| Objective:The purpose of this study was to investigate the efficacy of low dose of nalmefene for postoperative nociceptive hypersensitivity induced by remifentanil or opioids induced hyperalgesia(OIH),and whether differences in the timing of pre-induction or postoperative administration would cause differences in efficacy to support future clinical applicationsMethods:93 patients undergoing thyroidectomy(n=93),from ASAⅠorⅡ,21 to 69years old,body mass index(BMI)18 to 30 kg/m~2,and the random number table method was used to divide patients into 3 groups.Control group C(n=32):0.03 m L/kg of normal saline was administered 5 min before induction and immediately after discontinuation of the drugs.Nalmefene injected before induction group N1(n=31):nalmefene 0.3μg/kg was injected intravenously 5 min before induction+0.03 m L/kg of normal saline was injected intravenously immediately after withdrawal;Nalmefene injected after surgery group N2(n=30):nalmefene 0.3μg/kg was injected intravenously immediately after withdrawal,and normal saline 0.03 m L/kg was injected intravenously5 min before induction.During preoperative visit,we signed the experimental consent form with patients,measured the mechanical pain threshold of skin at a patient’s non-dominant hand forearm and at the surgical incision,teached patients to use the VAS scores,and instructed the patient to record the VAS scores at 2 h,4 h,8 h,12 h,and 24 h postoperatively.After entering the operating room,monitoring of vital signs of patents,and drugs were injected to veins of patients 5 minutes before induction.Then,anesthesia induction was started,intravenous slow push of midazolam 0.03 mg/kg,sufentanil 0.4μg/kg,etomidate 0.2 mg/kg,rocuronium 0.6 mg/kg,intraoperative maintenance of anesthesia with seflurane 1%,propofol 2 mg/kg/h,remifentanil 0.1μg/kg/min,and cisatracurium 0.1 mg/kg/h.After the operation,the drugs were stopped and the drugs were injected again.Patients were revisited 24 h after surgery.We measuring their mechanical pain thresholds and collected their VAS scores at the same time.Results:Compared with group C,group N1(152.53±59.24)and group N2(150.52±59.89)were significantly higher than group C(110.23±55.44),P<0.05;The mechanical pain threshold of postoperative incision in N1 group(82.91±49.59)and N2group(60.29±44.62)was significantly higher than that in C group(34.70±34.17),and N1 group was higher than that in N2 group,P<0.05;In group C,the threshold of forearm mechanical pain after operation(110.23±55.44)was lower than that before operation(198.72±45.68),in group N1,the threshold of forearm mechanical pain after operation(152.53±59.24)was lower than that before operation(196.32±56.42),in group N2,the threshold of forearm mechanical pain after operation(150.52±59.89)was lower than that before operation(201.73±43.97),P<0.05;In group C the mechanical pain threshold of postoperative incision(34.70±34.17)was lower than that before operation(197.47±49.36),in group N1 the mechanical pain threshold of postoperative incision(82.91±49.59)was lower than that before operation(198.03±61.45),in group N2 the mechanical pain threshold of postoperative incision(60.29±44.62)was lower than that before operation(199.03±45.52),P<0.05;In group C,the threshold of mechanical pain of postoperative incision(34.70±34.17)was lower than that of postoperative mechanical pain of forearm(110.23±55.44),in group N1,the threshold of mechanical pain of postoperative incision(82.91±49.59)was lower than that of postoperative mechanical pain of forearm(152.53±59.24),and in group N2,the threshold of mechanical pain of postoperative incision(60.29±44.62)was lower than that of postoperative mechanical pain of forearm(150.52±59.89),P<0.05;The VAS scores of patients after surgery were not different among the three groups,the changes of HR along the surgery had no difference among the three groups and the same is true of MAP,P>0.05.Conclusion:1.Low dose nalmefene can inhibit OIH,enhance patient’s satisfaction,and does not increase postoperative pain.2.The administration of 0.3μg/kg nalmefene 5 min before induction has a better inhibitory effect on postoperative OIH.3.The use of low dose of nalmefene will not affect intraoperative circulations. |
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