Jugular bulb oxygen saturation monitoring for evaluating cerebral ischemia

Traumatic brain injury challenges the health care team to employ treatment modalities to prevent secondary brain damage. Initially, the focus was on controlling intracranial pressure and maintaining cerebral perfusion pressure. It is now known it is more critical to determine whether flow matches the brain's metabolic needs as indicated by the cerebral metabolic rate of oxygen. Measuring cerebral metabolic rate of oxygen, the brain's oxygen consumption, is not attained easily due to technical reasons; therefore, it is calculated from more easily attained values (cerebral blood flow x arteriovenous oxygen content difference [AVDO2]). Continuous monitoring of cerebral venous O2 saturation is accomplished via the jugular vein. In most incidences where arterial O2 saturation is stable, then AVDO2 is inversely proportional to the jugular bulb O2 saturation. Jugular bulb O2 saturation, and therefore AVDO2, can be used to evaluate cerebral O2 supply and demand balance as it correlates with cerebral blood flow, with important exceptions as discussed. The most immediate value of jugular bulb O2 saturation monitoring lies in its ability to guide the effects of therapy on O2 supply and demand balance.