Drowning

Drowning occurs due to respiratory impairment from submersion or immersion in a liquid medium. Aspiration of water leads to hypoxemia, which affects all organ systems, resulting in respiratory insufficiency and acute respiratory distress syndrome (ARDS), cardiac arrhythmias, and neuronal damage. The management of drowning focuses initially on ventilatory support followed by cardiopulmonary resuscitation. As drowning is most often preventable, prevention is the focus of most interventions.

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Overview

Definition

  • Drowning: death secondary to asphyxia caused by submersion or immersion in a liquid medium
  • Non-fatal drowning: survival, at least temporarily, after suffocation (or loss of consciousness) by submersion in a liquid medium

Epidemiology

  • 3rd-most common cause of injury-related deaths worldwide
  • 370,000 drowning deaths worldwide each year
  • Peak incidence of drowning in the United States occurs between May and August.
  • Important cause of childhood fatalities worldwide: Children aged 1–4 have the highest drowning rates.
  • Non-accidental drowning deaths: male:female ratio of 2:1
  • Most often affects low- and middle-income patients (91% of unintentional drowning deaths)

Risk factors

  • Inadequate adult supervision
  • Inability to swim (or overestimation of swimming ability)
  • High-risk behaviors (especially in ages 15–25): use of alcohol and other drugs
  • Hypothermia
  • Concomitant trauma, stroke, or myocardial infarction
  • Seizure disorder

Diagnosis

Phyical exam

Clinical manifestations of drowning are due to the effects of hypoxemia.

Vital signs:

  • Hypotension 
  • Hypothermia
  • Hypoxemia 

Respiratory changes:

  • Water aspiration causes surfactant washout from the alveoli. This leads to:
    • Pulmonary edema
    • Respiratory insufficiency
    • Acute respiratory distress syndrome (ARDS) 
  • May experience shortness of breath, crackles, and wheezing
  • Even if the patient is initially stabilized, ARDS can develop insidiously over the next 72 hours.

Cardiovascular changes:

  • Arrhythmias often occur secondary to hypothermia and hypoxemia.
  • Tachycardia followed by sinus bradycardia
  • May progress to atrial fibrillation 

Neurologic changes:

Neuronal damage from hypoxia and ischemia causes:

  • Cerebral edema
  • Elevated intracranial pressure
  • Hypoxic encephalopathy
  • Seizures

Laboratory testing

  • Arterial blood gas (ABG): 
    • Metabolic and/or respiratory acidosis
    • Electrolyte abnormalities
  • Blood alcohol level and drug toxicology panel:
    • If warranted by context
    • To determine if the cause was not organic

Imaging

Imaging is done via X-ray.

  • Usually normal initially
  • ARDS usually does not show on X-ray until later in course.

Chest radiograph showing bilateral pulmonary parenchymal infiltrate compatible with ARDS

Image: “Fulminant nonocclusive mesenteric ischemia just after hip arthroplasty” by Auxiliadora-Martins M, Alkmin-Teixeira GC, Feres O, Martins-Filho OA, Basile-Filho A. License: CC BY 3.0

Management

While prevention is the most effective intervention, rapid resuscitation on-site is essential to improving patient prognosis.

1. Safely remove patient from the water and begin primary survey and resuscitation:

  • Check for breathing:
    • Normal breathing → supplement with oxygen (goal: oxygen saturation (SpO₂) > 90%)
    • If no effective breathing → begin rescue breathing. (Note: This is the priority! Begin rescue breathing immediately and then check for pulse to determine if cardiopulmonary resuscitation (CPR) is needed.)
  • Check for pulse:
    • No pulse → begin immediate CPR 
    • If pulse is found but breathing is not normal → continue rescue breathing/oxygen supplementation.
  • Intubate if:
    • Patient is apneic or in respiratory distress
    • Patient is unable to protect their airways
    • Inability to maintain partial pressure of oxygen (PaO₂) > 60 mm Hg or SpO₂ > 90% despite the use of high-flow oxygen or noninvasive ventilation
  • If hypothermic (core temperature < 33℃):
    • Remove wet clothing.
    • Begin rewarming.

2. Once patient has been resuscitated and stabilized, initiate secondary survey or transport to the nearest medical facility:

  • Head-to-toe assessment for signs of trauma
  • Asses for signs of substance abuse.
  • Interview witnesses.

3. Once the patient has arrived at a medical facility, perform the following:

  • Repeat or initial trauma evaluation
  • Frequent vital signs and clinical reassessment
  • Continuous oxygen supplementation and end-tidal carbon dioxide (CO₂) monitoring
  • Deliver appropriate IV fluids to correct electrolyte disturbances.
  • Continuous telemetry

Outcome and Prevention

Outcome

The following are associated with poor prognosis:

  • Submersion duration > 5 minutes
  • Initiation of basic life support > 10 minutes
  • Resuscitation duration > 25 minutes
  • Age > 14 years
  • Glasgow Coma Scale (GCS) < 5
  • Arterial blood pH < 7.1 on presentation

Prevention

The best prevention is education on water safety:

  • Gating access to swimming pools
  • Providing adult supervision
  • Not swimming alone
  • Use of personal flotation devices
  • Avoidance of alcohol and drugs while swimming

Differential Diagnosis

  • ARDS: a severe inflammatory reaction of the lung that is characterized by the presence of pulmonary infiltrates due to alveolar fluid accumulation (without evidence suggestive of a cardiogenic etiology). The main finding of ARDS is respiratory failure. Chest X-ray usually shows diffuse bilateral lung infiltrates (“butterfly opacity”). Management depends mainly on treating the underlying etiology and maintaining adequate oxygenation, which may require intubation and mechanical ventilation.
  • Pulmonary edema: a condition caused by excess fluid in the lungs. Pulmonary edema is a consequence of a disease process rather than a primary pathology. The condition is classified into cardiogenic and noncardiogenic based on the cause of the edema. Pulmonary edema is visible on chest X-ray.

References

  1. Drowning. (2020). WHO. https://www.who.int/news-room/fact-sheets/detail/drowning
  2. Tyler, Matthew D., et al. (2017). The Epidemiology of Drowning in Low- and Middle-Income Countries: A Systematic Review. BMC Public Health, 17(413). PubMed Central. https://doi.org/10.1186/s12889-017-4239-2

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