Central* | Peripheral | |
pH¶ | Add 0.03 to 0.05 units | Add 0.02 to 0.04 units |
PCO2 | Subtract 4 to 5 mmHg | Subtract 3 to 8 mmHg |
PCO2: partial pressure of carbon dioxide.
* Mixed venous blood, which is drawn from the distal port of a pulmonary artery catheter, gives similar results to central venous blood.
¶ Venous base excess is approximately 0.15 higher than the arterial values, and the venous lactate is approximately 0.12 higher than the arterial lactate. However, these values are rarely needed since they can be readily interpreted from peripheral venous blood.