Hypertonic saline in patients with poor-grade subarachnoid hemorrhage improves cerebral blood flow, brain tissue oxygen, and pH.

BACKGROUND AND PURPOSE

Delayed cerebral ischemia and infarction due to reduced CBF remains the leading cause of poor outcome after aneurysmal subarachnoid hemorrhage. Hypertonic saline (HS) is associated with an increase in CBF. This study explores whether CBF enhancement with HS in patients with poor-grade subarachnoid hemorrhage is associated with improved cerebral tissue oxygenation.

METHODS

Continuous monitoring of arterial blood pressure, intracranial pressure, cerebral perfusion pressure, brain tissue oxygen, carbon dioxide, pH, and middle cerebral artery flow velocity was performed in 44 patients. Patients were given an infusion (2 mL/kg) of 23.5% HS. In 16 patients, xenon CT scanning was also performed. CBF in a region surrounding the tissue oxygen sensor was calculated. Data are mean+/-SD.

RESULTS

Thirty minutes postinfusion, a significant increase in arterial blood pressure, cerebral perfusion pressure, flow velocity, brain tissue pH, and brain tissue oxygen was seen together with a decrease in intracranial pressure (P<0.05). Intracranial pressure remained reduced for >300 minutes and flow velocity elevated for >240 minutes. A significant increase in brain tissue oxygen persisted for 240 minutes. Average baseline regional CBF was 33.9+/-13.5 mL/100 g/min, rising by 20.3%+/-37.4% (P<0.05) after HS. Patients with favorable outcome responded better to HS in terms of increased CBF, brain tissue oxygen, and pH and reduced intracranial pressure compared with those with an unfavorable outcome. A sustained increase in brain tissue oxygen (beyond 210 minutes) was associated with favorable outcome (P<0.023).

CONCLUSIONS

HS augments CBF in patients with poor-grade subarachnoid hemorrhage and significantly improves cerebral oxygenation for 4 hours postinfusion. Favorable outcome is associated with an improvement in brain tissue oxygen beyond 210 minutes.