Figure 36-4 Effect of cardiac output on PO₂ . A, Arterial and mixed venous O₂ tension and content are shown at a cardiac output of 5 L/min. B, Assuming a constant V̇O₂ , an increase in cardiac output to 8 L/min increases the PaO₂ from 78 to 85 mm Hg. This occurs because Sv̄O₂ increases at higher cardiac output. The resulting increase in O₂ content of the shunted blood (here assumed to be 10% of cardiac output) then raises arterial O₂ content and PaO₂ . PO₂ values are in mm Hg, and O₂ content is in mL/dL.