Labor Epidural Analgesia without an Intravascular "Test Dose"

Background: This study prospectively evaluated the ability of aspiration to detect intravascular placement of multiple-orifice epidural catheters.

Methods: Multiple-orifice, 20-gauge epidural catheters were inserted in 1,029 laboring women. Catheters were observed and aspirated for blood or cerebrospinal fluid before they were tested with 2 ml local anesthetic. If the results of this test were negative (no spinal anesthesia), the authors induced and maintained labor analgesia with a dilute local anesthetic and opioid solution. Patients with bilateral sensory change and effective labor analgesia had a "positive" epidural catheter. Women with unilateral block, inadequate analgesia despite some sensory change or those who delivered before being adequately assessed had "equivocal" catheters. Patients with neither analgesia nor sensory change had "negative" catheters.

Results: Aspiration and observation identified 60 intravenously placed catheters. Six catheters, which were placed initially in a blood vessel, were withdrawn until aspiration was negative, and then the anesthetic was infused. Four of these catheters were positive and two were still positioned intravascularly. Two other catheters may have been intravenously placed despite negative results of aspiration. The incidence of false-negative results of aspiration was 0 to 2 of 1,085 (upper limit of 95% CI, 0.2% to 0.4%). No patient showed any signs or symptoms of local anesthetic toxicity.     

Dose-dependent Reduction of the Minimum Local Analgesic Concentration of Bupivacaine by Sufentanil for Epidural Analgesia 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 sufentanil by its effect on the MLAC of bupivacaine.

Methods: In this double-blind, randomized, prospective study, 147 parturients at Results: The MLAC of bupivacaine alone was 0.104% wt/vol (95% CI, 0.090 - 0.117). The addition of sufentanil at doses of 0.5 [micro sign]g/ml, 1 [micro sign]g/ml, and 1.5 [micro sign]g/ml resulted in significant reductions (P < 0.0001) in the MLAC of bupivacaine to 0.048% wt/vol (95% CI, 0.030 - 0.065), 0.021% wt/vol (95% CI, 0 - 0.055), and 0.009% wt/vol (95% CI, 0 - 0.023), respectively.     

硬膜外连续泵注芬太尼与布比卡因用于分娩镇痛的临床研究

目的：探讨硬膜外泵注芬太尼与布比卡因用于分娩镇痛的有效性及安全药物剂量。方法：以０．１５％布比卡因为对照,比较０．０００５％至０．００１２％范围内四种不同浓度芬太尼与之混合硬膜外泵注的分娩镇痛效果。结果：选用０．０００８％与０．００１％两种浓度芬太尼与０．１５％布比卡因混合泵注时,镇痛作用起效快,镇痛时间明显延长,而且不增加副作用。结论：硬膜外连续泵注芬太尼与布比卡因用于分娩镇痛能明显改善镇痛效果,芬太尼使用浓度以限制在０．０００８％至０．００１％为宜。     

Epidural Analgesia with a Combination of Bupivacaine and Buprenorphine in Rats

We determined the analgesic effects of epidural administration of either bupivacaine at 62.5, 125, 250, and 500 μg/kg; buprenorphine at 5 and 10 μg/kg; and the combination of bupivacaine at 125 μg/kg and buprenorphine at 5 or 10 μg/kg, using the tail flick (TF) and colorectal distension (CD) tests in rats and compared the results with those obtained using morphine at 100 μg/kg. In both the TF and CD tests, all doses of bupivacaine alone produced potent anti‐nociceptive effects, although the effect rapidly diminished after 20–30 min of administration. The administration of buprenorphine at 10 and 5 μg/kg produced mild to moderate anti‐nociceptive effects in both the TF and CD tests, and the effects were relatively constant throughout the 2‐h experimental period. Combinations of 5 or 10 μg/kg of buprenorphine with 125 mg/kg of bupivacaine produced a significantly higher percentage of maximum possible analgesic effect (%MPE) than that of the calculated additive effect of each drug alone in the TF and CD tests. The analgesic effect of this combination was similar to that of morphine. Minimal ataxia was observed in rats administered this combination.     

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.     

