Comparison of hemi diaphragmatic paresis between ultrasound and peripheral nerve stimulator guided interscalene brachial plexus block in patients undergoing arthroscopic shoulder surgery

Background: Shoulder disorders are the third most common cause of musculoskeletal conditions for which shoulder arthroscopy procedures are the mainstay of treatment. Interscalene brachial plexus block is a common regional anaesthesia technique that provides excellent surgical anaesthesia and postoperative analgesia for these procedures. Despite the benefits, a potential disadvantage is the transient ipsilateral hemi diaphragmatic paresis from spread of local anaesthetic to the phrenic nerve which is in close proximity to the brachial plexus leading to respiratory compromise. We hypothesise that ultrasound guided low dose block decreases the incidence of the compliaction as compared to peripheral nerve stimulator guided block.Materials and Methods: A prospective randomized intervention comparative study was conducted after attaining ethical committee approval and informed consent from the patient. 60 patients were randomized into 2 groups of 30 patients each to group U (ultrasound guided) and group N (PNS guided). Statistical analysis was done using the student T test for continuous data and chi squared test was used for nominal data.Results: The demographic profile and hemodynamic variations of both the groups was similar. There was a decrease in forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) values in the first 30 mins and 1 hour after block in group N as compared to group U which was statistically significant (p< 0> Conclusion: The incidence of HDP and decreased PFT values at post block 30 minutes and 1 hour were less in group U as compared to group N.