Intra-operative esmolol and pain following mastectomy: A randomised clinical trial.

BACKGROUND: Esmolol is a beta-1 selective blocker that has been shown to reduce postoperative pain. Its antinociceptive effects have not been tested following mastectomy. OBJECTIVE: To evaluate the safety, efficacy and antinociception of intra-operative esmolol infusion after mastectomy. DESIGN: Randomised, double-blinded, placebo-controlled trial. SETTING: Tertiary referral centre, Brasília, Brazil. Recruitment: July 2015 to July 2017. PATIENTS: Seventy women scheduled for mastectomy, ASA I to III, aged 18 to 75 years. Four were excluded. INTERVENTIONS: All underwent general anaesthesia. The intervention group received a bolus of 0.5 mg kg-1 of esmolol over 10 min followed by a continuous infusion of 100 µg kg-1 min-1. The placebo group received saline. MAIN OUTCOME MEASURES: The primary outcome was pain at rest 24 h after mastectomy as measured by a 0 to 10 numeric rating scale. RESULTS: Pain scores at rest 24 h after mastectomy were lower in esmolol-treated patients compared with placebo (mean difference = -1.51, 95% confidence interval (CI), -2.36 to -0.65, P = 0.001). On arrival in the postanaesthesia care unit (PACU), the occurrence of pain was also lower in the esmolol group, at rest and on effort (P = 0.009 and P = 0.013, respectively), on discharge from PACU (P = 0.009 and P = 0.015), 12 h (P = 0.01 and P = 0.007) and on effort in the 24 postoperative hours (P = 0.003). Mean morphine consumption was reduced by 77% in the esmolol group compared with the placebo group (mean difference  = -2.52 mg, 95% CI = -3.67 to -1.38, P < 0.001). The length of hospital stay was shorter for the esmolol group (mean difference = -6.9 h, 95% CI, -13.4 to -0.31, P = 0.040). CONCLUSION: Esmolol was well tolerated, allowed a notable reduction in the dose of rescue analgesics and demonstrated superior efficacy compared to placebo for pain management after mastectomy. TRIAL REGISTRATION: ClinicalTrials/NCT02466542.