Regional anesthesia – specifically, interscalene blocks – have been advocated as an alternative to intravenous opioids to manage pain in patients undergoing primary shoulder arthroplasty. They’ve generally done a good job of providing analgesia. [1-3] The problem, as described by Thomas (Quin) Throckmorton, MD, during a presentation at ICJR’s 7th Annual Shoulder Course, is that interscalene blocks are associated with some pretty serious side effects, including respiratory side effects similar to those associated with opioid use.