ASSESSMENT OF CARDIAC-PERFORMANCE - SHORT-TERM AND MEDIUM-TERM VARIABILITY OF IMPEDANCE CARDIOGRAPHY AT REST AND DURING DYNAMIC EXERCISE

Short- and medium-term variability of impedance cardiography at rest a nd during exercise at a heart rate of 155 - 160 beats/min were assesse d in 12 healthy men aged 21 - 28 years. Two consecutive measurements w ithin 1 min were performed 4 times at 2-hour intervals on 2 days 14 da ys apart. Ejection fraction was the most reproducible of all impedance cardiography parameters, the CV ranging from 3.3 - 5.9%. The short-te rm reproducibility of cardiac output and stroke volume at rest was goo d, the between-repeats coefficient of variation (CV) being 4 - 6%. The reproducibility weakened with longer time span (between-day CV being about 12%) and higher heart rates (exercise). However, even the betwee n-day reproducibility at rest was as good as that of heart rate. Betwe en-day CV during exercise were about 20%.