Intrathecal Clonidine Combined with Sufentanil for Labor Analgesia

Background: Intrathecal sufentanil provides rapid-onset and complete analgesia for the first stage of labor. The dose required to produce this effect can be associated with maternal respiratory depression, hypotension, nausea, or pruritus. Because clonidine potentiates the analgesic effects of opioids without increasing their side effects, the authors wanted to determine the efficacy of low doses of intrathecal clonidine (15 and 30 micro gram) combined with sufentanil.

Methods: Ninety-eight parturient requesting labor analgesia were studied. In a combined spinal-epidural technique, patients were randomly assigned to receive one of the following intrathecal solutions: either 15 micro gram clonidine (n = 10); 30 micro gram clonidine (n = 10); 2.5 micro gram sufentanil (n = 13); 5 micro gram sufentanil (n = 13); 2.5 micro gram sufentanil and 15 micro gram clonidine (n = 13); 2.5 micro gram sufentanil and 30 micro gram clonidine (n = 13); 5 micro gram sufentanil and 15 micro gram clonidine (n = 13); or 5 micro gram sufentanil and 30 micro gram clonidine (n = 13). Visual analog scores for pain, blood pressure, heart rate, sensory levels, incidence of nausea and pruritus, and motor blockade, and maternal and cord blood concentrations of clonidine were recorded.

Results: Patients receiving 30 micro gram intrathecal clonidine with 2.5 or 5 micro gram intrathecal sufentanil had significantly longer-lasting analgesia (145 +/- 36 and 145 +/- 43 min vs. 104 +/- 35 for those receiving 5 micro gram intrathecal sufentanil alone). Clonidine levels were undetectable in maternal serum.     

The Dose-Response of Intrathecal Sufentanil Added to Bupivacaine for Labor Analgesia

Background: Regional analgesia for labor often is initiated with an intrathecal injection of a local anesthetic and opioid. The purpose of this prospective, randomized, blinded study was to determine the optimal dose of intrathecal sufentanil when combined with 2.5 mg bupivacaine for labor analgesia.

Methods: One hundred seventy parous parturients with cervical dilation between 3-5 cm were randomized to receive intrathecal 0 (control), 2.5, 5.0, 7.5, or 10.0 [mu]g sufentanil combined with 2.5 mg bupivacaine, followed by a lidocaine epidural test dose, for initiation of analgesia (34 patients in each group). Visual analog scores and the presence of nausea, vomiting, and pruritus were determined every 15 min until the patient requested additional analgesia. Fetal heart rate tracings were compared between groups.

Results: Groups were similar for age, height, weight, oxytocin dose, duration of labor, and baseline visual analog scores. Duration of action was significantly shorter for control patients (39 +/- 25 min [mean +/- SD]) compared with those administered sufentanil, all doses (93 +/- 32, 93 +/- 47, 94 +/- 33, 97 +/- 39 min), but was not different among groups administered 2.5, 5.0, 7.5, or 10.0 [mu]g sufentanil. More patients who received 10 [mu]g sufentanil reported nausea and vomiting than did control patients. The severity of pruritus increased with administration of 7.5 and 10.0 [mu]g sufentanil. There was no difference in fetal heart rate changes among groups.     

Intrathecal Neostigmine and Sufentanil for Early Labor Analgesia

Background: Recent efforts to improve the combined spinal epidural (CSE) technique have focused on adding opioids to other classes of analgesics. In this study, the authors used intrathecal neostigmine in combination with intrathecal sufentanil to investigate the usefulness of neostigmine for reducing side effects and prolonging the duration of sufentanil.

Methods: One hundred six healthy pregnant women in labor were enrolled in this study, which was divided into four phases. In all phases, patients received a CSE anesthetic while in the lateral position. In phase I, three groups of six women each received intrathecal neostigmine, 5, 10, or 20 [mu]g, in an open-label, dose-escalating safety assessment. In phase II, 24 women received intrathecal sufentanil alone to establish an ED50 (dose that produces > 60 min of labor analgesia in 50% of patients). In phase III, an ED50 was established for sufentanil combined with a fixed dose of neostigmine (10 [mu]g). In phase IV, 40 women received either twice the ED50 of sufentanil alone or twice the ED50 of sufentanil plus neostigmine, 10 [mu]g.

