Low Concentration of Dezocine in Combination With Morphine Enhance the Postoperative Analgesia for Thoracotomy

Objective When morphine and dezocine are mixed together, the clinical interactions with analgesic effects and adverse events remain unknown. The authors aimed to investigate the efficacy of low concentrations of dezocine in combination with morphine for postoperative pain. Design A prospective, randomized, double-blinded clinical trial. Setting Cancer Institute and Hospital, National Cancer Center, China. Participants Sixty patients undergoing thoracotomy were randomized into 3 groups to investigate the analgesic efficacy of different ratios of morphine and dezocine. Interventions The morphine group (Group M) received morphine (1 mg/mL) alone for patient-controlled analgesia (PCA); the morphine+dezocine 1 group (Group MD1) received morphine (1 mg/mL) combined with dezocine (0.05 mg/mL) at a ratio of 20:1 for PCA; the morphine+dezocine 2 group (Group MD2) received morphine (1 mg/mL) combined with dezocine (0.1 mg/mL) at a ratio of 10:1 for PCA. Cumulative morphine consumption, verbal rating scores (VRS), and adverse events were evaluated throughout a 48-hour postoperative period. Measurements and Main Results Cumulative morphine requirements were (1) statistically higher in Group M than in Group MD2 at 24 and 48 hours after surgery and (2) statistically higher in Group M than Group MD1 at 48 hours after surgery. Postoperative VRS for evaluating pain were similar among the 3 groups. The incidence of postoperative nausea and pruritus was statistically higher in Group M than in Groups MD1 and MD2. The incidence of dizziness was not significantly different among groups. Conclusions The combination of morphine and dezocine at the concentrations [morphine (mg/mL)]/[dezocine (mg/mL)] of 1/0.05 (ratio 20:1) and 1/0.1 (ratio 10:1) may enhance postoperative analgesia after thoracotomy.