腰硬联合蛛网膜下腔注射芬太尼用于分娩镇痛的半数有效剂量的临床研究

Clinical Research on the ED50 of Intrathecal Fentanyl Combined with Epidural Anesthesia in Labor

目的:确定腰硬联合蛛网膜下腔注射芬太尼用于分娩镇痛的半数有效剂量(ED50),观察蛛网膜下腔注射半数有效剂量芬太尼的效果和副作用,并与蛛网膜下腔注射半数有效剂量的布比卡因进行对比。方法:首先,确定芬太尼用于分娩镇痛的半数有效剂量,筛选50例符合的产妇行腰硬联合分娩镇痛,蛛网膜下腔注射芬太尼的剂量始于25μg,如果镇痛有效,下一病例减少2.5μg芬太尼;如果无效则下一病例增加2.5μg芬太尼。用Probit回归分析计算芬太尼蛛网膜下腔注射行分娩镇痛的半数有效剂量和95%可信区间(95%CI)。第二步,筛选100例需要进行分娩镇痛的产妇,随机分入ED50芬太尼组(F组)和ED50布比卡因组(B组),比较两组药物镇痛效果及起效时间、产妇下肢运动阻滞程度及血压心率变化、胎心变化和镇痛全程药物追加次数。结果:芬太尼蛛网膜下腔注射分娩镇痛的ED50为11.5μg,95%CI为3.5-15.4μg。F组镇痛的平均起效时间为(12.0±3.8)min,两组镇痛的成功率没有统计学差异(P=0.218),F组需要追加PCA的病例百分率明显少于B组(P=0.018)。F组下肢运动阻滞程度轻于B组(P=0.018)。两组镇痛方法对产妇的血压、心率均无明显影响。两组胎心下降的发生率没有明显差异(P>0.05)。F组皮肤瘙痒的发生率明显增加(P=0.000)。结论:腰硬联合分娩镇痛蛛网膜下腔注射芬太尼的ED50为11.5μg,95%CI为3.5-15.4μg。蛛网膜下腔注射半数有效剂量的芬太尼可以提供简便、持久、满意和安全的镇痛效果,并且对下肢运动阻滞程度较小,但其所致皮肤瘙痒的发生率升高。

Objective： To determine the median effective dose of intrathecal fentanyl combined with epidural anesthesia in labor, and observe its advantages and side effects. Methods： Firstly, 50 healthy parturients in labor were recruited for the dose-finding study. Ini- tial dose of intrathecal fentanyl was 25μg. Doses varied in a 2.5 μg testing interval according to up-down sequential allocation. An ef- fective dose was directed to a decrement of 2.5 μg fentanyl for the next patient. An inadequate dose was directed to an increase of 2.5 μg fentanyl for the next patient. The Probit Regression was used to estimate the ED50 dose of intrathecal fentanyl and its 95% confi- dence intervals in labor analgesia. Secondly, another 100 healthy parurients were recruited and randomly allocated into fentanyl group（F group） injected with a dose of ED50 fentanyl and bupivacaine group （B group） administered with a dose of ED50 bupivacaine. The anal- gesia effect, onset time, motor block of lower limbs, rescue PCA, the effect on the blood pressure and heart rate of parturients and fetal were compared between the two groups. Results： The ED50 ofintrathecal fentanyl was 11.5 μg, and 95% CI is 3.5-15.4μg in labor analgesia. The average onset time was （12.0± 3.8） min. There was no obvious difference in the achievement of adequate analgesia between the two groups. Group F needs less rescued PCA than that of Group B. The degree of lower limbs motor block was less intense in fentanyl group than that in bupivacaine group. There was no dramatic influence on parturients＇ heart rate and blood pressure in the two groups. There was no marked difference in the incidence of fetal bradycardia. The occurrence ofpntritus was more in fentanyl group than that in bupi-vacaine group. Conclusion： The median effective dose of intrathecal fentanyl in labor analgesia was 11.5 μg and 95% CI was 3.5-15.4 μg. Intrathecal media effective dose of fentanyl could provide easy, long lasting, satisfactory and safe analgesia to parturients, and had less blockage on the motor of lower limbs, but this method may induce pnxritus which needn＇t medical treatment.