Intensive treatment of the nervous system quickly reveals that the brain cannot wait. As the most sensitive organ in the human body, severe hypoxia for several minutes can cause irreversible damage. In comparison, muscles can endure hours without oxygen. To prevent nerve cell damage, steps must be taken quickly and accurately.
In this scenario, medical decisions are often made based on metrics displayed on monitors in the intensive care unit (ICU). Clinical experience can bring disconcerting surprises. Even when parameters indicate stability, the brain may still be suffering.
Carlos Nassif, an intensive care physician with this problem. Despite following the correct treatment protocol with intracranial pressure (ICP) within safe limits and blood pressure and cerebral perfusion pressure (CPP) adequate, some patients showed signs of neurological deterioration. “There was a patient in whom all parameters seemed adequate, but a state of cerebral ischemia persisted, a state in which the brain did not receive as much oxygen as it needed,” Nassif told Agência FAPESP.
This led the expert to carry out clinical research at the 9 de Julho Hospital in São Paulo, Brazil. This study evaluated the Brazilian technology with support from FAPESP’s Small and Medium Enterprise Innovative Research Program (PIPE). This technique analyzes brain dynamics and intracranial compliance, the ability of the skull to accommodate increased volume without significantly increasing intracranial pressure. The doctor, who works in research and clinical care at Hospital 9 de July and Hospital das Clínicas (HC), a hospital complex managed by the University of São Paulo Faculty of Medicine (FM-USP), collected data over a five-year period.
The aim was to compare two neurocritical care models. One group of patients used only a treatment protocol based on the latest international guidelines, and the other group combined it with assessment of brain compliance and intracranial dynamics. The technology to measure compliance was developed by the startup Brain4Care, based on the research of Brazilian applied physics pioneer Sergio Mascareñas (1928-2021).
The device uses non-invasive sensors attached to the headband to detect minute movements of the skull in conjunction with the heartbeat. These movements are translated into signals that allow monitoring of compliance and intracranial dynamics. Until recently, it was thought that the skull was too hard to make such measurements.
brain monitoring
Patients with nerve injuries are monitored using a variety of indicators. One of the main metrics is ICP. Another widely used parameter is CPP, the force that drives blood flow to the brain. It is calculated from the difference between mean arterial pressure and ICP.
These numbers guide clinical decisions in ICUs around the world. Although international guidelines recommend specific ICP and cerebral perfusion levels to prevent oxygen deprivation and damage to brain tissue, these parameters may not accurately reflect what is occurring in clinical practice.
Brain4care tools allow teams to recognize the need for intervention and act immediately before ICP rises. This is a very different approach from the standard reactive attitude of only responding once a patient’s condition worsens. “Often, by the time symptoms appear, the damage is already irreversible,” warns Nassif.
The researchers compared their analysis of brain compliance with traditional testing and PtiO₂ (Brain Tissue Oxygen Partial Pressure), a technique considered the gold standard for neurological monitoring. This invasive method involves inserting a millimeter-sized sensor directly into the brain via a small catheter.
Once installed, this device will be able to measure the amount of oxygen in brain tissue and assess whether that area of the brain is receiving enough oxygen to maintain its function. “The cause of brain damage is impaired perfusion and the resulting lack of oxygen supply, and being able to measure it directly would provide a very important reference,” the doctor explains.
Because it requires surgical procedures, expensive sensors, specialized equipment, and specialized teams for implantation and monitoring, PtiO₂ is typically limited to high-complexity hospitals. In Brazil, even large hospitals like HCs are rarely widely available through SUS (an acronym for “Sistema Único de Saúde”, Brazil’s national public health network).
Historically, treatment of severe head trauma and stroke has relied on ICP and CCP monitoring. International guidelines state that if these values are within the prescribed target range, the patient is safe.
However, a comparison of these methods yielded unexpected results. Nassif observed that even when ICP and CCP were within the range recommended by international protocols, more than 80% of patients evaluated had dangerously low cerebral oxygenation levels. This suggests that many patients may be experiencing silent brain damage in the ICU.
This is concerning because brain injuries often worsen within minutes, hours, or days after the initial neurological event, a process known as secondary brain injury. Therefore, the goal of the medical team is not only to prevent death, but also to reduce the risk of severe neurological sequelae that can lead to procedures such as tracheostomy and feeding tube placement, as well as the cognitive impairment that has been documented in the medical literature.
Sometimes the worst outcome is not death. He survived despite suffering from severe after-effects. Our goal is not to keep patients alive at all costs. It’s so they can be productive. We don’t want people to become powerless and unable to interact with their families as a result. ”
Carlos Nassif
A doctor recalls a story about a colleague that made an impression on him. A young woman was hospitalized with severe cerebral hemorrhage due to an aneurysm and remained in the ICU for over 60 days. When she returned to the clinic for a follow-up visit, her doctor couldn’t believe his eyes. She had returned to work and showed no signs of neurological dysfunction.
