Interscalene Block Versus Infraclavicular Block Plus Suprascapular Nerve Block

PATIENT RECRUITMENT With the approval of the Ethics Committee of Hospital Clinico Universidad de Chile, 40 patients undergoing arthroscopic shoulder surgery will be recruited. Enrollment will be carried out by an investigator not involved in patient care. Patients' confidentiality will be protected. STUDY PROTOCOL: GENERAL All blocks will be performed by one of the coauthors and conducted preoperatively in an induction room. Sedation (2 mg midazolam and 50 μg fentanyl) will be provided for patient comfort. STUDY PROTOCOL: PERFORMANCE OF THE BLOCK Both study groups will receive an ultrasound-guided superficial cervical plexus block. In the ICB-SSB group, suprascapular nerve blocks will be carried out using a previously described technique. For infraclavicular brachial plexus blocks, 20 mL of levobupivacaine 0.25% with epinephrine 5 µg/mL will be injected dorsal to the axillary artery, medial to the coracoid process. In the ISB group, block will carried out using a previously described technique: 20 mL of levobupivacaine 0.25% with epinephrine 5 µg/mL will be deposited under the prevertebral fascial between the C5 and C6 roots. STUDY PROTOCOL: GENERAL ANESTHESIA All patients will undergo standardized general anesthesia STUDY PROTOCOL: POSTOPERATIVE ANALGESIA In the Recovery Room, all patients will receive acetaminophen (usual dose…) and ketoprofen (usual dose…) as well as patient controlled analgesia (morphine bolus = 1 mg; lockout interval = 8 minutes). On the surgical ward, all subjects will continue to receive acetaminophen (usual dise…), celecoxib (usual dose…) as well and patient controlled analgesia (morphine bolus = 1 mg IV; lockout interval = 8 minutes). STUDY PROTOCOL: OUTCOME MEASUREMENTS The primary outcome will be the pain score in the PACU at 30 30 minutes using a sensorimotor composite scale: Performance time, sensorimotorSensory function, Onset time The blinded investigator will also assess the presence of hemidiaphragmatic block at 30 minutes. A 2-6 MHz curvilinear US probe (Sonosite M-Turbo, SonoSite Inc, Bothell, WA, USA) and the M-mode will be employed in all subjects; the liver and spleen will serve as acoustic windows on the right and left side, respectively. Patients will be scanned along the anterior axillary line and the US probe, angled cranially POTENTIAL BENEFITS OF THE STUDY This study will allow us to determine if ICB-SSB constitutes a viable alternative to ISB. POTENTIAL SIDE EFFECTS OF THE STUDY Participation in this protocol will not put patients at higher risk for complications since ISB and ICB-SSB are commonly used to provide analgesia for shoulder surgery