Feasibility and safety of moderate hypothermia after acute ischemic stroke

Moderate hypothermia decreases ischemic damage in experimental stroke models. This multicenter study was performed to evaluate (1) the safety and feasibility of moderate hypothermia and (2) its potential to reduce intracranial hypertension in acute stroke patients.

Fifty prospective patients with cerebral infarction involving at least the complete middle cerebral artery (MCA) territory treated with moderate hypothermia were evaluated. Hypothermia was induced with the use of cooling blankets as well as alcohol and ice bags within 22+/-9h after stroke onset and maintained for 24-72 h; subsequently, patients passively rewarmed over a mean duration of 17 h. Outcome was assessed at 4 weeks and at 3 months.

Time required for cooling to <33 degrees C varied from 3.5 to 11h. The most frequent complications of hypothermic therapy were thrombocytopenia (70%), bradycardia (62%), and pneumonia (48%). Four patients (8%) died during hypothermia as a result of severe coagulopathy, cardiac failure, or uncontrollable intracranial hypertension. An additional 15 patients (30%) died during or after rewarming because of rebound increase in intracranial pressure (ICP) and fatal herniation. A shorter (<16 h) rewarming period was associated with a more pronounced rise of ICP. Elevated ICP values were significantly reduced under hypothermia.

Moderate hypothermia is feasible in patients with acute stroke, although it is associated with several side effects. Most deaths occur during rewarming as a result of excessive ICP rise. Our preliminary observation that a longer duration of the rewarming period limits the ICP increase remains to be confirmed in future studies.