Cooling for acute ischemic brain damage (COOL AID) - An open pilot study of induced hypothermia in acute ischemic stroke

Background and Purpose-Hypothermia is effective in improving outcome in experimental models of brain infarction. We studied the feasibility and safety of hypothermia in patients with acute ischemic stroke treated with thrombolysis. Methods-An open study design was used. All patients presented with major ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score > 15) within 6 hours of onset. After informed consent, patients with a persistent NIHSS score of >8 were treated with hypothermia to 32 +/-1 degreesC for 12 to 72 hours depending on vessel patency. All patients were monitored in the neurocritical care unit for complications. A modified Rankin Scale was measured at 90 days and compared with concurrent controls. Results-Ten patients with a mean age of 71.1 +/- 14.3 years and an NIHSS score of 19.8 +/-3.3 were treated with hypothermia. Nine patients served as concurrent controls. The mean time from symptom onset to thrombolysis was 3.1 +/-1.4 hours and from symptom onset to initiation of hypothermia was 6.2 +/-1.3 hours. The mean duration of hypothermia was 47.4 +/- 20.4 hours. Target temperature was achieved in 3.5 +/-1.5 hours. Noncritical complications in hypothermia patients included bradycardia (n=5), ventricular ectopy (n=3), hypotension (n=3), melena (n=2), fever after rewarming (n=3), and infections (n=4). Four patients with chronic atrial fibrillation developed rapid ventricular rate, which was noncritical in 2 and critical in 2 patients. Three patients had myocardial infarctions without sequelae. There were 3 deaths in patients undergoing hypothermia. The mean modified Rankin Scale score at 3 months in hypothermia patients was 3.1 +/-2.3. Conclusion-Induced hypothermia appears feasible and safe in patients with acute ischemic stroke even after thrombolysis. Refinements of the cooling process, optimal target temperature, duration of therapy, and, most important, clinical efficacy, require further study.