The supraclavicular lateral paravascular approach for brachial plexus regional anesthesia: a simulation study using magnetic resonance imaging.

UNLABELLED: In the supraclavicular lateral paravascular approach for brachial plexus regional anesthesia by Moorthy et al. (Moorthy's block), the patient is supine with the ipsilateral shoulder displaced anteriorly 5-8 cm. The needle direction is precisely defined in the coronal plane (using a Doppler flowprobe) but not in the sagittal plane. We sought to determine whether the block could be simplified by keeping the shoulder in a neutral position, if the needle direction in the sagittal plane could be more precisely described, and if the risk of pneumothorax appeared acceptably small. These questions were studied by magnetic resonance imaging in 10 volunteers. Volume datasets of the periclavicular region allowed precise positioning of simulated needles. In all volunteers, Moorthy's block could be performed with the shoulder in a neutral position. The optimal needle trajectory passed 5 mm posterior to the clavicle and was 25 degrees posterior to the coronal plane, never approaching the pleura closer than 18 mm. We conclude that Moorthy's block can be performed with the shoulder in a neutral position, that more precise instructions for the needle direction can be given, and that the risk of pneumothorax seems minimal. This should be confirmed by a clinical study. IMPLICATIONS: We studied an established method for brachial plexus block with needle advancement in the chest region in volunteers using magnetic resonance imaging. Our results suggest a simplification of the method and more guidelines for the needle angle to the skin, with a minimal risk for lung injury.