Blood Gas Comparison and Normal Reference Ranges

Blood Gas Comparison and Normal Reference Ranges

Blood Gas Type	Arterial-ABG	Venous-VBG	Mixed Venous
Sample source	Arterial puncture or arterial line	Central venous catheter or venous puncture	Distal lumen of PA catheter
pH	7.35–7.45	7.31–7.41*
PCO₂ mm Hg	35–45	41–51*
PO₂ mm Hg	80–100	35–42*
O₂ saturation %	95	70–75*
HCO₃ mEq/L	22–26	23–29*

*Mixed venous and venous blood gases have the same reference range with mixed venous being more accurate of the true venous state.