Mild hypothermia as a protective therapy during intracranial aneurysm surgery: A randomized prospective pilot trial

OBJECTIVE: To conduct a pilot trial of mild intraoperative hypothermia duri ng cerebral aneurysm surgery. METHODS: One hundred fourteen patients undergoing cerebral aneurysm clippin g with (n = 52) (World Federation of Neurological Surgeons score less than or equal to III) and without (n = 62) acute aneurysmal subarachnoid hemorrh age (SAH) were randomized to normothermic (target esophageal temperature at clip application of 36.5 degrees C) and hypothermic (target temperature of 33.5 degrees C) groups. Neurological status was prospectively evaluated be fore surgery, 24 and 72 hours postoperatively (National Institutes of Healt h Stroke Scale), and 3 to 6 months after surgery (Glasgow Outcome Scale). S econdary outcomes included postoperative critical care requirements, respir atory and cardiovascular complications, duration of hospitalization, and di scharge disposition. RESULTS: Seven hypothermic patients (12%) could not be cooled to within 1 d egrees C of target temperature; three of the seven were obese. Patients ran domized to the hypothermic group more frequently required intubation and re warming for the first 2 hours after surgery. Although not achieving statist ical significance, patients with SAH randomized to the hypothermic group, w hen compared with patients in the normothermic group, had the following: 1) a lower frequency of neurological deterioration at 24 and 72 hours after s urgery (21 versus 37-41 %), 2) a greater frequency of discharge to home (75 versus 57%), and 3) a greater incidence of good long-term outcomes (71 ver sus 57%). For patients without acute SAH, there were no outcome differences between the temperature groups, There was no suggestion that hypothermia w as associated with excess morbidity or mortality. CONCLUSION: Mild hypothermia during cerebral aneurysm surgery is feasible i n nonobese patients and is well tolerated. Our results indicate that a mult icenter trial enrolling 300 to 900 patients with acute aneurysmal SAH will be required to demonstrate a statistically significant benefit with mild in traoperative hypothermia.