Prospective Examination of Epidural Catheter Insertion

Background: Although it is generally accepted that inserting epidural catheters 3-4 cm into the epidural space minimizes complications, no prospective randomized examination of epidural catheter insertion length has been published.

Methods: Eight hundred healthy parturients requesting epidural analgesia were randomized to have open-tip epidural catheters inserted 2, 4, 6, or 8 cm within the epidural space. The incidences of intravenous cannulation, unilateral sensory analgesia, and subsequent catheter dislodgment were recorded. Catheter insertions that resulted in intravenous cannulation or unilateral analgesia were incrementally withdrawn and retested with additional local anesthetic to determine the effectiveness of epidural catheter manipulation.

Results: Epidural catheters inserted 8 cm within the epidural space were more likely to result in intravenous cannulation. Epidural catheters inserted 2 cm within the epidural space were less likely to result in unilateral sensory analgesia but were more likely to become dislodged. Twenty-three percent of epidural catheters inserted > 2 cm within the epidural space required manipulation. Epidural catheters inserted 2 or 4 cm required replacement more often than epidural catheters inserted 6 or 8 cm. Ninety-one percent and 50% of epidural catheters that resulted in unilateral sensory analgesia and intravenous cannulation, respectively, provided analgesia for labor and delivery after incremental withdrawal.     

Epidural Fentanyl Produces Labor Analgesia by a Spinal Mechanism

Background: The purpose of this study was to determine if epidural fentanyl produces analgesia in laboring patients by a primary spinal or supraspinal action.

Methods: Fifty-four parturients were randomized to receive epidural 0.125% bupivacaine plus one of three treatments: epidural saline-intravenous saline, epidural fentanyl (20 [micro sign]g/h)-intravenous saline, or epidural saline-intravenous fentanyl (20 [micro sign]g/h). The study treatments were administered by continuous infusion, whereas epidural bupivacaine use was patient controlled.

Results: Epidural bupivacaine use was significantly reduced by epidural (11.5 +/- 4.6 ml/h) but not by intravenous fentanyl (15.9 +/- 4.5 ml/h) compared with saline control (16 +/- 5.9 ml/h). Analgesia characteristics and side effects were similar among groups.     

Epidural Analgesia during Labor and Maternal Fever

Background: In recent observational studies, epidural analgesia during labor at patient request has been associated with maternal fever. The authors report a secondary analysis of fever in women who were randomized to receive either epidural or patient-controlled intravenous analgesia during labor.

Methods: Maternal tympanic temperature was measured during spontaneous labor in 715 women at term who were randomized to either epidural analgesia with bupivacaine and fentanyl or to patient-controlled intravenous analgesia with meperidine. Intent-to-treat analysis of women with fever (temperature >or= to 38.0 [degree sign]C) versus those without was performed using Student t test and Fisher exact to determine statistical significance (P < 0.05).

Results: Epidural analgesia was associated with maternal fever (odds ratio = 4.0; 95% confidence interval = 2.0-7.7), as was nulliparity (odds ratio = 4.1; 95% confidence interval = 1.8-9.1) and labor longer than 12 h (odds ratio = 5.4; 95% confidence interval = 2.9-9.9). These factors were all independent variables for maternal fever when analyzed using logistic regression.     

Dose-Response Study of Epidural Ropivacaine for Labor Analgesia

Background: Ropivacaine has been introduced for use in epidural analgesia in labor. However, there have been few formal dose-response studies of ropivacaine in this setting.

Methods: The authors performed a prospective, randomized, double-blind study examining the effectiveness of five different doses of ropivacaine (10, 20, 30, 40, and 50 mg) administered epidurally in a volume of 10 ml to establish analgesia in 66 parturients who were in active labor with cervical dilatation less than 4 cm. A dose was considered effective when the visual analog scale pain score decreased by 50% or more from baseline.

