Continuous interscalene brachial plexus nerve block prolongs unilateral diaphragmatic dysfunction

Abstract Background and objectives Single interscalene blocks (ISB) impair pulmonary function (< 24 h). We hypothesized that continuous ISBs would prolong pulmonary dysfunction until h48 compared with a single ISB. We compared the time course of spirometric and diaphragmatic dysfunction following single or continuous ISBs. Methods We prospectively included consecutive adult patients scheduled to undergo shoulder surgery under standard general anaesthesia with single ( n = 30) or continuous ( n = 31) ISB. Before ISB (baseline), spirometric tests were recorded and the diaphragm course was evaluated with a B-mode ultrasound technique every 12 h until h48. ISBs were performed with 15 mL 0.5% ropivacaine using an ultrasound technique approach. The continuous group received the same bolus followed by 0.2% ropivacaine 5 mL·h−1 (48 h). The primary end point was the reduction (> 25% from baseline) of forced vital capacity (FVC) over the study period (48 h). Results Patient characteristics were similar in both groups. Thirty minutes after blocks in the PACU, all patients demonstrated a similar and significant unilateral diaphragm paralysis (