Small airways dysfunction is associated with increased exacerbations in patients with asthma

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology

Background:

• Asthma exacerbations are poorly understood, especially in patients with recurrent events despite treatment.
• Peripheral airway dysfunction is a potential, yet under-investigated, factor contributing to asthma exacerbations.

Purpose of the Study:

• To compare peripheral ventilation heterogeneity and respiratory system mechanics in asthma patients with different exacerbation histories.
• To determine if peripheral airway dysfunction is associated with asthma exacerbations.

Main Methods:

• Recruited three groups of asthma patients: stable, exacerbation-prone, and treated-exacerbation.
• Measured spirometry, lung volumes, ventilation heterogeneity using multibreath nitrogen washout (MBNW), and respiratory system mechanics via oscillometry.
• Analyzed acinar ventilation heterogeneity (S_acin) and respiratory system reactance (X_rs) as markers of small airway function.

Main Results:

• The exacerbation-prone group exhibited significantly worse acinar ventilation heterogeneity (S_acin) and respiratory system reactance (X_rs) compared to the stable group.
• Patients with a recent history of exacerbation (treated-exacerbation group) showed spirometry deficits but comparable small airway function to the stable group.
• Worse small airway function, indicated by increased S_acin (MBNW) and ΔX_rs (oscillometry), was evident in patients who experienced exacerbations.

Conclusions:

• Peripheral airway dysfunction, evidenced by increased acinar ventilation heterogeneity and altered respiratory system reactance, is associated with asthma exacerbation history.
• These findings suggest that active peripheral airway dysfunction plays a role in the pathophysiology of asthma exacerbations.
• Multibreath nitrogen washout and oscillometry are valuable tools for assessing peripheral airway function in asthma management.