不同小剂量芬太尼、异丙酚组合对大脑皮层抑制速度和程度的影响

The effects on the rate and extent of cerebral cortical suppression induced by different lower doses of fentanyl combined with propofol

目的探讨不同小剂量芬太尼、异丙酚组合对大脑皮层抑制速度和程度的影响。方法选择60例拟行乳癌根治术的女性患者,将其分为四组:P组(异丙酚)、F1组(芬太尼1μg/kg+异丙酚)、F2组(芬太尼2μg/kg+异丙酚)和F3组(芬太尼3μg/kg+异丙酚)。麻醉诱导时P组给予生理盐水和异丙酚,其余各组给予不同剂量的芬太尼(1μg/kg、2μg/kg、3μg/kg)和异丙酚,异丙酚的输注速率为100mg/min,患者意识消失后停止输注异丙酚。记录从异丙酚输注开始至患者意识消失的时间和意识消失时的脑电双频谱指数(bispectral index,BIS)、BIS值达到60的时间(BIS60)、BIS最低值及其出现的时间;并计算各组异丙酚的用量。结果与P组相比较,F1、F2和F3组意识消失时间缩短、异丙酚用量减少,意识消失时的BIS值明显增高;F1组意识消失时间和异丙酚用量明显超过F2和F3组,但其BIS60的时间却明显快于后两组,三个芬太尼组BIS最低值及其时间基本相似。结论不同小剂量芬太尼、异丙酚组合对大脑皮层的抑制速度随芬太尼剂量的增加而呈现减缓趋势,但对大脑皮层的最大抑制程度相似。这说明BIS监测不能及时反映小剂量芬太尼所产生的意识变化程度,并且具有滞后现象,临床中应该予以警惕。

Objective To investigate the effects of lower doses of fentanyl combined with propofol on rate and extent of cerebral cortical suppression.MethodSixty female patients, were randomly allocated into four groups, group P（propofol only）, F1（fentanyl 1μg/ kg＋propofol）, F2（fentanyl 2μg/kg＋propofol） and F3 （fentanyl 3μg/kg＋propofol）. Normal saline, fentanyl 1, 2, 3μg/kg were given respectively. Thereafter propofol was infused at a constant rate of 100mg/min until loss of consciousness. Bispectral index （BIS） monitor was used to assess the cerebral cortical suppression. Time to loss of consciousness （LOC）, BIS values at LOC, time to BIS value of 60（BIS60）, the lowest BIS values and time to those were all recorded. The propofol consumption was calculated for each group.Result Time to LOC was significantly shortened and BIS values at LOC were significantly higher in the fentanyl/propofol groups compared to group P （P〈0.05, respectively）. Time to BIS60and propofol consumption were greater in group F1 than in groups F2 and F3 （P〈0.05, respectively）. The lowest BIS values and time to those were similar among three fentanyl/propofol groups.ConclusionThe suppressed rate of cerebral cortex caused by small doses of fentanyl combined with propofol tended to become slower with the higher dose of fentanyl, but the maximal extents of cerebral cortex suppression were comparable among the three fentanyl/propofol groups. This indicated that BIS monitoring failed to reflect the consciousness changes induced by small doses of fentanyl, and seemed to have time lag effect. This should arouse our alert in clinical practice.