Critically ill patients have greater than normal
oxygen demands because of enhanced energy requirements placed on them by the stress of acute illness, blood and fluid loss, surgery, wound healing, and hospitalization. Early recognition of major alterations in
oxygen transport variables,
oxygen delivery, oxygen consumption, and the
oxygen extraction ratio, by the
critical care team assists in the prevention and treatment of tissue
hypoxia in seriously ill and injured patients. Supranormal levels of
oxygen delivery are required to meet these increased
oxygen demands, to prevent tissue
hypoxia, and to correct tissue
oxygen debt. The
critical care team should promptly determine the patient's
oxygen transport variables on admission to the intensive care unit to provide a starting point for patient
resuscitation. When deviations from supranormal values of
oxygen transport variables in these patients are identified, specific interventions that improve
oxygen delivery to peripheral tissues should be implemented and evaluated for their effectiveness in normalizing the
oxygen extraction ratio. When serial measurements of
oxygen delivery, oxygen consumption, and the
oxygen extraction ratio follow each therapeutic intervention that is directed at increasing
oxygen delivery, the survival rate of
critically ill patients is significantly improved.