Relative Analgesic Potencies of Ropivacaine and Bupivacaine for Epidural Analgesia in Labor: Implications for Therapeutic Indexes

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 assess the relative analgesic potencies of epidural bupivacaine and ropivacaine by determining their respective minimum local analgesic concentrations.

Methods: Seventy-three parturients at Results: The minimum local analgesic concentration of ropivacaine was 0.111% wt/vol (95% confidence interval, 0.100-0.122), and the minimum local analgesic concentration of bupivacaine was 0.067% wt/vol (95% confidence interval, 0.052-0.082). Ropivacaine was significantly less potent than bupivacaine, with a potency ratio of 0.6 (95% confidence interval, 0.49-0.74). No difference in motor effects was observed.     

Maximum Tolerated Dose of Nalmefene in Patients Receiving Epidural Fentanyl and Dilute Bupivacaine for Postoperative Analgesia

Background: This study investigated the ability of the modified continual reassessment method (MCRM) to determine the maximum tolerated dose of the opioid antagonist nalmefene, which does not reverse analgesia in an acceptable number of postoperative patients receiving epidural fentanyl in 0.075% bupivacaine.

Methods: In the postanesthetic care unit, patients received a single intravenous dose of 0.25, 0.50, 0.75, or 1.00 [mu]g/kg nalmefene. Reversal of analgesia was defined as an increase in pain score of two or more integers above baseline on a visual analog scale from 0 through 10 after nalmefene administration. Patients were treated in cohorts of one, starting with the lowest dose. The maximum tolerated dose of nalmefene was defined as that dose, among the four studied, with a final mean probability of reversal of anesthesia (PROA) closest to 0.20 (i.e., a 20% chance of causing reversal). The modified continual reassessment method is an iterative Bayesian statistical procedure that, in this study, selected the dose for each successive cohort as that having a mean PROA closest to the preselected target PROA of 0.20.

Results: The modified continual reassessment method repeatedly updated the PROA of each dose level as successive patients were observed for presence or absence of ROA. After 25 patients, the maximum tolerated dose of nalmefene was selected as 0.50 [mu]g/kg (final mean PROA = 0.18). The 1.00-[mu]g/kg dose was never tried because its projected PROA was far above 0.20.     

A Double-blind Comparison of 0.125% Ropivacaine with Sufentanil and 0.125% Bupivacaine with Sufentanil for Epidural Labor Analgesia

Background: This study intends to evaluate the benefits of the administration of intermittent bolus doses of ropivacaine (0.125%) compared with bupivacaine (0.125%) after addition of sufentanil for analgesia during labor.

Methods: One hundred thirty American Society of Anesthesiologists physical status 1 or 2 parturients were studied. The 90 initial patients were assigned randomly to receive 10 ml bupivacaine, 0.125%, plus 7.5 [micro sign]g sufentanil (initial bupivacaine 0.125% group) or ropivacaine, 0.125%, plus 7.5 [micro sign]g sufentanil (ropivacaine 0.125% group). Forty additional patients were recruited and received 0.125% bupivacaine plus 7.5 [micro sign]g sufentanil (additional bupivacaine 0.125% group) or 0.100% bupivacaine plus 7.5 [micro sign]g sufentanil (additional bupivacaine 0.100% group). The duration of analgesia, visual analogue scores for pain, motor blockade (using a six-point modified Bromage scale), patient satisfaction scores, nausea, pruritus, heart rate, and blood pressure were recorded.

Results: Bupivacaine 0.125% and ropivacaine 0.125% coadministered with sufentanil provided rapid and complete analgesia. Onset of analgesia occurred after +/- 15 min and lasted +/- 90 min. After the third epidural injection, patients in the ropivacaine group experienced significantly less severe motor blockade than patients in the initial bupivacaine 0.125% group. At this point, 93% of the patients in the ropivacaine group were free from motor impairment versus 66% in the bupivacaine group (P < 0.05). Comparable levels of motor blockade were obtained in both additional groups. Patients' evaluation of their analgesia was worst in the bupivacaine 0.100% group.     

