What are the CNS effects of drowning?

Updated: Jun 19, 2019
  • Author: G Patricia Cantwell, MD, FCCM; Chief Editor: Joe Alcock, MD, MS  more...
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Hypoxic-ischemic brain injury is a foreboding sequelae of asphyxial cardiac arrest associated with drowning. The degree of CNS injury remains the major determinant of subsequent survival and long-term morbidity in cases of drowning. Two minutes after immersion, a child will lose consciousness. Irreversible brain damage usually occurs after 4-6 minutes. Most children who survive are discovered within 2 minutes of submersion. Most children who die are found after 10 minutes.

The areas of high risk in the brain are the metabolically active subcortical tissues and those with watershed perfusion. Global brain injury occurs in cases of hypoxemia and low-flow states resulting in energy failure, lipid peroxidation, free radical production, inflammatory processes, and release of excitotoxic neurotransmitters. Neuronal and glial functions are disrupted. Asphyxial cardiac arrest results in the development of microinfarctions as well as selective neuronal injury. [51, 52]

Primary CNS injury is initially associated with tissue hypoxia and ischemia. If the period of hypoxia and ischemia is brief or if the person is a very young child who rapidly develops core hypothermia, primary injury may be limited, and the patient may recover with minimal neurologic sequelae, even after more prolonged immersion.

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