The Comparative Effects of Desflurane and Isoflurane on Lumbar Cerebrospinal Fluid Pressure in Patients Undergoing Craniotomy for Supratentorial Tumors

Abstract

C erebral vasospasm continues to be a leading cause of morbidity and mortality after subarachnoid hemorrhage (SAH). Cerebral ischemia may ensue when autoregulation fails to compensate for spasm. How autoregulation is affected by vasospasm was examined using transcranial Doppler (TCD). The moving correlation coefficient between slow changes of arterial blood pressure and mean or systolic flow velocity, termed ''Mx'' and ''Sx,'' respectively, was used to characterize cerebral autoregulation. Vasospasm was declared when the mean flow velocity increased to more 120 cm/s and the Lindegaard ratio was more than 3. This occurred in 15 of 32 SAH patients. Based on the bilateral TCD recordings of the middle cerebral artery in vasospastic patients, Mx and Sx were calculated for baseline and vasospasm. Mx increased during vasospasm (0.46 ± 0.32; mean ± SD) and was markedly higher than at baseline (0.21 ± 0.24). Sx was also increased (0.22 ± 0.26 vs. 0.05 ± 0.21 at baseline). Mx correlated with mean flow velocity (r = 0.577) and the Lindegaard ratio (r = 0.672). Mx and Sx were higher on the vasospastic side (Mx, 0.44 ± 0.27; Sx, 0.16 ± 0.25). The increase in Mx and Sx during cerebral vasospasm demonstrated impaired cerebral autoregulation. Mx and Sx provide additional information on changes in autoregulation in SAH patients.