• Definitions:
    • Drowning: “A process resulting in primary respiratory impairment from submersion or immersion in a liquid medium”
      • Fatal drowning: Death at any time as a result of drowning
      • Nonfatal drowning: Survival after aspiration of fluid into the lungs or after a period of asphyxia secondary to laryngospasm
    • Water rescue: Any submersion or immersion incident without evidence of respiratory impairment
  • Scenario of drowning:
    • Now thought all drowning victims aspirate some amount of liquid
    • Previously classified as “wet” and “dry” drowning:
      • “Wet” drowning (90%): Aspiration of small amount of liquid into the lungs
      • “Dry” drowning (10%): Laryngospasm secondary to the presence of liquid in the oropharynx or larynx
    • End result: Hypoxia
    • No significant difference between freshwater and saltwater submersion
  • Pathophysiology:
    • Aspiration:
      • Small volume of water
      • Decreased lung compliance causing ventilation/perfusion mismatch and intrapulmonary shunting
      • No significant electrolyte changes
      • Grossly contaminated water: Risk for pulmonary infection
    • Hypoxemia:
      • Metabolic lactic acidosis
      • Multisystem organ dysfunction
      • Noncardiogenic pulmonary edema
      • Myocardial dysfunction (arrhythmias)
      • Coagulation abnormalities (disseminated IV coagulation)
      • Renal failure (usually acute tubular necrosis)
      • Cerebral hypoxia: Cerebral edema, increased intracranial pressure

Pediatric Considerations
  • Hypothermia:
    • More common in young children
    • Larger body surface-to-mass ratio
    • Decreases the metabolic rate
    • Survival with full recovery is possible (neuroprotective)
  • Diving reflex:
    • Young children are more susceptible
    • Triggered by submersion of face in cold water
    • Bradycardia ensues: Redistribution of blood flow to the heart and brain
    • Delays onset of hypoxia-related damage

Risk factors:
  • Lack of proper supervision
  • Alcohol or other drug abuse
  • Limited swimming ability or exhaustion
  • Trauma
  • Seizure disorder
  • Risky behavior
  • Pre-existing or concomitant medical problem
  • Attempted suicide
  • Poor education

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