A Blood gas test or blood gas analysis tests blood to measure blood gas tension values. It also measure blood PH ,and the level and base excess of bicarbonate.
| Blood Gas Component | Arterial | Venous |
| PH | 7.35-7.45 | 7.31-7.41 |
| PO2 | 80-100mm Hg | 35-40mm Hg |
| PCO2 | 35-45 mm Hg | 41-51mm Hg |
| HCO3 | 22-26 mEq/l or mmol/L | 22-26 mEq/L or mmol/L |
| Base Excess (BE) | -2 to +2 meq/L or mmol/L | -2 to +2 mEq/L or mmol/L |
| O2 saturatio | 95%–100% | 68%-77% |