Effects of dexmedetomidine on heart rate variability of elderly patients during the induction of general anesthesia

Objective To investigate the effects of dexmedetomidine on heart rate variability of elderly patients during the induction of general anesthesia.Methods Fifty cases of elderly patients with general anesthesia,ASA ⅠorⅡ,were randomly divided into dexmedetomidine group(group D)and normal saline group(group C),25 cases in each group.Group D received 20 ml infusion that contained 0.5μg/kg dexmedetomidine within 10 minutes before induction of general anesthesia and received the same infusion with a constant speed of 0.3μg·kg-1·h-1 untill 5minutes after intubation;Group C received the infusion of normal saline(NS)in the same way.The total power(TP),relative low frequency(LF),relative high frequency(HF),and the ratio of low frequency to high frequency(L/H)were recorded after entered the operating room(T0)and the moment after the dexmedetomidine infusion(T1),before(T2)and 1 min(T3),3 min(T4),5 min(T5)after indubation.Results Compared to T1,LF at T3-T5,HF at T4,T5 and TP at T5 in group D were significantly increased and LF/HF was significantly decreased at T3-T5(P0.05);Compared to group C,LF at T3-T5,HF and TP at T2-T5 were increased significantly and LF/HF was significantly decreased at T1-T5(P0.05).Conclusion Dexmedetomidine infusion during induction of general anesthesia can increase heart rate variability and balance the sympathetic and the vagus nerve tension,maintain the stability of cardiovascular function.