Results: A sigmoid dose-response curve and a probit log dose-response plot (linear regression coefficient, r = 0.84; coefficient of determination, r2 = 0.71) were obtained. The ED50 (median effective dose) obtained based on the maximum likelihood estimation was 18.4 mg (95% confidence interval, 13.4-25.4 mg). Time to onset of analgesia, duration of analgesia, time to two-segment regression of sensory block level, and incidence of motor block were not affected by the dosage of ropivacaine administered (P = 0.93, 0.12, 0.55, and 0.39, respectively). However, the upper level of sensory block was dose-related (P < 0.01).     

罗比卡因硬膜外分娩镇痛的临床研究

目的:研究低浓度罗比卡因病人自控硬膜外镇痛(PCEA)行分娩镇痛的效果.方法:选择109例ASAⅠ～Ⅱ级、头位、单胎足月妊娠的初产妇行PCEA(分娩镇痛组).另选100例条件相仿但不给予硬膜外阻滞的自然分娩产妇为对照组.分娩镇痛组给予0.1%罗比卡因+芬太尼(1μg/ml),PCEA基础注药速率为6ml/h,冲击量为2ml,锁定时间为10分钟.进行视觉模拟镇痛评分(VAS)和下肢运动神经阻滞评分(MBS).记录产程时间、生产方式.监测胎儿心率(FHR)、新生儿Apgar评分和SpO2.结果:分娩镇痛组用药后15～30分钟均感到无痛或只感到轻度可耐受的疼痛(VAS评分0.6±0.8).分娩镇痛组产妇MBS在镇痛前后无统计学差异(P＞0.05),所有产妇均能下床活动.分娩镇痛组产妇第一产程时间为464.9±173.5分钟,短于对照组第一产程时间(P＜0.05).分娩镇痛组第二产程时间为48.4±21.8分钟,对照组为46.7±20.6分钟,两组无统计学差异(P＞0.05).分娩镇痛组新生儿1、5分钟Apgar评分和SpO2与对照组无统计学差异(P＞0.05).结论:低浓度罗比卡因分娩镇痛效果确切,对运动神经阻滞轻,不影响产程及新生儿,是目前分娩镇痛较理想的方法.     

Effect of Epidural Epinephrine on the Minimum Local Analgesic Concentration of Epidural Bupivacaine in Labor

Background: The minimum local analgesic concentration (MLAC) has been defined as the median effective local analgesic concentration in a 20-ml volume for epidural analgesia in the first stage of labor. The aim of this study was to determine the local anesthetic-sparing efficacy of epidural epinephrine by its effect on the MLAC of bupivacaine.

Methods: In this double-blind, randomized, prospective study, 70 parturients who were at 7 cm or less cervical dilation and who requested epidural analgesia were allocated to one of two groups. After lumbar epidural catheter placement, 20 ml bupivacaine (n = 35) or bupivacaine with epinephrine 1:300,000 (n = 35) was administered. The concentration of bupivacaine was determined by the response of the previous patient in that group to a higher or lower concentration using up-down sequential allocation. Analgesic efficacy was assessed using 100-mm visual analog pain scores, with 10 mm or less within 30 min defined as effective.

Results: The MLAC of bupivacaine alone was 0.091% wt/vol (95% confidence interval, 0.081-0.102). The addition of epinephrine 1:300,000 (66.7 [mu]g) resulted in a significant reduction (P < 0.01) in the MLAC of bupivacaine to 0.065% wt/vol (95% confidence interval, 0.047-0.083). The lowest maternal blood pressure was significantly lower in the bupivacaine-epinephrine group (P = 0.03). There were statistically significant reductions in fetal heart rate (P = 0.011) in the bupivacaine-epinephrine group that were not clinically significant.     

