Analgesia and stress attenuation of ultrasound‐guided modified pectoral nerve block type‐II with different volumes of 0.3% ropivacaine in patients undergoing modified radical mastectomy for breast cancer: A prospective parallel randomized double‐blind controlled clinical trial

What Is Known and Objective A previous randomized clinical trial concluded that an optimal concentration of 0.3% ropivacaine could provide satisfactory analgesia for breast cancer patients undergoing modified radical mastectomy. We wondered if a smaller volume (30 ml vs. 40 ml) of 0.3% ropivacaine could still provide adequate analgesia in an ultrasound-guided PECS II block in modified radical mastectomy. Methods We performed a prospective parallel randomized double-blind controlled clinical trial. Eligible patients were assigned to either the P30 or P40 group (30 or 40 ml of 0.3% ropivacaine, respectively). The skin area of hypoesthesia, anaesthetic plane determined with ultrasound, pain visual analogue scale (VAS), anaesthetic dosages, and complications were recorded. Serum levels of interleukin-1β and interleukin-6 were measured postoperatively. Results and Discussion A total of 40 patients completed the trials, with 20 patients in each group. Although the skin area of hypoesthesia and the anaesthetic planes were significantly larger in the P40 group compared with the P30 group (p < 0.05), the VAS, analgesic and opioid doses, serum cytokine levels, anaesthetic toxicity, and complications had no significant differences between the two groups. What Is New and Conclusion Compared with 40 ml, 30 ml of 0.3% ropivacaine could provide adequate analgesia and reduce surgical stress in patients undergoing modified radical mastectomy for breast cancer.