Results: Neostigmine alone had no adverse effects on maternal vital signs, fetal heart rate, or Apgar scores. Neostigmine, 20 [mu]g, produced analgesia in one patient and severe nausea and vomiting in another. The ED50 for intrathecal sufentanil alone was 4.1 +/- 0.31 [mu]g, and the ED50 for intrathecal sufentanil combined with neostigmine, 10 [mu]g, was 3.0 +/- 0.28 [mu]g. The duration of analgesia and side effects from double these ED50s (sufentanil, 9 [mu]g, or sufentanil, 6 [mu]g, plus neostigmine, 10 [mu]g) were similar between groups.     

Intrathecal Sufentanil for Labor Analgesia Does Not Cause a Sympathectomy

Background: Intrathecal sufentanil (ITS) is frequently used to provide analgesia during labor. Decreases in blood pressure and sensory changes in this circumstance suggest that ITS may have a local anesthetic effect and thus cause a sympathectomy. To determine whether ITS given to laboring women causes a sympathectomy, the authors evaluated central and lower extremity temperature changes after ITS administration. These findings were compared with those in a control group of women having spinal anesthesia with bupivacaine for elective cesarean section in whom an extensive sympathectomy was expected.

Methods: Twenty parturients classified as American Society of Anesthesiologists' physical status 1 or 2 had temperatures measured centrally, at the calf, and at the great toe at frequent intervals after receiving 10 micro gram ITS for labor analgesia (sufentanil group, n = 10), or hyperbaric bupivacaine 12 mg in their spinal anesthetic for cesarean section (bupivacaine group, n = 10). Calf-to-toe temperature indices (C-T) were calculated by subtracting toe temperature from calf temperature. A decrease in this index means that the toe had warmed compared with the calf and is an indication of vasodilation and a sympathectomy.

Results: There was no significant change in the C-T indices or central temperature in the sufentanil group, but the C-T indices and central temperature decreased significantly in the bupivacaine group.     

Addition of Epinephrine to Intrathecal Bupivacaine and Sufentanil for Ambulatory Labor Analgesia

Background: The intrathecal combination of sufentanil and bupivacaine provides rapid, effective analgesia for labor with a limited duration. Many anesthesiologists have concerns that the use of intrathecal local anesthetics precludes maternal ambulation. This prospective, randomized, double-blind study was designed to determine whether the addition of epinephrine to the combination of sufentanil and bupivacaine would prolong intrathecal analgesia for labor. Patients' ability to ambulate was also assessed.

Methods: Thirty-nine patients received either an intrathecal control dose of 10 micro gram sufentanil plus 2.5 mg bupivacaine plus 0.2 ml normal saline (control group); or 10 micro gram sufentanil plus 2.5 mg bupivacaine plus 0.2 ml (0.2 mg) of epinephrine (EPI group).

Results: Seven patients (3 control, 4 EPI) delivered vaginally and two (1 control, 1 EPI) required cesarean delivery before requesting epidural analgesia. The duration (mean +/- SD) of intrathecal labor analgesia was prolonged significantly by the addition of epinephrine: control (n = 15): 145 +/- 23 min; EPI (n = 15): 188 +/- 25 min (P <0.0001). Maternal ambulation was demonstrated in 100% (19 of 19) of the control group and in 80% (16 of 20) of the EPI group (P = NS).     

A Comparison of Intrathecal Fentanyl and Sufentanil for Labor Analgesia

Background: The use of intrathecal opioids for labor analgesia continues to gain popularity, but there are limited data to guide this use. Previously, the authors established the ED50 for 60 min of labor analgesia from intrathecal sufentanil using an up-down sequential allocation study design. The current study first establishes an ED50 for intrathecal fentanyl using this same study design to establish an intrathecal potency ratio for fentanyl and sufentanil and then uses this ratio to compare the efficacy, duration of analgesia, and side effects from comparable doses of intrathecal fentanyl and sufentanil.

