The effectiveness of an anesthetic continuous-infusion device on postoperative pain control

Purpose: To evaluate the effectiveness of an anesthetic continuous-infusion device on postoperative pain after outpatient shoulder surgery. Type of Study: Double-blinded randomized trial. Methods: A prospective, double-blinded, randomized study of 50 consecutive patients undergoing outpatient arthroscopic shoulder surgery was performed. Patients were assigned by computer-generated randomized permuted block of four to 2 groups (25 each) receiving either a saline or 0.5% bupivacaine solution via an infusion pump after surgery. All patients gave informed consent and were randomized immediately before surgery. The surgical team, patient, clinic staff, and data collector were blinded to the randomization. Procedures performed included arthroscopic rotator cuff repairs, SLAP lesion repairs, subacromial decompressions, and capsular reefings. The infusion pump that was tested was used continuously for 48 hours and administered 2 mL each hour. For subacromial and rotator cuff surgery, the catheter was placed in the subacromial space. For glenohumeral surgery, the catheter was placed in the glenohumeral joint. Routine pain-control efforts were continued. Interviews were conducted at 1, 2, and 8 hours after surgery, followed by daily telephone interviews for I week. Visual analog scale (VAS), categorical pain scale (Likert) data, and oral medication use data were recorded. Results: Complete data sets were collected from 25 bupivacaine and 24 saline patients because I pump malfunctioned and was removed early. The average age of the bupivacaine group patients was 47.4 +/- 16.3 years (range, 16 to 84); patients in the saline group had an average age of 46.0 +/- 15.5 years (range, 19 to 73). There were 17 men and 8 women in the bupivacaine group and 16 men and 8 women in the saline group. The Likert and VAS mean values showed lower pain scores for the patients using the pump containing bupivacaine than for the saline group at all recorded times (P < .05) throughout the 7 days of data collection. The interval of greatest pain was on day 2. Postoperative oral medication use was always greater for the saline group than for those receiving bupivacaine. Conclusions: Postoperative pain control after arthroscopic shoulder surgery is essential so that these procedures can be successfully carried out in an outpatient setting. The first 2 postoperative days is the period of greatest pain. Continuous postoperative bupivacaine infusion is effective during this critical period, and the effect lingers even after the infusion is discontinued. The administration of bupivacaine via a continuous-infusion anesthetic pump statistically reduced postoperative pain after outpatient arthroscopic rotator cuff repairs, SLAP lesion repairs, subacromial decompressions, and capsular reefings.