A t~t i~~r t / 2 c~i i c~. c , wkirilc: cnflurane. 8r.eiiii; blood flow, glucose, lactate. oxygenation.Therc arc only few studies on the effect of propofol (24-diisopropylphcnol) on cerebral blood flow and metabolism in man. Stephen and co-workers' found a 51 YO decrease of cerebral blood flow in patients scheduled for coronary artery bypass surgery after a bolus injection of propofol 2 mg:'kg followed by an infusion of 0.2 nigjkginiinute. They noted a proportional decrease of 36% in cerebral oxygen consumption which was associated with a decrease in electroencephalographic (EEC) activity.We compared ccrcbral blood flow under stable and coiiipmiblc conditions o f Ptrco2 and niciin blood pressure ~ iri patients of AS.4 grade I w h o underwcnt 35% oxygen in riitrou5 owidc anaesthesia with cnfluranc 0.59,;1 before and during ii proporol infusion to ucliicvc stcady-state anaesthcaia. MethodsThirtecn paticnts ( 2 fcmalc) aged from 22 62 years schcdulcd Ihr intervertebral disc surgery were included in the ~t u d y after informed consent and approval by the hospital cthica! committee. N o preinedicatiori was given. Anaes- Monitoring consisted of lead I I ECG. I-pl T5 and Fp2 Th EEG recording, continuous blood pressure measurement via a radial artery cannula. jugular bulb pressure ria ii percutaneous catheter (Lcdcrcath 17-gauge), arterial and jugular bulb blood gas. glucosc and lactate analysis.A first CBF measurement was pcrformed when stable conditions were acheived. at least one hour after thiopentone induction. using the xenon 133 inhalation technique. Cerebral radioactivity decay and the expired xenon 133 were recorded by gamma camera (Elscint Apex 21 S) and cerebral blood flow was calculated using the initial slope index.An infusion of propofol (three-step infusion technique) was started a t H rate of 0.35 mgikgiminute (21 nigikgihour) [or 5 minute\ alier the first CBF inexurement. then at 0.2 iiig k p m i n u t e (12 mg k g ' h o u r ) I'or a furthcr 10 tninutcs and then at 0. I mg3 kg minute ( 6 m g ' k g . h o u r ) for tlic last 25 minutes. This scheme of propofol infusion was based on data collected l'rcmi ii previous personal ctiidy of 1 h patients wlicrc ii stable blood concentration 01'4 /1y.iiil w a s achicvsd after-30 minutes of infusion.Blood samples were drawn one minute before the $tart of the infusion and at 1. 2. 3. 4. 5. 7. 9, 1 1 . 13. IS. 20. 25. 30 and 40 minutes from the jugular bulb. and at 20. 30 and 40 minutes liom a periphcral vcin. Blood pressure WBS

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