Does prophylactic postoperative hypervolemic therapy prevent cerebral vasospasm and improve clinical outcome after aneurysmal subarachnoid hemorrhage?

BACKGROUND

Delayed cerebral vasospasm is a common cause of morbidity and mortality after acute aneurysmal subarachnoid hemorrhage. Hypovolemia and fluid restriction are risk factors for delayed vasospasm; hypervolemic therapeutic approaches are commonly used in patients with subarachnoid hemorrhage to prevent and to treat cerebral vasospasm.

OBJECTIVE

To determine if postoperative prophylactic hypervolemic therapy prevents cerebral vasospasm and improves clinical outcome in patients with aneurysmal subarachnoid hemorrhage.

METHODS

The objective was addressed through the development of a structured critically appraised topic. This included a clinical scenario, structured question, search strategy, critical appraisal, results, evidence summary, commentary, and bottom line conclusions. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and content experts in the field of vascular neurology.

RESULTS

One randomized controlled trial addressed the questions. There was no difference in the incidence of symptomatic cerebral vasospasm (20% each) or clinical outcome at 14 days and 3 months between the hypervolemic and normovolemic groups. Hypervolemic therapy also had no effect on measures of cerebral blood flow. A second quasi-randomized trial reached the same conclusions.

CONCLUSION

Available evidence is insufficient to support use of prophylactic hypervolemic therapy after surgery in patients with aneurysmal subarachnoid hemorrhage. Although completed studies may be insufficiently sensitive (underpowered) to detect a treatment effect, the magnitude of any as yet undetected benefit of prophylactic hypervolemic therapy is likely modest and its risks have not been systematically evaluated.