Near Infrared Based Cerebral Autoregulation Monitoring in Moderate/Severe Traumatic Brain Injury: Physiologic Correlates and Outcome Association
Traumatic brain injury (TBI) is one of the world’s leading causes of death and disability, leading to over 500 billion Canadian dollars in societal costs annually. Impaired blood flow to the brain has be recently identified as a main cause for ongoing brain damage after TBI. Control of brain blood flow is termed cerebral autoregulation (CA). Our ability to accurately measure CA in patients at the bedside in the intensive care unit (ICU), is limited to invasive techniques that require neurosurgery expertise and carry risk. Near infrared spectroscopy (NIRS), a technology that measures the absorption of light waves by various tissues, can be used to measure brain oxygen levels after TBI and adapted to provide non-invasive CA measurements continuously. However, prior to widespread adoption of NIRS-based CA monitoring, we need: A. a better understanding of whether such measurements accurately represent those seen with standard invasive techniques, B. understanding of association between NIRS CA measures and other brain physiology (such as pressure and oxygen delivery), C. understanding of potential patient characteristics which are predictive of impaired NIRS-based CA, and D. the association between NIRS-base CA monitoring and patient outcomes after TBI.