A comparison of the continuous supraclavicular brachial plexus block using the proximal longitudinal oblique approach and the interscalene brachial plexus block for arthroscopic shoulder surgery: A randomised, controlled, double-blind trial.

Background: Continuous interscalene brachial plexus block (ISB) is widely used for arthroscopic shoulder surgery, but the incidence of hemidiaphragmatic paresis (HDP) has been reported to reach 100%. Several methods, including injections distal to the C5-C6 nerve roots, have been attempted to reduce the HDP incidence. However, catheter placement distal to the C5-C6 nerve roots interferes with the surgical site.
Objective: Our primary objective was to describe a new technique, the supraclavicular brachial plexus block (SCB), using the proximal longitudinal oblique approach (PLO-SCB), which can facilitate catheter placement and, when compared with ISB, to test whether this would provide noninferior analgesia and spare the phrenic nerve.
Design: Prospective, randomised, double-blind study.
Setting: Operating rooms, postanaesthesia care unit, and wards.
Patients: Seventy-six patients aged 20 to 80 years scheduled for arthroscopic shoulder surgery.
Interventions: Patients were randomly assigned to the continuous PLO-SCB ( n  = 40) or the continuous ISB ( n  = 40) groups. All patients received an initial low-volume single-injection (5 ml 0.75% ropivacaine) followed by a patient-controlled infusion of 0.15% ropivacaine.
Main Outcome Measures: The primary outcomes were the incidence of HDP and pain scores. Secondary outcomes were respiratory function, postoperative analgesic consumption, sensory and motor function, and complications.
Results: The HDP incidence was significantly lower in the PLO-SCB group than in the ISB group at 30 min after block injection: 0% (0 of 38 patients) and 73.7% (28 of 38 patients), respectively ( P  < 0.001). Similarly, at 24 h after surgery, the incidences were 23.7% (9 of 38 patients) and 47.4% (18 of 38 patients) in the PLO-SCB and ISB groups, respectively ( P  = 0.002). Median [IQR] NRS pain scores at rest measured after surgery in the ISB and PLO-SCB groups were similar: immediately after surgery, 1 [0 to 2] vs. 1 [0 to 1], P  = 0.06); at 30 min, 2 [0.25 to 2] vs. 1 [0 to 2], P  = 0.065); and at 24 h 2 [0.25 to 3] vs. 1 [0 to 3], P  = 0.47, respectively.
Conclusion: For major shoulder surgery, compared with continuous ISB, continuous PLO-SCB was more sparing of diaphragmatic and respiratory function while providing noninferior analgesia. Catheter placement via the PLO approach is feasible without interfering with the surgical field.
Trial Registration: Registered by the Clinical Trial Registry of Korea (Seoul, Korea; KCT0004759, http: cris.nih.go.kr, principal investigator: Hyungtae Kim).
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