Original Article
The optimal concentration of bupivacaine and levobupivacaine for labor pain management using patient-controlled epidural analgesia: a double-blind, randomized controlled trial

https://doi.org/10.1016/j.ijoa.2018.05.002Get rights and content

Highlights

Abstract

Background

The study aim was to evaluate the efficacy and safety of different low concentrations of two local anesthetics for labor analgesia using patient-controlled epidural analgesia.

Methods

A double-blind, randomized controlled trial recruiting healthy nulliparous women was conducted from 2014 to 2017. Epidural analgesia was provided using local anesthetic and fentanyl. Patients were allocated to six groups, according to the concentration of bupivacaine or levobupivacaine (0.0625%, 0.1%, 0.125%). Analgesic efficacy, vital parameters, and side effects were evaluated at different time points. Satisfaction was evaluated using verbal and written scores. The primary outcome was the total dose of local anesthetic used.

Results

Two-hundred-and-thirty-seven cases were analyzed. The total dose of local anesthetic was significantly lower in the two lower concentration groups (P <0.0001). The rate of cesarean section was lower in 0.1% bupivacaine versus 0.1% levobupivacaine (P=0.005), 0.125% levobupivacaine (P=0.049) and 0.125% bupivacaine (P=0.002) groups. Pain breakthrough, patient-controlled and rescue boluses were significantly different between groups (P=0.03, P=0.003 and P <0.0001 respectively). The rate of motor block increased with higher concentrations (P=0.033), but the incidence of other maternal and fetal side effects was not significantly different. Satisfaction with labor analgesia did not differ across groups. Satisfaction score 72 hours after delivery was significantly lower than that two hours after delivery (P <0.0001).

Conclusions

Higher local anesthetic concentration resulted in higher total doses infused and greater motor block. Labor analgesia was less effective when the lowest concentrations were used, but patient satisfaction was unaffected.

Introduction

Patient-controlled epidural analgesia (PCEA), with or without background infusion, is commonly used to maintain labor analgesia.1 It results in greater maternal satisfaction when compared with a continuous infusion, presumably because women enjoy a certain level of control.2 Nevertheless, epidural analgesia has side effects and limiting the dose of local anesthetic (LA) may reduce some risks.3 Low concentrations of LA are now popular for epidural labor analgesia4, 5, 6 and optimize obstetric outcomes.3, 7 Patient-controlled epidural analgesia with dilute LA solutions and opioids is safe, provides less motor block, and increases patient satisfaction.5, 8 However, the efficacy of pain management decreases if very low concentrations of LA are used.

The aim of this study was to compare the efficacy and safety of bupivacaine and levobupivacaine at concentrations that are the standards for labor pain management with PCEA at our institution. To evaluate precisely the effect of LA concentration, the same concentration was used in all steps of analgesia (initial bolus, PCEA pump, rescue boluses), and the patient population was restricted to healthy nulliparous women with uncomplicated pregnancy and the spontaneous onset of labor. Our hypothesis was that the optimum choice for bupivacaine and levobupivacaine is the 0.1% concentration.

Section snippets

Methods

This single-center, double-blind, randomized controlled trial was carried out at a teaching hospital from the 18 September 2014 to 28 February 2017. Ethical approval was provided by the Kaunas Regional Ethics Committee of Biomedical Researches (number: BE-2-24). The trial was registered with the Australian and New Zealand Clinical Trials Registry (ANZCTR, trial ID: ACTRN12614001033639) and Universal Trial Number (UTN) – U1111-1160-0268. Written consent was obtained from all participants.

Results

During the study period, 246 patients were recruited and allocated into six groups. Nine patients were discontinued from the trial according to the protocol and data for 237 patients were analyzed. The CONSORT flow chart shows the number eligible, recruited, followed-up and the number in the final analysis (Fig. 1). All study groups were comparable with regard to the demographic characteristics and obstetric outcomes (Table 1).

The volume of the LA infused did not differ between groups (P=0.969)

Discussion

This prospective, randomized, double-blind trial compared three concentrations (0.0625%, 0.1%, and 0.125%, all with fentanyl) of two local anesthetics (bupivacaine and levobupivacaine) for labor epidural analgesia. Lower concentrations of local anesthetics reduced the dose used, caused less motor block and were associated with less effective analgesia, but that had no influence on patient satisfaction.

Most studies of low LA concentrations for labor epidural pain management have used higher

Acknowledgements

We would like to thank the medical staff from the Anesthesiology and Obstetric departments for their help.

Conflict of interest notification

The authors declare no conflict of interests.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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