Assessment of Cerebral Microvascular Circulation

One of the essential goals in taking care of anesthetized surgical patients is to maintain adequate tissue perfusion and oxygenation. This is especially true for vital organs like the brain. Unfortunately, neither cerebral oxygen consumption nor cerebral oxygen delivery are directly monitored in the clinical setting while this type of information is of particular importance when taking care of patients inflicted with critical neurologic conditions. In addition, cerebral autoregulation - the mechanism of maintaining a constant cerebral blood flow in the face of arterial blood pressure fluctuation, is also not routinely monitored. The recent establishment of Coherent Hemodynamics Spectroscopy (CHS) is promising in offering what is needed in this context. The uniqueness of CHS is that it does not add any additional monitoring modality other than the cerebral oximeter based on near-infrared spectroscopy (NIRS) that is currently used in clinical care. However, CHS is based on its own innovative algorithm that quantifies microvascular cerebral blood flow and oxygen consumption, separates arterial and venous blood, and assesses functional status of cerebral autoregulation while the conventional cerebral oximeters do not. The investigators have established collaborations with Dr. Fantini from Tufts University and Dr. Tromberg from Beckman Laser Institute who are both leading scientists in Biophotonics research and development. Based on the clinical strength at UCSF, it is the investigators collaborative plan to explore the clinical application of CHS in patients with and without intracranial pathophysiologies. The study protocol has been submitted for review at UCSF.