Nejm 1992;328:53

Cause:Water inhalation/immersion

Pathophys:Pulmonary edema, metabolic acidosis, and hypoxia with very rapid changes in V/Q ratios and lung elasticity occur. Fresh water may enter the circulation and may cause hypervolemia and hemodilution with red cell lysis, which in turn causes hyperkalemia leading to ventricular fibrillation and death, or hemoglobinemia/uria leading to renal damage; lung cells also lysed. Salt water pulls plasma into the alveoli and thus causes hypovolemia and hemoconcentration leading to pulmonary edema, anoxia, and death. Surfactant changes cause decreases in lung compliance.

7000 drowning deaths/yr in US; majority are freshwater; 1/4 are teenagers

Si:Drowning: ARDS with decreased lung compliance and consequent blood gas changes

If comatose, 40-50% recover, 10-20% die, and 30-50% survive w brain damage

Hypothermia (Hypothermia); ATN from hypotension and myoglobinuria; anoxic neurologic damage; diminished platelet numbers and/or function; DIC within hours in freshwater drowning (Ann IM 1977;87:60); ARDS; ventricular fibrillation; hypoglycemia; hyperkalemia; impaired drug clearance

Lab:

Chem:if K⁺ >2 × normal, universally fatal

Hem:Crit decreases over the 1st 1-2 h

Path:At postmortem, in freshwater drowning, lungs show intraalveolar and interstitial edema as well as altered surface tension. In saltwater drowning, major finding is pulmonary edema and only slight changes in surface tension

Rx:CPR, CPAP/PEEP, rx pH <7.1 w bicarb; avoid too high O₂ concentrations, which can further decrease surfactant; treat hypothermia (Hypothermia); antibiotics only if gastric aspiration or dirty water aspiration occurred. Initial abdominal thrust no use unless airway obstruction suspected