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© 2001 International Anesthesia Research Society
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Abstract |
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The combination of opioids with local anesthetics is commonly used for epidural labor analgesia. We examined whether increasing sufentanil in doses of 5, 10, and 15 µg prolonged the duration of labor analgesia produced by ropivacaine. One hundred healthy parturients in the first stage of labor who requested epidural analgesia were enrolled. Parturients were randomized to receive 12 mL ropivacaine 0.2% alone or with sufentanil 5 µg, sufentanil 10 µg, or sufentanil 15 µ g. The duration of analgesia, pain score, degree of motor blockade (using a four-point Bromage scale), heart rate, blood pressure, respiratory rate, oxygen saturation, and incidence of nausea and pruritus were recorded. The mean duration of epidural analgesia was 96 ± 32 min for patients without sufentanil, 134 ± 27 min for Group 5 (p < 0.01 versus control), 135 ± 33 min for Group 10 (p < 0.01 versus control), 130 ± 33 min for Group 15 (p < 0.01 versus control) without differences among sufentanil groups. Between 30 and 90 min, the sufentanil groups (5 µg, 10 µg, and 15 µg) had lower pain scores than the control group (p < 0.01 versus control) but there were no differences among the sufentanil groups. No patient in any group had a Bromage score more than 1. No significant difference was found for opioid-related side effects. We conclude that 5–10 or 15 µg sufentanil induced a similar prolongation of analgesia when combined with ropivacaine 0.2% for initiation of labor analgesia.
Implications: We studied the effect of adding one of three possible sufentanil doses to epidural ropivacaine 0.2% for labor analgesia. Adding sufentanil increased the duration of analgesia but there was no advantage in adding more than 5 µg of sufentanil.
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Introduction |
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Administration of ropivacaine alone provides adequate analgesia during the first stage of labor (1). The minimal effective concentration of epidural ropivacaine without adjuvant is approximately 0.2% (1). Epidural local anesthetics are often combined with lipid-soluble opioids for labor analgesia (2,3) to decrease the concentration of local anesthetics required and to enhance duration of analgesia (4,5). The goal of such a combination is to obtain an adequate sensory block that is long-acting and has minimal side effects (6). Although the duration of action is of little concern when continuous infusions are used, it is a major factor when an intermittent bolus technique is chosen. No study has evaluated the use of epidural sufentanil with ropivacaine in a dose-dependent manner in laboring women. The aim of this prospective, randomized, double-blinded study was to evaluate the effect of adding one of three sufentanil doses (5, 10 or 15 µg) to ropivacaine 0.2% on prolonging the duration of labor epidural analgesia.
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Methods |
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The Hospital Ethics Committee approved the study. After obtaining written consent, we studied 100 ASA physical status I or II women, with a singleton vertex pregnancy of
36 wk gestation, who requested epidural analgesia during labor. Only patients with uncomplicated pregnancies, cervical dilation <5 cm and normal fetal heart rate tracings were enrolled. We excluded patients receiving antihypertensive drugs and patients who had already received opioid analgesia. Each parturient received an IV infusion of 500 mL of lactated Ringer’s solution over 10 min before induction of epidural anesthesia and was positioned in the sitting position. The epidural space was cannulated at L2-3 or L3-4 by using the loss-of-resistance-to-saline technique and 3 cm of catheter was left in the epidural space. The parturient was then repositioned to the supine position with left uterine displacement. A double-blinded randomized trial design was applied in which the parturients were allocated according to a list of random numbers (by using a random numbers table) into four groups (sealed opaque envelopes). All injectates were prepared by an anesthesiologist not involved in data collection. Each syringe of coded study solution was freshly prepared. Each parturient received a test dose of lidocaine 2%, 2 mL with 1/200,000 epinephrine. Five minutes after the test dose, each patient received 14 mL solution consisting of 12 mL ropivacaine 0.2% in which was added saline 0.9% (2 mL) with sufentanil 5, 10, or 15 µg. A control group received the same dose of ropivacaine, without sufentanil added. The mixture was injected over 1 min. Arterial blood pressure and heart rate were monitored with a noninvasive monitor at 5, 10, and 15 min and every 15 min until the patient requested additional epidural anesthetic injection. When additional analgesia was requested, the study protocol and data collection were terminated. Subsequent top-up doses were not standardized.
