Brachial plexus block with or without ultrasound guidance.

Purpose Of Review: Should ultrasound or nerve stimulation be used for brachial plexus blocks? We investigated last year's literature to help answer this question.

Recent Findings: Many of the reports concluded that ultrasound guidance may provide a higher success rate for brachial plexus blocks than guidance by nerve stimulator. However, the studies were not large enough to conclude that ultrasound will reduce the risk of nerve injury, local anesthetic toxicity or pneumothorax.

Current threshold for nerve stimulation depends on electrical impedance of the tissue: a study of ultrasound-guided electrical nerve stimulation of the median nerve.

Background: Understanding the mechanisms causing variation in current thresholds for electrical nerve stimulation may improve the safety and success rate of peripheral nerve blocks. Electrical impedance of the tissue surrounding a nerve may affect the response to nerve stimulation. In this volunteer study, we investigated the relationship between impedance and current threshold needed to obtain a neuromuscular response.

Electrical nerve stimulation or ultrasound guidance for lateral sagittal infraclavicular blocks: a randomized, controlled, observer-blinded, comparative study.

Background: Ultrasound guidance is frequently used to perform infraclavicular brachial plexus blocks. In this study, we compared electrical nerve stimulation and ultrasound guidance for the lateral sagittal infraclavicular block.

Methods: Eighty patients, ASA 1-2, were randomized for either nerve stimulation (group NS) or ultrasound-guided blocks (group US).

Use of magnetic resonance imaging to define the anatomical location closest to all three cords of the infraclavicular brachial plexus.

Infraclavicular techniques are often used to perform brachial plexus blocks. In our volunteer study we used magnetic resonance imaging to identify the brachial plexus and axillary vessels in a sagittal plane corresponding to the lateral sagittal infraclavicular block. In 20 volunteers, all cords were positioned within 2 cm from the artery approximately within 2/3 of a circle.