An incremental exercise test was performed in 18 patients with interstitial lung
disease using bicycle ergometer to evaluate the exorcise capacity, the pattern of
ventilation, and gas exchange.
The maximum oxygen uptake (max VO2) was 1.02±0.34 L/min (46.4±
12.9% of predicted value). Anaerobic threshold was determined in 4 among 18 patients,
and the oxygen uptake at the determined anaerobic threshold was 0.87 L/min (39.8% of
predicted max VO2). The characteristic breathing pattern with exercise
was high frequency ventilation, which was more than 50 frequencies/min. With the
respect of contribution in the increase of minute ventilation, the fractional increase of
breathing frequency was significantly higher than that of tidal volume (p<0.01). The
breathing reserve decreased to 9.7±11.6%, but the heart rate reserve was preserved as
15.3±6.9%. The maximum oxygen pulse was 7.31±2.08 L/min/beat (59.1±15.3% of
predicted value). The PaO2 was 71.1±11.4 ㎜Hg at resting and it was
significantly decreased to 54.6±11.9 ㎜Hg (p<0.01) at maximal exercise and the range of
decrease in PaO2 was 15.9±10.1 ㎜Hg.
The correlation coefficients were investigated between the resting pulmonary function
parameters and the exercise testing parameters. There were significant correlations
between FVC and max VO2 (r=0.5776, n=18), and between resting
PaOa2and max VO2 (r=0.6983, n=15/p<0.01).
It can be concluded that the exercise test might be a valuable tool for determining the
degree of physiologic impairment in interstitial lung disease, and the parameters of lung
function at resting state may not reflect the exercise capacity which is closely related to
the severity of exertional dyspnea.
|