Restrictive and Interstitial Lung Disease

1. Restrictive and Interstitial Lung Disease J.B. Handler, M.D. Physician Assistant Program University of New England

2. SLE- systemic lupus erythematosis DLCO- diffusing capacity for carbon monoxide HRCT- high resolution computed tomography ALS- Amyotrophic Lateral Sclerosis RR- respiratory rate IFIP- idiopathic fibrosing interstitial pneumonia RA- rheumatoid arthritis Abbreviations

3. Restrictive Disease and Dysfunction • Collection of diseases that are characterized by reduction in volume of air within the lung parenchyma. • Abnormal reduction in pulmonary ventilation. • Restrictive pattern on PFT’s. • Compensated by RR. • Multiple etiologies: Most common are forms of interstitial lung disease. • Some diseases have both obstructive and restrictive components: Cystic fibrosis, others.

4. Interstitial Lung Disease • Heterogeneous group of diseases (>180) with common response to lung injury. • Idiopathic fibrosing interstitial pneumonia (IFIP), formerly called Idiopathic (primary) Pulmonary Fibrosis: Classic example of restrictive lung disease. • Multiple secondary etiologies- see below. • Pathology is similar, regardless of etiology.

5. Secondary Etiologies • Drug related: Amiodarone (potent anti-arrhythmic), bleomycin (tx cancer), some antibiotics (sulfonamides), others. • Occupational inhalation: Silica, asbestos, beryllium, others. • Connective tissue disorders: SLE, Polymyositis, RA, scleroderma. • Others: Radiation, amyloidosis, sarcoidosis. • Infections: Fungal (Coccoidiomycosis, Pneumocystis), Mycobacterium, some viruses.

6. IFIP • Diagnosis of exclusion • Must exclude other etiologies (via biopsy) before saying “idiopathic”. • Variations of IFIP exist, with varying response to therapy. • Characteristic clinical, radiographic, PFT and other findings. • Poor prognosis as with many other etiologies of interstitial lung disease.

7. Pathology • Inflammatory infiltrate in lung parenchyma/interstitium: • Inflammation of alveolar epithelium and capillary endothelium followed by: • Fibrosis of the alveoli and interalveolar septum • Inflammation can include the respiratory bronchioles. • Thickening of alveolar-capillary membrane by collagen and fibrous tissue. • Over timeFibrosis throughout lung parenchyma.

8. Terminal Respiratory Unit Images.google.com

9. Pathology/Pathophysiology • Inflammatory cellular and fibrotic response. • Inflammatory cells release chemical mediators activation of fibroblasts collagen deposition. • Tissue injury, vascular injury and permeability. • Epithelial injury thickens/breaks alveolar-capillary membraneimpaired diffusion of gas (DLCO).

10. Pathophysiology • Destruction of alveoli/capillariesV/Q mismatch; both shunting and increased dead space. • Ongoing repair/re-injury cycle; non- homogeneous scarring throughout lung. • Lung compliance.

11. Normal Lung Parenchyma Images.google.com

12. Pulmonary Fibrosis Images.google.com

13. Clinical Presentation (IFIP) • Insidious onset most often with gradual development of shortness of breath; initially exertional, then at rest. • Other etiologies may have acutechronic presentation. • History: Occupational exposure? Smoker? • Travel history (parasitic infections) • Risk factors for HIV

14. Clinical Presentation • Decreased activity tolerance • Dry, non-productive cough • +/- fever; depends on etiology • Presentation may vary depending on etiology

15. Physical Exam, Testing • Lungs: Fine, inspiratory crackles (like velcro) at lung bases. RR late. • Clubbing of fingers: bony growth and enlargement of terminal phalange; present 25-50% of cases. • Chest x-ray (see below): May appear normal until advanced disease. • HRCT- may be useful- confirms “honey-comb pattern”.

16. Clubbing of Fingers Images.google.com

17. Chest X-Ray Lung volume Interstitial “honeycombing” Indicates advanced Disease Images.google.com

18. PFT’s and ABG • Marked reduction in all lung volumes. • FVC, FEV1, bothoften markedly • Normal FEV1/FVC (or ) • DLCO • ABG: progressive hypoxemia due to both DLCO and V/Q mismatch. Worse with exercise. PCO2 reflects increased respiratory rate to accommodate hypoxemia. PCO2 levels rare except with end stage disease.

19. Lung Biopsy • Most important tool to confirm diagnosis and sort out underlying etiologies. • Trans bronchial biopsy- least invasive, but sample size to small in most cases. • Thoracoscopic biopsy- less invasive than open thoracotomy but still requires small incisions into thorax. • Open lung biopsy- requires thoracotomy; multiple samples obtained from different areas of lung.

20. Treatment • No data to show that any treatment improves survival or quality of life of in patients with IFIP. Progressive disease in most patientsdeath in 3-5 years. • Other etiologies sometimes respond to systemic corticosteroids (prednisone, et al) or immunosuppressive agents with varying degrees of improvement.

21. Restrictive Disease: Others • Neuromuscular diseases: ALS, Muscular Dystrophy, Polio,etc. • Impair lung inflation; restrictive pattern on PFT’s. • Kyphoscoliosis: Decrease lung volume; restrictive pattern on PFT’s. – abnl forward bending puts pressure on lungs • Pleural diseases: prevent lung expansion; restrictive pattern on PFT’s.

22. Scoliosis Images.google.com