Comparison of 90° and 120° Arm Positions in Costoclavicular Block

The costoclavicular approach of the infraclavicular brachial plexus block is widely used for upper extremity surgeries due to its reliable anatomy and high success rates. Patient positioning, particularly the degree of arm abduction, may influence the spread of local anesthetic and the characteristics of the block. However, the optimal arm abduction angle during this procedure remains unclear. This prospective randomized controlled trial aims to investigate the effect of two different arm abduction angles (90° and 120°) on block onset time and block success in patients undergoing hand, wrist, and forearm surgery under ultrasound-guided costoclavicular brachial plexus block. Patients will be randomly assigned to one of two groups according to the degree of arm abduction. The primary outcome is block onset time. Secondary outcomes include block success, sensory and motor block characteristics, perfusion index changes, hemodynamic parameters, readiness for surgery at 15 and 20 minutes, block performance time, need for additional anesthesia, postoperative neurological evaluation at 4 and 24 hours, complications, and patient satisfaction. The findings of this study are expected to provide evidence on optimal patient positioning to improve the effectiveness and reliability of ultrasound-guided costoclavicular brachial plexus block.

Inclusion Criteria: * Patients aged between 18 and 80 years. * Patients scheduled for elective upper extremity surgery (hand, wrist, forearm). * Patients classified as ASA I-III. * Patients who provide informed consent after being informed about the study. Exclusion Criteria: * History of previous surgery, scar tissue, tumor, or trauma that may alter brachial plexus anatomy. * Presence of infection, hematoma, severe edema, burn, or open wound at the block application site. * Known allergy to local anesthetics or other medications used in the study. * Coagulopathy, use of anticoagulants, or platelet count \< 100,000/mm³. * History of peripheral neuropathy, neurological deficit, cervical radiculopathy, or CRPS. * Pregnancy or breastfeeding. * Patients with BMI \< 18 kg/m². * Patients with BMI \> 35 kg/m². * Severe cardiac, pulmonary, renal, or hepatic failure. * Mental retardation, communication difficulties, or lack of cooperation. * Deformity, amputation, or large mass in the surgical extremity that may interfere with sensorimotor assessment. * Preoperative significant sensory loss, motor weakness, or signs of neurological disease. * Severe anemia (Hb \< 9 g/dL) or polycythemia (Hb \> 18 g/dL). * Psychiatric disorders, substance abuse, or any condition that may interfere with study compliance.