M. M. Lozano, S. Givens
Profusa, Inc, California, United States
Keywords: TBI; hemorrhage; tissue oxygen; continuous wireless monitoring
Physiological parameters were monitored in anesthetized Yorkshire swine that underwent combined brain injury and hemorrhagic shock (NMRC En Route and Critical Care Department). Lumee (Profusa, Inc) probes were placed subcutaneously for continuous tissue oxygen measurements 5 days before catheter placement and injury consisting of fluid percussion TBI followed by a 30% estimated blood volume (EBV) hemorrhage. Animals were grouped between injured (n=20) and instrumented-but-not-injured (n=9). The animals were observed for 2 hours post-injury and monitored with conventional methods for MAP, HR, CO, SpO2, and PaO2, and with Lumee technology (LOI: Lumee Oxygen Index) for tissue oxygenation. A characteristic pattern was observed between continuous measures of LOI and vital signs changes. There was a significant correlation between LOI and MAP (R=0.70±0.20), and LOI and CO (R=0.76±0.12) in injured animals indicating the early detection of the physiological outcomes of shock. Saturation (SpO2) and arterial blood gas measurements (PaO2, PvO2 or SO2) did not represent blood perfusion or were not continuous for early recognition of shock. This initial swine polytrauma study indicated that tissue oxygenation measured by an implantable hydrogel probe based on phosphorescent quenching is highly sensitive to changes in physiological changes in tissue perfusion soon after injury.