Differences in regional air trapping in current smokers with normal spirometry.

Area of Science:

• Pulmonary Medicine
• Radiology
• Respiratory Health

Background:

• Smoking is a major cause of lung disease, including chronic obstructive pulmonary disease (COPD).
• Early detection of smoking-related lung damage is crucial for intervention.
• Computed tomography (CT) can reveal structural lung changes not always apparent in spirometry.

Purpose of the Study:

• To investigate the prevalence and characteristics of regional air trapping in current smokers with normal spirometry.
• To determine if regional air trapping represents an early manifestation of smoking-related lung changes.
• To compare CT findings in smokers with and without air trapping to healthy individuals and COPD patients.

Main Methods:

• Utilized computed tomography (CT) scans of 40 current smokers, 40 COPD patients, and 40 healthy never-smokers.
• Assessed regional air trapping on end-expiratory CT scans.
• Measured emphysema, micronodules, and bronchial wall thickening on inspiratory scans.
• Calculated the expiratory/inspiratory (E/I) mean lung attenuation ratio to quantify static air trapping.

Main Results:

• Regional air trapping was detected in 63% of current smokers, 45% of never-smokers, and 8% of COPD patients (p<0.001).
• Smokers with air trapping exhibited a significantly lower E/I ratio (0.81) compared to those without (0.91) (p<0.001).
• Current smokers with air trapping had higher forced expiratory volume in 1 second (FEV1) and less emphysema on CT, contrasting with those without air trapping who resembled COPD.

Conclusions:

• Regional air trapping is a frequent finding in current smokers with normal spirometry, indicating potential early structural lung changes.
• The presence of air trapping in smokers with normal lung function suggests heterogeneity in smoking-related lung disease development.
• CT-assessed regional air trapping may serve as an early biomarker for smoking-induced lung damage, potentially aiding in risk stratification and early intervention.