Effects Of Dexmedetomidine On Heart Rate Variability Of Elderly Patients Before And After The Induction Of General Anesthesia

Objective: To explore the effect of dexmedetomidine on heart rate variability and hemodynamics in elderly patients before and after the induction of general anesthesia.Methods: 50 cases of elderly patients( 65~76 years old) with general anesthesia, ASA II, were randomly and equally divided into dexmedetomidine group( group D,n=25) and saline group( group C, n=25). Group D received the intravenous infusion with a loading dosage of 0.5 ?g / kg dexmedetomidine( diluted with 0.9 % sodium chloride solution to 20 ml) in 10 minutes before anesthesia induction and maintain dosage of 0.3 ?g /( kg·h) untill 5 min after intubation through vein by micro pump. And group C was given equal volume intravenous infusion of normal saline. When the infusion of the loading dosage was completed,just started the anesthesia induction.Observe the heart rate variability( HRV),including low frequency( LF)?high frequency( HF)?total power( TP) and LF / HF at after entered operation room( T0), the end of the loading dose( T1), the time before tracheal intubation( T2), and 1 min( T3), 3 min( T4), and 5 min( T5) after intubation with the application of heart rate variation power spectrum analysis technology.And record separately Heart Rate( HR) ?Mean Arterial Pressure( MAP) ?Pulse Oxygen Saturation( SpO2) and Electrocardiogram( ECG)at the corresponding time.Results: When compared with Group C, the HRV parameters LF?HF and TP are increased and LF / HF is remarkably lower in Group D( P<0.05); LF at T3~T5 and LF/HF at T1~T5 are lower, HF and TP at T2~T5 are increased( P<0.05). Each parameter of HRV is no statistical significance comparison in the group C. Compared with that at T1, LF at T3~T5?HF at T4~T5?TP at T5 are significantly increased and LF / HF at T3~T5 is lower in Group D(P<0.05). Compared with Group C, MAP is significantly increased at T2(P<0.05). MAP is remarkably lower at T2~T5 than T0 in both groups.When compared with T3, MAP at T1 in Group C is increased and lower at T2( P<0.05). HR at T1~T2?T5 is lower in Group D when compared with that in group C( P<0.05). HR at T1~T2 and T4~T5 in Group D and T4 in group C are remarkably lower than T0( P<0.05). HR at T2 and T4~T5 is significantly lower than T3 in group D( P<0.05) and at T0~T2, T4~T5 is not statistical significance compared with T3 in Group C(P>0.05).Conclusion:Intravenous infusion with dexmedetomidine could increase HRV and adjust the balance of the sympathetic and vagus nerve tension. It also can restrain the stress response of trachea intubation in elderly patients, which could stabilize the cardiovascular function.