Purpose: To describe a technique for the induction of hypothermia and its complications for the treatment of acute ischemic stroke.
Methods: Adults with acute (<8 hours), severe (National Institutes of Health Stroke Scale>14) ischemic stroke of the anterior circulation were enrolled. Patients were intubated, sedated, and paralyzed. Surface cooling to 32 degrees+/-1 degrees C was performed with a cooling blanket and an alcohol/ice bath. Hypothermia was maintained for 12-72 hours. Physiological parameters were measured continuously. A computed tomography scan of the brain was obtained at 24 hours. Rewarming was initiated 12 hours after middle cerebral artery recanalization at a rate of 0.25 degrees C/hour. All complications and adverse outcomes were documented from initiation of hypothermia until hospital discharge.
Results: Eighteen patients with a mean National Institutes of Health Stroke Scale=21.4+/-5.6 were treated. The goal temperature was reached within 3.2+/-1.5 hours. Cooling time was proportional to body weight (p=0.009) and decreased with immediate paralysis to prevent shivering (p=0.033). Maintenance and rewarming were characterized by fluctuations in core temperature. All patients developed a decrease in blood pressure, heart rate, and potassium values that were proportional to temperature (p<0.05). Complications were generally mild, but pneumonia and myocardial infarction or both occurred in five patients. There were trends for increased risk of complications with longer duration of hypothermia (p=0.08) and increasing age (p=0.0504). Rewarming was well-tolerated with rebound cerebral edema occurring in only one patient.
Conclusion: Surface cooling for the treatment of acute ischemic stroke can be performed rapidly with early neuromuscular paralysis. Advanced age and prolonged hypothermia may be associated with an increased risk of complications.