The impact of dexmedetomidine on heart rate variability during anesthesia emergence in elderly patients after total intravenous anesthesia

Objective To evaluate the impact of dexmedetomidine on heart rate variability during anesthesia emergence in elderly patients after total intravenous anesthesia.Methods Eighty six elderly patients(age≥65 years) scheduled for abdomen surgery in total intravenous were randomly divided into receive either dexmedetomidine(group D) or saline placebo(group C) intravenously.Group D received 10 ml infusion that contained 0.5 μg/kg Dex with constant speed and group C received infusion of normal saline(NS) within ten minutes before the end of surgery.The MAP,HR,total power(TP),relative low frequency(LF),relative high frequency(HF),and the ratio of low frequency to high frequency power ratio(LF/HF) were recorded before(T_0) and 5 min(T_1) and 10 min(T_2) after drug administration,during extubation(T_3),and at 5 min(T_4) and 30min(T_5) after extubation.Meanwhile,the blood were taken for analysis of plasma epinephrine(E),norepinephrine(NE) and cortisol(Cor).Results MAP,HR,and the concentration of E,NE was significantly increased in group C after drug administration.These values in group C were higher compared with group D.The concentration of Cor in group D was significantly increased at T_3,T_4,similarly,it was higher in group C at T_2-T_4 when compared to T_0.The LF/HF was higher in group C than that of T_0 and in group D.Conclusion A single-dose bolus injection of Dex before tracheal extubation attenuates airway-circulatory reflexes and promote HRV recovery by improving the autonomic nervous balance during extubation.