A Comparative Study Between Infraclavicular and Axillary Blocks for Assessment of Motor Power Using Handgrip Dynamometer

This randomized control trial is designed to include (52) patients ASA physical status I, II patients ranging from(18) to(60)years old scheduled for hand surgery

Patients meeting the inclusion criteria will be randomly assigned to receive either:

Group I: axillary block technique (n=26) (group A) GroupII: infraclavicular block technique( n=26)(group B) Anesthesia management After arrival to the anesthetic room, An 18-gauge intravenous cannula will be placed at the forearm contralateral to the operated arm, standard monitoring will be used (non-invasive arterial blood pressure, ECG, pulse oximetry) while performing the block and throughout the surgical procedure. Premedication will be given intravenously in the form of 0.03 mg/kg midazolam. 1 g paracetamol iv will be given for all patients Under aseptic conditions, a preliminary scan will be performed using siemens acuson x 300 ultrasound with 8-14 MHz linear transducer. A 50-mm block needle 22 gauge will be used. (SonoPlex Stim Cannula, Germany) All blocks will be given by one researcher using 20 ml of drug 0.25% bupivacaine (10 ml 0.5% bupivacaine + 10 ml normal saline).

Axillary block

Patients in group A will be placed in the supine position with the arm to be blocked abducted and externally rotated. After sterilization of the axilla, the Ultrasound probe with a linear high frequency (8-14 MHZ) transducer will be placed parallel to the anterior axillary fold at the axilla to identify the axillary artery and to identify the hyperechoic median, ulnar, and radial nerves in relation to the axillary artery. The musculocutaneous nerve which supplies the skin of the lateral side of the forearm had to be blocked also. It is found between the biceps brachii and coracobrachialis muscles. Lidocaine 1% was infiltrated subcutaneously 1 cm lateral to the probe. The needle is inserted in-plane from the anterior aspect and directed toward the posterior aspect of the axillary artery. All four nerves in the axillary region will be blocked. A local anesthetic will be administered adjacent to each of the four nerves (at least 5 ml for each).

Infraclavicular block

Patients in group B will be placed in the supine position with the head turned away from the side to be blocked. The arm is abducted to 90 degrees and the elbow flexed. the skin is disinfected and the transducer is positioned in the parasagittal plane to identify the axillary artery. Surrounding the artery are the three cords of the brachial plexus: the lateral, posterior, and medial cords. The needle is inserted in-plane short-axis technique from the cephalad end of the probe, with the insertion point just inferior to the clavicle. A local anesthetic will be injected posterior to the axillary artery to achieve a U-shaped distribution around the artery (cephalad, caudad, and posterior).

Injection of 5 ml lidocaine 2% will be also used in all patients to eliminate tourniquet pain and pain in the area of distribution of intercostobrachial nerve in case of use of a tourniquet

Block assessment

After completion of all block procedures. A formal assessment of block efficacy will be performed by an independent observer who will be masked to each subject's group allocation every 10 min after needle removal for 30 min. surgery will be started once surgical anesthesia will be achieved at any time point or until 30 min had elapsed. if surgical anesthesia will not be achieved at 30 min the block will be considered failed and general anesthesia will proceed.

Sensory blockade of the musculocutaneous, median, radial and ulnar nerves will be graded according to the previously validated 3 point scale using a cold test: respectively: 0 = no perception, 1 = decreased sensation, or 2 = normal sensation. A successful blockade is defined as a complete sensory blockade (i.e., sensory block score = 0) within 30 minutes of completing the block. If complete sensory blockade will not be achieved within 30 minutes, the affected subject will be excluded from the study and categorized as a block failure. The subject was offered a supplementary nerve block if there is sufficient time before surgery, or general anesthesia will be proceeded to achieve surgical anesthesia.

The procedural time (seconds) for each block will be recorded. This duration is defined as the interval from the ultrasound transducer's first contact with the subject to the time the block needle exit the skin. Block onset time will be recorded (from a completed injection of local anesthetic until loss of cold sensation) Duration of the block will be recorded, defined as the time from completing injection of the local anesthetic till complete recovery of sensory function, i.e., the cold test will be assessed every 30 min in the postoperative period till patient feel the cold sensation

The motor blockade will be assessed by testing patients' handgrip strength using a hydraulic handgrip dynamometer, baseline measurements will be recorded on both the ipsilateral and contralateral sides. hand grip strength will be measured preoperative, 30 min from a block, and after surgery. postoperative change in handgrip strength in the operative limb as a percent reduction of preoperative baseline strength will be measured. The time needed to regain full motor power will be measured.

All patients will be postoperatively monitored in the post-anesthesia care unit (PACU) for 1 h and thereafter discharged to their wards. Post-operative pain at the incision site will be assessed by visual analog scale (VAS) and a score of more than 3 when recorded will be taken as an endpoint for the duration of block and the patient was given supplementary analgesics i.e. Inj. Diclofenac Sodium 1-1.5 mg/kg intramuscular. Subject satisfaction will be assessed with a standardized question scored on a seven-point Likert scale: "Thinking about your nerve blocks, how satisfied were you with them: where 1 is not at all, 4 is neutral, and 7 is completely satisfied?"

Block related complications will be recorded such as failed block, motor weakness 24 h after the block local anesthetic toxicity, vascular puncture, paraesthesia, and pneumothorax.