Figure 7.

NIRS-derived regional tissue oxygen saturation (green probe) analyzes the oxygen concentration in cerebral microcirculation, which is predominantly from venous oxygenation. Jugular bulb venous saturation (blue probe) analyzes the remaining oxygen concentration that flows from the venous sinuses to the internal jugular vein. Both are indirect measurements of how much oxygen is being used by the brain. Brain tissue oxygenation tension (yellow probe) analyzes the dissolved oxygen within the cerebral plasma that diffuses across the blood brain barrier (BBB). (Figure modified from [57,58]).