| Blood Gas Value | Arterial | Venous |
|---|---|---|
| pH | 7.35 to 7.45 | 7.30 to 7.40 |
| Pco2 | 35 to 45 mm Hg | 42 to 48 mm Hg |
| HCO2 | 22 to 28 mEq/L | 24 to 30 mEq/L |
| PO2 | 80 to 100 mm Hg | 35 to 45 mm Hg |
| O2 Sat | >95% | 60-80% |
* Technically only the oxygen (Po2) and carbon dioxide (Pco2) pressure readings are true blood gas values. The pH indicates the balance between the bases and acids in the blood. The bicarbonate (HCO2) reading is an indirect measurment that is calculated from the pH and Pco2 levels.