Effect of Dexmedetomidine as an Adjuvant to Ropivacaine in Ultrasound-Guided Transversus Abdominis Plane Block for Post-Caesarean Analgesia: A Prospective Randomized Double-Blind Study

Abstract

Background: Effective analgesia after caesarean delivery facilitates early maternal mobilization and may support breastfeeding and maternal–infant interaction. Ultrasound-guided transversus abdominis plane (TAP) block provides predominantly somatic analgesia for the abdominal wall, but the duration of a single-shot block may be limited. Dexmedetomidine, an alpha-2 adrenergic agonist with analgesic and opioid-sparing properties, has been investigated as an adjuvant to local anaesthetics. This study evaluated whether adding dexmedetomidine to ropivacaine prolongs analgesia after caesarean section.

Methods: In this single-centre, prospective, randomized, double-blind comparative study, 54 women aged 18–40 years with American Society of Anesthesiologists (ASA) physical status II undergoing elective caesarean section under subarachnoid block were randomized equally to bilateral ultrasound-guided TAP block with either 0.2% ropivacaine plus normal saline (Group RS, n=27) or 0.2% ropivacaine plus dexmedetomidine 1 µg/kg (Group RD, n=27). Pain was assessed using a visual analogue scale (VAS) at predefined postoperative intervals. The primary outcome was pain-free duration, defined in the thesis as time until VAS >4/first rescue analgesia. Secondary outcomes included time to rescue analgesia, total 24-hour rescue analgesic requirement, haemodynamic variables, oxygen saturation, sedation score and adverse effects. Tramadol 50 mg intramuscularly was used as rescue analgesia.

Results: Baseline demographic variables were comparable between groups. Mean pain-free duration was significantly longer with dexmedetomidine: 8.67±3.19 hours versus 4.59±0.93 hours with ropivacaine alone (P<0.001). Mean total rescue analgesic requirement over 24 hours was 48.15±9.62 mg in Group RD compared with 100 mg in Group RS (P<0.001). VAS scores differed significantly between groups at 2, 4, 6, 8 and 12 hours; however, the direction of difference varied over time, with a higher mean VAS in Group RD at 8 hours. At 24 hours, VAS scores were similar (P=0.918). Haemodynamic variables showed statistically significant differences at selected time points, but baseline and 24-hour values were comparable. Sedation scores differed significantly at 4, 8 and 12 hours. No major block-related complications were reported in the study.

Conclusion: Within the limitations of this small, single-centre study, adding dexmedetomidine 1 µg/kg to 0.2% ropivacaine for bilateral ultrasound-guided TAP block was associated with a longer pain-free interval and lower 24-hour rescue tramadol requirement after caesarean delivery. Larger, adequately powered trials with standardized multimodal analgesia, rigorous repeated-measures analysis and systematic assessment of maternal and neonatal outcomes are warranted.