37_40_Interstitial lung diseases, fibrosis, sarcoidosis Flashcards
What are interstitial lung diseases (ILDs)?
A diverse group of rare, highly morbid pulmonary disorders characterized by inflammation and progressive scarring (fibrosis) of the lungs.
What is the interstitium of the lung?
The tissue area in and around the wall of the alveoli where O2 moves from the alveoli into the capillary network that covers the lung like a thin sheet of blood.
What part of the lungs do ILDs affect?
The distal airspaces and lung parenchyma.
What is the classification of ILD based on etiology?
Known etiology (40%) and Idiopathic interstitial pneumonia (IIP) (40%).
What are some known etiologies of ILD?
Drugs (amiodarone, bleomycin, immune checkpoint inhibitors, nitrofurantoin), CT diseases (RA, scleroderma, SLE, Sjonren’s syndrome), exposure to organic and inorganic dusts, autoimmune disorders.
What is idiopathic interstitial pneumonia (IIP)?
A category of ILD that includes major IIP, rare IIP, and unclassifiable IIP. Patients in this category usually have idiopathic pulmonary fibrosis (IPF).
What is granulomatous ILD?
A category of ILD that includes sarcoidosis.
What are some other types of ILD?
Pulmonary Langerhans cell histiocytosis and Lymphangiomatosis.
What are the symptoms of ILD?
Exercise induced dyspnea, dry cough, fatigue, exhaustion, clubbing of fingers, cor pulmonale.
What is the physical examination for ILD?
Initially no change, later definite fibrosis with Velcro-type crackles and bilateral fine crackles heard on chest auscultation during late inspiration.
What laboratory tests are done for ILD?
Serology to look for autoimmune antibodies (autoimmune diseases), inflammatory markers (CRP, ESR), sarcoidosis: serum ACE or Ca2+ levels.
What are the blood gas changes seen in ILD?
Progressive hypoxemia leading to later partial respiratory insufficiency, CO2 has a better diffusion capacity than O2, changes in O2 seen before changes in CO2, measure saturation change after exercise.
What is the role of chest X-ray in diagnosing ILD?
Not sensitive enough, only advanced stages can be seen, diffuse or nodular bronchovascular, reticulonodular or infiltrative pattern.
What is HRCT and its role in diagnosing ILD?
HRCT (high resolution CT) is required to make the small alveolar parts and distal parts of the lung more visible, pattern is usual interstitial pneumonia with reticulation (basal + subpleural predominance), honeycombing, and bronchiectasis (bronchi thickened with buildup of excess mucus).
What is bronchoscopy?
A diagnostic procedure that should be performed in all ILD patients except in case of extensive disease, and transbronchial lung biopsy is diagnostic for sarcoidosis, TB, cancer, eosinophil lung disease, and histiocytosis C.
When should cryobiopsy or VATS be performed in ILD patients?
In all other types of ILD except sarcoidosis, TB, cancer, eosinophil lung disease, and histiocytosis C.
What is bronchoalveolar lavage (BAL)?
A diagnostic method in which a bronchoscope is passed through the mouth/nose into an appropriate airway in the lungs, with a measured amount of fluid introduced and then collected for examination.
What is BAL diagnostic for?
Eosinophil lung diseases.
What does high cell numbers in BAL indicate?
Worse prognosis, might indicate hypersensitive pneumonitis (HP), drug-induced IDL or infection etc.
What happens to lung function with progression of the disease in ILD patients?
It becomes a restrictive ventilatory disorder with a decrease of FVC, FEV1, TLC, RV, and decreased diffusion capacity.
What is 6MWT?
A simple, low-cost and widely used test to assess functional capacity, exercise tolerance and response to therapy in individuals with various health conditions.
How is 6MWT performed?
Patient walks as far as possible in 6 minutes along a straight, flat and enclosed corridor with a hard surface, and the distance, pulse, saturation, and dyspnea scale are measured.
What is Idiopathic Pulmonary Fibrosis (IPF)?
The most common type of IDL characterized by irreversible pulmonary fibrosis and impaired pulmonary function.
What are the characteristics of IPF?
It is characterized by patchy, progressive bilateral interstitial fibrosis. Males are affected more than females. It occurs in people over 50 years old. Histological and radiological pattern referred to as idiopathic interstitial pneumonia (IIP).
What is the pathogenesis of IPF?
A favored theory is that repeated alveolar epithelial injury leads directly to abnormal wound healing and formation of fibroblastic and myofibroblastic foci that secrete excessive ECM (collagens). Epidemiological studies suggest that triggers include inhalation of metal/wood dust, smoking, GERD, or exposure to herpesviruses. Cytokine production by alveolar epithelial cells may play an important role in the development of fibrosis. Host genetic factors are also likely to be important in the pathogenesis of fibrosis, e.g. MUC5B gene polymorphisms and telomerase mutations.
What are the clinical features of IPF?
Dry (non-productive) cough, progressive dyspnea, velcro-type crackles (bilateral fine crackles heard during inspiration), cyanosis, cor pulmonale, and peripheral edema may develop in later stages, digital clubbing due to chronic hypoxia.
