Should Cerebral Near-infrared Spectroscopy be Standard of Care in Adult Cardiac Surgery?

Near-infrared spectroscopy (NIRS) is non-invasive, easy to use, and offers real-time monitoring of the oxygen content of cerebral tissue. An effective and user-friendly method of cerebral monitoring stands to offer a significant advance in patient care during adult cardiac surgery, particularly for surgery in which the continuity of cerebral vessels may be compromised. While the current evidence does not definitively show improvement in neurological outcomes, it can be argued that the overall risk to benefit ratio falls on the side of NIRS. NIRS also gives information about the oxygenation of systemic tissues. It may be that in surgery that does not involve the aortic arch, the value of NIRS will be in increased individualisation of patient management and improved systemic perfusion, impacting general outcomes as much as neurological outcomes. This review will summarise the need for neuromonitoring and the principles of NIRS. It will examine the thresholds used to define desaturation, the evidence for clinical benefit from NIRS, and the criticisms and limitations of NIRS. It will also discuss the uses of NIRS beyond improving neurological outcomes alone.