Motor block (modified Bromage score: 0 = ability to move hips, ankles, and knees; 1 = inability to raise extended leg; 2 = inability to flex knee; and 3 = inability to flex ankle, foot or knee), respiratory rate, and oxygen saturation (pulse oximeter, Cardiocap II; Datex, Helsinki) were recorded at the same intervals. Basal values were those obtained immediately before epidural injection.
Assessment of pain was made on a visual linear analog scale (VAS) of pain intensity at the same time intervals. Each patient was presented with a line 100 mm long and was told that the left end represented no pain and the right end the worst pain imaginable. They were then asked to make a mark on the line to indicate the intensity of their pain at the peak of a contraction. Patients could request additional analgesia (10 mL ropivacaine 0.2% via the epidural catheter) if pain relief was unsatisfactory 15 min after injection of the study drug. When additional local anesthetic was needed, the patient was excluded from data collection.
The time from study drug administration until a request for additional analgesia was noted (duration of analgesia). Patients who delivered <60 min after initiation of the epidural were excluded from data analysis. Side effects such as pruritus, nausea, and vomiting were recorded at the completion of the study. Hypotension, defined as a decrease in systolic arterial pressure of at least 20%, or a systolic blood pressure <100 mm Hg, was treated with IV ephedrine (6 mg every 5 min until systolic arterial pressure reached 100 mm Hg).
For all calculations, the INSTAT computer software package (GraphPad Instat, San Diego, CA) and the SOLO statistical software (BMDP, Los Angeles, CA) were used. A sample size calculation using the INSTAT computer software indicated that a sample size of 17 patients per treatment group should provide 90% power (assuming 
= 0.05) to detect a 30-min difference (SD) in analgesia duration.
Intragroup comparisons for continuous variables and VAS scores were performed by analysis of variance, followed by post hoc tests for comparisons with baseline (Bonferroni adjusted comparisons) to assess significant differences among groups. 
2 tests were performed for nominal variables. Results are expressed as mean ± SD. A P value of <0.05 was considered to be significant.
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Results |
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One hundred women agreed to participate in this study. Eighteen patients enrolled in the study were excluded from data analysis because delivery occurred <60 min after the initial injection (4 nulliparous and 5 multiparous) or because cesarean delivery was performed before she requested additional epidural analgesia (5 nulliparous and 4 multiparous). The data from the remaining 82 women were analyzed. None of these parturients had technical problems with the epidural catheter and none requested additional analgesia.
The groups were comparable with regard to age, weight at term, weeks of pregnancy, parity, VAS pain scores, and stage of cervical dilation at the time of entry into the study (Table 1). The mean duration of anesthesia was 96 ± 32 min (range 60–150) for patients without sufentanil, those receiving 5 µg had analgesia for 134 ± 27 min (range 75–180 min) (p < 0.01 versus control), the group receiving sufentanil 10 µg had analgesia for 135 ± 33 min (range 75–195 min; p < 0.01 versus control) and those receiving 15 µg had analgesia for 130 ± 33 min (range 75–195 min; p < 0.01 versus control) (Fig. 1). The mean VAS scores were comparable in the four groups at the beginning of the study (Table 1) and were significantly decreased within 5 min after drug injection (Fig. 2). Between 30 to 90 min, the sufentanil groups had lower pain scores than the control group (p < 0.01 versus control) but there were no differences among the sufentanil groups.
