Effect of Prolonged Therapeutic Hypothermia on Intracranial Pressure, Organ Function, and Hospital Outcomes Among Patients with Aneurysmal Subarachnoid Hemorrhage

Background: Global cerebral edema (GCE) with subsequent refractory intracranial hypertension complicates some cases of aneurysmal subarachnoid hemorrhage (aSAH), and typically is associated with poorer outcome. Treatment options for refractory intracranial pressure (ICP) cases are limited to decompressive hemicraniectomy (DHC) and targeted temperature management (TTM) with induced hypothermia (32–34 °C). No outcomes comparison between patients treated with either or both forms of refractory ICP therapy exists, and data on the effect of prolonged hypothermia on ICP and organ function among patients with aSAH are limited.

Methods: This is a retrospective study of aSAH patients who underwent DHC and/or prolonged hypothermia (greater than 48 h) for refractory ICP (i.e., ICP >20 mmHg after osmotherapy) in the intensive care unit of a single, tertiary-care academic center.

Results: Nineteen individuals with aSAH underwent TTM with or without DHC; sixteen patients underwent DHC alone. The patients in TTM group were younger (median age 44 years) than the DHC without TTM population (median age 60 years). TTM was started on median day 2 with a median duration of 7 days. There were no significant group differences in survival to discharge (59 % vs. 69 %) or in the mean modified Rankin score on follow-up (3.6 vs. 3.7), despite the TTM group having longer hospital length of stay (24 vs. 19 days, p = 0.03), longer duration of mechanical ventilation (20 vs. 9 days, p = 0.04), a higher cumulative fluid balance (12.8 vs. 5.1 L, p = 0.01), and higher APACHEII scores. The median maximal ICP decreased from 23.5 to 21 mmHg within 24 h of hypothermia initiation. There were no significant differences in other markers of end-organ function (respiratory, hematologic, renal, liver, and cardiac), infection rate, or adverse events between groups.

Conclusions: Use of prolonged TTM among aSAH patients with GCE and refractory ICP elevations is associated with a longer duration of mechanical ventilation but is not different in terms of neurological outcomes measured by modified Rankin score or organ function outcomes compared to patients who received DHC alone.