【摘要】 目的 观察颅脑手术病人不同呼气末二氧化碳分压（PaCO2）与脑代谢、脑血流、颅内压的相关性。方法 12例择期行颅脑手术病人,行七氟醚麻醉,待1.3MAC时,调整呼吸频率,使PETCO2达40、30、20mm Hg,每阶段稳定 30min.分别采清醒时及PETCO2各时段的颈内静脉、桡动脉血以及脑脊液作血气分析以及测定葡萄糖、乳酸含量,根据血气分析找出相对应的PaCO2,用修正Kety-Schmidt惰性气体饱和技术计算CBF,并由此根据动静脉差值计算出CMRO2、CMRglu值的变化。结果 与清醒时通气状态相比,PET COZ 20Tin Hg脑血流减少57.75％。CMROZ减少58.70％,,CMRglu减少46.93％,（P<0.05）。颈静脉血氧饱和度以及pH无明显变化（P>0.05）。P。COZ 40和20mm Hg时脑血流比P。,CO 30mm Hg时增加和减少了29.2％和11.3％（P<0.05）,随着PETCO2的降低ICP也呈不同程度的下降（r=0.857,P<0.01）。不同PETCO2下脑脊液中PH、乳酸盐和SjvO2无明显变化（P>0.05）。结论 1.3MAC七氟醚麻醉下,不同PET CO2时神经外科手术病人CBF、CMR和 ICP与 PETCO2变化相关,表明脑血管对CO2的反应性依然存在,但由于PETCO2　40mmHg时CBF增加,所以临床上应予避免。更多还原

【Abstract】 Objective To investigate the correlation between PaCO2 and cerebral blood flow (CBF), cerebral metabolism of oxygen (CMRO2), glucose (CMRglu) and lactate (CMRlact) and intracranial pressure during intracranial surgery. Methods Twenty ASA Ⅰ - Ⅱ patients (6 male, 6 female), aged between 26-54yr, weighing (65 ± 11) kg scheduled for elective intracranial surgery were studied. The patients were unpremedicated. Before general anesthesia radial artery was cannulated and a catheter was inserted into internal jugular vein and advanced cranially until jugular bulb. Lumber puncture was performed at L3-4 and a catheter was inserted into subarachnoid space for 3 cm, for pressure monitoring and CSF sampling. Anesthesia was induced with diazepam 10mg, fentanyl 3-4μg·kg-1, propofol 2mg·kg-1 and vecuronium 0.08mg·kg-1 iv. The patients were mechanically ventilated with a mixture of oxygen and argon (O2 : argon = 3 : 1) after tracheal intubation. Anesthesia was maintained with sevoflurane and intermittent iv boluses of vecuronium. Arterial and cerebral venous blood gases, glucose and lactate levels, CBF, ICP and CSF level of lactate were determined before anesthesia when patients were awake(Ⅰ) and during anesthesia when PETCO2 = 40, 30, 20 mm Hg (Ⅱ,Ⅲ,Ⅳ). CBF was measured by modified Kety-Schmidt inert gas saturation technique with argon. CMRO2 and CMRglu were calculated based on the difference in their arterial -cerebral venous blood levels. Results At PETCO2 20mm Hg (Ⅳ) CBF decreased by 57.75% and CMRO2 by 58.70% as compared with the baseline; CMRglu decreased by 46.93% as compared with the baseline. There was no significant change in lactate level, jugular venous blood O2 saturation and pH. ICP decreased from (22.14 ± 7.88)mm Hg( Ⅰ) to (17.57±5.03)mm Hg( Ⅱ ),(13.43±4.89)mm Hg(Ⅲ) and (10.00± 2.31)mm Hg(Ⅳ) and the differences were significant. All measurements were done when MAP and HR were stable. PET CO2 was (10± 2) mm Hg lower than PaCO2 . Conclusions Cerebral blood flow, cerebral oxygen and glucose metabolism and intracranial pressure change with changes in PET CO2 . Cerebral vascular reactivity to CO2 is not impaired by 1.3 MAC sevoflurane. Mild hypocapnia is necessary during neurosurgery.更多还原