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The oxygen uptake efficiency slope in children with congenital heart disease: construct and group validity
B C Bongers1, H J Hulzebos, A C Blank
1Child Development and Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
Insights
The oxygen uptake efficiency slope (OUES) is a valid measure of cardiopulmonary fitness in children with congenital heart disease (CHD). This effort-independent parameter differentiates between healthy children and those with CHD, and between different surgical repairs.
Area of Science:
- Cardiology
- Pediatric Exercise Physiology
- Pulmonary Rehabilitation
Background:
- The oxygen uptake efficiency slope (OUES) is a proposed objective measure of cardiopulmonary fitness, not requiring maximal exertion.
- Peak oxygen uptake (VO2peak) is commonly used but necessitates maximal exercise.
- Investigating OUES validity in pediatric congenital heart disease (CHD) populations is crucial.
Purpose of the Study:
- To assess the construct and group validity of the OUES in children with CHD.
- To determine if OUES is an independent and objective measure in this population.
Main Methods:
- Thirty-one children with CHD (16 Fontan repair, 15 Tetralogy of Fallot repair) underwent symptom-limited cardiopulmonary exercise testing.
- OUES was calculated at three different exercise intensities and normalized for body surface area.
- OUES, VO2peak, ventilatory threshold (VT), and ventilatory efficiency were compared to 46 healthy children.
Main Results:
- OUES values were consistent across different exercise intensities.
- Children with CHD exhibited significantly reduced OUES compared to healthy controls.
- Fontan patients showed lower OUES than Tetralogy of Fallot patients, with strong correlations between OUES, VO2peak, and VT.
Conclusions:
- The OUES is a valid, effort-independent measure of cardiopulmonary fitness in children with CHD.
- OUES demonstrates construct validity through strong correlations with VO2peak and VT.
- OUES exhibits group validity by differentiating between healthy children, children with CHD, and surgical subgroups.
Objective:
The oxygen uptake efficiency slope (OUES) has been proposed as an independent and objective alternative to the peak oxygen uptake (VO(2peak)), which does not require maximal exercise. The aim of this study was to investigate the construct and group validity of the OUES in children with congenital heart disease (CHD).
Methods:
Thirty-one patients with CHD, of which 16 patients (mean age ± SD 11.2 ± 2.7 years) with a Fontan repair and 15 patients (mean age ± SD 13.2 ± 3.6 years) with surgical repair of tetralogy of Fallot (ToF) completed a symptom-limited cardiopulmonary exercise test. The OUES was calculated and normalized for body surface area at three different exercise intensities: (1) using 100% of the exercise data; (2) using the first 75% of the exercise data; and (3) using exercise data up to the ventilatory threshold (VT). Furthermore, peak oxygen uptake (VO(2peak)), VT, ventilatory efficiency (V(E)/VO(2)-slope), and ventilatory drive (V(E)/VCO(2)-slope) were calculated and compared with values of 46 healthy children (mean age ± SD 12.2 ± 2.4 years).
Results:
In all three groups, the OUES values determined at the three different exercise intensities were not significantly different from each other. Moreover, the OUES was significantly reduced in the children with CHD, with significantly lower values in the Fontan patients compared to ToF. Strong correlations were found between the OUES and both the VO(2peak) and VT in Fontan and ToF patients.
Discussion:
The OUES provides a valid measure of cardiopulmonary fitness in children with CHD, which is independent of exercise intensity and strongly correlated with VO(2peak) and VT (construct validity). Furthermore, the OUES is capable of differentiating between healthy children and children with CHD and between Fontan and ToF patients (group validity). Therefore, the OUES may be a valid, effort-independent parameter of cardiopulmonary fitness in children with CHD.
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