The Effect of Interscalene Peripheral Nerve Block With 0.25% Bupivacaine vs 0.125% Bupivacaine on Lung Function

• Lung function [ Time Frame: At discharge from the post-anesthesia care unit, within 5 hours of the completion of surgery ] [ Designated as safety issue: Yes ]
  Lung function was evaluated by examining diaphragm movement using ultrasound imaging and room air oxygen saturation. Both were assessed prior to any intervention to establish a baseline, and again on discharge from the PACU, within 5 hours of the completion of surgery.
  
  

• Pain relief [ Time Frame: At discharge from the post-anesthesia care unit, within 5 hours of the completion of surgery ] [ Designated as safety issue: No ]
  Pain relief was assessed by recording the amount of opioid administered intraoperatively and in the PACU. Pain scores were recorded at the time of discharge from the PACU, within 5 hours of the completion of surgery.
  
  
• Satisfaction with pain control [ Time Frame: Within 30 days ] [ Designated as safety issue: No ]
  A follow-up phone call was made to patients within 30 days of surgery to assess the presence of any complications related to the block and overall satisfaction with pain control.
  
  

Prior to placement of interscalene brachial plexus peripheral nerve block (ISPNB), diaphragm function was assessed using ultrasound as normal, no movement, or paradoxical. Room air SpO2 was recorded. Patients were randomized to receive either 0.25% bupivacaine or 0.125% bupivacaine. ISPNB was performed using a coded syringe of the study drug, so that the anesthesiologists performing the nerve block, the patient, and the nurses assessing the patient were blinded as to the concentration. Patients were given a general endotracheal anesthesia for rotator cuff repair, and opioids were administered at the discretion of the attending anesthesiologist. When patients met criteria for PACU discharge, diaphragm function was again assessed using ultrasound and room air SpO2 was recorded.