Reliability of peak $$\dot V{\text{O}}_2 $$ and maximal cardiac output assessed using thoracic bioimpedance in children

Abstract

The purpose of this study was to evaluate the reliability of a thoracic electrical bioimpedance based device (PhysioFlow) for the determination of cardiac output and stroke volume during exercise at peak oxygen uptake (peak VO(2) in children. The reliability of peak VO(2) is also reported. Eleven boys and nine girls aged 10-11 years completed a cycle ergometer test to voluntary exhaustion on three occasions each 1 week apart. Peak VO(2) was determined and cardiac output and stroke volume at peak VO(2) were measured using a thoracic bioelectrical impedance device (PhysioFlow). The reliability of peak VO(2) cardiac output and stroke volume were determined initially from pairwise comparisons and subsequently across all three trials analysed together through calculation of typical error and intraclass correlation. The pairwise comparisons revealed no consistent bias across tests for all three measures and there was no evidence of non-uniform errors (heteroscedasticity). When three trials were analysed together typical error expressed as a coefficient of variation was 4.1% for peak VO(2) 9.3% for cardiac output and 9.3% for stroke volume. Results analysed by sex revealed no consistent differences. The PhysioFlow method allows non-invasive, beat-to-beat determination of cardiac output and stroke volume which is feasible for measurements during maximal exercise in children. The reliability of the PhysioFlow falls between that demonstrated for Doppler echocardiography (5%) and CO(2) rebreathing (12%) at maximal exercise but combines the significant advantages of portability, lower expense and requires less technical expertise to obtain reliable results.

Influence of training status and exercise modality on pulmonary O2 uptake kinetics in pre-pubertal girls

“…The HR, RER and blood [lactate] criteria that are commonly applied for the acceptance of a _ VO 2 'max' both in adult and paediatric populations has recently been challenged (Barker et al 2009;Poole et al 2008b). Consequently, the peak _ VO 2 values reported here cannot be definitively stated to reflect a maximal effort and are presented for consideration within the limits of reliability reported for peak _ VO 2 determined using this traditional methodology (Welsman et al 2005).…”

Cardiac function and arteriovenous oxygen difference during exercise in obese adults

“…The Physio Flow uses a high-frequency and low-amperage alternating electrical current via six electrodes. The Physio Flow has been found to be a valid and reliable estimate of cardiac output and stroke volume at rest and during moderate to high-intensity exercise in healthy normal weight (Charloux et al 2000;Palmieri et al 2006;Richard et al 2001;Tordi et al 2004;Welsman et al 2005), overweight (Richard et al 2001;Palmieri et al 2006), and obese (Palmieri et al 2006) participants. Richard et al (2001) evaluated the reproducibility and accuracy of the Physio Flow against the direct Fick method during an incremental exercise test from rest to maximal exercise in normal-weight and overweight participants.…”

“…Test-retest reproducibility was reported as an intraclass correlation coefficient for stroke volume (0.77) and cardiac output (0.56). Welsman et al (2005) reported reliability of the Physio Flow during highintensity cycling exercise (comparing three trials). When three trials were analyzed together, error expressed as a coefficient of variation was 9.3% for cardiac output and 9.3% for stroke volume.…”

Determinants of maximal oxygen uptake in moderate acute hypoxia in endurance athletes

“…Cardiac output ð _ QÞ was measured using a non invasive impedance cardiograph device, the PhysioFlow PF-05 (Manatec biomedical, Paris, France). The PhysioFlow concept and methodology have been recently validated at rest and at exercise (Charloux et al 2000) and during a maximal progressive exercise (Richard et al 2001;Welsman et al 2005). This bioimpedance method of _ Q determination uses changes in thoracic impedance during cardiac ejection to calculate stroke volume (SV).…”