Effect of Epidural Volume Extension Using Low-Dose Sufentanil Combined with Low-Concentration Ropivacaine on Visceral Pain During Cesarean Sections: A Randomized Trial

Visceral pain is common in cesarean sections conducted under combined spinal-epidural anesthesia (CSE). Epidural volume extension (EVE) is a technique for enhancing the effect of intrathecal blocks by inducing epidural fluid boluses in the CSE. Whether EVE that uses different drugs can reduce visceral pain during cesarean sections is rarely studied. In this study, we compared the effect of EVE that used low-dose sufentanil, either alone or combined with low-concentration ropivacaine, on visceral pain during cesarean sections under CSE. A prospective, randomized controlled study. The study was performed in the Jiaxing University Affiliated Women and Children Hospital. We randomly allocated 100 healthy patients to 4 groups to receive spinal hyperbaric bupivacaine followed by EVE with 10 mL of 0.9% saline (Group NS), 10 mL of 0.15% ropivacaine (Group R), 10 mL of 10 mu-g sufentanil (Group S), or a combination of 10 mL of 0.15% ropivacaine and 10 mu-g sufentanil (Group RS) through the epidural catheter 15 minutes thereafter. The primary outcome was the incidence of visceral pain. Each occurrence of visceral pain during the procedure was recorded. Every patient's pain level was evaluated on the visual analog scale (VAS). The consumption of sufentanil during patient-controlled intravenous analgesia (PCIA) and patient satisfaction scores under anesthesia were recorded within 48 hours after surgery. Maximum sensory block levels, segmental increases after EVE, time for sensory regression to the tenth thoracic dermatome (T10), and time for motor recovery to modified Bromage 0 were compared among each group. Visceral pain occurred in 60% (15/25), 56% (14/25), 24% (6/25) and 12% (3/25) of patients in the NS, R, S, and RS groups, respectively. The incidence of visceral pain was significantly lower in the RS group than in the NS or R groups (P < 0.05) but not significantly different from the S group. The S and RS groups have significantly lower VAS scores compared to the NS and R groups (P < 0.05). Sufentanil consumption during PCIA in the R and RS groups was significantly lower than in the NS group. Patients' overall intraoperative satisfaction scores were significantly higher in the S and RS groups than in the NS or R groups. This study has limitations in its sample size, time point of EVE implementation, absence of laboratory indicators, and lack of assessment of postoperative visceral pain, necessitating future studies to address these issues. EVE at 15 minutes afte