Mixed venous oxygen.

In critically ill patients, measurement of mixed venous oxygenation is useful as an indicator of the adequacy of tissue oxygenation and as an indirect reflection of cardiac output. The flexible fiberoptic pulmonary artery catheter oximeter permits continuous in vivo measurements of the mixed venous oxygen saturation. However, in some groups of critically ill patients, such as those with adult respiratory distress syndrome or sepsis, measurements of mixed venous oxygen may be misleading and should be interpreted with caution.