The Effects Of Etomidate Continuous Infusion On Adrenal Function In Dogs

Objective:To study the adrenal function after continuous etomidate infusion of different doses in dogs.Methods:Twenty-four healthy adultmale dogs were randomly divided into control group(group C,n=6) with only sodium pentobarbital anesthesia,and three experimental groups received infusion of etomidate at the rate of 10μg.kg-1.min-1(groupE1, n=6),20μg.kg-1.min-1 (group E2,n=6),30μg.kg-1.min-1(group E3,n=6)respectively.The dogs were also anesthesitized with 2.5% sodium pentobarbitone (25mg/kg) intraperitoneally and cathetered in femoral artery and femoral vein.MAP,CVP,ECG,SpO2,PETCO2,BIS were monitored.Group C were anesthtized with 2.5% sodium pentobarbitone(12.5mg/kg) at intervals by intraperitoneal injection appropriately and maintained 4h with the BIS value 40-60;the three experimental groups were continuously infused etomidate 3h respectively and were monitored 1h on withdrawal.All groups were added vecuronium (0.05mg/kg) to maintain muscle relaxation every 30 minutes.Radioimmunoassay was used to detect serum cortisol,aldosterone,plasma adrenaline,and plasma noradrenaline concentrations before intubation(To),at lh,2h,3h,and 4h after intubation (T1-4).Results:In group C no statistically significant differences were found at each time point in cortisol,aldosteron,adrenaline,noradrenaline concentrations (P>0.05).In group E1 cortisol concentration was significantly lower than that in group C at T3 (P<0.05) and it has recovered to the base levels at T4(P>0.05);but the difference between aldosterone, adrenaline,noradrenaline concentrations were not significant (P>0.05).The cortisol, aldosterone concentrations in group E2and E3 was significantly lower at T1,T2,T3 than To (P<0.01);and although it were increased after stopping the etomidate at T4(P<0.01),it was still lower than the level of To;and adrenaline,noradrenaline concentrations showed no statistical difference compared with group C(P>0.05).Conclusion:The cortisol and aldosterone concentrations were decreased with the doses and times of infusion of continuous etomidate,however,there were no effect on adrenaline, noradrenaline,it is cautious that etomidate will be applied to patients with hypoadrenocorti-cism.As etomidate of 10μg.kg-1.min-1 for a short time has little effect on adrenocortical and adrenal medulla function,it may be safe for the clinical continuous maintenance of anesthesia.