A Comparison of the Cerebral Hemodynamic Effects of Sufentanil and Isoflurane in Humans Undergoing Carotid Endarterectomy

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Abstract
Prompted by reports of potentially deleterious cerebral vasodilation by the synthetic opoid sufentanil, the authors compared the effects of either isoflurane/N2O and sufentanil/N2O on cerebral blood flow (CBF), arteriovenous difference in oxygen content (AVDO2), and CBF reactivity to changes in Paco2 during carotid endarterectomy. Cerebral blood flow was measured using the iv method of 133-Xe CBF determination and AVDO2 was measured using systemic arterial-jugular venous oxygen content differences. Patients, age 68 ± 1 yr (mean ± SE), received either isoflurane (n = 10), 0.75% in O2 and N2O, 1:1; or sufentanil (n = 10), 1.5–2 μg/kg bolus and then 0.2–0.3 μg ± kg-1 · h-1 infusion in addition to O2 and N2O, 2:3. Measurements were made immediately before carotid occlusion, and then at two levels of Paco2 (approximately 32 and 42 mmHg) after insertion of a temporary in-dwelling bypass shunt. Prior to carotid occlusion, there was no significant difference in CBF (ml · 100 g-1 · min-1) between patients receiving isoflurane (22 ± 3) or sufentanil (20 ± 2). Similarly, there was no difference in AVDO2 (vol-%) between isoflurane (4.5 ± 0.7) and sufentanil (5.4 ± 0.8) groups. Using a two-way ANOVA design with anesthetic as the between-group factor and elevation of Paco2 as the within-group repeated measure, there was a significant effect of hypercarbia to increase CBF (P < 0.0001) and decrease AVDO2 (P < 0.001). The product of AVDO2 and CBF, which reflects cerebral metabolic oxygen consumption, remained constant (P = 0.364). There was no difference in AVDO2 or CBF between anesthetic groups. CBF reactivity to changes in Paco2 was similar for both anesthetic regimens. The average slope of the CO2 response (ml · 100 g-1 · min-1 · mmHg-1) was 1.7 ± 0.3 for isoflurane and 1.1 ± 0.2 for sufentanil, respectively, and did not differ significantly. Both sufentanil and isoflurane in combination with N2O, when used in elderly patients with occlusive cerebrovascular disease, have similar effects on cerebrovascular hemodynamics.