A whole-cortex fNIRS system to shine light on the problem of post-operative delirium

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PROJECT SUMMARY: For individuals > 60 years of age, the dangers of surgery include more than surgical complications: postoperative delirium (POD) is an established concern with reported incidence rates that exceed 50% for certain surgeries, including cardiac surgery. Nearly 3.9 million elderly patients are at risk for POD due to cardiac surgery alone. The dangerous sequelae associated with POD include increased perioperative morbidity, increased duration of hospitalization and increased risk of dementia, the additional costs of which amount to ~$152 billion. Despite the large number of investigations related to POD, no satisfactory intraoperative biomarkers or preoperative predictors have emerged that can prevent or curtail the dysfunction, exposing a critical gap in our understanding of signs and contributors to the condition. New methods of assessment are needed to guide changes and interventions in surgical procedures that can reduce the incidence of POD. A common shortcoming in research studies on delirium has been the lack of awareness and understanding of neurocognitive changes during surgery. Consequently, such studies are inadequate to identify what aspects of surgery contribute to delirium and to guide changes to surgical procedures that can possibly prevent it. Neuromonitoring during surgery has been largely limited to inconclusive cerebral oximetry and electroencephalography (EEG) studies. Cerebral oximetry lacks perspective of the whole cortex during surgery – missing potentially critical landmarks for delirium biomarkers; EEG studies suffer from low spatial resolution and high susceptibility to signal artifacts. Moreover, current tools are bulky and have unreliable adhesive attachments that imbue susceptibility to motion, mobility limitations, setup difficulty and inconsistency in data quality due to changes in sensor positioning expected during the perioperative workflow. In contrast, functional near infrared spectroscopy (fNIRS)-based perioperative monitoring of the whole cortex would offer better spatial resolution, lower susceptibility to artifacts, and a better view of the brain before, during and after surgery. We propose a novel fNIRS cap for perioperative monitoring to overcome the usability and sensing limitations of current neuroimaging technologies. This cap will improve on our first-generation wireless fNIRS system (Bowden) and leverage the immobilizing features of our novel granular jamming technology (Webster). In Aim 1 we will develop the fNIRS electronics, integrate them with granular jamming and perform mechanical and electrical testing. In Aim 2 we will perform i) a human pilot study to confirm the physiological validity of the results in a mock operating room and ii) a nested intraoperative pilot study (Shah) to confirm the feasibility to detect changes in fNIRS data correlated with the anesthesia care record. If successful, our novel cap will enable more comprehensive study of intraoperative contributors to and indicators of POD and other postoperative cognitive disorders.