 Patients admitted to the ICU may have delayed awakening after their critical illness has resolved. Though most either are due to metabolic causes or delayed elimination of sedative medications, more serious pathologies such as intracranial hemorrhage, ischemic stroke, and vasogenic edema may also be the cause of coma. These pathologies all result in increases in intracranial pressure ICP with cerebral edema. Identifying elevated intracranial pressure elevations have so far, relied on invasive monitoring techniques requiring placement of an intracranial or intraventricular catheter. 