Cerebral pathology may alter the cerebrovascular reactivity to
carbon dioxide (CO2). In the present study, in patients with
brain tumors, we examined the cerebral vascular reactivity to CO2 in the cerebral hemispheres with and without
tumors under intravenous and inhalational
anesthesia. Twenty-nine patients undergoing
craniotomy for frontotemporal
gliomas were randomized to receive
intravenous anesthesia with
propofol or inhalational
anesthesia with
isoflurane. Cerebral blood flow velocity in the middle cerebral artery (VMCA) and pulsatality index were measured under normocapnia and
hypocapnia in the normal cerebral hemisphere and the hemisphere with
tumor.
Hypocapnia significantly decreased the VMCA in both the cerebral hemispheres under both the
anesthetic techniques (P < 0.006). The percentage change in VMCA was similar between the hemispheres with and without
tumor both under
isoflurane (3.45 +/- 4.11% on the normal side and 2.91 +/- 2.40% on the
tumor side; mean difference 0.54 +/- 1.31%; 95% CI -2.18 to +3.27) and
propofol anesthesia (2.32 +/- 2.64% on the normal side and 1.69 +/- 4.04% on the
tumor side; mean difference 0.63 +/- 1.2%; 95% CI -1.83 to +3.10). The changes in pulsatality index also were not significantly different between the hemispheres. In conclusion, cerebrovascular response to
hypocapnia is similar between the normal and the abnormal cerebral hemispheres both under intravenous and inhalational
anesthesia.