Utility of the Pectoral Nerve Block (PECS II) for Analgesia Following Transaxillary First Rib Section

Background: The transaxillary approach to resection of the first rib is one of several operative techniques for treating thoracic outlet syndrome. Unfortunately, moderate to severe postoperative pain is anticipated for patients undergoing this particular operation. While opioids can be used for analgesia, they have well-described side effects that has led investigators to search for clinically relevant alternative analgesic modalities. We hypothesized that a regional analgesic procedure, commonly called a pectoral nerve (PECS II) block, which anesthetizes the second through sixth intercostal nerves as well as the long thoracic nerve and the medial and lateral pectoral nerves, would improve postoperative analgesia for patients undergoing a transaxillary first rib resection. Methods: We performed a retrospective study by reviewing the charts of all patients that had undergone a transaxillary first rib resection for thoracic outlet syndrome during the defined study period. Patients that received a PECS II block were compared to those that did not. The primary outcome was a comparison of numeric rating scale pain scores during the first 24 hours following the operation. Secondary outcomes included cumulative opioid consumption during the same time period. Results: Pain scores during the first 24 hours following the operation were not statistically different between groups (Block Group: 3.9 [2.1-5.3] [median (IQR 25-75%)] versus Non-block Group: 3.6 [2.4-4.1]; P = 0.40. In addition, opioid use through the first 24 hours after the operation was not significantly different (43.5 [22.0-81.0] [median morphine equivalents in mg's] versus 42.0 [12.5-75.0]; P = 0.53). Conclusions: An ultrasound-guided PECS II nerve block did not reduce postoperative pain scores or opioid consumption for patients undergoing a transaxillary first rib resection. However, a prospective, randomized, study with improved power would be beneficial to further explore the potential utility of a PECS II block for patients presenting for this surgical procedure.