adults ( 24 ). Unlike adults, Ellis et al demonstrated in children that the partial pressure of end-tidal carbon dioxide (PETCO 2 ; a surrogate measure of PaCO 2 ) and MCA V during exercise were not correlated, and the change in MCA V during exercise did not mimic the changes in PETCO 2 to the same
Christine M. Tallon, Ryan G. Simair, Alyssa V. Koziol, Philip N. Ainslie and Alison M. McManus
M.R. Johnson and P. Hopkins-Price
Children may undergo exercise testing for multiple reasons. Exercise testing measures multiple physiologic parameters when the body is under stress and can be performed by cycle or treadmill protocols. A higher oxygen consumption (VO2) has been noted by treadmill protocols. The oxygen uptake efficiency slope (OUES) and slope of ventilation to carbon dioxide (VE/VCO2) are newer parameters of cardiopulmonary response. Differences in OUES and VE/VCO2 slope have not been compared in regards to method of testing.
Clinical exercise tests performed by graded treadmill (Treadmill group) were compared with those performed by cycle ergometer (Cycle controls) from a previous study carried out at a separate institution. Exercise testing of persons with cystic fibrosis (Cycle CF) was evaluated during the same study. Age, weight, height, body mass index, sex, pulmonary function, maximal heart rate, VO2max, VEmax, end tidal carbon dioxide (ET-CO2), OUES and VE/VCO2 slope were compared by unpaired student’s T-test among the three groups. Pearson product moment correlations compared VO2max, OUES and VE/VCO2 slope in all three study groups.
The Treadmill group and Cycle controls had similar age, height, weight, BMI and baseline pulmonary function. The Cycle CF group had lower height, weight and BMI but similar age and pulmonary function to the other two groups. VO2max, and VEmax were significantly higher in Treadmill group than cycle controls. OUES was higher in the Treadmill group than cycle controls (p=0.07). Correlation between VO2max and OUES was 0.89 in treadmill group, 0.96 in cycle controls and 0.93 in cycle CF.
This study suggests OUES and VO2max, are highly correlated in healthy controls whether obtained by cycle or treadmill protocols. Variation in the level of correlation between VE/VCO2 slope and VO2max existed in the three study populations. VE/VCO2 slope correlated highest with end tidal carbon dioxide at maximal exercise and this may confound the use of the VE/VCO2 slope in healthy populations. No clear advantage to testing by treadmill or cycle ergometry was determined in this study and testing can be determined based on institutional preference.
Marco Van Brussel, Bart C. Bongers, Erik H.J. Hulzebos, Marcella Burghard and Tim Takken
). Figure 1 —The 7-step interpretative strategy for pediatric CPET. CPET, cardiopulmonary exercise testing; HR peak , heart rate at peak exercise; P ET CO 2 , partial end-tidal carbon dioxide tension; RER, respiratory exchange ratio; RER peak , RER at peak exercise; VE, minute ventilation; VE/WR, minute