Efficacy of Preoperative Ultrasound Guided Pectoral Nerve Block for Intraoperative Opioid Sparing Effect and Postoperative Analgesia in Patients Undergoing Surgery for Breast Cancer.

Forty adult female participants scheduled for elective breast cancer surgery under general anesthesia are randomly allocated to receive either general anesthesia plus Pecs block(Pecs group, n=20) or general anesthesia alone (control group, n=20).

After arrived in the operating room，all patients undergo operation under total intravenous anesthesia (TIVA) with or without pectoral nerves blocks(PECS) . After anesthesia induction，the participants in the Pecs group receive an ultrasound-guided Pecs block before the start of the operation.

Pecs block technology：After cleaning the infraclavicular and axillary regions , the linear probe is placed below the lateral third of the clavicle. After recognition of the appropriate anatomical structures, then the block is performed . The needle is advanced to the tissue plane between the pectoralis major and pectoralis minor muscle at the vicinity of the pectoral branch of the acromiothoracic artery, and 10 mL of 0.5% ropivacaine deposited. In a similar manner, 20 mL is deposited at the level of the third rib between the pectoralis minor muscle and the serratus anterior muscle .

During operation the remifentanil administration in each group is guided using the surgical pleth index( SPI). the SPI target range was 20 to 50 Anesthetic depth is maintained and continuously adjusted with propofol to achieve Bispectral Index (BIS) between 40 and 60.

primary outcome intraoperative remifentanil consumption secondaty outcome postoperative pain score and rescue analgesic requirement