Reduced Exercise Tolerance and Pulmonary Capillary Recruitment with Remote Secondhand Smoke Exposure

RATIONALE: Flight attendants who worked on commercial aircraft before the smoking ban in flights (pre-ban FAs) were exposed to high levels of secondhand smoke (SHS). We previously showed never-smoking pre-ban FAs to have reduced diffusing capacity (Dco) at rest. METHODS: To determine whether pre-ban FAs increase their Dco and pulmonary blood flow ([Image: see text]) during exercise, we administered a symptom-limited supine-posture progressively increasing cycle exercise test to determine the maximum work (watts) and oxygen uptake ([Image: see text]) achieved by FAs. After 30 min rest, we then measured Dco and [Image: see text] at 20, 40, 60, and 80 percent of maximum observed work. RESULTS: The FAs with abnormal resting Dco achieved a lower level of maximum predicted work and [Image: see text] compared to those with normal resting Dco (mean±SEM; 88.7±2.9 vs. 102.5±3.1%predicted [Image: see text]; p = 0.001). Exercise limitation was associated with the FAs' FEV(1) (r = 0.33; p = 0.003). The Dco increased less with exercise in those with abnormal resting Dco (mean±SEM: 1.36±0.16 vs. 1.90±0.16 ml/min/mmHg per 20% increase in predicted watts; p = 0.020), and amongst all FAs, the increase with exercise seemed to be incrementally lower in those with lower resting Dco. Exercise-induced increase in [Image: see text] was not different in the two groups. However, the FAs with abnormal resting Dco had less augmentation of their Dco with increase in [Image: see text] during exercise (mean±SEM: 0.93±0.06 vs. 1.47±0.09 ml/min/mmHg per L/min; p<0.0001). The Dco during exercise was inversely associated with years of exposure to SHS in those FAs with ≥10 years of pre-ban experience (r = −0.32; p = 0.032). CONCLUSIONS: This cohort of never-smoking FAs with SHS exposure showed exercise limitation based on their resting Dco. Those with lower resting Dco had reduced pulmonary capillary recruitment. Exposure to SHS in the aircraft cabin seemed to be a predictor for lower Dco during exercise.