Hemodynamic Response to Exercise as Measured by the Solar IKG Impedance Cardiography Module and Correlation with Metabolic Variables

Objective Impedance Cardiography (ICG) has been shown to be a feasible and accurate method for non-invasive measurement of cardiac index (CI). Aim of this investigation was the correlation of hemodynamic variables under exercise as measured by a specific ICG-monitor (Solar IKG-Modul, Version 3.0, GE-Healthcare, Freiburg, Germany) with metabolic variables. Methods Ten healthy volunteers were included in the investigation doing ergometer exercise (5 min equilibration followed by 5 min each at 50, 75, 100 and 125 W). Hemodynamic parameters were obtained by ICG. Metabolic variables were assessed by indirect calorimetry with the Deltatrac II Metabolic monitor using a helmet system for spontaneous respiration. Results CI increased throughout exercise (baseline: 3.0 ± 0.4 l/min/m 2 ; 125 W: 4.8 ± 0.5 l/min/m 2 ). Heart rate (baseline: 87.2 ± 13.4 bpm; 125 W: 152.7 ± 22.4 bpm) and contractility (velocity index) (baseline: 48.9 ± 9.3/1000 s; 125 W: 70.5 ± 10.0/1000 s) showed a continuous rise while the stroke index decreased after an initial rise (baseline: 35.0 ± 4.6 ml/m 2 ; 50 W: 37.6 ± 4.9 ml/m 2 ; 75 W: 41.2 ± 5.9 ml/m 2 ; 125 W: 32.3 ± 6.1 ml/m 2 ). VO 2 (baseline: 335.2 ± 84.1 ml/min; 125 W: 1298.9 ± 282.3 ml/min) and VCO 2 (baseline: 255.4 ± 74.5 ml/min; 125 W: 1342.5 ± 282.5 ml/min) increased throughout exercise. There was a good correlation in the individual fits between hemodynamic and metabolic variables. Conclusion CI in healthy volunteers, as measured by the Solar IKG-Modul, correlates well with O 2 -consumption and CO 2 -production in individual subjects, thus indicating the metabolic needs under exercise conditions in healthy individuals.