The epidemiology and clinical course of immersion brain injury of childhood drowning cases are reviewed from the University of California, Davis, Sacramento. In 1986 there were 2,122 childhood drownings in the United States. Children 0-4 years of age accounted for 36% of all deaths and most of these occurred in residential pools. Children with a seizure disorder are at increased risk for drowning with rates several times higher than expected. Alcohol use is a contributing factor among adolescents in 40-50% of males. The outcome of drowning is largely determined by events occurring in the first ten minutes after the incident. Consciousness is lost after two minutes of anoxia, and irreversible brain damage occurs after four to six minutes. Survival is unusual after immersions of longer than five minutes. Prompt resuscitation is vital; almost all subjects who ultimately survive are making a spontaneous respiratory effort within five minutes after extraction from the water and most do so within two minutes. Children who still require CPR in the emergency department have a poor prognosis: 35-60% die, and 60-100% of the survivors are severely brain damaged. Resuscitative measures may achieve somatic survival of the heart and other vital organs but brain function remains severely impaired. The patient in the permanent vegetative state breathes spontaneously and may exhibit random movements but has no purposeful activity or thought. Life expectancy of these children is estimated to average 18 months in institutions and longer in home care. Failure to provide timely resuscitation and lack of knowledge of CPR techniques among pool owners is associated with a poor outcome in drowning and near-drowning incidents. Pentobarbital therapy, at one time thought to be a promising addition to standard therapy for near drowning, has recently been shown to be ineffective. 
COMMENT. Since the outcome of an immersion event is determined within a few minutes of the onset of the incident, the emphasis is on primary prevention. Mandatory pool fencing and training in cardiopulmonary resuscitation for pool owners should be stressed. Children with epilepsy are often permitted to swim in pools but not in lakes with poor underwater visibility. Strict supervision must be observed since the risks of drowning are several times higher than for the average child.