| A-a O2 | alveolo-arterial oxygen tension |
|---|---|
| AaPCO2, (A-a)PCO2 | alveolo-arterial carbon dioxide tension difference |
| AaPO2, (A-a) PO2 | alveolo-arterial oxygen tension difference |
| ATS | Achard-Thiers syndrome; acid test solution; alpha-D-tocopherol acid succinate; American Thoracic Soc... |
| CTH | ceramide trihexoside; chronic tension headache; cystathionase |