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Background and Aims Recent studies suggest a possible antinociceptive effect of esmolol. The aim of this study is to investigate the effect of an infusion of esmolol on intraoperative nociception, as well as on postoperative acute and chronic pain.

Methods In this interim analysis, 35 patients scheduled for inguinal hernia repair were randomized with identical blinded syringes to either the esmolol group, receiving a loading dose of 0.5 mg/kg of esmolol and maintenance dose of 50 mcg/Kg/min or to the placebo group, receiving saline. Intraoperative nociception as assessed by the percentage of anesthesia time during which NOL was<25 as well as postoperative acute and chronic pain with NRS and DN4 scores were analyzed.

Results Intraoperatively, the percentage of time NOL was<25 was higher in the esmolol group versus the control group (p=0.007). The esmolol group demonstrated lower NRS scores on arrival to PACU than the control group at rest and during movement (p 0.019 and 0.015 respectively) and lower NRS scores at discharge from PACU than the control group at rest and during movement (p 0.037 and 0.014 respectively). More patients required additional analgesia in PACU in the control group versus the esmolol group (p=0.01). Cumulative morphine consumption in the PACU was lower in the esmolol group versus the control group (p=0.004). No effect of esmolol on chronic neuropathic pain was demonstrated.

Conclusions Intraoperative esmolol administration seems to decrease intraoperative nociception and to affect aspects of postoperative recovery by mitigating early postoperative pain levels and decreasing the need for opioid rescue medication following inguinal hernia repair.