Effect of low-dose esketamine on remifentanil-induced postoperative hyperalgesia / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effects of low-dose esketamine on remifentanil-induced postoperative hyperalgesia in the patients.Methods:Ninety-six American Society of Anesthesiologist Physical Status classificationⅠ or Ⅱ patients, aged 18-60 yr, with body mass index of 18-30 kg/m 2, scheduled for elective thyroidectomy under general anesthesia, were divided into 3 groups ( n=32 each) using a random number table method: control group (group C), esketamine administered before anesthesia induction group (group K1), and esketamine administered immediately after the end of surgery group (group K2). Esketamine 0.4 mg/kg was intravenously injected in group K1, and the equal volume of normal saline was given instead in C and K2 groups at 5 min before anesthesia induction. Anesthesia was induced by intravenous injection of propofol, remifentanil and rocuronium. Remifentanil was intravenously infused at a rate of 0.3 μg · kg -1·min -1 and 1.5%-2.5% sevoflurane was inhaled for anesthesia maintenance. Esketamine 0.4 mg/kg was intravenously injected in group K2 and the equal volume of normal saline was given instead in C and K1 groups immediately after the end of surgery. The mechanical pain thresholds of surgical incision and forearm of non-dominant hand were measured at 1 day before surgery and 30 min, 6 h, 24 h and 48 h after surgery, and flurbiprofen axetil was intravenously injected for rescue analgesia when the NRS score≥4 or the patient needed sedation. The intensity of pain was estimated using numeric rating scale at 30 min, 6 h, 24 h and 48 h after surgery. The intraoperative consumption of remifentanil, use of vasoactive drugs, recovery time, tracheal extubation time, duration of PACU stay, postoperative rescue analgesia and adverse reactions were recorded. Results:Compared with C group, the mechanical pain threshold around surgical incision and of the forearm of non-dominant hand was significantly increased at 30 min and 6 h after surgery in K1 and K2 groups ( P<0.05). Compared with C and K1 groups, the emergence time, tracheal extubation time, and duration of PACU stay were significantly prolonged, and the incidence of hallucinations and increased glandular secretion was increased in group K2 ( P<0.05). There were no significant differences in the consumption of remifentanil, intraoperative utilization rate of atropine and ephedrine, numeric rating scale scores at each time point after surgery, incidence of postoperative nausea and vomiting, and rate of rescue analgesia among the three groups ( P>0.05). Conclusions:Intravenous injection of small dose of esketamine (0.4 mg/kg) before anesthesia induction and immediately after the end of surgery can reduce postoperative hyperalgesia induced by remifentanil, and administration before anesthesia induction provides better efficacy in the patients.