Respiratory effects and analgesic efficacy of different local anesthetic volumes in ultrasound-guided interscalene brachial plexus block for shoulder arthroscopy: Prospective randomized study

Abstract

Background: The exact volume of local anesthetics that can be used in interscalene brachial plexus (ISBP) that produce adequate analgesia with minimal effect on phrenic nerve is a matter of debate. Objectives: This study aimed to compare the effect of three different volumes of local anesthetics in (ISBP) on the incidence of diaphragmatic hemiparesis and the postoperative analgesia in patients scheduled for shoulder arthroscopy. Design: Prospective Randomized Double-blind study. Setting: Single-center study. Methods: Seventy-five patients scheduled for shoulder arthroscopy were randomly distributed into three groups according to the volume of levobupivacaine 0.25% used in ISBP block; - (group I: 5 ml), (group II: 10 ml), and (group III: 15 ml). Main outcome measures: The incidence of diaphragmatic hemiparesis (primary outcome) was assessed by ultrasound assessment of diaphragmatic excursion. Moreover, the postoperative pain score and the rescue analgesic consumption were measured (secondary outcomes). Results: The incidence of diaphragmatic hemiparesis or paralysis was higher in group III in comparison to groups I and II (P = 0.019 and 0.037) with no statistically significant difference between groups I and II (P = 0.576). The postoperative pain score was significantly lowered in groups II and III as compared to group I (P < 0.05). The postoperative tramadol consumption was higher in group I in comparison to groups II and III (P = 0.0011 and 0.009) with a non-statistically significant difference between groups II and III (P = 0.577). Conclusion: The use of 10 ml volume of levobupivacaine 0.25% in ISBP block had a lesser incidence of diaphragmatic hemiparesis or paralysis in comparison to the use of 15 ml volume and had a better postoperative analgesic profile in comparison to the use of 5 ml volume. Trial registration: The study was registered at clinicaltrial.gov (I.D: NCT04549779)