RESUMO
Objective To evaluate the effect of ultra-low dose naloxone on postoperative hyperalgesia caused by large-dose remifentanil.Methods Forty ASA Ⅰ-Ⅲ adult patients,scheduled for gastrointestinal surgery,were randomly assigned into 2 groups (n =20 each):large dose remifentail group (group R) and ultra-low dose naloxone group (group N).Anesthesia was induced with iv injection of remifentanil,propofol and cisatracurium and maintained with inhalation of sevoflurane and infusion of remifentanil.The patients were tracheal intubated and mechanically ventilated.In group R,remifentanil was infused at a rate of 0.25 μg· kg-1 · min-1 starting from the beginning of skin incision.The infusion rate was adjusted according to hemodynamics during operation and subsequently increased/decreased by 0.05 μg· kg-1· min-1 each time.In group N,naloxone was infused at 0.1 μg·kg-1· h-1 while infusing remifentanil,naloxone infusion was stopped at the beginning of peritoneum closure and the other treatments were similar to those previously described in group R.All patients were sent to post-anesthesia care unit after surgery and stayed there for 90 min.Morphine was given when need.The patient-controlled intravenous analgesia was used for postoperative analgesia after leaving post-anesthesia care unit.The first pain time was calculated.The morphine consumption and complications such as nausea,vomiting and pruritus were recorded at 15,30,60 and 90 min and 2,6,24,48 and 72 h after surgery.Results Compared with group R,the morphine consumption was significantly reduced at each time point after surgery,the first pain time was prolonged,and incidence of nausea was decreased (P ＜ 0.05),while no significant change was found in the incidence of vomiting and prutirus in group N (P ＞ 0.05).Conclusion Infusing ultra-low dose naloxone (0.1μg· kg-1 ·h-1) during operation can attenuate postoperative hyperalgesia caused by large-dose remifentanil in patients.