Efficacy of Ketamine versus Magnesium Sulphate as Adjuvants to Levobupivacaine in Ultrasound Bilevel Erector Spinae Block in Breast Cancer Surgery (a Double-Blinded Randomized Controlled Study).

Purpose: Breast surgeons seek simple, safe, effective, and novel regional anesthesia techniques for postoperative analgesia. Erector spinae plane (ESP) block is a new ultrasound-guided technique. We aimed to explore the analgesic effect of adding ketamine and magnesium sulfate as adjuvants to levobupivacaine in ESP. Patients and Methods: Sixty female patients (aged 18-60 years) with breast cancer, weighing 50-90 kg who were scheduled for modified radical mastectomy (MRM) were randomly allocated into three groups (20 patients each) to receive an ESP block with 20 mL 0.25% levobupivacaine with adjuvants according to the following groups: group C: levobupivacaine; group K: levobupivacaine + 2 mg/kg ketamine; and group M: levobupivacaine + 2 mg/kg magnesium sulfate. The block was administered preoperatively before anesthesia induction. Postoperatively, hemodynamics, visual analog scale scores, the first request for analgesia, total analgesic consumption, and side effects were observed for 48 hours. Results: The total amount of Morphine rescue analgesia was significantly lower in groups M (7.00 ± 0.61 mg) and K (7.50 ± 0.58 mg) than in group C (14.40 ± 3.47 mg) during the first 48 h postoperatively. Nine (45%) patients in group M and 13 (65%) patients in K, compared with 20 (100%) patients in group C, requested analgesia. The time to first request of analgesia was significantly longer in groups M (30 h) and K (24 h) than in group C (7 h). No hemodynamic changes or serious side effects were observed. Conclusion: Magnesium sulphate and ketamine seem to be both effective adjuvants to levobupivacaine in ESP blocks for postoperative analgesia in patients undergoing MRM, with slightly better analgesia provided by magnesium sulphate.