A comparison of postoperative cognitive function and pain relief with fentanyl or tramadol patient-controlled analgesia

Abstract

Study Objective The use of different opioids for patient-controlled analgesia (PCA) may affect postoperative cognitive function differently. Patient-controlled analgesia fentanyl has been shown to preserve cognitive function better than morphine. The effect of PCA tramadol on cognitive function is unknown. This study aims to compare postoperative cognitive function and analgesia of PCA fentanyl or tramadol. Design Prospective randomized double-blinded study. Setting Metropolitan teaching hospital. Patients 30 ASA physical status I, II, and III patients undergoing lower abdominal operations. Interventions Patients received standard general anesthesia for their operations. Postoperatively, patients received either fentanyl (group F, 10 μg bolus, n = 17) or tramadol (group T, 20 mg bolus, n = 13) for PCA. Group F patients also received fentanyl boluses and group T patients received tramadol boluses intraoperatively. Measurements Cognitive function was measured using Mini-Mental State Examination and Benton Visual Retention Test (BVRT) preoperatively and on days 1 and 2. Pain was measured by numerical rating scale. Results No differences were found in postoperative Mini-Mental State Examination or BVRT scores, but significantly fewer (29.4%; 95% confidence interval [CI], 13.3%-53.1%) group F patients were able to complete BVRT compared with group T patients (84.6%; 95% CI, 57.8%-95.7%; 95% CI of difference, 19.4%-74.8%) ( P = 0.010) on day 1. In the first 24 hours, group F and group T patients had similar analgesia at rest, but group T patients had better analgesia during cough (mean Numeric Rating Scale, 7.6; 95% CI, 7.0-8.2 vs 6.0; 95% CI, 4.8-7.2, group F vs group T) ( P = 0.018; 95% CI of difference, 0.4-2.8). No differences were found in frequency of side effects or patient satisfaction. Conclusions Tramadol or fentanyl PCA has similar cognitive effects on days 1 and 2; however, patients receiving tramadol PCA are more motivated to undergo cognitively demanding tasks and have slightly better analgesia on postoperative day 1.