Arthroscopic shoulder surgery involves dynamic and severe postoperative pain. Interscalene brachial plexus block (IBPB) provides adequate analgesia but the spread of local anaesthetics administered causes a phrenic nerve block which entrains a non-negligible incidence of Hemidiaphragmatic paralysis acute (HDPA).~The primary study objective is to determine the HDPA diagnosed by using diaphragmatic thickness index in Ultrasound (US) after Low Volume (10 mL) versus Standard Volume (20 mL) of Levobupivacaine 0,25% for IBPB. Secondary end-points are 1) HDPA diagnosed by using FVC and FEV1 in spirometry, 2) HDPA diagnosed by using diaphragmatic excursion in US, 3) postoperative pain regarding time to first analgesic consumption and 24-hour cumulative total consumption of Patient-controlled analgesia (PCA) pump of Morphine IV and (4) postoperative harms between two trial-arms.~This study is a comparative, prospective, Unicenter, double-blind and two-arm RCT. 48 patients will be included.~This RCT would demonstrate a low volume dose IBPB decrease the HDPA after IBPB in patients undergoing SAS, by using spirometry and ultrasound and it will not provide inferior postoperative analgesia according to opioid requirements of postoperative PCA in comparison to standard volume dose used in current practice.
Arthroscopic shoulder surgery involves dynamic and severe postoperative pain. Interscalene brachial plexus block (IBPB) provides adequate analgesia but the spread of local anaesthetics administered causes a phrenic nerve block which entrains a non-negligible incidence of Hemidiaphragmatic paralysis acute (HDPA).~This is a comparative, prospective, Unicenter, double-blind, two-arm, randomized and controlled clinical trial. 48 patients will be included.~This RCT would demonstrate a low volume dose IBPB decrease the HDPA after IBPB in patients undergoing SAS, by using spirometry and ultrasound and it will not provide inferior postoperative analgesia according to opioid requirements of postoperative PCA in comparison to standard volume dose used in current practice.