Interstitial Lung Disease Flashcards
Name four types of interstitial lung disease
Sarcoidosis
Pneumoconiosis
Fibrosing alveolitis
Extrinsic allergic alveolitis
Four changes which can result in pleural effusion
Increased hydrostatic pressure (congestive HF)
Decreased oncotic pressure (hypoalbuminaemia)
Decreased pleural pressure (atelectasis)
Increased endothelial permability (pneumonia)
Bleeding (trauma)
Decreased lymph drainage (malignancy, thoracic duct rupture)
Extrapulmonary causes of restriction
Pleural effusion
Pleural thickening
Pneumothorax
Scoliosis
Sarcoidosis
Multisystem granulomatous disorder (lungs, eyes and skin most commonly affected). Lymphocytic infiltration of the alveoli form non-caseating granulomas. Mostly affects young women
Symptoms: erythema nodosum, SOB, cough. Examination:raised ACE, restrictive LFTs, hypercalcaemia
CXR: bilateral hilar lymphadenomathy, pulmonary infiltrate, fibrosis
Treat with corticosteroids (+methotrexate)
Fibrosing alveolitis
Infiltration and fibrosis of the alveolar walls, common in patients over 50. Occurs in Rheumatoid arthritis.
Presents as gradually worsening exertional dyspnoea. Dry cough, clubbing and inspiratory crackles in the lung.
Basal bilateral fibrosis occurs in patches of the lung, (reticulonodular formations) causes a ground-glass/honeycomb appearance on CT and traction bronchiectasis
Pirfenidone is an anti-fibrotic given in the early stages of disease. Not an inflammatory disease so steroids of little benefit.
Extrinsic allergic alveolitis
Acute or chronic presentations caused by exposure to antigen which causes interstitial lymphocytic inflammation with granulomas.
Damage predominantly in the upper lobe of the lung (better ventilated)
Reaction is related to the dose of the inhaled antigen.
Acute presentation: dyspnoea, cough, malaise, and pyrexia. Fine inspiratory velcro crackles on auscultation. Restrictive spirometery Ground glass appearance of the lung on CXR and soft tissue nodules
Treat by avoiding cause and high dose corticosteroids.
Interstitial space in the lung
Potential space between alveolar cells and the capillary basement membrane. Only evident in disease states if it becomes filled with fibrous tissue or fluid
How does interstitial lung disease affect gas exchange?
Fluid and fibrous tissue in the interstitial space impairs gas exchange because the diffusion pathway between the alveolar air and the blood is increased.
Oxygen uptake is impaired more than CO2 because there is greater resistance to O2 diffusion.
Development of fibrous tissue also makes the lungs less compliant, which restricts ventilation because the lung volume is decreased.
Diseases caused by asbestos inhalation
Benign pleural plaques
Asbestosis (pulmonary fibrosis)
Mesothelioma
Asbestosis
Caused by inhalation of asbestos.
Penetrates the alveoli to produce alveolitis. There is an influx of macrophages which coat the fibres to produce asbestosis bodies. Alveolitis eventually develops into fibrosis.
Presentation of sarcoidosis
dry cough, dyspnoa, erythema nodosum, raised ACE, restrictive LFTs, hypercalcaemia
DDx of restrictive spirometry
Thoracic kyphosis Muscular dystrophy Myasthenia gravis Interstitial Lung disease Pleural thickening
What is heard on auscultation in a patient with interstitial lung disease
velcro-like crackles
Why do patients with sarcoidosis have hypercalcaemia?
Activated macrophages produce calcitriol independent of PTH and is therefore not controlled by negative feedback.
Vitamin D increases Ca2+ reabsorption from the gut
Hypercalcaemia causes renal stones and nephrocalcinosis
Give three examples of occupational lung diseases and the associated environmental factors
Farmer’s lung - EAA due to exposure to antigens in mouldy hay
Asbestosis (builders) - plaques and fibrosis due to inhalation
Silicosis - coal miners
