Continuous Assessment of Cerebral Autoregulation With Near-Infrared Spectroscopy in Adults After Subarachnoid Hemorrhage

Abstract

Background and Purpose-In patients with subarachnoid hemorrhage, the assessment of cerebral autoregulation aids in prognosis as well as detection of vasospasm. Mx is a validated index of cerebral autoregulation based on measures of cerebral perfusion pressure and mean flow velocity on transcranial Doppler but is impractical for longer-term monitoring. Near-infrared spectroscopy is noninvasive and suitable for continuous monitoring of cerebral tissue oxygenation using the Tissue Oxygenation Index. In this study, we compared near-infrared spectroscopy-based indices of cerebral autoregulation (TOx) with Mx in patients with subarachnoid hemorrhage. Methods-Arterial blood pressure, intracranial pressure, mean flow velocity, and Tissue Oxygenation Index were recorded.Mx and TOx were calculated as moving correlation coefficients between 10-second averaged values of cerebral perfusion pressure and mean flow velocity and between cerebral perfusion pressure and Tissue Oxygenation Index. We also calculated TOxA, the moving correlation coefficient between arterial blood pressure and Tissue Oxygenation Index. Results-Fifty-one recording sessions were performed in 27 patients with subarachnoid hemorrhage with a total duration of 62.5 hours. Correlations of Mx and TOx over time varied markedly among individual recordings. However, time-averaging over the entire recording interval in each of the 51 recordings, we found correlations between Mx and TOx and between Mx and TOxA were highly significant. This correlation was even stronger after correction for multiple sampling for each patient, reaching rϭ0.81 for Mx and TOx and rϭ0.72 for Mx and TOxA. Conclusion-Near-infrared spectroscopy can be used to continuously assess cerebral autoregulation in adults after subarachnoid hemorrhage. (Stroke.

Cerebral Autoregulation after Subarachnoid Hemorrhage: Comparison of Three Methods

“…Furthermore, THRT in prospective observational studies was shown to be useful in predicting clinical deterioration after SAH. 2,6 However, while clinical and experimental data exist supporting the validity of Sxa and TOxa, 13,23,25,31,32,34 neither index has been evaluated for its power to predict DCI. The mean flow index, Mx, which is derived from mean FV and CPP and its noninvasive version, Mxa, where ABP is used instead of CPP, have been previously investigated in patients with SAH.…”

“…(3) Near-infrared spectroscopy-based autoregulation, TOxa, was calculated as a moving, linear correlation coefficient between values of tissue oxygenation index and ABP from a 300-second window with an update every 10 seconds. [23][24][25] The minimum monitoring time required for results to be considered meaningful was 30 minutes.…”

“…Previous data suggest that blood pressure-based indices correlate well with cerebral perfusion pressure (CPP) based indices. 25,31,33 The physiologic basis for the correlation coefficient methodology has been described elsewhere. 25,32 Briefly, a passive transmission of ABP fluctuations to FV and tissue oxygenation index, respectively, is suggestive of passive pressure-flow relationship and therefore impaired autoregulation.…”

“…Both TCD and near-infrared spectroscopy (NIRS) are modalities where the correlation coefficient method has been experimentally and clinically verified. [23][24][25] We have previously described in a prospective study that continuous indices of autoregulation (TCD and NIRS derived) are predictive of DCI. 9 However, the interrelationship between the two continuous indices as well as THRT has not been fully elucidated.…”

Shedding light on the adult brain: a review of the clinical applications of near-infrared spectroscopy

“…In this study, there was a significant correlation (r = 0.49, p < 0.001) between THx, a measure of autoregulation derived from the total haemoglobin index (measured using spatially resolved spectroscopy with a Hamamatsu NIRO 200) and arterial blood pressure, and the PRx. The same group has also demonstrated a correlation between TOIx, a measure of autoregulation derived from the TOI (Hamamatsu NIRO 200), and the Mx in a group of 27 patients following poor-grade subarachnoid haemorrhage [51].…”