# Non-invasive monitoring of brain health during cardio-pulmonary bypass

> **NIH NIH R01** · MASSACHUSETTS GENERAL HOSPITAL · 2020 · $605,055

## Abstract

PROJECT SUMMARY
Despite continued improvements, major vascular and cardiac surgeries involving cardio-pulmonary bypass (CPB) still result
in high rates of neurological injury. Pathophysiologic changes during CPB result in pharmacokinetic alterations that
complicate the management of anesthesia and significantly alter major organ blood flow. Both anesthetic and analgesic
agents target the central nervous system and, in conjunction with potentially impaired cerebral auto-regulation, can result in
insufficient delivery of oxygen to the brain. While systemic hemodynamic and respiratory monitoring of the patients has
been used for a long time, there is no accepted standard for assessing brain health. A number of cerebral oximeters, based
on continuous-wave near-infrared spectroscopy measurements exist on the market. However, despite studies showing some
utility in that drops in brain hemoglobin oxygen saturation (SO2) during surgery have been correlated with neurological
deficits, they have not been adopted as clinical standards. This is largely because they are based on inexpensive technology
and approaches that require many assumptions, making them sensitive to extracerebral contamination and unable to
provide a quantitative threshold for guiding clinical interventions. Further, interpretation of SO2 alone is ambiguous, as it
reflects the combined influence of multiple systemic and cerebral physiological parameters and clinical conditions, including
cerebral blood flow, oxygen consumption, hematocrit, and temperature.
In this application, we propose to develop a state-of-the art non-invasive brain health monitoring tool to provide real-time
feedback on multiple aspects of the brain functional status. Leveraging the substantial experience of our group in
instrumentation development, we will combine frequency domain near-infrared spectroscopy as well as diffuse correlation
spectroscopy measurements at multiple distances with intrinsic or ultrasound assisted estimates of tissue layer thicknesses
to obtain quantitative measures of perfusion, hemoglobin oxygenation and cerebral oxygen metabolism by means of
innovative Monte Carlo based light transport modeling algorithms. We will determine the accuracy and precision of our
measurements using both tissue-realistic phantoms and a miniature pig animal model. Next, we will perform validation
measurements in healthy human subjects during normoxic, hyperoxic and hypercapnic states while monitoring brain
perfusion and regional venous oxygenation using MRI methods. Finally, we will perform a pilot clinical measurements in
patients undergoing cardiovascular surgery under cardio-pulmonary bypass. We hypothesize that decreases in brain
oxygenation and perfusion during surgery are predictive of neurological injury, development of new ischemic lesions on
diffusion weighted MRI and extended hospital stay and superior to current cerebral oximeters. We will demonstrate the
feasibility of monitoring cerebral health using...

## Key facts

- **NIH application ID:** 9828111
- **Project number:** 5R01NS100750-03
- **Recipient organization:** MASSACHUSETTS GENERAL HOSPITAL
- **Principal Investigator:** Stefan Alexandru Carp
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $605,055
- **Award type:** 5
- **Project period:** 2017-12-01 → 2022-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9828111

## Citation

> US National Institutes of Health, RePORTER application 9828111, Non-invasive monitoring of brain health during cardio-pulmonary bypass (5R01NS100750-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9828111. Licensed CC0.

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