DESFLURANE INCREASES BRAIN-TISSUE OXYGENATION AND PH

Background: Desflurane anesthesia can produce cerebral metabolic depre ssion and increase cerebral blood flow. We evaluated the effect of des flurane on brain tissue oxygen pressure (PO2), carbon dioxide pressure (PCO2) and pH during neurosurgery. Methods: Following a craniotomy, t he dura was opened and a Paratrend 7 sensor, which measures PO2, PCO2, pH and temperature, was inserted into brain tissue. In 6 control pati ents in group 1, anesthesia was maintained constant with 3% end-tidal desflurane over 60 min, including a 30-min stabilization period. In gr oup 2, 9 patients were ventilated with 3% desflurane under baseline co nditions. After a 30-min stabilization period, baseline tissue gases a nd pH were measured and end-tidal desflurane was increased to 6% and t hen 9% for 15-min intervals. Mean arterial pressure (MAP) was maintain ed with intravenous phenylephrine. Results: Under baseline conditions, cardiovascular and brain tissue measures were similar between the 2 g roups. Increasing end-tidal desflurane from 3% to 9% produced burst-su ppression EEG in all patients and significantly increased tissue PO2 a nd pH and decreased PCO2. No parameters changed significantly in the c ontrol group during steady-state anesthesia. Conclusion: These results show that 9% desflurane can improve brain tissue metabolic status bef ore temporary brain artery occlusion if cerebral perfusion pressure is maintained. This may be particularly important in patients with sympt oms of ischemia before surgery. (C) Acta Anaesthesiologica Scandinavic a 41 (1997).