Mixed venous hemoglobin saturation: theory and application

SvO2 measurement by reflectance oximetry incorporated into a thermodilution catheter is a reliable method of assessing the adequacy of oxygen delivery and is currently the best method of continuously monitoring oxygen supply-demand relationships. The SvO2 measurement continuously monitors the tissue status of oxygenation. It is an early warning indicator of detrimental changes in supply and demand and is an on-line tool in guiding therapeutic management and evaluating the effectiveness of interventions. SvO2 monitoring is of value in the critically ill cardiac and general surgical patients, not only during the surgical intervention but also in the postoperative period when managing derangements of ventilation and circulation. In our experience, continuous surveillance of the SvO2 currently is the best rapidly responsive indicator of cardiopulmonary function and oxygen transport.