Efficacy of vertical infraclavicular plexus block vs. modified axillary plexus block: A prospective, randomized, observer-blinded study

Background: Despite containing severe risks, infraclavicular approaches to the brachial plexus gained increasing popularity. Likewise, the vertical infraclavicular plexus block improved anesthesia compared to the standard axillary approach but contains the risk of pneumothorax. Therefore we modified the standard axillary technique by inserting a proximal directed catheter, referred to as a high axillary plexus block. We prospectively compared quality and onset of neural blockade after vertical infraclavicular plexus block (VIP) and high axillary plexus block (HAP) in two randomized groups (30 patients in each). Methods: In group VIP the insulated needle was inserted midway between the ventral process of the acromion and the jugular notch. In group HAP, first an axillary needle was placed. Through this a stimulating catheter was inserted in a proximal direction (10-15 cm); correct placement was confirmed by nerve stimulation. All patients received 40 ml ropivacaine 0.75% (300mg). Discriminating between analgesia and anesthesia, a blinded observer assessed progression of neural blockade every 5 min for 60 min by pin prick. Incomplete blocks were supplemented 60 min after initial injection. Results: All patients in both groups demonstrated sufficient surgical anesthesia. No patient needed systemic supplementation or general anesthesia. However, vertical infraclavicular plexus block indicated superior anesthesia compared to high axillary plexus block, regarding musculocutaneous, axillary and radial nerve, which were completely blocked with a higher success rate and in a shorter time interval (P < 0.05). Conclusions: While both techniques provide sufficient surgical anesthesia, vertical infraclavicular plexus block demonstrated a partially higher success rate and a faster onset than high axillary plexus block.