Correlation Between Noninvasive Blood Vessel Functionality Parameters and Cerebral Hemodynamics in Neurocritical Care Patients

For this research, the investigators will strategically position two noninvasive sensors on the patients' foreheads, specifically over the temporal region. It is imperative that the skin in this area is accessible, free from hair or any underlying wounds beneath the sensor. These sensors are specifically designed to gather crucial data on cerebral oxygen saturation (StO2) and blood volume index (BVI). As per FDA recommendations, should the monitoring extend beyond 6 hours, it is advisable to replace the sensor adhesive to ensure optimal functionality and accuracy. The collected information will be transmitted to the investigators' monitoring system, equipped with preinstalled software that offers real-time insights into several key parameters: 1. Regional Tissue Oxygen Saturation (StO2): This parameter provides data on regional hemoglobin oxygen saturation in the cerebral tissue beneath the sensor. It is captured using our cerebral oximetry sensors and offers critical insights into tissue oxygenation. 2. Blood Volume Index (BVI): BVI provides information on the regional blood-to-tissue volume ratio in the cerebral tissue beneath the sensor, again captured using our cerebral oximetry sensors. BVI is instrumental in understanding blood volume dynamics in the brain. 3. Mean Arterial Pressure (MAP) and Systolic Blood Pressure (SBP): Real-time MAP and SBP data will be pulled from the Philips patient monitor, providing a comprehensive overview of the patient's circulatory status. 4. Intracranial Pressure (ICP): Similar to MAP and SBP, real-time ICP data will also be pulled from the Philips patient monitor, offering valuable insights into intracranial dynamics. 5. Vasodilation/Constriction Index (VDC): VDC is a derived parameter from BVI, signifying the relative change in blood vessel cross-sectional area. An increase indicates vessel dilation, while a decrease indicates vessel constriction. This index offers insights into cerebral vessel reactivity. 6. Vascular Resistance Index (VR): VR is a derived parameter from BVI, indicating the percent change in blood vessel resistance based on the Hagen-Poiseuille formula. VR helps assess the resistance to blood flow within cerebral vessels. 7. Volume Reactivity Index (VRx): VRx is a real-time moving Pearson Correlation Coefficient between Blood Volume Index (BVI) derived from our Cerebral Oximetry sensors and MAP. This parameter is derived from Pressure Reactivity Index (PRx), making VRx a non-invasive alternative to the invasive PRx. VRx is used to assess autoregulation.