Central venous oxygen saturation monitoring: role in adult donor care?

Monitoring oxygen saturation of blood drawn from a catheter placed within the superior vena cava (Scvo2) has recently been promoted as a substitute for evaluating oxygen saturation of mixed venous blood drawn from the pulmonary artery (Svo2). The Svo2 reflects the balance between oxygen delivery and oxygen consumption throughout the body and, among critically ill patients, may be helpful for assessing resuscitation, cardiac function, or oxygen homeostasis end points. Use of Scvo2 instead has been promoted because of its easier access and recent use during resuscitation of patients with severe infections. Although data from healthy subjects and critically ill patients are available, no study has been done among organ donors to evaluate customary values for either Scvo2 or Svo2 or how well the values correspond. After loss of oxygen consumption in the brain following brain death, the customary values for these variables may be different from values in other groups of patients. Therefore, until donor-specific normative values for these important parameters are identified, we do not recommend that Scvo2 be used to evaluate the balance between donor oxygen consumption and delivery or as a variable to guide treatment.