异丙酚对兔脑血管二氧化碳反应性的剂量效应

The dose effect of propofol on cerebrovascular reactivity to carbon dioxide in rabbits.

作者信息

Kang F C, Chang P J, Wang L K, Sung Y H, Chen T Y, Tsai Y C

机构信息

Department of Anesthesiology, National Cheng Kung University, College of Medicine, Tainan, Taiwan, R.O.C.

出版信息

Acta Anaesthesiol Sin. 1999 Mar;37(1):3-8.

PMID:10407520

Abstract

BACKGROUND

Propofol has several properties beneficial to intracranial operation such as reduction in cerebral metabolic rate and cerebral blood flow (CBF) in a dose-dependent manner while leaving autoregulation intact. Several studies have demonstrated that the responsiveness of CBF to changes in arterial carbon dioxide tension (PaCO2) is maintained during propofol anesthesia in both humans and animals. These studies showed a significant difference in the CBF-CO2 reactivity slope between awake and propofol anaesthetized groups, but no comparison with different doses of propofol was made. To determine the dose effect of propofol on cerebrovascular CO2 reactivity, we used laser Doppler flowmetry (LDF) to detect the changes of CBF during propofol anesthesia.

METHODS

Ten rabbits were studied using LDF on the parietal cortex. After surgical preparation, anesthesia was maintained with 66% N2O in O2, morphine 10 mg/kg and pancuronium. Three experimental conditions were studied sequentially with intravenous administration of the following drugs: (1) normal saline (control), (2) propofol 20 mg/kg/h i.v., (3) propofol 40 mg/kg/h i.v. Mean arterial pressure, rectal temperature and hematocrit were kept constant. The arterial carbon dioxide tension (PaCO2) was adjusted to three levels during each condition: 20-25 mmHg (hypocapnia), 35-40 mmHg (normocapnia) and 45-50 mmHg (hypercapnia). CBF was measured continuously and recorded after the target PaCO2 had been reached.

RESULTS

There were no differences among all conditions in mean arterial pressure and heart rate. The changes of CBF as PaCO2 increased at the three different CO2 levels during each of the conditions were significantly different. The slope of CBF-CO2 reactivity among three different propofol doses was not significantly different.

CONCLUSIONS

These data indicate that cerebral vasomotor responsiveness to CO2 during propofol anesthesia is preserved and that the slope of CBF-CO2 reactivity is independent of propofol doses as mean arterial blood pressure is maintained.

摘要

背景

丙泊酚具有多种有利于颅内手术的特性，如以剂量依赖方式降低脑代谢率和脑血流量（CBF），同时保持自身调节功能完整。多项研究表明，在人和动物的丙泊酚麻醉期间，CBF对动脉二氧化碳分压（PaCO2）变化的反应性得以维持。这些研究显示，清醒组和丙泊酚麻醉组之间的CBF-CO2反应斜率存在显著差异，但未对不同剂量的丙泊酚进行比较。为了确定丙泊酚对脑血管CO2反应性的剂量效应，我们使用激光多普勒血流仪（LDF）检测丙泊酚麻醉期间CBF的变化。

方法

使用LDF对10只家兔的顶叶皮层进行研究。手术准备后，用66%的氧化亚氮、10 mg/kg吗啡和泮库溴铵维持麻醉。依次静脉注射以下药物研究三种实验条件：（1）生理盐水（对照），（2）丙泊酚20 mg/kg/h静脉注射，（3）丙泊酚40 mg/kg/h静脉注射。平均动脉压、直肠温度和血细胞比容保持恒定。在每种条件下，将动脉二氧化碳分压（PaCO2）调整到三个水平：20 - 25 mmHg（低碳酸血症）、35 - 40 mmHg（正常碳酸血症）和45 - 50 mmHg（高碳酸血症）。在达到目标PaCO2后，连续测量并记录CBF。