Cerebral Oximetry – Any Value ?

Cerebral oximetry monitoring, used with the intention of optimizing perioperative outcomes, is increasingly being used in the setting of both cardiac and non-cardiac surgery. Cerebral oximetry had its early beginnings in the 1980s with the work of Jöbsis and colleagues. By using multi-wavelength light sources in the near infrared range, these early investigations demonstrated the potential utility of exploiting the ability of the differential absorption of light by oxygenated and de-oxygenated hemoglobin in brain (and possibly other) tissue. Cerebral oximetry integrates venous and arterial signals to give a mixed (in an approximately 3:1 ratio of venous to arterial blood) overall tissue oximetric signal. By integrating this oximetric data and comparing it to validated direct measurements of jugular venous saturation, these devices (with at least 5 commercial devices now on the market worldwide and likely more to be approved soon), produce a continuous output of tissue (i.e. brain) oxygen saturation. This saturation information can then be integrated with our understanding of oxygenation delivery and utilization conditions to allow modifications to made in perioperative physiologic conditions with the aim of optimizing overall tissue oxygenation, and ideally, corresponding end-organ function and outcome.