Acceptance of Transverse Sweep vs Backtracking Method for Ultrasound-guided Interscalene Block in Awake Patients

Abstract

Background: Ultrasound-guided interscalene block is widely practiced for upper extremity surgery. There are two methods of identifying the brachial plexus by interscalene method—transverse sweep and backtracking. These methods are also used to scan stellate ganglion and do interventional procedure for Complex Regional Pain Syndrome 1 (CRPS1) and Complex Regional Pain Syndrome 2 (CRPS2). The aim of this study was to compare the two methods in an awake patient, the level of patient's comfort, acceptance, and presence of any symptoms like coughing, choking, vomiting, dyspnea, and pain. Materials and methods: In total, 100 patients undergoing upper extremity surgery requiring interscalene block were scanned with SonoSite Edge, high-frequency linear probe (6–13 Hz) by both the transverse and backtracking methods. All patients were subjected to both the methods of scanning, and the level of patient's comfort was compared. We categorized the comfort level into three levels—comfortable, mild discomfort, and significant discomfort. We measured pain with the help of unidirectional verbal rating scale as no pain, mild, moderate, and severe. Also, we recorded the associated symptoms including choking sensation, nausea, vomiting, cough, and dyspnea. Results: Even though the number of events was smaller in number in the transverse sweep method, the backtracking method scored over the transverse method. The transverse method caused some percentage of nausea (4%), choking (12%), dyspnea (6%), and mild pain (12%) and was statistically worse than the backtracking method. Although the comfort levels were not comparable statistically, due to lack of sufficient subgroups, transverse sweep patients had discomfort ranging from mild to significant compared with the comfortable feeling reported by all, when the backtracking method was used. Conclusion: The acceptance of the backtracking method was better than the transverse sweep method while scanning for ultrasound-guided block in awake patients.