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Maternal heart rates were comparable in all groups before administration of the study drug: 83 ± 20 beats · min-1 for control, 84 ± 14 beats · min-1 for Group 5, 80 ± 8 beats · min-1 for Group 10, and 80 ± 13 beats · min-1 for Group 15. Heart rates did not differ among the groups throughout the study period. Mean arterial pressure was comparable among the groups at baseline: 91 ± 6, 85 ± 7, 90 ± 12, and 92 ± 7 mm Hg, respectively. Two patients in the control group, one patient in Group 5 µg, three in Group 10 µg, and two in Group 15 µg needed IV ephedrine 6 mg for transient hypotension followed by rapid return of systolic arterial pressure more than 100 mm Hg (P = NS) (Table 2). No alterations of SpO2 were observed at any time. Basal respiratory rates were comparable among the groups and no significant change in respiratory rates was noted throughout the study. No patient in any group had a Bromage score more than 1, and the number of patients exhibiting motor blockade was respectively: 3 in control group, 6 in Group 5, 5 in Group 10 and 3 in Group 15 (P = NS). The incidence of side effects was small, as depicted in Table 2. No difference was found among the groups in regard to nausea and the incidence of pruritus was more in Group 15 µg (29%); however, the difference did not reach statistical significance (P = 0.51).
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Discussion |
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Ropivacaine is widely used for labor epidural analgesia (1,3,7) and has been evaluated as a sole anesthetic as well as in combination with opioids (1,2,6). No previous study has compared the consequences on analgesia duration in labor if combined with different sufentanil doses. The results of the present study demonstrate that the addition of sufentanil 5, 10, or 15 µg significantly prolonged the epidural analgesia produced by ropivacaine in laboring women.
Intermittent injections are one of several ways to initiate and maintain epidural analgesia in laboring patients (1,8). If this technique is chosen, the duration of analgesia produce by various ropivacaine-sufentanil mixtures would be clinically valuable information.
When combined with sufentanil 5, 10 or 15 µg, we found that the duration of analgesia produced by ropivacaine 0.20% increased by approximately 40 minutes (50%) compared to ropivacaine 0.20% alone. Vertommen et al. (9) found that 10 µg of sufentanil added to bupivacaine 0.125% increased analgesia duration by 50% during the first stage of labor. A 40% prolongation of analgesia was also achieved by the combination of either 7.5 or 15 µg of sufentanil with bupivacaine 0.125% (10). Thus, our results are consistent with previous studies in laboring patients showing that opioids increase the duration of epidurally injected local anesthetics (6,9,10). Sufentanil as an epidural bolus injection in a dose-response fashion has only been tested with bupivacaine (9,11). In our study, the increase in mean analgesia duration between sufentanil 5, 10, or 15 µg groups did not reach statistical significance. Thus, it appears that epidural sufentanil bolus <10 µg are the optimal dose for pain relief in labor.
The control solution prepared in our work consisted in 12 mL of ropivacaine 0.20% added to saline 2 mL thus making a final concentration of 0.17% ropivacaine. Although this is slightly <0.2%, the difference should be clinically inconsequential. Beilin et al. (1) found that ropivacaine 0.20% is the smallest efficient concentration to reach adequate analgesia when local anesthetic is used alone. In this study, these authors used a verbal pain score, whereas a VAS was used in the present study (1). VAS scores <20 to 30/100 are usually considered successful for an analgesic technique (6,12–14). VAS scores <20/100 were obtained in all patients in our work.
Beilin et al. (1) also reported that using ropivacaine 0.20% resulted in minimal hemodynamic changes and motor blockade. Our results support their findings, in that the hemodynamic consequences of small-dose sufentanil added to ropivacaine were modest. There was no difference in ephedrine requirements between control and sufentanil groups. Heart rate was also comparable in all groups throughout the study.
None of the parturients had a Bromage score more than 1. Only 17 patients among 82 experienced a slight motor blockade (Bromage score = 1). Severe motor block was not expected because of the relatively small ropivacaine concentration used.
A potential side effect of sufentanil, like other neuraxial opioids, is pruritus. Some authors (15,16) have reported a dose-response relationship between lipid-soluble opioids and pruritus when opioids are given intrathecally. In our study, the incidence of pruritus was more frequent in the 15 µg group. This result, however, is difficult to analyze because the sample size determination was made for analgesia duration and not for side effects. Also, because sufentanil doses higher than 15 µg were not evaluated, we cannot comment on dose-dependent pruritus (15,16).
