Effects of Ropivacaine Concentrations on Prolonged Labor Analgesia

Background:

With changes in medical models and improvements in quality of life, parturients have higher expectations for childbirth, making the alleviation and elimination of labor pain an important aspect of modern obstetrics. Intrathecal labor analgesia is widely used in clinical practice to relieve labor pain. However, studies on prolonged labor analgesia, especially following the replacement of the first analgesic pump, are scarce. Medical institutions often continue to use traditional analgesic formulations without relevant guidelines or expert consensus. Prolonged analgesia may reduce pain tolerance in parturients, possibly necessitating adjustments in local anesthetic concentration to improve analgesic effectiveness. Given the clinical research gap, this study aims to explore the effects of different concentrations of ropivacaine on prolonged labor analgesia and its impact on maternal and neonatal safety.

Objective:

To investigate the effects and maternal-neonatal safety of using different concentrations of ropivacaine for prolonged labor analgesia, providing clinical evidence for optimizing labor analgesia regimens.

Methods:

This single-center prospective randomized controlled study will collect clinical data from parturients receiving labor analgesia at Chengdu Jinjiang District Maternal and Child Health Hospital from May to August 2025. Participants meeting the inclusion and exclusion criteria will be included. Following the replacement of the first analgesic pump, parturients will be randomly assigned to receive one of two ropivacaine concentration regimens (Group H: 0.12% ropivacaine; Group N: 0.1% ropivacaine). Data collection will include demographic information, pain scores, labor-related parameters, neonatal outcomes, and adverse reactions.

Interventions:

1. Group H: 0.12% ropivacaine + 0.5µg/ml sufentanil 2. Group N: 0.1% ropivacaine + 0.5µg/ml sufentanil Following the replacement of the first analgesic pump, parturients will receive the respective ropivacaine concentration formulation, with pain relief effects and labor-related indicators assessed at specified intervals.

Primary Outcome:

Pain scores at different time points (T0: at pump replacement; T1: 0.5 hours after pump replacement; T2: 1 hour after pump replacement; T3: at full cervical dilation or during transition to cesarean section).

Secondary Outcomes:

1. Labor-related indicators: Duration of first, second, and third stages of labor, blood loss, rate of instrumental delivery, mode of delivery (vaginal/cesarean). 2. Neonatal indicators: Neonatal weight, Apgar scores at 1 minute, 5 minutes, and 10 minutes. 3. Adverse reactions: Hypotension, nausea/vomiting, intrapartum fever (T≥38.0℃).

Hypothesis:

Different concentrations of ropivacaine for prolonged intrathecal labor analgesia will have varying effects on pain control and maternal-neonatal safety, with higher concentration ropivacaine (0.12%) likely being more effective in pain relief, while both concentrations are expected to show no significant difference in maternal and neonatal safety.

Ethics Approval:

This study has received approval from the ethics committee of Chengdu Jinjiang District Maternal and Child Health Hospital (Approval Number: 202312). All participants must sign an informed consent form to ensure the respect of participant rights and data confidentiality. The study will strictly adhere to relevant ethical standards and legal regulations to protect participant safety and privacy.

Funding:

This study is funded by the following projects:

1. Chengdu Medical Research Project (No. 2023465) 2. Chengdu Medical Research Project (No. 2022548) 3. Chengdu Medical Research Project (No. 2023304)

• Modified Bromage score [Time frame: From pump replacement to the end of labor analgesia.]
• Mode of delivery [Time frame: At the end of delivery]
• Neonatal Apgar score [Time frame: 10 minutes after the delivery of the fetus]
• nausea and vomiting questionnaire [Time frame: From pump replacement to the end of labor analgesia.]