Intracranial compliance
The technology developed by Brain4care challenges classical interpretations of brain physiology, such as the Monroe-Kelly theory, formulated by Scottish doctors Alexander Monroe and George Kelly in the 18th century. According to this principle, the skull is a rigid compartment and the total volume within the cranial cavity, consisting of brain tissue, blood, and cerebrospinal fluid, remains constant. If one of these components increases, another must be decreased to prevent an increase in ICP.
Nassif observed that by comparing intracranial compliance data with transcranial Doppler tests that measure cerebral blood flow, the brain4care device was able to identify the blood pressure that would provide optimal perfusion for each patient. This allows for individualization of clinical management. Currently, injured brains are treated based on static protocols and population averages, which can potentially miss critical windows for optimizing treatment and compromise recovery.
Waveforms generated from data captured by Brain4care sensors indicate whether the brain is protected or in distress. Nassif explains that they used the tool to identify the optimal blood pressure for each patient. What is appropriate for a 70-year-old patient with a history of hypertension may be different than what a 20-year-old patient needs.
Additionally, blood pressure changes depending on the severity of the injury and may also change throughout the patient’s recovery process. “There is no single fixed value that is suitable for everyone. The actual needs of the individual must be assessed on a case-by-moment basis. Adjustments made in the morning can lead to edema during the night,” explains Nassif. “For example, if blood pressure remains elevated after brain edema subsides, the excess blood flow can induce or worsen the edema and cause further damage.”
Clinical research results
Nassif’s study compared two groups of patients with severe neurological disorders. One group was treated according to conventional guidelines, and the other group was further monitored for intracranial compliance. To minimize potential bias, the analysis included only critically ill patients, most of whom required mechanical ventilation or vasopressor administration.
The results were published in a magazine Cost effectiveness and resource allocationPatients monitored with Brain4Care showed lower overall mortality (5.88% vs. 37.25%), increased proportion of patients discharged functionally independent (58.8% vs. 27.5%), and shorter length of stay. The average length of stay in the ICU decreased by 3.7 days, and the average length of stay in the hospital decreased by 4.14 days. In other words, with this technology, beds become available faster.
Beyond the medical aspects, there are also economic implications. According to the estimates used in this study, a neurological ICU stay for critically ill patients costs between R$13,000 and R$15,000 per day. There was a significant difference in readmissions, with readmissions of 12.5% in the intracranial compliance group versus 38.7% in the control group, resulting in a savings of R68,800 per patient. Twice as many patients monitored with Brain4care were discharged directly to their home without the need for a reserve hospital or home care.
Potential impact on public health
Traumatic brain injury is one of the leading causes of death and disability worldwide. According to the World Health Organization (WHO), approximately 50 million people sustain head injuries each year.
According to data from the Brazilian Ministry of Health, this type of injury is one of the main causes of hospitalization among young people and is often associated with traffic accidents. Another important group includes patients who have suffered a stroke, which is the second leading cause of death and the leading cause of permanent disability worldwide.
In this context, technologies that improve brain monitoring have the potential to change outcomes for thousands of patients. One advantage of Brain4care is that, unlike intracranial sensors such as PtiO₂, its device does not require surgery or implantation into the brain. This eliminates the need for highly specialized teams to implant the device and opens up possibilities for use in hospitals with varying levels of infrastructure.
next step
The São Paulo study is the first step in clinical evaluation of this technology. Further studies should include more patients from different hospital centers.
Nassif is considering applying the tool to other clinical situations, such as patients with septic shock, the most severe form of sepsis. In this condition, changes in cerebral perfusion can lead to neurological deficits and negatively impact patient outcomes.
Septic shock is one of the leading causes of death in the ICU. Research teams often focus on monitoring the kidneys, lungs, and heart and ignore the brain. This explains why many survivors of severe infections experience a decline in neurological function several months after hospital discharge.
Despite scientific debate and technological advances, Nassif succinctly summarizes the goals of his research: “When a patient returns home and resumes their normal life after a severe brain injury, it shows that the treatment was worth it.”
The technology developed by Brain4care puts Brazil at the forefront of this field and demonstrates that cutting-edge technology does not need to be imported or prohibitively expensive. This technology eliminates the need for expensive, disposable, and invasive sensors, making it much more affordable. This technology gently monitors vital signs by capturing the brain’s electrical activity through the skull. Only accurate data is obtained without drilling holes in the skull.
When Mascarenhas devised this method, he heard from colleagues that if it was correct, it would change the medical literature. He proved that the skull is not as rigidly fixed as previously thought, reinterpreting Monroe and Kelly’s work and paving the way for personalized and accessible medical care for neurological crisis patients.
sauce:
São Paulo Research Foundation (FAPESP)
Reference magazines:
Moreira, CEN; others. (2026). Impact of intracranial compliance-based hemodynamic management on outcomes in critically ill patients – preliminary results and exploratory economic evaluation. Cost effectiveness and resource allocation. DOI: 10.1186/s12962-026-00721-4. https://link.springer.com/article/10.1186/s12962-026-00721-4
