Ultrasound-Guided Axillary or Infraclavicular Nerve Block for Upper Limb Surgery

Onset Time of Brachial Plexus Anesthesia With the Axillary or Infraclavicular Approach Under Real-Time Ultrasound Guidance: a Randomized Controlled Trial

This study aims to detect differences in onset time of brachial plexus (i.e., arm) anesthesia using two different nerve block techniques. Using ultrasound guidance, axillary (i.e., at the armpit) and infraclavicular (i.e., below the collarbone) blocks will be performed to patients undergoing upper limb surgery. The investigators will analyze how long it takes for anesthesia to be adequate for pain-free surgery, thus determine the optimal technique for this kind of surgery.

Real-time ultrasound guidance has substantially reduced the risk of pneumothorax and/or vascular puncture during infraclavicular brachial plexus blocks. The role of this technique has thus been expanded to overlap those procedures for which an axillary nerve block would be commonly considered as first choice. A reference block for upper limb surgery thanks to its safety profile and clinical efficacy, the axillary approach may be more painful or unpleasant for some patients. The investigators aim to determine possible differences in onset time and patient acceptance between the two techniques.

General anesthesia will be induced if pain during surgery develops which is intractable with iv fentanyl ≤150 µg.

Blocks will be performed under high-resolution real-time ultrasound guidance. Patients will be in the supine position. With the abducted arm flexed 90° at the elbow, the transducer will scan for the axillary artery in its short-axis. Individual nerves will be sought for around the artery. A 22G, 17°-bevel needle will be advanced in-plane to inject aliquots of local anesthetic around each nerve structure up to the prescribed dose.

Blocks will be performed under high-resolution real-time ultrasound guidance. Patients will be in the supine position. The linear transducer will be initially positioned between the middle and lateral third of the clavicle, scanning on a parasagittal plane. The axillary artery and veins will then be sought for. We will try to visualize the three cords of the brachial plexus separately, and to inject local anesthetic around each of them. If this is not possible, the needle will be positioned cranially and posteriorly to the artery, and the injection will be made from there. A 20 G, 17°-bevel needle will be used for all blocks.

Inclusion Criteria: ASA Physical Status Class <4 Scheduled upper extremity orthopedic surgery Exclusion Criteria: Psychiatric or cognitive disorder Allergy to study drugs Contraindication to nerve block at the assigned site