Cooling body may protect brain after heart attack

Lowering body temperature with a cooling blanket appears to be safe and may help prevent brain damage in some patients who have had a heart attack, according to preliminary study findings. However, more research is needed before induced hypothermia can be recommended as a way to protect brain function in individuals who have suffered cardiac arrest, which can cut off blood supply to the brain and cause brain damage. "Larger numbers of patients need to be treated and compared to patients who receive only standard treatment," researchers from the University of Texas-Houston Medical School, said. Exactly how hypothermia protects the brain is not clear, but Grotta suggested that it may reduce inflammation and suppress the release of damaging chemicals in brain cells that are released by the sudden stopping and restarting of blood flow. Studies in animals indicate that lowering body temperature can prevent brain damage, so researchers tested the feasibility and safety of cooling blankets in nine patients after cardiac arrest. Each patient, who was on life support, was sedated and wrapped in two cooling blankets--one around the torso and the other around the pelvis and legs. The goal was to lower body temperature to about 33 degrees Celsius (91.4 degrees Fahrenheit) within 2 hours, and to maintain that temperature for 24 hours. Reducing body temperature took longer than planned--an average of 6.5 hours--from the time of cardiac arrest, the researchers report. Overall, four of the nine patients survived, and of those, three showed no signs of brain damage. One patient was discharged but was left with significant memory problems. The authors point out that many of the complications were similar to those normally seen in cardiac arrest patients and that none interfered with recovery. Additional studies and ways to shorten the time to hypothermia are needed, researchers noted. "Mild-to-moderate induced hypothermia after cardiac arrest is feasible and safe. However, external cooling is slow and imprecise," the researchers conclude. "Efforts to speed the start of cooling and to improve the cooling process are needed."