Methods: Seventy-five healthy nulliparous women requesting labor analgesia were enrolled in this two-part study. In phase I, 20 women received varying doses of fentanyl to establish an ED50 for 60 min of labor analgesia. In phase II, 55 women were randomized to receive either 36 [mu]g intrathecal fentanyl or 8 [mu]g sufentanil (2 times the ED50s) via a combined spinal-epidural technique and by double-blinded design. Pain relief, side effects, block height, maternal hemodynamics, and fetal heart rate were assessed throughout the study. The duration of spinal analgesia was considered to be the time from injection of study drug to the time of the patient's first request for additional analgesia.

Results: The ED50 of intrathecal fentanyl for 60 min of labor analgesia was found to be 18.2 [mu]g, and therefore, the potency ratio of intrathecal sufentanil to intrathecal fentanyl at the ED50 level is 4.4:1. The duration of spinal analgesia was significantly longer from 8 [mu]g intrathecal sufentanil than from 36 [mu]g intrathecal fentanyl (104 +/- 34 vs. 79 +/- 34 min, P = 0.009). Otherwise, patient demographics, maternal hemodynamics, duration of labor, mode of delivery, motor block, subjective leg weakness, pruritus, nausea, pinprick sensory levels, visual analog scale pain scores, fetal bradycardia, and Apgar scores were similar between groups.     

Baricity, Needle Direction, and Intrathecal Sufentanil Labor Analgesia

Background: Intrathecal sufentanil relieves labor pain but centrally mediated side effects are common. Preventing rostral spread of intrathecal sufentanil should limit these side effects. Both direction of the lateral opening of a pencil-point needle and drug baricity modify the spread of intrathecal local anesthetics. This randomized, prospective, double-blind study examines the effects of these variables on intrathecal sufentanil labor analgesia.

Methods: Forty laboring, full-term parturients, whose cervixes were dilated less than 5 cm and who requested analgesia for labor were enrolled. Combined spinal epidural analgesia was induced in patients in the sitting position. They were allocated to receive 10 micro gram intrathecal sufentanil diluted with either normal saline or dextrose with the aperture of the pencil-point needle directed cephalad or caudad during drug injection. Thus there were four groups of ten patients: dextrose up, dextrose down, saline up, and saline down. Sufentanil was diluted with normal saline to a concentration of 10 micro gram/ml. The study drug was made by mixing 1 ml sufentanil solution with either 1 ml 10% dextrose or 1 ml normal saline. Visual analog scores for pain, pruritus, nausea, and pain relief were recorded before and 5, 10, 15, and 30 min after drug injection.

Results: Baricity, but not needle orientation, influenced pain relief and pruritus. Sufentanil in dextrose produced less itching but also less analgesia. Nine of 20 women in the dextrose groups compared with 1 of 20 in the saline groups requested additional analgesia by 30 min.     

Low-dose Clonidine and Neostigmine Prolong the Duration of Intrathecal Bupivacaine-Fentanyl for Labor Analgesia

Background: Intrathecal (IT) opioid and local anesthetic combinations are popular for labor analgesia because of rapid, effective pain relief, but the duration of analgesia is limited. This study was undertaken to determine whether the addition of clonidine and neostigmine to IT bupivacaine-fentanyl would increase the duration of analgesia without increasing side effects for patients in labor.

Methods: Forty-five healthy parturients in active labor were randomized to receive a 2-ml IT dose of one of the following dextrose-containing solutions using the combined spinal-epidural technique: (1) bupivacaine 2.5 mg and fentanyl 25 [mu]g (BF); (2) BF plus clonidine 30 [mu]g (BFC); or (3) BFC plus neostigmine 10 [mu]g (BFCN). Pain, sensory levels, motor block, side effects, maternal vital signs, and fetal heart rate were systematically assessed.

Results: Patients administered BFCN had significantly longer analgesia (165 +/- 32 min) than those who received BF (90 +/- 21 min;P < 0.001) or BFC (123 +/- 21 min;P < 0.001). Pain scores, block characteristics, maternal vital signs, Apgar scores, maternal satisfaction, and side effects were similar among groups except for nausea, which was significantly greater in the BFCN group (P < 0.05 as compared with BFC).     

