4.2 - Idiopathic Pulmonary Fibrosis

Question 1

What is idiopathic pulmonary fibrosis?

Answer 1

It is also known as cryptogenic fibrosing alveolitis, and it is a specific form of chronic, progressive and fibrosing interstitial pneumonia with an unknown cause

Question 2

Who develops (Idiopathic pulmonary fibrosis) IPF?

Answer 2

• It occurs in adults and the disease is limited to the lungs. It is associated with the histopathologic and or radiologic pattern of usual interstitial pneumonia (UIP)
• it is strongly linked to cigarette smoking. Also exposure to stone, metal, wood and organic dusts has been suggested as a risk factor.
• It is more common in men than women.

Question 3

What symptoms are associated with IPF and how do they progress?

Answer 3

There is a gradual onset of symptoms usually over several months:

• Progressive dyspnea that is slow or rapid
• A nonproductive cough. Comorbid COPD or CHF may contribute to this symptom

Ask about prior exposure to inorganic dusts, organic* *dusts, fumes, chemotherapy, radiation, or HIV

Question 4

What laboratory/diagnostic tests are done for IPF?

Answer 4

• Chest x-ray - is typically obtained in adults with cough and progressive shortness of breath. Changes with the lung parenchyma especially in the lower lobes is demonstrated on chest x-ray and high resolution CT scan. Other changes include interstitial infiltrates, nodules and cystic changes called “honeycombing”
• High resolution computed tomography (HRCT) - should be obtained on all patients with suspicion of IPF. The characteristics that confirm IPF include peripheral, bibasilar reticular opacities, opacities with architectural distortion, traction bronchiectasis and honeycombing. Honeycombing is further described as cystic airspaces approximately 3 to 10 cm in diameter usually in a sub pleural location.
• PFTs - Complete PFTs, spirometry, lung volumes, diffusing capacity for carbon monoxide (DLCO) and resting and ambulatory pulse oximetry are obtained in virtually all patients with ILD. In patients with IPF, studies typically show a restrictive ventilatory defect. Some patients may show a coexisting bronchoconstriction in their small airways. The diffusing capacity of lung for carbon dioxide is commonly reduced. This is a manifestation of altered ventilation and perfusion in the lungs.
• ABG and pulse oximetry - may show hypoxemia as the disease progresses. When the disease is severe, there is retention of carbon dioxide.
• Routine lab findings generally are not helpful
• If IPF is suspected, antinuclear antibodies should be obtained
• PPD test should be done
• The patient should be tested for prior exposure to deep fungi such as Histoplasma capsulatum (chicken coops in the Midwest), and Coccidioides immitis (dust in the Southwest desert and Central Valley of California)

Question 5

How do you treat patients with IPF?

Answer 5

1. Corticosteroids (prednisone 1 mg/kg/day for 12 weeks)

• Use for acute exacerbations although scientific evidence/support for benefit is lacking
• Many patients report subjective improvement
• Far fewer demonstrate objective improvement on x-ray or on PFTs
• Use caution with the elderly population because of the significant side effects of bone demineralization, immunosuppression and hyperglycemia

2. Alternative treatments that may be considered in selected patients include cyclophosphamide (Cytoxan) 1 mg/kg/day or azathioprine (Imuran) 3 mg/kg/day although data to support immunosuppressive therapy in this setting is limited

3. CPAP/BIPAP - Noninvasive use of positive airway pressure (by mask) may be beneficial in selected patients

4. Lung transplantation - remains the ultimate therapy in those with advanced IPF. Patients should be referred for transplant at the time of diagnosis

Question 6

What is the prognosis for patients with IPF?

Answer 6

Prognosis is often poor due to the continued progression of the disease. Patients with rapidly progressive or end stage disease should be counseled on palliative care and end of life issues

• Pulmonary rehabilitation - has been associated with improvements in six minute walk and quality of life
• Patients have a widely variable course but those diagnosed with spirometry showing mild, moderate, severe disease have been reported to have median survivals of 55.6, 38.7 and 27.4 months respectively