Di Marco F, Terraneo S, Job S, Rinaldo RF, Sferrazza Papa GF,
Roggi MA, Santus P, Centanni S

Respir Med. 2017 Jun;127:7-13. doi: 10.1016/j.rmed.2017.04.006. Epub 2017 Apr 10.

BACKGROUND: The need for additional research on symptomatic smokers with normal
spirometry has been recently emphasized. Albeit not meeting criteria for Chronic
obstructive pulmonary disease (COPD) diagnosis, symptomatic smokers may
experience activity limitation, evidence of airway disease, and exacerbations.
We, therefore, evaluated whether symptomatic smokers with borderline spirometry
(post-bronchodilator FEV1/FVC ratio between 5th to 20th percentile of predicted
values) have pulmonary function abnormalities at rest and ventilatory constraints
during exercise.
METHODS: 48 subjects (aged 60 ± 8 years, mean ± SD, 73% males, 16 healthy, and 17
symptomatic smokers) underwent cardiopulmonary exercise testing (CPET), body
plethysmography, nitrogen single-breath washout test (N2SBW), lung diffusion for
carbon monoxide (DLCO), and forced oscillation technique (FOT).
RESULTS: Compared to healthy subjects, symptomatic smokers showed: 1) reduced
breathing reserve (36 ± 17 vs. 49 ± 12%, P = 0.050); 2) exercise induced dynamic
hyperinflation (-0.20 ± 0.17 vs. -0.03 ± 0.21 L, P = 0.043); 3) higher residual
volume (158 ± 22 vs. 112 ± 22%, P < 0.001); 4) phase 3 slope at N2SBW (4.7 ± 2.1
vs. 1.4 ± 0.6%, P < 0.001); 5) no significant differences in DLCO and FOT
results.
CONCLUSIONS: In smokers with borderline spirometry, CPET and second-line
pulmonary function tests may detect obstructive pattern. These subjects should be
referred for second line testing, to obtain a diagnosis, or at least to clarify
the mechanisms underlying symptoms. Whether the natural history of these patients
is similar to COPD, and they deserve a similar therapeutic approach is worth
investigating.