury death in children aged 1–4 years ^[5]
• Second leading cause of unintentional injury death in children aged 5–14 years after motor vehicle accidents ^[6]
• Third leading cause of unintentional injury death worldwide ^[7]
• > 3500 drowning deaths in the US each year ^[1]
• ♂ > ♀ ^[8]

Epidemiological data refers to the US, unless otherwise specified.

• Patient risk factors ^[9]
  • Age < 14 years
  • Male sex
  • Seizure disorder
  • Other preexisting medical conditions, e.g., cardiovascular disease, Parkinson disease, dementia ^[10]
  • Socioeconomic factors: rural residence, poor education, low income ^[11]
  • Poor or no swimming ability ^[11]
• Situational risk factors ^[9]
  • Ingestion of alcohol or other drugs that alter mentation
  • Lack of supervision
  • Proximity to bodies of water
  • Risky behavior
  • Hypothermia or hyperthermia (while swimming or bathing) ^[12]
  • Residence in an area prone to flooding

Submersion → panic → breath holding → respiratory drive overcomes breath holding → aspiration of liquid or laryngospasm → hypoxemia → organ hypoxia (especially cerebral and cardiac) → possible injury or death ^[12]

Clinical presentation depends on the duration of respiratory impairment, the core body temperature, and the effectiveness of initial resuscitation. ^[9][12][13]

• Pulmonary
  • Dyspnea/apnea
  • Cyanosis
  • Signs of pulmonary edema (e.g., rales, foam in the airway)
• Cardiovascular
  • Hypotension
  • Cardiac arrhythmia
  • Cardiac arrest
• Neurologic
  • Altered mental status
  • Loss of consciousness
  • Abnormal pupil examination
  • Seizures
• Other
  • Clinical features of hypothermia
  • Gastric distention and/or vomiting

If the patient has been on a dive, examine them for diving-related injuries, e.g., barotrauma and air embolism.

Initial diagnostics ^[1][9][13]

• Laboratory studies
  • Arterial blood gas: may show respiratory failure and/or metabolic acidosis
  • CMP, CBC: typically normal
• ECG
  • May help determine the precipitating cause of drowning (e.g., arrhythmia, ischemia)
  • ECG findings in hypothermia include QTc prolongation and J waves.
• CXR
  • May show x-ray findings of pulmonary edema (e.g., bilateral diffuse opacities) ^[14]
  • Initial CXR may underestimate the degree of pulmonary injury.
  • Repeat CXRs are indicated for persistent respiratory symptoms.

Additional diagnostics

Further diagnostics may be obtained to determine the precipitating cause of drowning (e.g., seizures or intoxication) and to rule out complications.

• Toxicology studies: ethanol level, urine toxicology screen
• CT head and/or CT cervical spine: to rule out suspected traumatic injury
• CT chest and/or lung ultrasound: to further evaluate pulmonary injuries
• EEG: to rule out subclinical seizures in obtunded patients ^[13]

Obtain an EEG in patients who remain unresponsive after drowning to assess for subclinical seizure activity. ^[13]

Postmortem features of drowning ^[15]

• Pulmonary
  • Pleural effusion
  • Pulmonary edema
  • Paltauf spots: bright red spots of ∼ 1 cm in diameter, which occur due to capillary hemorrhage of the pleura
• Gastrointestinal: Wischnewsky spots (gastric mucosal petechial hemorrhages associated with hypothermia)
• External
  • White or pink foam cone over the nostrils and/or mouth
  • Pallor and wrinkling of the palms, soles, fingers, and toes
  • Prone body position: back upwards, head and extremities dangling downwards
  • Travel abrasions and lacerations on the forehead, backs of the hands, knees, and dorsum of the feet

• Notify emergency medical services.
• Maintain personal safety during the rescue.
• Begin immediate basic life support in unresponsive patients if there is:
  • No danger to the rescue team
  • No obvious sign of irreversible death
  • Submersion time < 60 minutes
• Implement cervical spine precautions only if trauma is suspected. ^[1][16]

Rescuers should not put their lives at risk to save a drowning person.

