Optimum Interval Time of Programmed Intermittent Epidural Bolus of Ropivacaine 0.08% with Sufentanil 0.3 mg/mL for Labor Analgesia: A Biased-Coin Up-and-Down Sequential Allocation Trial
Epidural anesthesia is a highly effective method for alleviating labor pain. Over the years, advancements in epidural techniques have led to the development of epidural infusion pumps, including high-pressure pumps. Among these, the programmed intermittent epidural bolus (PIEB) technique has gained widespread use in obstetric analgesia due to its superior maternal satisfaction and lower incidence of adverse events compared to continuous epidural infusion (CEI). However, the optimal parameter settings for PIEB, particularly the interval duration between boluses, remain unclear. This study aimed to determine the optimal interval time for PIEB using a regimen of ropivacaine 0.08% and sufentanil 0.3 mg/mL, a combination commonly used in China for labor analgesia.
The study was conducted as a double-blind sequential allocation trial using a biased-coin up-and-down design. The primary objective was to identify the effective interval 90% (EI90%), defined as the interval duration that provides effective analgesia in 90% of women during the first stage of labor without breakthrough pain. The study enrolled nulliparous women at term, with cervical dilation between 2 and 5 cm, who requested epidural analgesia. The bolus volume was fixed at 10 mL of ropivacaine 0.08% with sufentanil 0.3 mg/mL. Participants were divided into four groups based on PIEB intervals: 60, 50, 40, and 30 minutes.
The study began with a loading dose of 10 mL of the anesthetic solution administered through the epidural catheter. After ensuring adequate analgesia (defined as a visual analog scale [VAS] score of less than 1), PIEB was initiated with the assigned interval. The study used a biased-coin design to determine the interval for each subsequent participant based on the response of the previous participant. The primary outcome was the effectiveness of the PIEB regimen, defined as the absence of breakthrough pain requiring additional measures such as patient-controlled epidural analgesia (PCEA) or manual bolus within the first 6 hours of labor. Secondary outcomes included the maximum sensory block level, degree of motor block, and incidence of adverse events such as hypotension.
A total of 44 women were included in the final analysis. The results showed that the estimated optimal interval for PIEB was 44.1 minutes (95% confidence interval [CI] 41.7–46.5 minutes) using the truncated Dixon and Mood method and 39.5 minutes (95% CI 32.5–50.0 minutes) using isotonic regression analysis. Based on these findings, the study concluded that the optimal PIEB interval for the given regimen is approximately 42 minutes. This interval provided effective analgesia in 90% of participants without significant adverse events.
The study also examined the sensory block levels and motor block degrees across the different interval groups. It was observed that shorter intervals (30 and 40 minutes) resulted in higher sensory block levels compared to longer intervals (50 and 60 minutes). Specifically, nearly 20% of participants in the 30-minute group had a sensory block level above T6, compared to 5.3%, 0%, and 0% in the 40, 50, and 60-minute groups, respectively. However, no cases of hypotension were reported, and only one participant in the 30-minute group experienced mild motor block.
The findings of this study highlight the safety and efficacy of ropivacaine 0.08% with sufentanil 0.3 mg/mL for labor analgesia when administered via PIEB. Ropivacaine, an amide-type local anesthetic, has pharmacological properties similar to bupivacaine but is associated with less motor blockade and cardiovascular and central nervous system toxicity. The study demonstrated that ropivacaine, at the specified concentration and interval, provides effective analgesia with minimal adverse effects.
The study also addressed the broader context of labor analgesia in China, where the rate of epidural analgesia remains low despite efforts to increase its adoption. The standardization of PIEB parameters, as investigated in this study, could contribute to improving the safety and efficacy of labor analgesia, thereby increasing its acceptance and utilization.
Several limitations of the study were noted. First, the study focused exclusively on nulliparous women during the first stage of labor with cervical dilation less than 5 cm. Therefore, the findings may not be applicable to multiparous women or later stages of labor. Second, the study used a specific combination of ropivacaine and sufentanil, and the results may not generalize to other anesthetic regimens. Future research is needed to explore the optimal PIEB settings for different stages of labor and for multiparous women.
In conclusion, this study provides valuable insights into the optimal interval time for PIEB using ropivacaine 0.08% with sufentanil 0.3 mg/mL for labor analgesia. The findings suggest that an interval of approximately 42 minutes is effective in providing analgesia for 90% of nulliparous women during the first stage of labor. This regimen is associated with minimal adverse effects and could serve as a standardized approach to improve the safety and efficacy of labor analgesia. Further studies are warranted to confirm these findings and to explore their applicability to other stages of labor and different patient populations.
doi.org/10.1097/CM9.0000000000000669
Was this helpful?
0 / 0