Chronopharmacology of Intrathecal Sufentanil for Labor Analgesia: Daily Variations in Duration of Action

Background: The pharmacokinetic and pharmacodynamic characteristics of opioids vary throughout the day, as demonstrated for oral morphine in chronic pain. However, little is known about the chronobiology of intrathecal lipid soluble opioids used for labor analgesia. The aim of this prospective study was to determine whether the duration of action of intrathecally administered sufentanil is influenced by the time of administration.

Methods: Ninety-one women in the first stage of labor were enrolled. Labor analgesia was first provided by 10 [mu]g intrathecal sufentanil. The duration of action of intrathecal sufentanil was measured and analyzed by the cosinor method to determine periodic intraday variation.

Results: Pain assessed by a visual analog score was not different among patients (70 +/- 17 mm) before the injection of intrathecal sufentanil. Rhythm analysis revealed a mean (+/- SD) duration of analgesia (mesor) of 93.0 +/- 3.8 min. A highly significant 12-h rhythm was found, with two peaks: One was near midnight (0.78 +/- 0.6 h), and the other was near noon (12.78 +/- 0.6 min) (P < 0.01). The amplitude of this 12-h component was 16.1 +/- 5.5 min.     

The Dose-Response Relation of Intrathecal Fentanyl for Labor Analgesia

Background: This study determined the dose-response relation of intrathecal fentanyl for labor analgesia and described the onset, duration, and quality of analgesia when used as the sole analgesic.

Methods: Eighty-four parturients in active labor who requested analgesia were randomized to one of seven treatment groups. They received 5-45 micro gram intrathecal fentanyl as part of a combined spinal-epidural technique. Visual analog pain scores were recorded before and at intervals after injection patients requested additional analgesia. The occurrence and severity of pruritus, nausea, and vomiting were also recorded. Maternal blood pressure was recorded before injection and at intervals after injection. Fetal heart rate was recorded before and 30 min after injection.

Results: By 5 min after injection, pain scores were significantly different among groups (P < 0.001). Mean duration of analgesia increased to 89 min as the dose increased to 25 micro gram. Maternal diastolic blood pressure was significantly lower 10 and 30 min after injection. There was no difference among groups in the incidence of pruritus; nausea and vomiting were uncommon. Fetal heart rates did not change after injection. A dose-response curve indicates that the median effective dose of intrathecal fentanyl for labor analgesia is 14 micro gram (95% confidence interval, 13-15 micro gram).     

Bupivacaine Augments Intrathecal Fentanyl for Labor Analgesia

Background: Intrathecal fentanyl has been shown to be an effective analgesic for labor; this study investigated the analgesic effect of low-dose bupivacaine added to intrathecal fentanyl for labor analgesia.

Methods: Ninety parturients in active labor who requested regional analgesia were randomized to receive an intrathecal injection of either fentanyl, 25 [micro sign]g; bupivacaine, 1.25 mg, with fentanyl, 25 [micro sign]g; or bupivacaine, 2.5 mg, with fentanyl, 25 [micro sign]g, as part of a combined spinal-epidural technique. Visual analog pain scores were recorded before and at intervals after injection until the patient requested further analgesia. Maternal blood pressure and fetal heart rate were recorded before and at intervals after injection. Lower-extremity muscle strength was tested before and 30 min after injection; anesthetic level to cold sensation and the presence and severity of pruritus were recorded.

Results: Duration of analgesia was longer in the group receiving bupivacaine, 2.5 mg, and fentanyl, 25 [micro sign]g, than the group receiving plain fentanyl (108 vs. 92 min; P < 0.05). Onset of analgesia was faster in both groups receiving bupivacaine compared with plain fentanyl (P < 0.05). No differences in muscle strength after injection were found in any group, although anesthetic levels to cold were documented in all patients in the bupivacaine groups, and 21 of 30 in the plain fentanyl group. Baseline fetal heart rates did not change after injection in any group, and maternal blood pressure was unchanged.     

