Patient-controlled analgesia versus patient-controlled analgesia plus continuous infusion after hip replacement surgery

OBJECTIVE: To compare the efficacy and adverse effect profile of patient-controlled analgesia (PCA) versus PCA plus continuous infusion (PCACI) after hip replacement surgery. DESIGN: Prospective, randomized, open pilot study. SETTING: Large teaching institution. PARTICIPANTS: Thirty-four patients undergoing hip replacement or revision of hip replacement surgery. INTERVENTIONS: Patients were randomized to receive PCA morphine: 1 mg with 6-minute lockout, or PCACI, using the same dose, with a 0.5-1 mg/h continuous infusion. Pain intensity, sedation, narcotic use, injection/attempt ratio (I/A), and adverse effects were assessed. RESULTS: No significant differences in pain intensity were identified. Morphine use was not different between groups: PCA 61.8 +/- 35.0 and PCACI 74.2 +/- 54.9 mg (p =0.394). A trend toward an increased 12-hour I/A ratio was evident in the PCACI group: PCA 0.73 +/- 0.18 and PCACI 0.86 +/- 0.17 (p =0.073). Patient-reported adverse effects, sedation, and inability to sleep secondary to pain occurred similarly. Eight of 18 PCACI patients required discontinuation of either the continuous infusion mode or of PCA therapy entirely secondary to adverse effects. CONCLUSIONS: When compared with PCA therapy, PCACI was not associated with improved pain control and more patients receiving PCACI required discontinuation of therapy secondary to adverse effects.