The purpose of this research, which has been determined as non-significant risk by the central IRB overseeing the study, is to obtain information to help further develop a machine (a medical device) to measure the pressure around the brain from the outside (this pressure is called intracranial pressure or ICP). Monitoring and managing ICP is an important part of care for patients with conditions such as Traumatic Brain Injury (TBI). However, the current way of measuring ICP requires surgery to drill a hole into the skull, and therefore can introduce additional risks such as infections and pain.

Recent research has shown it may be possible to measure ICP without needing surgery. This technology is in development, but large amounts of data is required to build these new devices.

Through collecting a large database of information from patients who have both the routine surgical device and the research device applied to their head, the research team will work to develop and test an effective and potentially safer way of monitoring patient ICP.

A prospective, observational study, determined as non-significant risk by the Central IRB, to assess and improve performance of a non-invasive ICP estimation system. The development of non-invasive systems is intended to replace the need for invasive ICP monitors. Participants serve as their own controls with concurrent, synchronous measurements of ICP (measured invasively as per standard clinical practice), Arterial Blood Pressure (ABP- measured invasively as per standard clinical practice), and measurements of a novel non- invasive cerebral blood-flow index (CBFi) from the CoMind One EFS device. These signals will be recorded simultaneously. The ABP and CBFi will serve as inputs to a model which outputs a non-invasive estimate of ICP, and the invasive ICP signal will be used to supervise and evaluate the performance of the non-invasive ICP estimation model. A large volume of data shall be collected for the purposes of training and testing the non-invasive ICP model. The Sponsor will report limits of agreement (LOA) between data-driven estimates of ICP and the invasively measured signal. In addition, this study will compare metrics built on non-invasive estimation of ICP or CBFi that indicate the state of CAR, and the limits of Autoregulation.

Inclusion Criteria:

1. Male or female sex at birth, and aged 18 years or older on the date of enrollment.
2. Receiving continuous invasive ICP monitoring (Bolt or EVD) as part of standard care.
3. Invasive ICP monitor catheter penetrating the parenchyma or ventricles.
4. Receiving continuous invasive ABP monitoring as part of standard care.

Exclusion Criteria:

1. Presence of any implant (cosmetic or otherwise) in the frontal bone in such proximity to the CoMind One EFS Sensor that they might physically touch.
2. Open wounds on the forehead such that CoMind One EFS Sensor cannot be safely placed over an area of intact skin
3. Presenting with radiographic evidence of a non-intact skull at the recording site on admission.
4. If patient is enrolled in an intervention/study that may interfere with SoC ICP measurements or the CoMind One EFS device measurement then the patient is ineligible.
5. Patients with decompressive craniectomy will be excluded unless a CoMind One EFS recording can be made from intact skull.

Any participant (18 years or older) who is undergoing invasive ICP monitoring and continuous ABP monitoring as part of their normal medical treatment at selected clinical sites. The majority of such participants will have sustained a Traumatic Brain Injury (TBI), but some may have Intracerebral Haemorrhage (ICH), Encephalitis, various metabolic Encephalopathies (notably hepatic), Hydrocephalus (both communicating and non-communicating), or Stroke, although this is not an exhaustive list of participant conditions.