Article

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.

Langue : ANGLAIS