Effect of mild hypoxemia on bronchial responsiveness.

: Nonspecific bronchial responsiveness may be influenced by a number of stimuli. A potentially important stimulus with significant clinical implications is hypoxemia. To investigate the effect of hypoxemia on baseline pulmonary function and bronchial responsiveness, 13 subjects (eight with mild asthma and five normal) were tested on two separate days within a 1-week period. Spirometry measured before and after breathing room air through the experimental circuit for ten minutes was not significantly different. Likewise, there was no difference in baseline spirometry during mild hypoxemia (arterial saturation of 90%) compared with air breathing. The eight asthmatic subjects underwent a methacholine bronchoprovocation challenge on each of the two test days. The PC20FEV1 measured on the "hypoxemic" day (3.7 +/- 4.5 mg/mL) was not significantly different from the measured on the "room air" day (2.5 +/- 2.4 mg/mL, P greater than .05). We conclude that mild hypoxemia does not significantly affect baseline spirometry nor bronchial responsiveness.