Keeping a cool head, post-hypoxic hypothermia--an old idea revisited.
Hypoxia-ischaemia produces permanent brain damage by processes that continue for many hours after reoxygenation/reperfusion. This provides a window of opportunity for therapy aimed at preventing further loss of brain cells. Reducing brain temperature by 2-6 degrees C for 3-72 h after reoxygenation/reperfusion has been shown to reduce brain damage by 25-80% in controlled trials with six different neonatal animal models of hypoxia-ischaemia. No adverse effects from mild hypothermia have been documented. The mechanisms of protection are unknown but may include a reduction in extracellular excitotoxic amino acids, reduced nitric oxide synthesis and inhibition of apoptosis. Mild hypothermia is currently the most promising clinically feasible neural rescue therapy for full-term infants at risk of developing hypoxic-ischaemic encephalopathy, but clinical use must be restricted to approved trial protocols.
Thoresen
M
M
Department of Paediatrics and Institute of Experimental Medicine, Ullevål University Hospital, Oslo, Norway.
Wyatt
J
J
D000222:Adaptation, Physiological; D000818:Animals; D000831:Animals, Newborn; D001831:Body Temperature; D001921:Brain / Q000503:physiopathology*; D001927:Brain Diseases / Q000209:etiology / Q000517:prevention & control*; D005311:Fetal Hypoxia / Q000628:therapy*; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects; D000860:Hypoxia / Q000150:complications*; D002534:Hypoxia, Brain / Q000628:therapy; D007223:Infant; D007231:Infant, Newborn