In the search for a reliable, cooperation-independent, noninvasive alternative to invasive intracranial pressure (ICP) monitoring in children, various approaches have been proposed, but at the present time, none are capable of providing fully automated, real-time, calibration-free, continuous, and accurate ICP estimates.
Now a team of scientists from MIT and Boston Children’s Hospital has created a new technique to monitor intracranial pressure (ICP) in the brain. Increased intracranial pressure (ICP) is a rise in pressure around the brain. It may be due to an increase in the amount of fluid surrounding your brain or swelling of the brain tissue itself from injury or from an illness such as epilepsy.
Under normal conditions, ICP is between 5 and 15 millimeters of mercury (mmHg). In case of traumatic injury or swelling caused by inflammation, pressure can go above 20 mmHg, impeding blood flow into the brain.
The condition is life-threatening. Less common treatments for increased ICP include removing part of the skull, taking medicines to induce coma and deliberately chilling the body, or inducing hypothermia.
All these procedures are done for patients in intensive care units who are at high risk of elevated ICP.
Scientists started working on a less invasive way to monitor ICP more than 10 years ago. They even developed an approach to estimate ICP based on two measurements: arterial blood pressure, which is taken by embeddings a catheter at the patient’s wrist, and the velocity of blood flow entering the brain, estimated by holding an ultrasound probe to the patient’s temple.
For their study, they developed a mathematical model of the relationship between blood pressure, cerebral blood flow velocity, and ICP. They tested the model on data collected several years earlier from patients with traumatic brain injury at Cambridge University, with encouraging results.
In this new study, scientists wanted to improve the algorithm that they were using to estimate ICP. They also wanted to develop advanced methods to gather their own data from pediatric patients.
By collaborating with Robert Tasker, director of the pediatric neurocritical care program at Boston Children’s Hospital, scientists identified patients for the study and help move the technology to the bedside. They tested their technique on patients whose guardians approved the procedure.
Blood vessel pressure and ICP were estimated as a feature of the patients’ routine monitoring, so the additional element was the ultrasound measurement. Scientists thus devised an approach to automate the data analysis so just data segments with the most noteworthy sign-to-noise ratio were used, making the appraisals of ICP progressively exact.
Andrea Fanelli, the study’s lead author, said, “We built a signal processing pipeline that was able to automatically detect the segments of data that we could trust versus the segments of data that were too noisy to be used for ICP estimation. We wanted to have an automated approach that could be completely user-independent.”
Tasker said, “The ICP estimates generated by this new technique were, on average, within about 1 mmHg of the measurements taken with the invasive method. From a clinical perspective, it was well within the limits we would consider useful.”
During the study, scientists focused on patients with severe injuries because those are the patients who already had an invasive ICP estimation being done. Be that as it may, the new technique could permit ICP monitoring to be extended to incorporate patients with diseases, for example, meningitis and encephalitis, as well as malaria, which would all be able to cause brain swelling.
Tasker said, “In the past, for these conditions, we would never consider ICP monitoring. What the current research has opened up for us is the possibility that we can include these other patients and try to identify not only whether they’ve got raised ICP but some degree of magnitude to that.”
Nino Stocchetti, a professor of anesthesia and intensive care medicine at Policlinico of Milan, Italy, who was not involved in the research, said, “These findings are very encouraging and may open the way for reliable, non-invasive neuro-critical care. As the authors acknowledge, these results ‘indicate a promising route’ rather than conclusive: additional work, refinements, and more patients remain necessary.”
Thomas Heldt, the W. M. Keck Career Development Professor in Biomedical Engineering in MIT’s Institute of Medical Engineering and Science, said, “This estimate could be of greatest benefit in the pediatrician’s office, the ophthalmologist’s office, the ambulance, the emergency department, so you want to have a completely noninvasive arterial blood pressure measurement. We’re working to develop that.”
The research was funded by the National Institutes for Neurological Disorders and Stroke, Maxim Integrated Products, and the Boston Children’s Hospital Department of Anesthesiology, Critical Care, and Pain Medicine.
The study is published in the of Neurosurgery: Pediatrics.