Comparison of the Effects of Interscalene Block and Superior Trunk Block on Pulmonary Functions

The interscalene block (ISB) is one of the peripheral nerve blocks providing surgical anesthesia and postoperative analgesia in shoulder arthroscopy, eliminating the need for general anesthesia. It is performed by administering local anesthetics (LA) to the C5-C6 roots between the scalene muscles at the level of the cricoid cartilage. ISB-related side effects, such as diaphragmatic paralysis, can occur with the spread of LA to the phrenic nerve over the anterior scalene muscle. To prevent this, a superior trunk block (STB) can be performed by administering LA close to the supraclavicular region where the C5-C6 roots merge into the superior trunk (further away from the phrenic nerve). Although there are studies in the literature demonstrating diaphragmatic paralysis using ultrasound and/or spirometry, no study evaluating diaphragmatic paralysis simultaneously with both ultrasound and spirometry under regional anesthesia alone has been found. Therefore, in this study, the investigators aim to assess the effects of this side effect on diaphragmatic excursion using ultrasound simultaneously and on respiratory functions using spirometry.