Restrictive and Interstitial Lung Disease

J.B. Handler, M.D.

Physician Assistant Program University of New England 1

Abbreviations

      SLE- systemic lupus erythematosis DL CO - 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 2

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.

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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. 4

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.

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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.

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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.

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Terminal Respiratory Unit

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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 (



DL CO ).

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Pathophysiology

   Destruction of alveoli/capillaries dead space.



V/Q

mismatch; both shunting and increased Ongoing repair/re-injury cycle; non homogeneous scarring throughout lung.

 Lung compliance.

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Normal Lung Parenchyma

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Pulmonary Fibrosis

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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 13

Clinical Presentation

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

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”.

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Clubbing of Fingers

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Chest X-Ray

 Lung volume Interstitial “honeycombing” Indicates advanced Disease Images.google.com

PFT’s and ABG

     Marked reduction in all lung volumes.



FVC,



FEV

1, both often markedly

Normal FEV 1

/FVC (or  ) 

DL CO

ABG: progressive hypoxemia due to both  DL CO and V/Q mismatch. Worse with exercise. hypoxemia.   PCO PCO 2 2 reflects increased respiratory rate to accommodate levels rare except with end stage disease.

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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.

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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. 20

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.

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Scoliosis

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