Which measure helps assess diffusion capacity of the lung for carbon monoxide?

Which measure helps assess diffusion capacity of the lung for carbon monoxide?

• A. Lung diffusion capacity
• B. MIP
• C. PEFR
• D. DLCO

Answer: (D)

DLCO, or diffusing capacity of the lung for carbon monoxide, measures how well gases move from the alveoli into the blood. CO is used because it binds hemoglobin almost instantly, so the rate of uptake is limited mainly by the alveolar–capillary membrane and the capillary blood volume, not by blood flow. The test is usually done with a single-breath technique and the result is the DLCO value, typically given in ml/min/mmHg and often corrected for hemoglobin. A normal DLCO indicates the membrane and capillary bed are functioning well; a reduced DLCO points to diffusion impairment from thickened or scarred membranes (like interstitial lung disease), loss of surface area (emphysema), or decreased capillary blood volume (pulmonary hypertension). MIP measures inspiratory muscle strength, and PEFR reflects airway flow, neither of which assesses diffusion capacity. A general term like “lung diffusion capacity” isn’t as specific as DLCO, which is the established test for this measurement.

DLCO, or diffusing capacity of the lung for carbon monoxide, measures how well gases move from the alveoli into the blood. CO is used because it binds hemoglobin almost instantly, so the rate of uptake is limited mainly by the alveolar–capillary membrane and the capillary blood volume, not by blood flow. The test is usually done with a single-breath technique and the result is the DLCO value, typically given in ml/min/mmHg and often corrected for hemoglobin. A normal DLCO indicates the membrane and capillary bed are functioning well; a reduced DLCO points to diffusion impairment from thickened or scarred membranes (like interstitial lung disease), loss of surface area (emphysema), or decreased capillary blood volume (pulmonary hypertension). MIP measures inspiratory muscle strength, and PEFR reflects airway flow, neither of which assesses diffusion capacity. A general term like “lung diffusion capacity” isn’t as specific as DLCO, which is the established test for this measurement.