The aim of the study is to compare the onset time of the costoclavicular approach of brachial plexus block with that of the lateral-sagittal infraclavicular approach in adults distal upper limb surgeries.

Regional anesthesia is commonly used for distal upper limb surgeries as it provides effective surgical anesthesia, reduces opioid consumption, and offers prolonged postoperative analgesia. Ultrasound-guided infraclavicular brachial plexus block is a well-established technique for these procedures. The traditional lateral-sagittal infraclavicular approach (LS-ICB) provides reliable anesthesia but may require multiple needle redirections to achieve adequate spread of local anesthetic around the cords of the brachial plexus. The costoclavicular (CC) approach is a newer ultrasound-guided infraclavicular technique in which the three cords of the brachial plexus are clustered together in the costoclavicular space, potentially allowing easier needle placement and faster spread of local anesthetic.

This prospective randomized controlled trial will include 50 adult patients undergoing distal upper limb surgery under regional anesthesia. Participants will be randomly assigned into two equal groups (25 patients each). Group CC will receive an ultrasound-guided costoclavicular brachial plexus block, while Group ICB will receive an ultrasound-guided lateral-sagittal infraclavicular brachial plexus block.

In both groups, the block will be performed using a mixture of 2% lidocaine and 0.5% bupivacaine in a 1:1 ratio with a total volume of 0.3 mL/kg, administered under real-time ultrasound guidance.

The primary outcome of the study is the time to onset of complete sensory and motor blockade after injection of the local anesthetic solution. Sensory block will be assessed using pinprick testing in the distributions of the median, ulnar, radial, and musculocutaneous nerves.

Secondary outcomes include block performance time, block success rate, incidence of complications (such as vascular puncture, pneumothorax, or local anesthetic systemic toxicity), postoperative pain scores, and total analgesic consumption during the first 24 hours after surgery. The findings of this study may help identify the most effective and safe infraclavicular block technique for distal upper limb surgeries.

Inclusion Criteria:

• ASA physical status I-III
• Distal upper limb surgery requiring brachial plexus block.
• Patient approval after written and informed consent to participate.

Exclusion Criteria:

• Patient refusal.
• Allergy to drugs used.
• Infection at puncture site.
• Coagulopathy or anticoagulant therapy.
• Pre-existing neuropathy or neurological deficit in the affected limb.
• Severe pulmonary disease.
• BMI > 40 kg/m².