Determination of the Full Dose-Response Relation of Intrathecal Bupivacaine, Levobupivacaine, and Ropivacaine, Combined with Sufentanil, for Labor Analgesia

Background: Ropivacaine and levobupivacaine are local anesthetics that produce less motor block and greater sensory-motor separation when compared with equal milligram doses of bupivacaine. Although minimum local analgesic concentration studies suggested that they are less potent than bupivacaine, full dose-response studies have not been performed. The current trial describes the dose-response relation of levobupivacaine, ropivacaine, and bupivacaine, combined with sufentanil, when used for intrathecal labor analgesia.

Methods: Four hundred fifty term parturients in active labor were included in this double-blind, randomized trial. Combined spinal-epidural anesthesia was performed, and ropivacaine, levobupivacaine, or bupivacaine was intrathecally administered in a dose of 1.0, 1.5, 2.0, 2.5, 3.0, or 3.5 mg, always combined with 1.5 [mu]g sufentanil. Patients were considered responders to spinal analgesia if the visual analog scale score for pain was less than 25 mm within 15 min and the visual analog scale score remained less than 25 mm for 45 min. Patient demographics, obstetric data, maternal side effects, and fetal and neonatal well-being were noted. Group-specific dose-response curves were constructed using a probit regression model.

Results: The ED95 of bupivacaine was 3.3 mg (95% confidence interval, 2.9-4.1). The ED95s of ropivacaine and levobupivacaine were 4.8 mg (95% confidence interval, 4.0-6.7) and 5.0 mg (95% confidence interval, 4.1-7.0), respectively. Racemic bupivacaine was significantly more potent than ropivacaine (P = 0.0027) and levobupivacaine (P = 0.0006). Ropivacaine and levobupivacaine were of similar potency (P = 0.91).     

Epidural Administration of Neostigmine and Clonidine to Induce Labor Analgesia: Evaluation of Efficacy and Local Anesthetic-sparing Effect

Background: Epidural clonidine produces analgesia without motor impairment, and is associated with a local anesthetic-sparing effect during labor. The authors have recently demonstrated that epidural neostigmine initiates selective labor analgesia devoid of adverse effects. Both drugs possess common analgesic mechanisms mediated through spinal acetylcholine release. This study evaluates their epidural combination in parturients.

Methods: At the beginning of labor, parturients were randomly allocated to one of five groups to receive one of the following after a test dose: 150 [mu]g epidural clonidine, 750 [mu]g neostigmine, or 75 [mu]g clonidine combined with 250, 500, or 750 [mu]g neostigmine. A pain score (visual analog scale, 0-100) was recorded before administration and at regular intervals until request for a supplemental injection. Subsequent analgesia was provided by continuous epidural infusion of ropivacaine.

Results: Parturients did not differ regarding demographic data and initial pain score. Clonidine 150 [mu]g, neostigmine 750 [mu]g, and 75 [mu]g clonidine plus 250 [mu]g neostigmine produced ineffective and short-lasting effects. Clonidine 75 [mu]g plus 500 [mu]g neostigmine and 75 [mu]g clonidine plus 750 [mu]g neostigmine presented comparable durations of 90 +/- 32 and 108 +/- 38 min (mean +/- SD), respectively, and final analgesic efficacies, with 72.2% and 84%, respectively, of the parturients reporting a visual analog scale score of less than 30 out of 100 after 30 min. Ropivacaine use was significantly reduced in all clonidine groups (average, 9.5 mg/h) in comparison with neostigmine alone (17 +/- 3 mg/h). No adverse effects were observed for 75 [mu]g clonidine combined with any dose of neostigmine while maternal sedation (20%) and hypotension (33%) occurred with 150 [mu]g clonidine alone.     

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.     

A Comparison of Median Effective Doses of Intrathecal Levobupivacaine and Ropivacaine for Labor Analgesia

Background: The study was designed to determine and compare the median effective doses (MEDs) of intrathecal ropivacaine with levobupivacaine for labor analgesia.

