Assessment of the Incidence of Diaphragmatic Paralysis by Ultrasound After Different Volumes of Supraclavicular Block

Background: Ipsilateral diaphragmatic paralysis, purportedly caused by the retrograde diffusion of the local anesthetic (LA) inside the neural sheath, occurs after supraclavicular blocks, like interscalene blocks. Therefore, we have tried using ultrasonography (US) to evaluate diaphragmatic paralysis after varying volumes of supraclavicular brachial plexus blocks (SCB) Aim: to use an ultrasound to compare the diaphragmatic paralysis incidence with varying amounts of LA volumes used in supraclavicular brachial plexus block. Methods: In a randomized controlled clinical study, 60 patients with American Society of Anesthesiologists (ASA) Physical Status I, II&III were randomly assigned to take LA of 25 ml of 0.25% bupivacaine or 30 ml of 0.25% bupivacaine. An in-plane supraclavicular block was carried out under ultrasound guidance. Before and at 30, 45, and 60 minutes after administering the block, diaphragmatic thickness was measured using a linear transducer set to 10 MHz, and diaphragmatic excursion was measured using a curvilinear 3.5 MHz transducer. Results: While the diaphragmatic thickness fraction was negligible about the volume, there was a decrease in diaphragmatic excursion in the group that received 30 mL of diaphragmatic excursion reduction. The T-test was used to analyze the pre- and post-block data. In group 2, which received a larger volume, the likelihood of a decrease in diaphragmatic excursion was less than 0.05, indicating statistical significance. Conclusion: findings imply that even in cases of supraclavicular brachial plexus block, there is a higher chance of unintentional phrenic nerve blocking. The incidence is higher at higher volumes, and the ensuing hemidiaphragmatic paralysis is volume-dependent.