Relative importance of hypertension compared with hypervolemia for increasing cerebral oxygenation in patients with cerebral vasospasm after subarachnoid hemorrhage.

OBJECT: Hypervolemia and hypertension therapy is routinely used for prophylaxis and treatment of symptomatic cerebral vasospasm at many institutions. Nevertheless, there is an ongoing debate about the preferred modality (hypervolemia, hypertension, or both), the degree of therapy (moderate or aggressive), and the risk or benefit of hypervolemia, moderate hypertension, and aggressive hypertension in patients following subarachnoid hemorrhage. METHODS: Monitoring data and patient charts for 45 patients were retrospectively searched to identify periods of hypervolemia, moderate hypertension, or aggressive hypertension. Measurements of central venous pressure, fluid input, urine output, arterial blood pressure, intracranial pressure, and oxygen partial pressure (PO2) in the brain tissue were extracted from periods ranging from 1 hour to 24 hours. For these periods, the change in brain tissue PO2 and the incidence of complications were analyzed. During the 55 periods of moderate hypertension, an increase in brain tissue PO2 was found in 50 cases (90%), with complications occurring in three patients (8%). During the 25 periods of hypervolemia, an increase in brain oxygenation was found during three intervals (12%), with complications occurring in nine patients (53%). During the 10 periods of aggressive hypervolemic hypertension, an increase in brain oxygenation was found during six of the intervals (60%), with complications in five patients (50%). CONCLUSIONS: When hypervolemia treatment is applied as in this study, it may be associated with increased risks. Note, however, that further studies are needed to determine the role of this therapeutic modality in the care of patients with cerebral vasospasm. In poor-grade patients, moderate hypertension (cerebral perfusion pressure 80-120 mm Hg) in a normovolemic, hemodiluted patient is an effective method of improving cerebral oxygenation and is associated with a lower complication rate compared with hypervolemia or aggressive hypertension therapy.

Effect of intraventricular sodium nitroprusside on cerebral hemodynamics and oxygenation in poor-grade aneurysm patients with severe, medically refractory vasospasm.

OBJECTIVE: Sodium nitroprusside (SNP) was recently suggested as a treatment for cerebral ischemia in patients with severe, medically refractory vasospasm after subarachnoid hemorrhage. In this study, we sought to objectify the effect on cerebral hemodynamics and oxygenation (PbrO2) when using intraventricular SNP as a last resort therapy in poor-grade patients with subarachnoid hemorrhage; severe, medically refractory vasospasm; and compromised cerebral blood flow. METHODS: Thirteen of 185 consecutive patients with subarachnoid hemorrhage developed severe, medically refractory vasospasm and were treated with intraventricular SNP. All of these patients' neurological conditions were classified as Hunt and Hess Grade IV. SNP doses ranged from 10 to 40 mg with single-dose treatment and from 2 to 8 mg/h with continuous infusion. Angiography or PbrO2 measurement was used to assess the treatment effects. RESULTS: In 6 of the 13 patients, SNP improved cerebral hemodynamics, as demonstrated by increased PbrO2 or decreased cerebral circulation time. Only 1 patient showed increased diameter of the spastic vessel, however. Maximum increase in PbrO2 ranged from 5 to 52 mmHg. Adverse effects were hypertension in five patients, vomiting in three patients, and cardiac arrhythmia in one patient. Cerebral infarctions caused by vasospasm occurred in 6 (46%) of the 13 patients. No differences between SNP responders and SNP nonresponders were noted. CONCLUSION: In patients with severe, medically refractory vasospasm, intraventricular SNP may improve PbrO2 and cerebral blood flow, but the effect is highly variable. On the basis of the improvements we observed in 6 of 13 patients, intraventricular SNP administration is justified as a last resort therapy in patients with cerebral ischemia and impending infarction. Our findings suggest that SNP may be more effective when initiated early and administered continuously.