Begin basic life support with an emphasis on ventilation immediately after rescue to optimize the chance of successful resuscitation. ^[9]

Use cervical spine precautions only if trauma is suspected to avoid unnecessary delays in airway management. ^[1][16]

Approach ^[1][9][13]

• Begin advanced cardiac life support in unresponsive patients. ^[16]
• Start continuous cardiac and respiratory monitoring, e.g., SpO₂, EtCO₂.
• Evaluate for clinical features of respiratory distress and begin respiratory support.
  • Localized rales: Begin low-flow oxygen, e.g., nasal cannula.
  • Signs of pulmonary edema
    • Begin high-flow oxygen, e.g., nonrebreather mask
    • Consider intubation with lung-protective ventilation
  • Goal: SaO₂ > 92%
• Begin management of shock with IV fluid resuscitation.
• Begin treatment of hypothermia if core body temperature is < 32° C.
• In unresponsive patients, initiate neuroprotective measures (e.g., therapeutic hypothermia, normoglycemia) and obtain EEG.

Tympanic membrane temperatures may not be accurate in a patient who has drowned. ^[13]

Respiratory support ^[1][9][17]

Aspiration of fluid into the lung results in surfactant destruction and washout, which can cause acute respiratory distress syndrome (ARDS).

• Management of ARDS
  • Use a lung-protective ventilation strategy and maintain SaO₂ > 92%.
  • Avoid permissive hypercapnia to prevent secondary brain injury.
  • Use supraglottic airway devices and non-invasive positive-pressure ventilation (NIPPV) with caution.
  • Ventilator weaning should generally be delayed for 48 hours.
• Supportive treatment
  • Place an orogastric tube in intubated patients to reduce gastric distension and prevent aspiration.
  • Consider prophylactic antibiotics only if drowning occurred in water with a high pathogen count, e.g., water containing sewage.
  • Corticosteroids are indicated only for the treatment of bronchospasm.

Hemodynamic support ^[9]

• Cardiac arrest: Manage with standard ACLS. ^[16]
  • The presenting rhythm is usually PEA or asystole, but a shockable rhythm is a good prognostic sign.
  • For patients with hypothermia, recommendations for hypothermic cardiac arrest apply.
  • Consider termination of ACLS if asystole persists after 20 minutes in a fully rewarmed patient. ^[17]
• Hemodynamic instability
  • Cardiac dysfunction with low cardiac output may occur after drowning.
  • Initial treatment: IV fluid resuscitation, correction of hypothermia, and improved oxygenation
  • Additional management should be guided by POCUS, echocardiography, and/or advanced cardiac monitoring.

Initiate rewarming and do not withhold life-saving treatment from hypothermic patients who appear clinically dead (e.g., dilated pupils, areflexia, rigidity) without signs of irreversible death. ^[16][18]

Disposition ^[9][13][19]

• ICU admission: all patients requiring ongoing respiratory or hemodynamic support
• Hospital admission: all symptomatic patients
• Discharge: Consider for asymptomatic individuals with normal mental status and respiratory function after observation for at least 4–6 hours. ^[1]

• Initiate ACLS in unresponsive patients.
• Start oxygen therapy for all patients with rales and/or respiratory distress.
• Begin advanced airway management and mechanical ventilation for pulmonary edema and/or respiratory failure.
• Begin immediate hemodynamic support.
• Place an orogastric tube in intubated patients.
• Obtain laboratory studies, CXR, and ECG.
• Trauma suspected: Obtain CT of the head and/or cervical spine.
• Persistently unresponsive patients: Initiate neuroprotective measures and obtain EEG.

• ARDS
• Pulmonary edema
• Pneumothorax
• Acute tubular necrosis (due to hypoxemia)
• Brain death
• Elevated intracranial pressure
• Infection (e.g., pneumonia, meningitis)
• Cardiac arrest

We list the most important complications. The selection is not exhaustive.

Factors associated with a poor outcome include: ^[13]

• Age < 3 years
• Submersion > 5 minutes
• CPR delayed > 10 minutes
• Prolonged CPR
• Glasgow coma scale score of 3
• Hypothermia
• Severe acidosis
• Nonreactive pupils

• Swimming education
• Safety equipment (e.g., life jackets)
• Water rescue training
• Water safety signs posted at potential sites of drowning
• Rescue equipment and personnel (e.g., lifeguards) at recreational swimming locations (e.g., pools, beaches)
• Avoidance of alcohol and drug consumption before swimming
• Installing barriers around potential water hazards (e.g., pools, wells, waterfronts)
• Close supervision of children around water (e.g., during bathing as well as swimming)