Assessment of Diaphragmatic Function after Ultrasound Guided Interscalene Block with Different Volumes of Local Anesthetic in Patients Undergoing Shoulder Surgery

Abstract

Background: Interscalene brachial plexus block (ISBPB) is effective for postoperative analgesia after shoulder surgery but is linked to diaphragm dysfunction. This study compare the impact of two volumes of bupivacaine (10 ml and 15 ml) on diaphragmatic function, oxygen saturation, pain control, and opioid requirements. Aim: To reduce the incidence of diaphragmatic paralysis following interscalene block in adult patients undergoing shoulder surgery. Patients and Methods: Adults (18-60 years) undergoing elective shoulder surgery were randomly divided into two groups: Group A (15 ml bupivacaine) and Group B (10 ml bupivacaine). Pre, intra, and post-operative assessments included diaphragmatic function, oxygen saturation, sedation score, motor power, pain control, and opioid requirements. Results: Patients in both groups showed no paradoxical diaphragmatic movement within the first 30 minutes. However, after 30 minutes, Group A (15 ml) had a significantly higher frequency of diaphragmatic paresis. No significant difference was found in postoperative pain and opioid consumption within 48 hours. Conclusion: Low volume interscalene block provides comparable analgesia to high volumes but is associated with a lower incidence of side effects and hemi-diaphragmatic paresis.