低浓度布比卡因复合芬太尼硬膜外分娩镇痛的临床观察

目的：观察硬膜外低浓度布比卡因复合芬太尼行分娩镇痛的临床效果。方法：５０例产妇随机分为镇痛组（Ｅ组）和对照组（Ｃ组）。Ｅ组在宫口开至３～４ｃｍ时开始硬膜外注药，采用首量＋持续背景量＋ＰＣＡ（ＬＣＰ）模式。镇痛药为０．１２５％布比卡因（每毫升含２μｇ芬太尼）。宫口开至８～９ｃｍ时停药。Ｃ组按产科常规处理。结果：硬膜外镇痛对产妇的生命体征无明显影响。Ｅ组产妇疼痛感比Ｃ组显著良好（Ｐ〈０．０１）。运动不受影响，但对宫缩的感觉部分缺失，助产率显著高于Ｃ组（Ｐ〈０．０５）。结论：０．１２５％布比卡因复合芬太尼用于硬膜外分娩镇痛能取得良好的镇痛效果。     

硬膜外布比卡因镇痛对剖宫产术后催乳素及婴儿体重的影响

目的：观察剖宫产术后病人自控硬膜外镇痛（ＰＣＥＡ）对催乳素（ＰＲＬ）、母乳量及婴儿体重的影响。方法：选择６０例健康足月产妇,择期在硬膜外麻醉下施行剖宫产术。术毕随机等分为镇痛组和对照组。镇痛组行ＰＣＥＡ,注入０．２％布比卡因（２ｍｌ／ｈ）持续７２小时镇痛。对照组术毕拔出硬膜外导管。两组采用放射免疫分析法测定血浆ＰＲＬ。结果：镇痛组ＶＡＳ明显低于对照组（Ｐ〈０．０１）。两组术后ＰＲＬ较术前明显升高（Ｐ〈０．０１）,镇痛组术后ＰＲＬ又显著高于对照级殖 组婴儿体重增加明显高于对照组（Ｐ〈０．０５）,肠蠕动恢复时间明显快于对照组（Ｐ〈０．０１）,镇痛组睡眠好。两组宫缩无显著性差异（Ｐ〉０．０５）。结论：剖宫产术后经卡因ＰＣＥＡ能促进ＰＲＬ分泌,增加婴儿体重。     

Thoracic Epidural Analgesia I-A Double-Blind Study between Bupivacaine and Etidocaine

A double-blind comparison was made in 40 patients undergoing thoracic epidural analgesia with either bupivacaine 0.5 % or etidocaine 1.0 %, both with adrenaline 5 μg/ml. All patients were undergoing elective upper abdominal surgery. They were studied both pre- and postoperatively. The parameters measured were: onset time, segmental spread and duration of analgesia; and also systolic blood pressure, heart rate and peak expiratory flow rate. In respect of these parameters, no major differences were found between the two solutions under the conditions of the study. The overall results, however, differ in many respects to those found when these agents are used in lumbar epidural analgesia.     

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.     

布比卡因分别复合芬太尼、咪唑安定或曲马多用于术后硬膜外自控镇痛的比较

目的：比较布比卡因分别复合芬太尼,咪唑安定,曲马多行术后硬膜外自控镇痛（ＰＣＥＡ）的临床效果。方法：６０例在腰麻加硬膜外麻醉下行择期妇科手术的病人分为四组。Ａ组：０．１２５％布比卡因：Ｂ组：０．１２５％布比卡因＋芬太尼,Ｃ组０．１２５％布比卡因＋咪唑安定,Ｄ组：０．１２５％布比卡因＋曲马多ＰＣＥＡ参数设置,负荷剂量６ｍｌ,单次剂量３ｍｌ,锁定时间３０分钟,持续剂量２ｍｌ／ｈ。术后分别记录２４小时用     

Spinal Analgesia with Glucose-Free Bupivacaine - Effects of Volume and Concentration

Spinal analgesia using 22.5 mg glucose-free bupivacaine, given either as 3.0 ml of 0.75% solution or 4.5 ml of 0.5% solution was studied in a double-blind fashion in 40 patients scheduled for transurethral surgery. No differences in onset, duration and regression of analgesia or motor blockade were noticed, indicating that dosage (in mg) is more important than either volume or concentration when glucose-free bupivacaine solutions are used for spinal analgesia. The cardiovascular effects were small and no side-effects attributable to the spinal anaesthetic were seen.