Impact of interscalene versus superior trunk blocks as sole anesthetics on respiratory outcomes for shoulder arthroscopy: a randomized controlled trial

The interscalene block (ISB) provides effective analgesia for shoulder surgery but commonly results in hemidiaphragmatic paralysis (HDP). The superior trunk block (STB) is an alternative technique to reduce this complication while maintaining effective analgesia. This randomized trial compared ISB and STB used as sole anesthetic techniques, without general anesthesia, for shoulder arthroscopy, focusing on diaphragmatic excursion, spirometry, and clinical respiratory outcomes. This prospective randomized observer-blinded study included 123 patients allocated to either ISB (n = 62) or STB (n = 61) groups. The diaphragmatic excursion (DE) was assessed using ultrasound, and forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were determined by spirometry before and after the block. The time to the first postoperative analgesic requirement was recorded. The DE, FEV1, FVC, and FEV1/FVC reductions were significantly lower in the STB group (p < 0.05). The HDP incidence was lower in the STB (p < 0.01) when compared to the ISB group. Both groups demonstrated comparable analgesia. The STB provides analgesia with less respiratory complications compared to the ISB, making it a favorable choice for patients at risk of pulmonary compromise. ClinicalTrials.gov identifier: NCT06703281. Date: 11/21/2024. ESAIC Mentorship Programme ID: ESAIC_MSP_2024_BB.