Abnormal blood oxygen level Abnormal mixed venous oxygen saturation 2025-10-27T09:02:07Z Abnormal oxygen saturation in mixed venous blood (SvO2). SvO2 can be measured in a sample of mixed venous blood drawn from the distal lumen of a catheter placed in the pulmonary artery. The SvO2 is dependent on arterial oxygen saturation, hemoglobin concentration, cardiac output, and tissue oxygen demands. A fall in SvO2 usually implies anemia, arterial oxygen desaturation, and/or decreased cardiac output; however, a normal or high value does not exclude such disturbances. When employed in conjunction with the other indicators of tissue oxygenation available in an intensive care unit, SvO2 can be useful as a guide for both prognosis and urgency of therapy.