Effects of sedation with low-dosage dexmedetomidine on cardiac function in elderly surgical patients

Objective To investigate the influence of continuous infusion of low-dose dexmedetomidine(DEX) for sedation on cardiac function index in elderly surgical patients,and assess the impacts on circulation.Methods Sixty elderly surgical patients were randomized into DEX group and control group(30 each).The sex ratio of the patients was 24/36(male/female),and age from 65 to 89 years.After the cannulation of left radial artery,the arterial pressure continuous cardiac output(APCO) monitor(Edwards,USA) was connected,and the cardiac function index was continuously monitored,including cardiac output index(CI),stroke volume index(SVI),heart rate(HR) and mean arterial pressure(MAP).The patients in DEX group were infused with DEX at 0.4μg(kg·h) for 10min following intrathecal anesthesia,then the infusion rate was adjusted from 0.2 to 0.4μg(kg·h) to keep the bispectral index values(BIS) maintained between 75 and 85.Normal saline was administered with an equal volume in control group.The MAP,HR,respiration rate(RR),pulse oxygen saturation(SpO2),the partial pressure of end-tidal carbon dioxide(PETCO2) and BIS were recorded immediately at the DEX infusion(T0),and 10min(T1),20min(T2),30min(T3),60min(T4) after DEX infusion,and the end of surgery(T5).All cardiac function data were statistically analyzed,and P0.05 was considered as statistic significance.Results All hemodynamic and respiratory parameters in both groups were normal during operation.When DEX infusion was given for 10min,the systolic blood pressure(SBP) in DEX group was lowered by about 7%-11% compared with that in T0(P0.05),but such change was not observed in control group.The BIS values in DEX group declined significantly in T1-5 groups compared with that in T0 and control group(P0.05).No significant difference of CO/CI and SV/SVI was found within various time points or between the two groups(P0.05).Conclusion The sedation with continuous infusion of small-dosage DEX during intrathecal anesthesia in elderly surgical patients may have little impact on cardiac function index,but the conclusion remains to be verified with large sample and multicenter research.