不同穿刺点硬膜外镇痛分娩效果比较

目的探讨不同穿刺点硬膜外镇痛分娩的效果。方法将 12 0例单胎足月初产妇随机分为两组各 6 0例。观察组以L1～L2 为穿刺间隙 ,对照组为L3 ～L4。两组镇痛方法、所用药物及浓度相同。观察两组镇痛药首剂量、起效时间 ,PCA次数 ,VAS评分 ,运动神经阻滞评分 ,第一、二产程时间 ,分娩方式 ,新生儿Apgar评分 ,产后 2h出血量等指标。结果VAS评分、运动神经阻滞程度、新生儿Apgar评分、产后 2h出血量两组比较 ,差异无显著性意义(均P >0 .0 5 ) ;其余项观察组均优于对照组 (均P <0 .0 5 )。结论L1～L2 间隙穿刺硬膜外镇痛分娩 ,有良好的镇痛效果 ,可缩短产程 ,提高自然分娩率。     

Effect of Epidural Analgesia with Ambulation on Labor Duration

Background: Ambulatory epidural analgesia (AEA) is a popular choice for labor analgesia because ambulation reportedly increases maternal comfort, increases the intensity of uterine contractions, avoids inferior vena cava compression, facilitates fetal head descent, and relaxes the pelvic musculature, all of which can shorten labor. However, the preponderance of evidence suggests that ambulation during labor is not associated with these benefits. The purpose of this study is to determine whether ambulation with AEA decreases labor duration from the time of epidural insertion to complete cervical dilatation.

Methods: In this prospective, randomized study, 160 nulliparous women with AEA were randomly assigned to one of two groups: AEA with ambulation and AEA without ambulation. AEA blocks were initiated with 15-20 ml ropivacaine (0.07%) plus 100 [mu]g fentanyl, followed by a continuous infusion of 0.07% ropivacaine plus 2 [mu]g/ml fentanyl at 15-20 ml/h. Maternal measured variables included ambulation time, time from epidural insertion to complete dilatation, stage II duration, pain Visual Analogue Scale scores, and mode of delivery. APGAR scores were recorded at 1 and 5 min. Results are expressed as mean +/- SD or median and analyzed using the t test, chi-square, or the Mann-Whitney test at P <= 0.05.

Results: The ambulatory group walked 25.0 +/- 23.3 min, sat upright 40.3 +/- 29.7 min, or both. Time from epidural insertion to complete dilatation was 240.9 +/- 146.1 min in the ambulatory group and 211.9 +/- 133.9 min in the nonambulatory group (P = 0.206).     

硬膜外阻滞麻醉镇痛对产程的影响

为探讨硬膜外阻滞麻醉镇痛对产程的影响,将100例初产妇随机分为观察组（行硬膜外阻滞麻醉分娩）和对照组（正常分娩）各50例,观察两组产妇的总产程及第一产程时间,活跃期宫口扩张速率和胎头下降速率。结果观察组产妇的部产程及每产程时间均较对照组明显缩短;宫口扩张和胎头下降速率较对照组显著增快（均P＜0．01）,表明硬膜外阻滞麻醉用于分娩镇痛的同时能明显促进产程进展。     

病人自控硬膜外镇痛行分娩镇痛的临床观察

目的：观察病人自控硬膜外镇痛（ＰＣＥＡ）行分娩镇痛对母婴及产程的影响。方法：１００例产妇分为ＰＣＥＡ组（ｎ＝４２）和对照组（ｎ＝５８）。ＰＣＥＡ组在第一产程活跃期开始施行ＰＣＥＡ,记录两组产妇分娩过程中的产程时间、产程各时段的视觉模拟评分（ＶＡＳ）、分娩方式及新生儿Ａｐｇａｒ评分。观察ＰＣＥＡ组产妇麻醉前后腹部和下肢肌力情况。结果：两组产妇各产程时间、分娩方式和新生儿Ａｐｇａｒ评分无统计学差异。ＰＣＥＡ组产程各时段的ＶＡＳ评分明显小于对照组（Ｐ〈０．０１）,产妇麻醉后腹部和下肢和略有减弱,但不影响第二产程进程。结论：ＰＣＥＡ行分娩镇痛时母婴安全,镇痛效果确切。