Efficacy of different doses of dezocine for decreasing minimum alveolar concentration of desflurane

Abstract

Objective To evaluate the efficacy of different doses of dezocine for decreasing the minimum alveolar concentration (MAC) of desflurane.Methods ASA physical status Ⅰ or Ⅱ patients of both sexes,aged 50-70 yr,undergoing elective lower abdominal surgery performed under general anesthesia,were divided into 4 groups:control group (group C)and different doses of dezocine groups (D1,D2 and D3 groups).Before induction of anesthesia,in D1,D2 and D3 groups,dezocine 0.050,0.075 and 0.100 mg/kg were intravenously infused,respectively,while in group C,the equal volume of normal saline was given instead of dezocine.The adverse reactions were observed.Propofol 3 mg/kg was given for induction of anesthesia 15 min later until patient' s consciousness and spontaneous respiration disappeared.Laryngeal mask airway was inserted and the patients were mechanically ventilated.Up-and-down sequential allocation was used to determine the MAC of desflurane during maintenance of anesthesia.The end-tidal concentration of desflurane was set at 8.0％ and maintained at this level for at least 5 min before skin incision in the first patient.Each time the concentration of desflurane increased/decreased in the next patient depending on whether or not the body movement developed.The ratio between the two successive concentrations was 0.9.The point between the positive response and negative response served as a cross-over point.After at least 7 independent cross-over points were observed in each group,the experiment was stopped.The MAC and 95 ％ confidence interval of desflurane were calculated.Results No adverse reactions developed in each group.The MAC of desflurane was significantly lower in D1-3 groups than in group C,in groups D2.3 than in group D1,and in group D3 than in group D2.Conclusion Dezocine 0.100 mg/kg injected intravenously at 15 min before induction of anesthesia provides a better efficacy for decreasing the MAC of desflurane in the patients. Key words: Analgesics,opioid; Anesthetics, inhalation; Dose-response relationship, drug