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Emergency And Acute Medicine – Drowning
Basics Description
Drowning is a process resulting in primary respiratory impairment from submersion or immersion in a liquid medium. Fatal drowning refers to death at any time as a result of the drowning process, while nonfatal drowning occurs when the victim survives after interruption of submersion. Water rescue describes submersion or immersion without respiratory impairment. All drowning victims aspirate some amount of liquid; previously used terms such as “wet” and “dry” drowning are obsolete. The final common pathway is hypoxia, with no clinically significant difference between freshwater and saltwater drowning.
Pathophysiology
Aspiration of small volumes of water decreases lung compliance, causing ventilation–perfusion mismatch and intrapulmonary shunting, usually without major electrolyte disturbances. Grossly contaminated water increases the risk of pulmonary infection. Hypoxemia leads to lactic acidosis, multisystem organ dysfunction, noncardiogenic pulmonary edema, myocardial dysrhythmias, coagulation abnormalities including disseminated intravascular coagulation, acute renal failure, and cerebral hypoxia resulting in cerebral edema and increased intracranial pressure.
Pediatric Considerations
Hypothermia is more common in children due to a higher body surface area–to–mass ratio and may be neuroprotective by lowering metabolic rate. The diving reflex, particularly in young children exposed to cold water, causes bradycardia and preferential blood flow to the heart and brain, delaying hypoxic injury.
Alert
Risk factors include inadequate supervision, alcohol or drug use, limited swimming ability, trauma, seizure disorder, risky behavior, pre-existing medical conditions, suicide attempt, and poor water safety education.
Diagnosis Signs And Symptoms
Findings include cardiopulmonary arrest, cyanosis, dyspnea, copious pulmonary secretions, altered mental status or loss of consciousness, hypothermia, cerebral edema or neurologic injury, and evidence of trauma. Cervical spine injury is rare.
Essential Workup
Obtain witness and EMS information, initiate early airway management and cardiopulmonary resuscitation when indicated, and measure core temperature to assess hypothermia.
Diagnostic Tests And Interpretation
Laboratory studies include arterial blood gas, complete blood count, electrolytes, blood urea nitrogen, creatinine, glucose, and alcohol or toxicology screening. Imaging includes chest radiography, which may show infiltrates or acute respiratory distress syndrome but can be normal initially, electrocardiography showing bradyarrhythmias or tachyarrhythmias, and computed tomography of the brain or cervical spine when indicated.
Differential Diagnosis
Consider dysrhythmias such as long QT syndrome, myocardial infarction, seizure, syncope, trauma, or suicide attempt as causes of submersion. In pediatric patients, always consider abuse or neglect, particularly in bathtub incidents.
Treatment Prehospital
Address airway, breathing, and circulation, avoid further aspiration, secure the airway, initiate early cardiopulmonary resuscitation, apply cervical spine precautions when indicated, and begin rewarming. Abdominal thrusts are not recommended as they delay effective resuscitation and increase aspiration risk.
Initial Stabilization And Therapy
Manage airway and oxygenation, remove wet clothing, initiate rewarming, and support circulation.
Emergency Department Treatment
Correct hypoxemia, intubate with positive end-expiratory pressure if needed, treat acidosis, and evaluate for traumatic injuries. In cardiac arrest, follow advanced cardiac life support protocols and continue resuscitation until core temperature exceeds 32°C or return of spontaneous circulation occurs. Corticosteroids have no proven benefit. Poor prognostic indicators include prolonged submersion, severe acidosis, need for cardiopulmonary resuscitation, low oxygen saturation, and low Glasgow Coma Scale score.
Medication
Epinephrine, vasopressin, lidocaine, and sodium bicarbonate may be administered when clinically indicated.
Follow-Up And Disposition
Patients with respiratory symptoms, neurologic abnormalities, abnormal imaging or laboratory findings, or those requiring ventilatory support should be admitted, often to intensive care. Symptomatic patients or those with significant submersion history require observation. Patients may be discharged only after at least eight hours of observation with no respiratory distress, no neurologic impairment, and reliable caregivers.
Pearls And Pitfalls
All drowning patients require observation for delayed complications. Hypothermia may be protective. Prevention through supervision and water safety education is essential.
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