Retrospective Comparison of Extrafascial versus Intrafascial Interscalene Brachial Plexus Block with Reduced Volume: Impact on Hemidiaphragmatic Paralysis and Hemodynamic Effects in Shoulder Surgery Patients.

Abstract

Background and aim: Interscalene Brachial Plexus Block (ISBPB) is commonly used for shoulder surgery anesthesia to reduce opioid use and general anesthesia complications. However, it may cause diaphragmatic paresis due to phrenic nerve involvement. This study compares the incidence of hemidiaphragmatic paralysis and the frequency of side effects-including hemodynamic changes and postoperative complications-between the Extrafascial (ExF) and Intrafascial (InF) approaches for ISBPB using reduced anesthetic volume. The aim is to assess whether the ExF approach may be preferable in patients with reduced cardiopulmonary reserve (eg, COPD or heart failure).

Methods: A retrospective study was conducted at Federico II University in Naples, Italy, including 61 patients undergoing shoulder surgery from January 2024 to October 2024. About 33 patients received ExF while 28 received InF ISBPB, all with Ropivacaine 0.5% (10 mL), Mepivacaine 2% (5 mL), and Dexamethasone (4 mg). The primary outcome was the incidence of hemidiaphragmatic paralysis, evaluated via ultrasound pre and 30 minutes after the block by assessing diaphragm excursion, thickness, and thickening fraction. Secondary outcomes included intraoperative hemodynamic changes and postoperative complications: pain (NRS), analgesic/antiemetic requests, PONV, pruritus, shivering, anxiety, and discomfort.

Results: The TF significantly decreased after the block in both groups (p < 0.001), with no intergroup. Diaphragm paralysis occurred in 28 patients in each group (p = 0.093), without clinical respiratory effects. The InF group had more hypotension episodes (100% vs 30.3%, p = 0.002), and significantly lower mean and systolic blood pressure values at 1 and 2 hours after-block. No cases of anxiety, pruritus, shivering, or discomfort were observed. NRS was higher in the InF group at 6 hours but lower at 12 and 24 hours. Analgesic/antiemetic needs were similar; PONV was more frequent in the ExF.

Conclusion: Both approaches resulted in similar rates of hemidiaphragmatic paralysis. However, ExF was associated with fewer hemodynamic effects, suggesting potential benefit in high-risk cardiopulmonary patients.