Measures: - **pO<sub>2</sub>**: oxygen in the blood (if ↓, use the [[A-a gradient]] to figure out why) - **pCO<sub>2</sub>**: carbon dioxide in the blood - **HCO<sub>3</sub>**: bicarbonate in the blood (some labs report tCO<sub>2</sub>, which is very similar and the two can be used interchangeably) - **pH**: blood pH The sample is taken from an artery, not a vein. ![[ABG interpretation.png]]