It is difficult to prognosticate in individual cases because data from the literature, much of it in the paediatric age group, arise from widely different situations. These situations range from childhood bath and pool incidents in fresh water to boating, swimming and diving activities in the open sea. Nevertheless, several reasonably consistent observations emerge.
Factors that negatively affect outcome include submersion time, time to initiation of effective CPR, severe metabolic acidosis, Glasgow Coma Scale (GCS <5), cardiac arrest and the presence of fixed dilated pupils. However, complete recoveries have been reported despite the presence of one or more of these adverse predictors.
Poor prognostic factors
Prolonged submersion.Prolonged time to effective cardiopulmonary resuscitation.Cardiac arrest.Absence of spontaneous respiration.Prolonged coma.
Several pooled series indicate that 90 per cent of patients who arrive at least arousable with spontaneous respiration and purposeful response to pain will survive neurologically intact. In contrast, of the patients in this series who arrived comatose, 34 per cent died, and 20 per cent of the survivors had neurological damage18.
Unresponsive coma, decorticate and decerebrate rigidity, areflexia and fixed dilated pupils are not in themselves diagnostic signs of death, although they are, of course, signs of a poor prognosis. Patients who arrive in hospital in asystole usually have a poor prognosis, and one series reported a 93 per cent mortality rate after cardiac arrest. Current treatment regimens do not alter the outcome.
The rapid development of severe hypothermia, either before or during the final submersion, is probably protective and helps to explain some spectacular recoveries after prolonged periods of submersion. The role of the diving reflex remains controversial.