Kusenbach G, Wieching R, Barker M, Hoffmann U, Essfeld D
Kinderklinik, Rheinisch-Westfälische Technische Hochschule Aachen, Germany.
Eur J Appl Physiol Occup Physiol. 1999 Jan;79(2):192-6. doi: 10.1007/s004210050494.
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 (F(I)O2) of either 0.21 or 0.40. With a F(I)O2 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 V02 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(I)O2 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 VO, 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.
研究表明，患有囊性纤维化（CF）的患者，无论其身体素质如何，均表现出摄氧量（VO₂）动力学受损。本研究使用伪随机二进制序列运动测试，即在亚最大运动强度下通过自行车测力计测定，研究了补充氧气是否能改善CF患者的VO₂动力学，该测试同时应用不同频率的正弦波运动。研究对象为9名CF患者和13名健康对照者（HC），他们在呼吸湿度和温度适宜、吸入气中氧分数（F(I)O₂）分别为0.21或0.40的空气时进行运动。当F(I)O₂为0.21时，CF患者在静息状态（0.91对0.81）和运动过程中（0.97对0.89）的呼吸交换率（R）均高于HC。CF患者的氧饱和度（SO₂）略低，但在运动过程中仍保持在90%以上（92.7%对95.2%）。频谱分析显示，在CF患者中，VO₂与运动强度之间的振幅比（AR）在较宽频率范围内较低（P < 0.05）。此外，CF患者在较低频率下表现出更大的负相移（PS）（P < 0.005）。当F(I)O₂为0.40时，两组的SO₂均升高至约97%；而CF患者的R仍高于HC（0.92对0.81）。在对照组中，补充氧气提高了AR，但CF患者的VO₂动力学未受到显著影响。在HC中，补充氧气期间AR的增加表明在亚最大运动开始时VO₂存在心肺限制。在CF患者中，低AR和PS表明由于肌肉中氧利用受损导致VO₂反应减弱，因为补充氧气使SO₂恢复正常，但未能改善R和VO₂动力学。
