What is the clinical significance of no regional airspace consolidation with findings suggestive of air trapping, and how does it correlate with auscultation (listening to internal sounds of the body with a stethoscope)?

From the Guidelines

The patient's imaging study showing air trapping without regional airspace consolidation suggests possible small airway disease, and the next step should be to perform pulmonary function tests (PFTs) including spirometry with bronchodilator response to evaluate for reversible airway obstruction, as recommended by the GOLD Science Committee in 2025 1. The finding of air trapping is concerning for obstructive lung disease, such as asthma or chronic obstructive pulmonary disease (COPD). According to the GOLD Science Committee recommendations, using pre- and post-bronchodilator spirometry can help diagnose COPD and differentiate it from other conditions 1.

• The GOLD Science Committee recommends using pre-BD spirometry to rule out COPD and post-BD measurements to confirm the diagnosis, which can help reduce clinical workload and limit COPD overdiagnosis 1.
• If PFTs confirm obstructive disease, treatment with a short-acting bronchodilator such as albuterol 90 mcg, 2 puffs every 4-6 hours as needed for symptoms, may be initiated, and for persistent symptoms, a maintenance inhaler such as a long-acting beta-agonist/inhaled corticosteroid combination (like fluticasone/salmeterol 250/50 mcg twice daily) may be considered.
• Air trapping occurs when air cannot be fully expelled from the lungs due to airway obstruction, causing hyperinflation, which is commonly seen in obstructive lung diseases where narrowed airways trap air during exhalation, leading to increased residual volume and decreased exercise tolerance.
• Clinical correlation with auscultation findings is also essential, as wheezing on auscultation and patient self-reported wheezing can be useful in diagnosing airflow obstruction, as noted in the American College of Physicians guideline update 1.

From the Research

Air Trapping Findings

• The impression of no regional airspace consolidation with findings suggesting air trapping correlates with the need for auscultation to determine the underlying cause of air trapping 2, 3.
• Air trapping can be caused by various conditions, including bronchiectasis, interstitial lung disease, tree-in-bud opacities, and small airways disease 2, 3.
• The diagnosis of air trapping relies on accurate patient history and concomitant findings on computed tomography (CT) scans 3.

Correlation with Auscultation

• Auscultation is essential in correlating the findings of air trapping with the underlying cause, as it can help identify abnormal lung sounds associated with specific conditions 2, 3.
• The combination of CT scan findings and auscultation results can narrow down the differential diagnosis of air trapping 2, 3.

Underlying Causes of Air Trapping

• Bronchiectasis, interstitial lung disease, and small airways disease are common causes of air trapping 2, 3.
• Other conditions, such as constrictive bronchiolitis, hypersensitivity pneumonitis, and diffuse idiopathic neuroendocrine cell hyperplasia, can also cause air trapping 3.
• Chronic obstructive pulmonary disease (COPD) is another condition associated with air trapping, and its severity can be estimated using forced spirometry 4, 5.

Estimating Air Trapping Severity

• Forced spirometry can be used to estimate the severity of air trapping in COPD patients, with parameters such as forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) being useful in predicting hyperinflation 5.
• The ratio of residual volume to total lung capacity (RV/TLC) is also a useful parameter in estimating air trapping severity 4, 5.