Dose-Finding Study: MEV90 for Local Anesthetic in Interscalene Block for Supraclavicular Nerves Block

Inclusion Criteria: * Age ≥ 18 years * ASA physical status I to III * Body Mass Index (BMI) between 18 and 35 kg/m² * Weight ≥ 50 kg * Scheduled for shoulder arthroscopy requiring an interscalene brachial plexus block for analgesia * Able to provide informed consent Exclusion Criteria: * Inability to provide informed consent * Coagulopathy (platelet count ≤100,000; INR ≥1.4) * Significant pulmonary disease (restrictive or obstructive) * Renal insufficiency (creatinine ≥1.2 mg/dL) * Hepatic insufficiency (transaminases ≥100 U/L) * Allergy to local anesthetics * Pregnancy * Pre-existing neuropathy * Previous surgery in ipsilateral cervical or supraclavicular region * Contralateral hemidiaphragmatic paralysis or vocal cord paralysis