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Diffusing Capacity
Aka: Diffusing Capacity, Diffusing Capacity of the Lung for Carbon Monoxide, DLCO- See Also
- Background
- Capacity of lung to transfer gas across alveoli
- Alveoli exposed to Carbon Monoxide
- Measure disappearance of Carbon Monoxide from the lung
- Technique: Single-Breath DLCO for patients at rest
- Patient takes a full Vital Capacity breath
- Inhalation mixture
- Carbon Monoxide 0.3% (Used to determine gas transfer)
- Helium 10% (Used to determine Lung Volume)
- Oxygen 21%
- Nitrogen 68%
- Breath held to Total Lung Capacity for 10 seconds
- Alveolar gas sample taken after washout
- Requires baseline Hemoglobin
- Results are adjusted based on the Hemoglobin level
- Corrected DLCO = DLCO / (0.07 x Hemoglobin)
- Causes: Decreased DLCO
- Restrictive Lung Disease
- Idiopathic Pulmonary Fibrosis
- Asbestosis
- Sarcoidosis
- Berylliosis
- Hypersensitivity pneumonitis
- Langerhans CellHistiocytosis X
- Miliary Tuberculosis
- Silicosis (advanced stage)
- Pneumonectomy
- Bronchiolitis Obliterans with Organizing Pneumonia
- Obstructive Lung Disease
- Cystic Fibrosis
- Emphysema
- Silicosis (early stages)
- Normal lung function tests
- Chronic Pulmonary Embolism
- Congestive Heart Failure
- Interstitial Lung Disease prior to PFT restrictive lung changes
- Primary Pulmonary Hypertension
- Connective Tissue Disease with lung involvement
- Dermatomyositis or Polymyositis
- Inflammatory Bowel Disease
- Rheumatoid Arthritis
- Systemic Lupus Erythematosus
- Systemic sclerosus
- Granulomatosis with Polyangiitis (previously known as Wegener's Granulomatosis)
- Restrictive Lung Disease
- Causes: Increased DLCO
- Asthma
- Left-to-right cardiac shunt
- Polycythemia Vera (see below)
- Pulmonary Hemorrhage
- Causes: Normal DLCO
- Causes: Falsely Abnormal DLCO (if Hemoglobin not 15 g/dl)
- See corrected DLCO for Hemoglobin Above
- Falsely elevated DLCO
- Falsely reduced DLCO
- References