The effects of esmolol on postoperative remifentanil-induced hyperalgesia

Abstract

Objective To investigate the effects of peri-operative esmolol for patients undergoing laparoscopic radical hysterectomy of cervical cancer on remifentanil-induced hyperalgesia.Methods Fifty patients American Society of Anesthesiology (ASA) Ⅰ-Ⅱ undergoing laparoscopic radical hysterectomy of cervical cancer were randomly assigncd by a table of random numbers to two groups (n=25).Before the induction of anesthesia,the group esmolol (group Ⅰ),patients were administered 0.5 mg/kg esmolol,10 μg·kg-1·min-1 maintained to extubation,and the group control (group Ⅱ) patients received normal saline of the same volume.Anesthesia was induced with remifentanil 2 μg/kg,midazolam 0.05 mg/kg,etomidate 0.2 mg/kg,rocuronium 0.6 mg/kg,maintained with propofol 3 mg· kg-1· h-1-6 mg· kg-1· h-1 and remifentanil 0.15 μg· kg-1· min-1-0.5 μg· kg1· min-1,cisatracurium besilate for injection 0.1 mg·kg-1 ·h-1 in both groups.Thirty minutes before the expected end of surgery,1 μg/kg Fentanyl was administered intravenously.At the end of surgery,patients received fentanyl patient controlled intravenous analgesia (PCIA).Peri-incisional pain thresholds were measured for baseline values before operation,at 24 h and 48 h repeated postoperatively.Pain thresholds were established by an detecting meter for pain threshold.The visual analogue scale (VAS) was assessed at 30 min,6,24 h after surgery.Total fentanyl consumption was recorded for 24 h and 48 h after surgery.Results peri-incision region pressure pain thresholds were obviously higher at 24 h [(3.21±0.23) kg/cm2] and 48 h [(3.18±0.19) kg/cm2] postoperatively in group Ⅰ than group Ⅱ [(2.69±0.21),(2.62±0.20) kg/cm2] (P＜0.05).In group Ⅰ,pain thresholds were higher at 24 h [(3.21±0.23) kg/cm2] and 48 h [(3.18±0.19) kg/cm2] postoperatively compared with preoperative baseline values [(2.93±0.17) kg/cm2] (P＜0.05).Pain thresholds in group Ⅱ at 24 h [(2.69±0.21) kg/cm2] and 48 h [(2.62±0.20) kg/cm2] postoperatively were lower compared with preoperative baseline values [(2.91±0.18) kg/cm2].In group Ⅰ,the VAS scores at 30 min [(4.56±1.36) score],6 h [(3.64±1.32) score] and 24 h [(2.52± 1.08) score] postoperatively were significantly lower compared with group Ⅱ [(5.84± 1.70),(4.68±1.41),(3.20± 1.12) score] at all evaluation times (P＜0.05).The fentanyl consumption was lower at 24 h [(0.53±0.03) mg] and 48 h [(1.09±0.09) mg] postoperatively compared with group Ⅱ [(0.55±0.04),(1.15±0.08) mg] (P＜0.05).Conclusions Peri-operative esmolol for patients undergoing laparoscopic radical hysterectomy of cervical cancer may attenuate remifentanil-induced hyperalgesia and reduce the required dosage of the postoperative fentanyl. Key words: Esmolol; Remifentanil; Hyperalgesia; Pain thresholds