Combined Pulmonary Fibrosis and Emphysema: Pulmonary Function Testing and a Pathophysiology Perspective

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Radiology

Background:

• Combined pulmonary fibrosis and emphysema (CPFE) is increasingly recognized.
• CPFE exhibits severe imaging and gas exchange abnormalities, yet mild spirometric impairment.
• Understanding CPFE pathophysiology is key for clinical management.

Purpose of the Study:

• To explore gas exchange and mechanical abnormalities in emphysema, fibrosis, and CPFE.
• To correlate pathophysiologic findings with pulmonary function testing (PFT) patterns in CPFE.
• To elucidate the impact of combined processes on PFT results.

Main Methods:

• Review of gas exchange and mechanical pathophysiologic abnormalities.
• Analysis of PFT patterns in relation to emphysema and fibrosis.
• Correlation of imaging findings (CT) with physiological data.

Main Results:

• CPFE lung elastance and compliance are intermediate between emphysema and fibrosis alone.
• CPFE shows preserved FEV1/FVC ratio despite emphysema on CT.
• Severe reduction in diffusing capacity for carbon monoxide (DLCO) is uniformly observed in CPFE.
• Higher lung volumes in CPFE compared to pulmonary fibrosis alone.

Conclusions:

• CPFE pathophysiology results in significant gas exchange impairment (reduced DLCO).
• Despite normal spirometry, CPFE patients often have severe functional impairment and poor prognosis.
• Understanding CPFE pathophysiology aids clinicians in managing these complex lung diseases.