Methods: In this double-blind study, 100 parturients in early labor were randomized to receive either intrathecal ropivacaine or levobupivacaine. For each drug, the patients were assigned to receive one of the five doses studied, namely 1, 1.5, 2, 2.5, or 3 mg. Effective analgesia was defined as a pain score (0-100 visual analog scale) of less than 10 within 15 min of injection, lasting for 45 min or more after the induction of analgesia. MEDs were derived from probit analysis. The duration of analgesia rendered by the two drugs at 2.5 and 3 mg was also compared.

Results: The MED for levobupivacaine was 1.07 mg (95% confidence interval, 0.88-1.25 mg), and the MED for ropivacaine was 1.40 mg (95% confidence interval, 1.20-1.61 mg). Levobupivacaine was found to be 1.31 (95% confidence interval, 1.04-2.01) times more potent than ropivacaine. At doses of 2.5 mg or greater, there was no significant difference in duration of analgesia between levobupivacaine (median, 63.5 min; range, 46-123 min) and ropivacaine (median, 59.0 min; range, 47-93 min; P = 0.18). We detected no difference in the incidence of hypotension, nausea and vomiting, motor block, or abnormal fetal heart tracing between the two drugs.     

Minimum Local Analgesic Doses of Ropivacaine, Levobupivacaine, and Bupivacaine for Intrathecal Labor Analgesia

Background: Doses for intrathecal opioid-local anesthetic mixtures have been arbitrarily chosen. The aim of this study was to compare the analgesic efficacies of intrathecal ropivacaine, levobupivacaine, and bupivacaine for labor analgesia and to determine the analgesic potency ratios for these three drugs. For this purpose, the authors used the up-down sequential allocation model, which estimates the minimum local analgesic dose for intrathecal local anesthetic.

Methods: Ninety-seven nulliparous term parturients in spontaneous labor, requesting combined spinal-epidural analgesia, were randomly allocated to one of three groups to receive 0.25% spinal ropivacaine, levobupivacaine, or bupivacaine. The initial dose of the local anesthetic drug was chosen to be 2.5 mg, and the testing interval was set at 0.25 mg. The subsequent doses were determined by the response of the previous parturient. Efficacy was accepted if the visual analog pain score decreased to 10 mm or less on a 100-mm scale within 30 min. The minimum local analgesic dose was calculated using the method of Dixon and Massey.

Results: The intrathecal minimum local analgesic dose was 3.64 mg (95% confidence interval, 3.33-3.96 mg) for ropivacaine, 2.94 (2.73-3.16) mg for levobupivacaine, and 2.37 (2.17-2.58) mg for bupivacaine. The relative analgesic potency ratios were 0.65 (0.56-0.76) for ropivacaine:bupivacaine, 0.80 (0.70-0.92) for ropivacaine:levobupivacaine, and 0.81 (0.69-0.94) for levobupivacaine:bupivacaine. There were significant trends (P <= 0.021) for greater motor block with bupivacaine and levobupivacaine.     

Epidural Neostigmine Combined with Sufentanil Provides Balanced and Selective Analgesia in Early Labor

Background: This study evaluated the efficacy of an epidural single dose of neostigmine combined with sufentanil to provide selective and balanced analgesia at the beginning of labor.

Methods: After informed consent, 125 healthy parturients were randomly allocated to receive, after a test dose, a single injection of either epidural sufentanil 20 [mu]g (minimal analgesic dose) or 10 [mu]g or a combination of sufentanil 10 [mu]g with neostigmine 250, 500, or 750 [mu]g in a total volume of 12 ml. Pain scores were recorded at regular intervals to determine onset and duration of analgesia. Maternal and fetal vital parameters as well as side effects were closely monitored.

Results: Parturients did not differ concerning demographic data. Epidural neostigmine 500 [mu]g with sufentanil 10 [mu]g produced effective analgesia (visual analog scale <30 mm within 10 min in 72% parturients and within 15 min in 85% parturients; average duration of 119 min, confidence interval 96-142 min) that was as effective as epidural sufentanil 20 [mu]g. Epidural combination with neostigmine 250 [mu]g was ineffective, whereas 750 [mu]g did not produce higher effect than 500 [mu]g. No motor block was recorded. Maternal and fetal vital parameters remained stable during labor.     

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.