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Effects of hyperoxia on oxygen uptake kinetics in cystic fibrosis patients as determined by pseudo-random binary sequence exercise

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European Journal of Applied Physiology and Occupational Physiology Aims and scope Submit manuscript

Abstract

Patients with cystic fibrosis (CF) have been shown to exhibit impaired oxygen uptake (O2) kinetics independent of their physical fitness. This study investigated whether oxygen supplementation improves O2 kinetics in CF as determined by cycle ergometry at submaximal exercise intensities using a pseudo-random binary sequence exercise test i.e. a simultaneous application of different frequencies of sinusoidal work. The subjects were 9 CF patients and 13 healthy controls (HC) and they exercised while breathing humidified and heated air with a fractional concentration of oxygen in inspired air (F IO2) of either 0.21 or 0.40. With a F IO2 of 0.21 the respiratory exchange ratio (R) was higher in CF than in HC both at rest (0.91 vs 0.81) and during exercise (0.97 vs 0.89). Oxygen saturation (SO2) was slightly lower in CF, but remained above 90% during exercise (92.7% vs 95.2%). Spectrum analysis revealed that in CF, the amplitude ratio (AR) between O2 and exercise intensity was lower over a wide frequency range (P < 0.05). In addition, CF showed a larger negative phase shift (PS) at lower frequencies (P < 0.005). With a F IO2 of 0.40, SO2 increased to about 97% in both groups; while R remained higher in CF (0.92) compared to HC (0.81). In the control group, the O2 supplement raised AR but the O2 kinetics of the CF patients were not significantly affected. In HC the enhanced AR during oxygen supplementation would suggest a cardiopulmonary limitation of O2 at the onset of submaximal exercise. In CF patients low AR and PS would indicate an attenuated O2 response attributable to an impaired oxygen utilization in the muscles because the oxygen supplement normalised SO2 but failed to improve R and O2 kinetics.

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Accepted: 1 August 1998

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Kusenbach, G., Wieching, R., Barker, M. et al. Effects of hyperoxia on oxygen uptake kinetics in cystic fibrosis patients as determined by pseudo-random binary sequence exercise. Eur J Appl Physiol 79, 192–196 (1999). https://doi.org/10.1007/s004210050494

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  • DOI: https://doi.org/10.1007/s004210050494

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