Prognosis

In a retrospective review of patients who drowned or nearly drowned in Brazil in 1997 those graded 2 were reported to have a mortality rate of 0.6%.[17] Patients with drowning severity Grade 5 had a mortality rate of 44%, while mortality among grade 6 cases (cardiopulmonary arrest) was reported at 93%.[17] Since then, small single center studies report similar mortality rates.

Of grade 6 drowning cases fully resuscitated, only 7% to 11% recover fully or partially (Cerebral Performance Categories Scale CPC 1 and CPC 2).[17][46][49] Studies have established that outcome is almost entirely determined by the duration of submersion.[65] Additionally, a low Glasgow Coma Scale score, lack of pupillary response, acidosis, and hypotension are all associated with increased morbidity and mortality.[66][67] To date, most studies on the subject are based on weak evidence, and prognostic tools lack validation.[66]

The following points are consistent throughout most studies:

  • Submersion time is the most important prognostic factor. Known submersion time <10 minutes is a good prognostic factor and >25 minutes is a poor prognostic factor.[66]

  • Successful resuscitation without sequelae is rare, but possible, following prolonged submersion in cold or icy water (anecdotally, some people may survive extended submersion in warm water without sequelae).[12][17]​​[68]

  • Most patients who are awake and alert on arrival at the emergency department, or whose mentation improves to near-normal early in treatment, have good neurological outcomes.[63][64]

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