Perioperative respiratory and analgesic effects of ultrasound-guided extrafascial versus interfacial interscalene brachial plexus block in patients undergoing shoulder arthroscopy

Background: It has been shown that placing local Anesthetics (LA) as far as 4 mm laterally from the sheath of the brachial plexus throughout US-guided ISBPB can result in beneficial analgesia for shoulder surgeries, demonstrating the significance of needle-nerve proximity in the context of ISBPB. The distance to the phrenic nerve is increased by this extrafascial injection, which may lessen the possibility that the local anesthetic spread would block it. The purpose of this work is to compare the effects of extrafascial and intrafascial (ISBPB) on the diaphragmatic excursion (phrenic nerve blockade). Methods: This work was performed on 50 adult individuals, their age ranges between 21-60 years of both sexes with American Society of Anesthesiologists (ASA) physical state classification I-II who were planned for shoulder arthroscopic surgery under general anaesthesia. Patients were allocated into two groups at random (25 patients each) according to the US-guided method of interscalene block: Group I (Intrafascial injection group): 10 ml of 0.5% bupivacaine were given to the individuals for intrafascial (conventional) ISBPB. Group E (Extrafascial injection group): 10 ml of 0.5% bupivacaine were given to the individuals for extrafascial ISBPB. Results: In group I, at PACU, the diaphragmatic excursions were significantly lower when compared to pre-block values. In group E, At PACU, the diaphragmatic excursions were comparable to pre-block values ( P value = 0.062). After 30 minutes of block, the extrafascial block (group E) had a significantly ( P value = 0.005) lower effect on diaphragmatic excursion than intrafascial block (group I). The same effect was observed at PACU. Extrafascial block had a significantly ( P value <0.001) lower effect on a diaphragmatic excursion to intrafascial block. No difference between both groups was observed regarding the analgesic properties. Conclusions: Given the increased incidence of partial hemi-diaphragmatic paralysis (HDP) with an intrafascial approach, extrafascial method to interscalene brachial plexus block is likely a more appropriate choice.