A clinically oriented nomogram for the derivation and interpretation of alveolar-arterial oxygen gradients.
This paper is designed for those familiar with arterial blood gases, alveolar-arterial (A-a) oxygen gradients, and their application in the clinical setting. The concept of a gradient is reviewed, and several examples of clinical applications are given. A nomogram of A-a gradients is presented for two representative altitudes. Using only the PaO2 and PaCO2 available from blood gases, the corresponding A-a gradient can be found quickly. Further, the nomogram is presented in such a way as to facilitate interpretation of results. Finally, we present a computer program that will allow the production of a nomogram of A-a gradients appropriate for a specific altitude.
D000328:Adult; D000531:Altitude; D001158:Arteries; D001784:Blood Gas Analysis / Q000379:methods*; D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010313:Partial Pressure; D011650:Pulmonary Alveoli / Q000502:physiology*; D012129:Respiratory Function Tests / Q000379:methods; D012131:Respiratory Insufficiency / Q000175:diagnosis; D014692:Ventilation-Perfusion Ratio
D002245:Carbon Dioxide; D010100:Oxygen