Why does temperature matter after cardiac arrest?
Return of spontaneous circulation is not the end of resuscitation.
After cardiac arrest, the brain may remain injured by a complex cascade of ischemia-reperfusion physiology.
During the arrest, cerebral oxygen delivery falls. ATP production fails. Ion gradients collapse. Excitotoxic neurotransmitters accumulate. Calcium enters cells. Mitochondrial dysfunction and free radical production follow.
When circulation returns, reperfusion can paradoxically amplify injury through inflammation, oxidative stress, endothelial dysfunction, and microvascular impairment.