Project Spotlight: Intracranial Pressure Monitoring

The healthy brain maintains a relatively constant blood flow to the brain even when there are changes in blood pressure or intracranial pressure (ICP). The mechanism preserving blood flow is called cerebral autoregulation (CA), which is known to be impaired in a variety of diseases, such as diabetes, Parkinson’s disease, stroke, and traumatic brain injury (TBI). Currently, ICP can only be measured by placing an invasive pressure sensor inside the brain. This project, led by Jana Kainerstorfer, PhD, Assistant Professor of Biomedical Engineering at Carnegie Mellon University and Elizabeth Tyler-Kabara, MD, Neurological Surgery at UPMC Children’s Hospital of Pittsburgh, seeks to establish an optical technique called near-infrared spectroscopy (NIRS) as a non-invasive method to monitor ICP in humans. Development of a non-invasive ICP sensor would optimize patient treatment in cases where invasive ICP is not possible or could be dangerous to the patient. Dr. Kainerstorfer shares insights about the project.

Please share a little about your background and your research experiences.

I have a PhD in Physics from the University of Vienna in Austria in partnership with the National Institutes of Health, Maryland. My post-doctoral research was performed at Tufts University in Boston. I was trained in biomedical optical imaging, ranging from instrument design to signals processing, to clinical translation of imaging devices. My lab’s research is focused on developing noninvasive optical imaging methods for disease detection and/or treatment monitoring, with a particular emphasis on diffuse optical spectroscopic imaging methods. Applications include cerebral monitoring in traumatic brain injury and breast cancer imaging.

What led you to the PHDA?

At the time of grant submission to CMLH, we had preliminary data from pre-clinical studies that would indicate that non-invasive intracranial pressure sensing is possible. We already had a clinical collaborator and the technology was mostly developed. The CMLH enabled us to refine the methods and translate the instrument to the clinic to be tested on humans.

Walk us through your project.

The project aims to measure intracranial pressure (ICP) non-invasively. Continuous measurements of ICP are currently only possible by means of invasive pressure probes, which require surgery. Knowing ICP and how the brain compensates for pressure changes in order to maintain steady blood flow is important in many diseases, including traumatic brain injury, hydrocephalus, and stroke. We are developing non-invasive ways to measure ICP as well as to quantify such blood flow regulation. For this, we measure cerebral hemodynamic changes with optical techniques, such as near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS). Specifically, these techniques measure the light interaction with the brain, by placing optical probes on the surface of the head. Changes in light intensity and other properties allow us to quantify hemoglobin concentration in the brain as well as blood flow in the cerebral microvasculature. We have shown recently that such hemodynamic changes can be used to calculate ICP in the brain. The project is focused on translating the methods to the clinic. We are collaborating with Drs. Elizabeth Tyler-Kabara and Robert Clark at UPMC Children’s Hospital. We are working with children in the pediatric ICU, who already have an invasive ICP sensor placed. We place the optical probes on the head of the children and measure hemodynamic changes over time. Using the data, we then apply the algorithm previously developed to extract ICP non-invasively.

In what ways has UPMC played a role lending clinical expertise and sharing data?

Our clinical collaborators guide the project in terms of necessary metrics to be achieved to be clinically viable. Clinical access is critical for the success of the project. Without access to patients, the project would not be possible. The willingness for collaboration between engineers and the clinical environment is outstanding at UPMC. The support we have received and the help in accessing patients is unpaired with any other institutions.

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