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Definition

A disorder characterized by hypoxemia, with or without aspiration, following submersion in fresh or salt water.

History

Symptoms: Alteration in mental status, tachypnea, wheezing, cyanosis, hypothermia, laryngospasm.

General: Prolonged submersion in fresh or salt water is frequentlY associated with motor or recreational vehicles, boating, or shallow water diving accidents. Water entering the upper airway results in laryngospasm. Ten to twenty percent of near-drowning episodes occur without direct aspiration, but present with hypoxemia on the basis of persistent laryngospasm. In aspiration events, the extent of injury is dependent on the amount of water inhaled.

Age: Any, but primarily in the first or second decades. Incidence of 90,000/yr with a 5 to 1 male to female ratio.

Onset: Rapid.

Duration: Postimmersion symptoms may occur 24 to 48 hours after the event.

Intensity: Varies from patients who are awake and alert to those who are comatose with severe cardiopulmonary dysfunction.

Aggravating Factors: Co-existant multi system trauma (e.g., spinal cord injury).

Alleviating Factors: Early intervention, correction of hypoxia.

Associated Factors: Often occurs in the setting of multi system trauma. Cervical spine injuries may be present (e.g., diving injuries). Substance abuse or child abuse are frequently encountered.

Physical Examination

General: Patient presentations range along a continuum from mild respiratory and cardiovascular sequelae to cardiovascular arrest and coma. Core body temperature is recorded to evaluate for hypothermia.

Cardiovascular: The patient may experience cardiac arrest due to prolonged hypoxemia.

Neurologic: Mental status changes (e.g., confusion, lethargy) due to hypoxemia or direct neurologic trauma (e.g., head or spinal cord injuries) may be present. Definitive mental status evaluation should be performed after hypothermia is corrected. Cervical spine should be palpated for tenderness in diving injuries to evaluate for potential injury.

Pulmonary: Persistent laryngospasm is a common occurrence and must be ruled out by careful airway inspection in the immediate resuscitative period. Auscultation may reveal wheezirig, rales, or rhonchii. Tachypnea and cyanosis are common. Symptoms consistent with pulmonary edema.

Pathophysiology

Laryngospasm is due to water entering the upper airway. Eighty to ninety percent of near drowning episodes are associated with aspiration. The extent of pulmonary injury is dependent on the amount of water aspirated.

Diagnostic Studies

Laboratory

Electrolytes: Usually show minor changes in serum sodium and chloride regardless of the salt content of the water aspirated.

Arterial blood gasses: A profound metabolic acidosis is common as is hypoxia and hypercarbia. Serial arterial blood gasses are utilized to assess the adequacy of airway and ventilatory support.

Toxicology screen: For ETOH and drugs. Frequently associated with near-drowning episodes, especially those occurring with alterations in neurologic function.

Radiology

Chest x-ray: Consistent with non cardiac pulmonary edema.

Cervical spine radiographs: If the patient was diving, to rule out fracture.

Skeletal survey: Indicated if multiple trauma suspected.

Abdominal radiographs: May show gastric dilitation.

Other

ECG: May show supraventricular tachycardia due to hypoxia, acidosis, or cardiac arrest.

Differential Diagnosis

As near drowning is due to an acute, traumatic event, the concept of differential diagnosis does not apply.

Treatment

Inspect the upper airway to rule out laryngospasm. Maintain an adequate airway, with intubation if necessary, especially if the signs of hypoxemia are present. Maintenance of the airway will reduce the likelihood of gastric dilitation or aspiration of gastric contents. Intubated patients should be placed on an FIO2 of 100 percent. Positive end expiratory pressure ventilation may be required to ensure adequate gas exchange. Nasogastric tube (on low intermittent suction) may be placed to decompress gastric dilitation and to prevent aspiration of gastric contents. Cardiac monitoring and appropriate cardiac support are indicated, in accordance with the Advanced Cardiac Life Support guidelines.

Hypothermia can occur with even brief periods of immersion. It is treated with warmed intravenous solutions and oxygen. Core body temperature must be monitored.

Pediatric Considerations

The diving reflex, manifested by slowed heart rate, shunting of blood preferentially to the brain and heart in response to cold water submersion, is more prominent in the young patient. Patient survival has been documented with submersions of up to 40 minutes. Resuscitative measures should be aggressively attempted despite an initially bleak presentation.

Obstetrical Considerations

No specific indications.

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