Effects of different doses of dexmedetomidine on cardiac conduction system / 临床麻醉学杂志

ABSTRACT

Objective To investigate the effect of dexmedetomidine on cardiac conduction system at different loading doses.Methods Eighty male patients with orthopedic surgery,aged 20-65 years,falling into ASA physical atatus Ⅰ or Ⅰ,were randomly divided into groups D1,D2,D3 and C with 20 in each.Groups D1,D2 and D3 were infused with dexmedetomidine 0.3,0.5 and 0.8μg/ kg using a micro-pump for 10 min,group C infused 0.9％ NaCl solution in the same manner.MAP,HR,SpO2 were recorded and ECG was traced before injection (T1),5 min (T2),10 min (T3) after injection and 10 min after the end of pumping (T4).P wave duration,P-R interval,QRS time,and QTc value were calculated.Results There was no significant difference in SpO2,P wave duration,P R interval and QRS time among the four groups.There was no significant difference in MAP,HR and QTc value in group C and group D1.Compared with that in group C,MAP was significantly decreased,HR was significantly slowed down and QTc value was significantly shortened in group D2 and D3 from T2 to T4 (P ＜ 0.05).Conclusion Dexmedetomidine does not affect the cardiac conduction system.0.5 μg/kg and 0.8μg/kg dexmedetomidine can effectively shorten the QT interval.To avoid severe bradycardia,patients with low heart rate should use no more than 0.5 μg/kg dexmedetomidine.