Evaluation of Fentanyl as an Adjuvant to Bupivacaine in Ultra Sound Guided Transversus Abdominis Plane Block for Postoperative Analgesia in Patients Undergoing Abdominal Hysterectomy

Abstract

BACKGROUNDThe transversus abdominis plane (TAP) block is a regional analgesia technique that forms part of the multimodal approach to postoperative pain management for abdominal surgeries. Local anaesthetics like Bupivacaine with longer duration are preferred for TAP block. However, even that is insufficient to match the duration of postoperative pain in abdominal surgeries. The current study was to evaluate if Fentanyl as an adjuvant to bupivacaine in ultrasound guided TAP block improves the duration and quality of postoperative analgesia following abdominal hysterectomy. METHODSForty four patients, aged 18-60 years of American Society of Anaesthesiologist (ASA) Physical status I or II, posted for elective open abdominal hysterectomy under general anaesthesia were recruited by convenience sampling technique, to receive TAP block using 19.5 ml of bupivacaine hydrochloride 0.25% + 0.5 ml saline 0.9% (Group B, n=22) or 19.5 ml of bupivacaine hydrochloride 0.25% + 0.5 ml Fentanyl (25 microgram)( Group BF, n=22), after the completion of surgery but prior to extubation. Visual analogue scale (VAS) scores at rest and movement were assessed on the emergence, at 0, 2, 4, 6, 12 and 24-hours (h). Time to First Analgesic (TFA), when VAS ≥4 cm (≥40 mm) or on demand was noted. The incidence of postoperative nausea and vomiting (PONV) and sedation were compared. RESULTSVAS score was significantly lower in the study group, at rest at 2h (14.68 vs. 20.63, p=0.006), 4h (24.46 vs. 24.77, p=0.02), 6h (22.27 vs. 28.45, p=0.002) and 12h (18.90 vs. 21.00, p=0.043) and that with movement, at 2h (20.45 vs. 25.86, p=0.006), 4h (25.23 vs. 30.95, p=0.001) and 6h (29.14 vs. 33.90, p=0.006). TFA was significantly lower in study group (398.73 minutes vs. 537.09 minutes, p<0.001). PONV was comparable in both groups. Sedation score in study group was relatively significant at 4 hours, (p<0.001). CONCLUSIONSFentanyl as an adjuvant to bupivacaine in ultrasound guided transversus abdominis plane block, following abdominal hysterectomy under general anaesthesia improves the quality and duration of postoperative analgesia without any major adverse effects.