Comparison of Mean Duration of Post-operative Analgesia in Patients Undergoing Lower Abdominal Surgeries Receiving Ultrasound Guided Transversus Abdominis Plane (TAP) Block with Bupivacaine and Dexmedetomidine versus Bupivacaine and Dexamethasone

Abstract

Objective: To compare the mean duration of post-operative analgesia in patients undergoing lower abdominal surgeries receiving ultrasound-guided TAP block with bupivacaine plus dexmedetomidine versus bupivacaine plus dexamethasone. Methodology: This randomized controlled trial (NCT07508202), conducted at the Department of Anesthesia, Pakistan Institute of Medical Sciences (PIMS) in Islamabad from March 26, 2026, to June 26, 2026, enrolled a total of 60 patients aged 18–60 years with ASA physical status I–II who were scheduled for lower abdominal procedures, and divided them equally into two groups of 30 patients each. In Group A, a bilateral ultrasound-guided transversus abdominis plane (TAP) block was performed at the end of surgery using 20 mL of 0.25% bupivacaine combined with 4 mg of dexamethasone, whereas Group B received the same volume of 0.25% bupivacaine along with 0.5 μg/kg of dexmedetomidine. The primary outcome measured was the duration of postoperative analgesia, defined as the time interval from the completion of the block to the patient's first request for rescue analgesia, with the aim of determining which adjuvant offers superior prolongation of analgesic effect in lower abdominal surgeries. Results: When comparing the dexamethasone group to the dexmedetomidine group, the mean duration of post-operative analgesia was substantially greater (420.03 ± 39.05 minutes vs. 370.30 ± 33.00 minutes; p < 0.001). Stratified analysis demonstrated consistently longer analgesia duration with dexamethasone across age groups, gender, ASA status, BMI categories, and surgery duration subgroups. Conclusion: Ultrasound-guided TAP block with bupivacaine and dexamethasone provided a considerably longer duration of postoperative analgesia compared with dexmedetomidine in patients undergoing lower abdominal operations. Keywords: Analgesia, Bupivacaine, Dexamethasone, Dexmedetomidine, TAP block, Ultrasound-guided.