Alveolar/Arterial Gradient and Arterial/Alveolar Oxygen Ratio
Davis’s Laboratory and Diagnostic Tests Online, powered by Unbound Medicine, provides nurses and students access to 400+ test monographs containing reference ranges, indications, patient preparation and result interpretation. Explore these free sample topics:
-- The first section of this topic is shown below --
Alveolar-arterial difference, A/a gradient, a/A ratio.
To assist in assessing oxygen delivery and diagnosing causes of hypoxemia such as pulmonary edema, acute respiratory distress syndrome, and pulmonary fibrosis.
Arterial blood collected in a heparinized syringe. Specimen should be transported tightly capped and in an ice slurry.
(Method: Selective electrodes that measure Po2 and Pco2)
|Alveolar/arterial gradient||Less than 10 mm Hg at rest (room air)|
|20–30 mm Hg at maximum exercise activity (room air)|
|Arterial/alveolar oxygen ratio||Greater than 0.75 (75%)|