A reduction of brain temperature by 10 °C decreases ATP consumption by approximately 50%, which can double the time the brain can survive.The younger the person, the better the chances of survival. In one case, a child submerged in cold (37 °F (3 °C)) water for 66 minutes was resuscitated without apparent neurological damage. However, over the long term significant deficits were noted, including a range of cognitive difficulties, particularly general memory impairment, although recent magnetic resonance imaging (MRI) and magnetoencephalography (MEG) were within normal range. Children
Drowning is a major worldwide cause of death and injury in children. An estimate of about 20% of non-fatal drowning victims may result in varying degrees of ischemic and/or hypoxic brain injury. Hypoxic injuries refers to a lack or absence of oxygen in certain organs or tissues. Ischemic injuries on the other hand refers inadequate blood supply to certain organs or part of the body. These injuries can lead to an increased risk of long-term morbidity. Prolonged hypothermia and hypoxemia from nonfatal submersion drowning can result in cardiac dysrhythmias such as ventricular fibrillation, sinus bradycardia, or atrial fibrillation. Long-term neurological outcomes of drowning cannot be predicted accurately during the early stages of treatment. Although survival after long submersion times, mostly by young children, has been reported, many survivors will remain severely and permanently neurologically compromised after much shorter submersion times.
Comparatively, aspiration of hypertonic seawater draws liquid from the plasma into the alveoli and similarly causes damage to surfactant by disrupting the alveolar-capillary membrane. Still, there is no clinical difference between salt and freshwater drowning. Once someone has reached definitive care, supportive care strategies such as mechanical ventilation can help to reduce the complications of ALI/ARDS.Whether a person drowns in freshwater or salt water makes no difference in respiratory management or its outcome. People who drown in freshwater may experience worse hypoxemia early in their treatment, however, this initial difference is short-lived and the management of both fresh water and salt water drowning is essentially the same. Cold-water immersion
Submerging the face in water cooler than about 21 °C (70 °F) triggers the diving reflex, common to air-breathing vertebrates, especially marine mammals such as whales and seals. This reflex protects the body by putting it into energy-saving mode to maximise the time it can stay underwater. The strength of this reflex is greater in colder water and has three principal effects:
Bradycardia, a slowing of the heart rate to less than 60 beats per minute. Peripheral vasoconstriction, the restriction of the blood flow to the extremities to increase the blood and oxygen supply to the vital organs, especially the brain.