Osmosis Question of the Week July 29, 2016

July 29, 2016

Answer: D. Decreased FVC, decreased FEV1, normal FEV1/FVC ratio, and decreased DLCO

This patient has interstitial lung disease as evidenced by the three classical symptoms of: cough, fine crackles (often described as "Velcro-like crackles"), and digit clubbing. These 3 symptoms can be remembered by the mnemonic "3Cs" (cough, crackles, clubbing). Other clues to this patient's diagnosis are his unresponsiveness to bronchodilators, and his long history of rheumatoid arthritis.

Common causes of interstitial lung disease are idiopathic, environmental (eg, asbestosis/silicosis), hypersensitivity (eg, bird fancier's lung), autoimmune (eg, rheumatoid arthritis, lupus), and drug-induced (eg, amiodarone). The disease is characterized by fibrosis of the lung parenchyma. This results in volume restriction (decreased FVC), and impaired gas diffusion in the lung (decreased DLCO).

Major takeaway: Pulmonary fibrosis is associated with systemic connective tissue disease such as rheumatoid arthritis. It has the symptom triad of cough, crackles, and clubbing. It causes decreased total lung capacity (TLC) and gas diffusion in the lungs.

For more on pulmonary fibrosis, read here.


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