Effect of Different Doses of Butorphanol on Postoperative Shivering in Elderly Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

Purpose: This study was designed to investigate the effects of different doses of butorphanol on postoperative shivering and quality of recovery in elderly patients.Patients and Methods: A total of 147 elderly patients (aged 60 or older) scheduled for elective transurethral resection of the prostate were enrolled in the current study. Patients were randomly and evenly assigned into four groups: Group C (0.9% normal saline), Group B1 (butorphanol 0.01 mg/kg), Group B2 (butorphanol 0.02 mg/kg) and Group B3 (butorphanol 0.03 mg/kg). All drugs were diluted to 5mL and injected intravenously slowly 5 min before induction of anesthesia. The primary outcome measure was the incidence of postoperative shivering in the post-anesthesia care unit. Quality of Recovery-40 (QoR-40) scores were assessed on postoperative day (POD) 1, 2 and 3. Perioperative core and skin temperature, extubation time and adverse events were also recorded.Results: Patients among the four groups had comparable baseline characteristics. Compared with Group C, the incidence of shivering was significantly lower in Group B2 and B3 (P = 0.006 and P = 0.005, respectively). The QoR-40 scores on POD1 were significantly higher in all butorphanol groups than that in Group C (P < 0.0083). In Group B2 and B3, patients experienced lower pain intensity (P < 0.001). In addition, the incidence of catheter-related bladder discomfort (CRBD) was lower in all butorphanol groups than in Group C (P < 0.0083).Conclusion: Butorphanol 0.02 or 0.03 mg/kg could effectively prevent the occurrence of postoperative shivering in elderly patients scheduled for transurethral resection of the prostate, provided effective postoperative recovery and postoperative analgesia.