Effect of adding dexamethasone to ropivacaine for ultrasound-guided serratus anterior plane block in patients undergoing modified radical mastectomy: A preliminary trial

Background and Aims: Ultrasound-guided serratus anterior plane (SAP) block is a field block with high efficacy. We studied the analgesic effect of the addition of dexamethasone to ropivacaine in SAP block for modified radical mastectomy (MRM). Methods: Sixty patients undergoing MRM were randomised into two groups. Patients in Group P (n = 30) received 0.375% ropivacaine (0.4 ml/kg) with normal saline (2 ml) and those in group D (n = 30) received 0.375% ropivacaine (0.4 ml/kg) with 8 mg of dexamethasone (2 ml) in ultrasound-guided SAP block. The primary objective was to compare the time to first rescue analgesia and the secondary objectives were to compare the intraoperative fentanyl requirement, total diclofenac and tramadol requirements, and occurrence of nausea and vomiting in 24 hours, postoperatively. The statistical analysis was done using Mann-Whitney U-test, Chi-square test, Fisher's exact test, and Kaplan Meier survival estimates. Results: More patients required rescue analgesia in 24 hours in group P (33%) than group D (10%, P = 0.04). The probability of a pain free-period was significantly higher in group D than group P (P = 0.03, log-rank test). Intra-operative fentanyl requirement and postoperative diclofenac and tramadol requirements were comparable in both the groups. The incidence of postoperative nausea and vomiting was significantly more in Group P than Group D. Conclusion: Addition of dexamethasone to ropivacaine for SAP block increases the time to first rescue analgesic in the postoperative period.