BACKGROUND: When compared to the standard epidural technique, the dural puncture epidural (DPE) technique is reported to provide quicker onset of labor analgesia and improved quality of analgesia. Recently, the DPE technique was found to lower the effective dose for 90% (ED90) of patients receiving bupivacaine for labor analgesia by 35%. However, key pharmacological differences between bupivacaine and ropivacaine and the effect of a DPE technique on ropivacaine doses have not been studied. Therefore, we aimed to determine the effective dose for 50% (ED50) and ED90 of ropivacaine for labor analgesia in parturients when initiated with the DPE and standard epidural techniques.
METHODS: Study participants were randomized to receive one of the five doses of ropivacaine (12, 15, 18, 21, and 24 mg) undergoing one of the two epidural techniques (either a DPE or standard epidural technique). A total volume of 20 mL of local anesthetic was administered epidurally. Effective analgesia was defined as the patient reporting an NRS pain score < 3 at 20 minutes following drug administration. The ED50 and ED90 values of epidural ropivacaine for labor analgesia were determined using probit analysis, and comparisons were made using the relative median potency ratio.
RESULTS: The ED50 of ropivacaine for initiating labor analgesia using the DPE vs standard epidural techniques was 18.6 mg (95% CI, 16.4 to 21.1 mg) vs 19.2 mg (95% CI, 17.0 to 21.8 mg), respectively. The ED90 values were 30.5 mg (95% CI, 26.6 to 38.3 mg) vs 31.1 mg (95% CI, 27.1 to 39.2 mg), respectively. The relative median potency ratio for ropivacaine with DPE vs standard epidural technique was -0.6 (95% CI, -4.0 to 2.6).
CONCLUSION: Our findings suggest that there is no dose-sparing effect of ropivacaine when using the DPE technique vs a standard epidural technique for labor analgesia.
