Measurements of Cardiac Output During Constant Exercises: Comparison of Two Non-Invasive Techniques

Abstract We compared cardiac output (CO) determined simultaneously by electrical impedance cardiography method (CO ICG ) and by the CO 2 rebreathing technique (CO 2REB ) during three different steady-state exercises (target heart rate of 120, 140, and 160 min -1 ) in 8 healthy fit young men. The mean difference correlation coefficient obtained between the values of CO ICG and CO 2REB was 0.85 and the mean difference (CO ICG -CO 2REB ) was 0.06 l/min (0.12 %). At 120 min -1 , CO ICG was lower than CO 2REB but the tendency was reversed at 140 and 160 min -1 where CO ICG was higher than CO 2REB . This evolution may be explained by the difficultly of using CO 2 rebreathing technique at the highest steady-state exercises and by the progressive acidemia due to exercise. The present results suggest that electrical impedance cardiography method provides acceptable evaluation of CO and may favourably replace the CO 2 rebreathing technique during mild (or moderate) to high steady-state exercises.