Fig. 2.

Examples of using NIRS derived autoregulation indices to identify ${\mathrm{MAP}}_{\mathrm{opt}}$. (a) Data from a pediatric cardiac arrest patient. Top graph shows the time course of fluctuations in MAP and ${\mathrm{S}}_{\mathrm{t}}{\mathrm{O}}_2$ over a 24-h period. Second from top, temporal fluctuations in COx are shown. Periods of time with poor autoregulation (i.e., $\mathrm{COx}>0.3$) are shaded gray. Second from bottom, method for deriving ${\mathrm{MAP}}_{\mathrm{opt}}$ (MAP where COx is minimized) and both ULA and LLA (BP where COx > 0.3) is shown. Bottom graph shows temporal trends in ${\mathrm{MAP}}_{\mathrm{opt}}$ superimposed on top of the patient’s actual BP. Areas shaded dark gray represent periods of time when actual MAP was significantly below ${\mathrm{MAP}}_{\mathrm{opt}}$ (defined as periods where $\mathrm{MAP}<{\mathrm{MAP}}_{\mathrm{opt}}-5\mathrm{mmHg}$). (b) Similar data from adult patients with non-traumatic subarachnoid hemorrhage. Black trace represents patient’s actual MAP, red trace represents trends in ${\mathrm{MAP}}_{\mathrm{opt}}$ calculated from COx. Shaded red areas represent the range of intact autoregulation. The top curve shows a patient with BP trends where MAP largely stayed within ULA and LLA, whereas bottom curve shows a patient where BP often exceeded the ULA. [(a)- taken from Ref. 30 and (b)- taken from Ref. 31].