• Except In the presence of left to right shunts, slow aspiration from the distal lumen of a catheter placed in the pulmonary artery can provide a sample of mixed venous blood. The oxygen saturation of such a sample (S[unk]O2) is dependent on arterial oxygen saturation, hemoglobin concentration, cardiac output, and tissue oxygen demands. A fall in S[unk]O2 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, S[unk]O2 can be useful as a guide for both prognosis and urgency of therapy.
(Arch Intern Med 1983;143:1400-1402)
Kandel G, Aberman A. Mixed Venous Oxygen SaturationIts Role in the Assessment of the Critically Ill Patient. Arch Intern Med. 1983;143(7):1400–1402. doi:10.1001/archinte.1983.00350070120019