The Effect Of Dexmedetomidine Combining Priming Dose Of Fentanly On Fentanly-induced Cough

Objectives:Studies have shown that dexmedetomidine(DEX) and a priming dose of fentanyl can effectively suppress the response of fentanyl-induced cough (FIC). This topic aims at further reducing the incidence of FIC but having no effect on the patients’oxygen saturation and hemodynamic through combining these two methods and different mechanisms to suppress the fentanyl-induced cough.Methods:Altogether168patients, American Society of Anesthesiologists physical status class Ⅰ or Ⅱ, aged18～70, weighing40～80kg, undergoing elective surgical procedures were randomly allocated into four groups:Control group (group S+S)、Pre-emptive fentanyl group (group S+F)、DEX group (group D+S) and Combined group(group D+F). Group S+S, intravenously administered0.25ml/kg isotonic saline in10min, then received1ml isotonic saline iv, and finally administered fentanyl4μg/kg I min later; group S+F intravenously administered0.25ml/kg isotonic saline in10min, then received pre-emptive fentanyl0.5μg/kg, and finally administered fentanyl3.5μg/kg1min later; group D+S intravenously administered1.0μg/kg DXM in10min, then received1ml isotonic saline iv, and finally administrated fentanyl4μg/kg1min later; group D+F intravenously administered1.0μg/kg DXM in10min, then received pre-emptive fentanyl0.5μg/kg and finally administered fentanyl3.5μg/kg1min later. A fentanyl bolus is injected into all patients in less than2s. Record the incidence and severity of cough during the next60s. Any episode of cough within60s of fentanyl administration was classified as FIC. Mean arterial pressure (MAP) and heart rate (HR) were recorded immediately before injection (TO) and every2min thereafter for10min (T1-5). Induction of general anesthesia commenced1min after fentanyl injection.Results:The incidence of FIC was45.2%、23.8%、21.4%and7.1%in group S+S、S+F、D+S and D+F. Group S+F、group D+S and group D+F had a significantly lower incidence than group S+S (P＜0.05). Group D+F had a lower incidence than group D+S and group S+F(P＜0.05). The FIC incidence in group D+S and group S+F had no significant differences. However, there was no significant difference in the severity among the four groups (P＞0.05). MAP and SPO2showed no significant differences among four groups at the same time point (P＞0.05). HR was not statistically different among four groups before giving drugs (P＞0.05). In group D+S and group D+F, HR decreased significantly from baseline during T2-T5(P＜0.05), while there were no changes in group S+S and group S+F, but we did not witness any HR<50bmp in our patients.Conclusions:Pretreatment with dexmedetomidine(1.0μg/kg) combining priming dose of fentanyl (0.5μg/kg) could significantly reduced the incidence of cough caused by fentanyl injection; intravenous infusing dexmedetomidine (1.0μg/kg) decreased heart rate, but does not appear the phenomenon of heart rate＜50bmp; intravenous infusing dexmedetomidine (1.0μg/kg) has less impact on respiration and circulation system.