Study objectives: We determined whether emphysema
demonstrated on high-resolution CT (HRCT) scanning in apparently well
smokers is associated with airflow obstruction.
Interventions: Lung function testing and limited HRCT
Design: Lung function measurements and scans
were analyzed independently of each other. We used analysis of
covariance to compare FEV1 and maximum expiratory flow at
50% of vital capacity (MEF50) values after suitable
corrections, between subjects with and without parenchymal damage
(emphysema and/or reduced carbon monoxide transfer coefficient[
Kco]), and to compare indexes of parenchymal damage
between subjects with and without airflow obstruction.
Setting: Radiology and lung function departments of a
district general hospital.
current cigarette smokers and 20 lifetime nonsmoking control subjects
(aged 35 to 65 years) who volunteered following publicity in local
media. In all subjects, FEV1 was > 1.5 L; no
subjects were known to have lung disease.
results: FEV1 and MEF50 were measured
spirometrically; static lung volumes were measured by helium dilution
and body plethysmography; Kco was measured by a
single-breath technique. HRCT scans were analyzed for emphysema by two
radiologists. Of smokers, 25% had HRCT emphysema, generally mild;
16.3% and 25% had reduced FEV1 and MEF50,
respectively; 12.5% had reduced Kco. Smokers with airflow
obstruction were not more likely to have parenchymal damage. Smokers
with parenchymal damage did not have reduced airway function.
Nonsmokers generally had normal airways and parenchyma.
Conclusions: “Normal” smokers with lung damage had
either airflow obstruction or parenchymal damage, but not generally