Relationship of hypotension and cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage

Objectives: Changes in systemic arterial blood pressure and the degree of cerebral vasospasm were investigated in 125 patients with aneurysmal subarachnoid hemorrhage. Methods: Systemic arterial blood pressure was measured every 2 hours in each patient for a period of more than 2 weeks, and a fall in systemic blood pressure (FBP) was defined as a decrease of > 40 mmHg of systolic blood pressure between two consecutive measurements. Results: A total of 91 FBPs occurred in 52 (41.6%) of 725 patients despite specific post-operative management to prevent hypovolemia. Five (5.5%) of the 91 FBPs occurred just before the onset of symptomatic vasospasm. Symptomatic vasospasm was observed in 36 (69.2%) of 52 patients with FBP and in 32 (43.8%) of 73 patients without FBP (p < 0.01, chi-squared test). A hypodense area on computed tomographic scans in association with cerebral vasospasm was observed in 25 (48.1%) of 52 patients with FBP and in 21 (28.8%) of 73 patients without FBP (p < 0.05). Discussion: We conclude that FBP might result from delayed cerebral vasospasm and/or brain dysfunction owing to subarachnoid hemorrhage itself.