Identifying airways responsible for heterogeneous ventilation and mechanical dysfunction in asthma: an image...

Area of Science:

• Pulmonary Medicine
• Computational Biology
• Medical Imaging

Background:

• Asthma involves airway narrowing, leading to impaired lung function and ventilation defects.
• The relative contribution of small versus large airways to asthma pathophysiology remains debated.

Purpose of the Study:

• To investigate the role of small and large airways in asthma-related mechanical dysfunction and ventilation defects using image functional modeling.
• To determine if small airway constriction alone or in combination with large airway constriction is necessary to replicate observed asthma symptoms.

Main Methods:

• Developed an image functional modeling approach synthesizing Positron Emission Tomography (PET) imaging and mechanical data with computational lung models.
• Mapped PET-derived ventilation defects to computational models to identify critical airway sizes (<2.39 mm, mostly <0.44 mm).
• Simulated airway constriction in models to match measured lung resistance, elastance, and PET ventilation defects in six asthma patients.

Main Results:

• Matching both mechanical impairment and PET ventilation defects required either constriction of small airways (<2.4 mm) alone or simultaneous constriction of small and large airways.
• Constriction of large airways alone did not replicate the observed ventilation defects.
• Ventilation dysfunction in asthma is linked to heterogeneous, near-complete closures primarily in small airways.

Conclusions:

• Small airways play a critical role in ventilation defects observed in asthma.
• Image functional modeling provides insights into the heterogeneous nature of airway dysfunction in asthma.
• Therapeutic strategies targeting small airways may be crucial for improving ventilation in asthma patients.