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

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Deutscher übersetzter Titel:Auswirkungen von Hyperoxie auf die Sauerstoffaufnahmekinetik von Patienten mit zystischer Fibrose, ermittelt durch eine pseudo-randomisierte binär-sequentielle Belastung
Autor:Kusenbach, G.; Wieching, R.; Barker, M.; Hoffmann, Uwe; Essfeld, D.
Erschienen in:European journal of applied physiology
Veröffentlicht:79 (1999), 2, S. 192-196, Lit.
Format: Literatur (SPOLIT)
Publikationstyp: Zeitschriftenartikel
Medienart: Gedruckte Ressource Elektronische Ressource (online)
Sprache:Englisch
ISSN:1439-6319, 0301-5548
DOI:10.1007/s004210050494
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Erfassungsnummer:PU199901306521
Quelle:BISp

Abstract des Autors

Patients with cystic fibrosis (CF) have been shown to exhibit impaired oxygen uptake (VO2) kinetics independent of their physical fitness. This study investigated whether oxygen supplementation improves VO2 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 (FiO2) of either 0.21 or 0.40. With a FiO2 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 VO2 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 FiO2 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 VO2 kinetics of the CF patients were not significantly affected. In HC the enhanced AR during oxygen supplementation would suggest a cardiopulmonary limitation of VO2 at the onset of submaximal exercise. In CF patients low AR and PS would indicate an attenuated VO2 response attributable to an impaired oxygen utilization in the muscles because the oxygen supplement normalised SO2 but failed to improve R and VO2 kinetics. Verf.-Referat