Background: Pectoral nerve block (PECS block) is an evolving regional anesthetic technique for breast cancer surgery. Addition of dexmedetomidine may prolong the duration of analgesia of sensory blocks.

This study aimed to compare the effects of Ultrasound-guided PECS II block by either bupivacaine or bupivacaine/dexmedetomidine mixture for perioperative analgesia in modified radical mastectomy (MRM).
Patients and Methods: Forty five female patients undergoing elective unilateral MRM were randomly assigned into 3 equal groups; general anesthesia (GA) group: received conventional GA alone, GA/PECS-B group: received conventional GA plus PECS II block by bupivacaine, and GA/PECS-BD group: received conventional GA and PECS II block by bupivacaine/dexmedetomidine mixture. Intraoperative fentanyl, standard postoperative paracetamol and rescue morphine were given when required. Intra, postoperative opioids consumptions, time to first rescue analgesia, visual analogue scale (VAS), incidence of postoperative nausea and vomiting (PONV), incidence of patient and surgeon satisfaction,
and hospital length of stay (LOS) were recorded.
Results: Intraoperative fentanyl, postoperative VAS and morphine consumption were significantly lower, time to first rescue analgesia was significantly longer (p=0.001) and hospital LOS were significantly shorter in GA/PECS-BD group than GA/PECS-B and GA groups and in GA/PECS-B group than GA group. Incidences of PONV and patient and surgeon satisfaction in GA/PECS-B and GA/PECS-BD groups were comparable and significantly lower (p= 0.022) than GA group.
Conclusion: PECS II block produces excellent analgesia in modified radical mastectomy demonstrated by diminished intra- and postoperative opioid requirements, delayed rescue analgesia and lower pain score. Addition of dexmedetomidine can improve the quality of PECS block.