This is a study of adult patients with a severe and sudden brain injury who have a drain placed in their brain to measure pressure. The purpose of the study is to monitor the pressure in the brain using a monitor placed on the forehead, and compare this to a drain placed in the brain.

The device is a non-invasive brain pulse oximeter. It uses red and near-infrared light and provides a signal which represents the change in blood volume associated with each heartbeat.

The brain signal allows a number of clinically important end-points to be determined, including brain blood flow, oxygen and pressure levels.

The T-Pot (US) Study will be undertaken in patients that require invasive brain monitoring.

The primary aim of the study is to assess the accuracy of the brain pulse oximeter compared with the traditional invasive intracranial pressure (ICP) monitoring.

Inclusion Criteria:

• 1. Adult brain-injured patients who have undergone external ventricular drain insertion for cerebrospinal fluid drainage and invasive intracranial pressure monitoring as part of standard medical care
• 2. Adult brain-injured patients who have undergone external ventricular drain insertion for cerebrospinal fluid drainage and invasive intracranial pressure monitoring that have concomitant continuous electroencephalography (EEG) monitoring as part of standard medical care

Exclusion Criteria:

• 1. Inability to obtain the brain pulse oximeter signal from at least one brain hemisphere due to interface issue such as severe agitation, head dressing, severe skin or bone trauma, or skull removal preventing brain pulse detection for the initial monitoring session.

  a. Note: If unable to obtain brain pulse oximeter signal for subsequent monitoring sessions, the only the recordings that were obtained will be used for analysis

• 2. Hemodynamically unstable patients (defined as increasing vasopressors requirements)

• 3. Patients with unstable mechanical ventilation support defined as increasing fractional inspired oxygen (FiO2) requirements