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This Month in Anesthesiology  |   September 1999
Effects of Sevoflurane and Isoflurane on Cerebral Blood Flow Examined. Matta et al. (page 677) 
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This Month in Anesthesiology
This Month in Anesthesiology   |   September 1999
Effects of Sevoflurane and Isoflurane on Cerebral Blood Flow Examined. Matta et al. (page 677) 
Anesthesiology 9 1999, Vol.91, 5A. doi:
Anesthesiology 9 1999, Vol.91, 5A. doi:
Using propofol to induce an isoelectric electroencephalogram, Matta et al.  compared the intrinsic vasodilatory effects of 0.5 and 1.5 minimum alveolar concentration (MAC) sevoflurane and isoflurane in 20 patients who required analgesia for routine spinal neurosurgical procedures. Anesthesia was induced with 2.5 mg/kg propofol, 2 μg/kg fentanyl, and 0.5 mg/kg atracurium. A propofol infusion was used to achieve electroencephalogram isoelectricity. In addition to routine monitoring, transcranial doppler was used to measure blood flow velocity in the middle of the cerebral artery, providing an indirect measure of cerebral blood flow. Matta et al.  accomplished this using a specially designed frame to hold the transcranial doppler probe in position so that the angle of insonation and vessel diameter remained constant during the study period.
All measurements were performed before surgery began. Cerebral blood flow, blood pressure, and heart rate were recorded after 20 min of isoelectric electroencephalogram, and patients were then allocated to receive either age-adjusted 0.5 MAC (0.8–1%) or 1.5 MAC (2.4–3%) end-tidal sevoflurane; or age-adjusted 0.5 MAC (0.5–0.7%) or 1.5 MAC (1.5–2%) end-tidal isoflurane. Measurements were performed 15 min later. Both agents increased cerebral blood flow at 0.5 and 1.5 MAC, but the increase was significantly less with sevoflurane. Because of its “weak” intrinsic vasodilatory action, sevoflurane is unlikely, the authors report, to cause significant increases in intracranial pressure.