Why does emphysema, characterized by loss of elastic recoil, lead to airway collapse during exhalation?

From the Guidelines

Emphysema leads to airway collapse during exhalation because the destruction of alveolar walls and elastic fibers reduces the lung's elastic recoil, as supported by the most recent study from 2025 1. This destruction of elastic fibers and alveolar walls results in a loss of pulmonary elastic recoil, making the small airways more likely to collapse during expiration, as noted in the 1997 BTS guidelines for the management of chronic obstructive pulmonary disease 1. The pathophysiology involves proteolytic enzymes breaking down elastin fibers, often triggered by cigarette smoke exposure or alpha-1 antitrypsin deficiency. Key points to consider include:

• The loss of elastic recoil due to emphysema reduces the lung's ability to maintain airway patency during exhalation 1
• The destruction of alveolar walls and elastic fibers leads to airway collapse, causing the characteristic hyperinflation seen in emphysema patients 1
• The use of anti-inflammatory treatment may be beneficial in some cases, as the presence of inflammatory cells within the airway wall and lumen provides a rationale for such treatment 1
• Airway eosinophilia is associated with a measurable bronchodilator response to β agonists and relatively less emphysema for any degree of airflow limitation 1. In normal lungs, elastic recoil helps maintain airway patency by providing outward traction on airways during exhalation. When this elastic recoil is diminished in emphysema, the airways lose their structural support and become more susceptible to collapse, especially during forced exhalation when intrathoracic pressure increases. This collapse traps air in the lungs, causing the characteristic hyperinflation seen in emphysema patients. As airways collapse during exhalation, patients develop the classic "air trapping" and barrel chest appearance. This mechanism explains why emphysema patients often purse their lips when breathing out - this creates back pressure that helps keep smaller airways open longer during exhalation, allowing more complete emptying of the lungs. The most recent study from 2025 1 highlights the importance of considering the effects of bronchodilators on lung physiology in COPD, including the loss of elastic recoil and airway collapse during expiration.

From the Research

Emphysema Characterization and Airway Collapse

• Emphysema is characterized by the loss of elastic recoil in the lungs, which can lead to airway collapse during exhalation 2.
• The loss of elastic recoil is associated with reduced alveolar attachments and increased lung size, but not with air-flow limitation in mild emphysema 2.
• The structural and functional changes in lungs with mild emphysema include reduced elastic recoil, increased lung size, and some size distribution changes in the small airways 2.

Relationship Between Elastic Recoil and Airway Collapse

• The relationship between elastic recoil and airway collapse is crucial in understanding the pathophysiology of emphysema 2.
• The loss of elastic recoil can lead to airway collapse during exhalation, which can further exacerbate the disease 2.
• However, the exact mechanisms underlying the relationship between elastic recoil and airway collapse are not fully understood and require further research.

Management of Emphysema and COPD

• The management of emphysema and COPD involves a combination of pharmacological and non-pharmacological approaches 3, 4, 5.
• Bronchodilators, inhaled corticosteroids, and phosphodiesterase-4 inhibitors are some of the pharmacological agents used to manage COPD 3, 6, 5.
• Non-pharmacological approaches include long-term oxygen therapy, pulmonary rehabilitation, and lung-volume-reduction surgery 3, 4, 5.