Drowning

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.

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.