Evaluation of respiratory muscle dysfunction in patients with idiopathic pulmonary fibrosis: a prospective observational study with magnetic resonance

Yang, X., Wang, H., Liu, A. et al. Evaluation of respiratory muscle dysfunction in patients with idiopathic pulmonary fibrosis: a prospective observational study with magnetic resonance imaging. BMC Pulm Med 25, 118 (2025). https://doi.org/10.1186/s12890-025-03572-6

Summary of Evaluation of respiratory muscle dysfunction in patients with idiopathic pulmonary fibrosis: a prospective observational study with magnetic resonance imaging

Abstract: This prospective observational study aimed to quantitatively evaluate diaphragm and chest wall dysfunction in patients with idiopathic pulmonary fibrosis (IPF) using dynamic magnetic resonance imaging (Dyn-MRI). A total of 96 IPF patients and 50 age- and gender-matched controls underwent assessments including Dyn-MRI, pulmonary function tests (PFTs), 6-minute walk distance (6MWD), and high-resolution CT. During quiet breathing, no significant differences were observed between groups. However, during deep breathing, IPF patients had reduced diaphragmatic and chest wall motion. Notably, diaphragmatic height and curvature area ratios were higher in IPF patients and correlated with disease severity, including lower PFT scores and 6MWD, indicating significant respiratory muscle dysfunction.

Key Points:

1. Diaphragm and Chest Wall Assessment via Dyn-MRI: The study employed Dyn-MRI to evaluate diaphragm and chest wall motion in IPF patients, offering a radiation-free, non-invasive method that allows simultaneous visualization of respiratory muscle activity during different breathing efforts.

2. Patient Cohort and Controls: The study included 96 IPF patients and 50 healthy, age- and gender-matched controls; IPF patients had lower total lung volumes (TLV), FVC, FEV1, TLC, and DLCO values and demonstrated reduced physical performance via the 6MWD.

3. Quiet vs. Deep Breathing Findings: No significant difference in chest wall and diaphragmatic function was found during quiet breathing, but during deep breathing, IPF patients had significantly decreased anterior-posterior (AP), cranial-caudal (CC), and lung area ratios compared to controls.

4. Altered Diaphragm Curvature in IPF: Diaphragmatic motion was more limited in the posterior and apical regions, and IPF patients showed increased diaphragm curvature height (DH) and area (DA), likely due to restrictive physiology and reduced lung compliance.

5. Functional Correlations with Disease Severity: Diaphragmatic and chest wall motion metrics during deep breathing were significantly correlated with TLV, FVC%, FEV1%, TLC%, and DLCO%, indicating that Dyn-MRI-derived metrics are reflective of lung function.

6. Exercise Capacity and Dyspnea Association: A strong correlation was observed between reduced diaphragmatic motion and worse 6MWD and MRC dyspnea scores, emphasizing the clinical relevance of respiratory muscle dysfunction in symptomatic limitation.

7. No Correlation with HRQoL or Fibrosis Extent: Interestingly, respiratory muscle dysfunction did not correlate with health-related quality of life scores or the extent of fibrosis on HRCT, suggesting other systemic factors contribute to muscle weakness.

8. Chest Wall Motion Specificity: Chest wall restriction was most evident in the dorsal-ventral (AP) direction, particularly at the diaphragm dome level, aligning with known pathophysiologic changes in restrictive lung diseases.

9. Comparative Mobility Patterns: While diaphragm motion reserve decreased in IPF, it remained unchanged during quiet breathing, unlike COPD patients who typically show increased diaphragmatic mobility in compensation.

10. Limitations and Future Directions: The single-center design, absence of severely symptomatic patients, and lack of diaphragmatic thickness or muscle strength measurements limit the findings; future studies are needed to explore treatment implications and prognostic use.

Conclusion: The study demonstrated that Dyn-MRI can detect significant diaphragmatic and chest wall dysfunction in patients with IPF during deep breathing, with these dysfunctions correlating with traditional severity markers like lung function and exercise capacity. The findings support the integration of respiratory muscle evaluation into IPF management and suggest Dyn-MRI as a valuable tool for comprehensive respiratory assessment.

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Discussion Questions:

1. How might Dyn-MRI influence future approaches to monitoring and managing respiratory dysfunction in patients with fibrotic lung diseases like IPF?

2. Given that diaphragmatic and chest wall dysfunction correlated with functional impairment but not fibrosis extent, what other pathophysiological mechanisms might contribute to respiratory muscle dysfunction in IPF?

3. Could targeted respiratory muscle training or rehabilitation improve diaphragmatic mobility and outcomes in IPF, and how might this be integrated into clinical care pathways?

Javier Amador-Castañeda, BHS, RRT, FCCM, PNAP

Interprofessional Critical Care Network (ICCN)

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