In conclusion, our results demonstrate a benefit in adding sufentanil to epidural ropivacaine for analgesia during the first stage of labor. As there were no differences in the efficacy of the 5, 10 and 15 µg sufentanil groups, the combination of sufentanil 5 µg with ropivacaine 0.20% is recommended.
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Acknowledgments |
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Supported, in part, by a grant from the Hospices Civils de Lyon, France.
Special thanks to Dr. Boris Bryssine, Dr. Christine Raupp, Dr. Pacôme, Dr. Balay, nurses staff and medicals staffs of Croix-rousse Hospital, Edouard Herriot Hospital, and Lyon-Sud Hospital who participated to this study.
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References |
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Beilin Y, Galea M, Zahn J, Bodian CA. Epidural ropivacaine for the initiation of labor epidural analgesia: a dose finding study. Anesth Analg 1999; 88: 1340–5.
[Abstract/Free Full Text] - Meister G, Owen M, D’Angelo R, Gaver R. Comparison of 0.125% ropivacaine + fentanyl 2 µg/ml and 0.125% bupivacaine + sufentanil 2µg/ml in laboring patients [abstract]. Anesthesiology 1998; 89: A1023.
- Palmer CM, Van Maren G, Nogami W, Alves D. Low-dose ropivacaine for initiation of epidural labor analgesia [abstract]. Anesthesiology 1998; supplement, A29.
- Cousins MJ, Mather LE. Intrathecal and epidural administration of opioids. Anesthesiology 1984; 61: 276–310.[Web of Science][Medline]
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Birnbach DJ. Analgesia for labor. N Engl J Med 1997; 337: 1764–6.
[Free Full Text] - Gautier P, De Kock M, Van Steenberge A, et al. A double-blind comparison of 0.125% ropivacaine with sufentanil and 0.125% bupivacaine with sufentanil for epidural labor analgesia. Anesthesiology 1999; 90: 772–8.[Web of Science][Medline]
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[Abstract/Free Full Text] - Dounas M, O’Kelly BO, Jamali S, et al. Maternal and fetal effects of adrenaline with bupivacaine (0.25%) for epidural analgesia during labour. Eur J Anaesthesiol 1996; 13: 594–8.[Web of Science][Medline]
- Vertommen JD, Lemmens E, Van Aken H. Comparison of the addition of three different doses of sufentanil to 0.125% bupivacaine given epidurally during labour. Anaesthesia 1994; 49: 678–81.[Web of Science][Medline]
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Van Steenberge A, Debroux HC, Noorduin H. Extradural bupivacaine with sufentanil for vaginal delivery: a double-blind trial. Br J Anaesth 1987; 59: 1518–22.
[Abstract/Free Full Text] - Phillips GH. Epidural sufentanil/bupivacaine combinations for analgesia during labor: effect of varying sufentanil doses. Anesthesiology 1987; 67: 835–8.[Web of Science][Medline]
- Jorrot JC, Lirzin JD, Dailland P, et al. Association sufentanil-bupivacaine 0. 125% par voie péridurale pour l’analgésie obstétricale: comparaison avec le fentanyl et un placebo. Ann Fr Anesth Réanim 1989;8:321–5.
- Herman NL, Calicott R, Van Decar TK, et al. Determination of the dose-response relationship for intrathecal sufentanil in laboring patients. Anesth Analg 1997; 84: 1256–61.[Abstract]
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Mantha S, Thisted R, Foss J, et al. A proposal to use confidence intervals for visual analogic scale data for pain measurement to determine clinical significance. Anesth Analg 1993; 77: 1041–7.
[Abstract/Free Full Text] - Chaney MA. Side effects of intrathecal and epidural opioids. Can J Anaesth 1995; 42: 891–903.[Web of Science][Medline]
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Herman NL, Choi KC, Affleck PJ, et al. Analgesia, pruritus, and ventilation exhibit a dose-response relationship in parturients receiving intrathecal fentanyl during labor. Anesth Analg 1999; 89: 378–83.
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