Fentanyl versus dexamethasone or both as adjuvants to bupivacaine in an ultrasound-guided paravertebral block in patients undergoing modified radical mastectomy: a randomized double-blind clinical study

BACKGROUND: This study aimed to compare the effect of dexamethasone added to fentanyl and bupivacaine with the effect of either dexamethasone or fentanyl alone when combined with bupivacaine in the thoracic paravertebral block (TPVB).METHODS: Sixty female patients (aged 18-60 years), scheduled for modified radical mastectomy were enrolled. Patients received preoperative unilateral paravertebral block using 0.3 mL/kg of 0.5% bupivacaine combined with 8 mg dexamethasone (group 1), 1 μg/kg fentanyl (group 2), or 8 mg dexamethasone + 1 μg/kg fentanyl (group 3). The study drugs were diluted with normal saline 0.9% up to 25 mL volume. The primary outcome was the time to first postoperative analgesics request, Secondary outcomes were total analgesic consumption, verbal rating pain scale (VRS) over the first 24 hours postoperatively, hemodynamic parameters, and adverse effects.RESULTS: The time to first analgesic request for intravenous (IV) nalbuphine was longer in group 2 (15.75±0.9 h, P<0.001) than group 1 (10.45±1.1 h, P<0.001), while no patients requested it in group 3 (P<0.001). The total analgesic consumption of IV nalbuphine was lower in group 2 (8.6±3.5mg, P=0.04) than group 1 (11.3±2.1 mg), with a significant difference between group 2 and 3 (P<0.001). From the 8th till the 24th hours postoperatively, patients in group 3 showed the significantly lowest median VAS scores, followed by patients in group 2 (P<0.001) and lastly patients in group 1. There were no significant adverse effects.CONCLUSIONS: Dexamethasone and fentanyl combination enhances the analgesic effect of bupivacaine in TPVB.