WS21.8 Validity of the Oxygen Uptake Efficiency Slope (OUES) as a parameter of maximal and submaximal exercise testing in children with mild CF

Abstract

Objective Maximal oxygen consumption (VO2max) is considered as gold standard of maximal exercise testing. The Oxygen Uptake Efficiency Slope is stated as a valuable parameter of submaximal exercise. We sought to investigate the validity of OUES at different levels of exercise duration in children with mild CF. Methods 20 CF-patients with mild respiratory limitation (9 boys, age 12.45 yrs, FEV1 91.8% and BSA 1.44 m 2 ) were analysed. OUES was calculated at three levels of exercise intensity: at 50%, 75% and 100% (OUES50, OUES75 and OUES100). OUES/BSA was correlated with VO2max, VO2max/kg, maximal minute ventilation at exercise (VE), VE/VCO2, respiratory exchange ratio (RER). Results OUES50/BSA (1254±205), OUES75/BSA (1332±234) and OUES100/BSA (1348±233) all correlated strongly with VO2max (1704±518 ml/min) (correlation coefficient 0.69, 0.69, 0.66 respectively, P=0.001) and VO2max/kg (36.2±7 ml/kg/min) (P Conclusion The strong correlation between OUES values at 50%, 75% or 100% of activity and VO2max proves that OUES values are valid submaximal parameters in children with mild CF. Due to the fact that only OUES75 is equal to OUES100, it is important that the patients can perform at least 75% of the predicted maximal exercise to be reliable. OUES values have no correlation with maximal minute ventilation during maximal exercise.