title: The oxygen uptake efficiency slope in children with congenital heart disease: construct and group validity.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors: Child Development and Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: B C
authors: BC
authors: Bongers
authors: H J
authors: HJ
authors: Hulzebos
authors: A C
authors: AC
authors: Blank
authors: M
authors: M
authors: van Brussel
authors: T
authors: T
authors: Takken
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D001944:Breath Tests; D002648:Child; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006330:Heart Defects, Congenital / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D011379:Prognosis; D015203:Reproducibility of Results; D012720:Severity of Illness Index
chemical_list: D010100:Oxygen