A randomised comparative study of erector spinae plane block versus low-dose ketamine-dexmedetomidine intravenous infusion as intraoperative opioid-free analgesia for modified radical mastectomy.

Abstract

Opioid-sparing analgesia for acute postoperative pain after breast cancer surgery is crucial due to opioid-related side effects. The utilisation of erector spinae plane block and low-dose intravenous ketamine-dexmedetomidine are widely recognised as non-opioid analgesic methodologies. The objective of this study was to conduct a randomised trial to examine the analgesic efficacy of both approaches while minimising the use of opioids. Seventy-two female patients scheduled for unilateral modified radical mastectomy were recruited. They were allocated randomly to Group ESPB, which received ipsilateral ultrasound-guided erector spinae plane block by 20 mL bupivacaine 0.5% at the level of T5 after induction of general anaesthesia, and Group Ket-Dex, which received intravenous (IV) bolus 0.25 mg/kg of ketamine and 0.5 µg/kg of dexmedetomidine, followed by an IV infusion of 0.25 mg/kg of ketamine and 0.3 µg/kg of dexmedetomidine per hour. Total postoperative morphine consumption (24 h) was the primary outcome. The secondary outcomes were pain scores over 24 hours during rest, duration of analgesia, isoflurane consumption, time to awakening, postoperative nausea and vomiting (PONV), and postoperative serum cortisol level. The postoperative morphine consumption over 24-hour in Group ESPB was 3.26 mg (0-6.74) versus 2.35 mg (2.08-4.88) in Group Ket-Dex (P = 0.046). Group Ket-Dex had lower pain scores at rest, longer analgesia duration, longer awakening time, and lower postoperative serum cortisol levels. Intravenous low-dose ketamine-dexmedetomidine infusion intraoperatively with inhalational-based general anaesthesia provides superior opioid-sparing analgesia to that of ESPB in patients undergoing unilateral non-reconstructive modified radical mastectomy, with less postoperative opioid consumption and stress response.