Abstract TP546: Association of Near-Infrared Spectroscopy Defined Regional Cerebral Oxygen Saturation with Progression of Cerebral White Matter Hyperintensity Lesions in Comatose Patients

Abstract

Background: Real-time regional cerebral oxygen saturation (rScO 2 ) measurement using near-infrared spectroscopy (NIRS) may aid in the identification of intracerebral ischemia in critically ill patients. Ischemia to the cerebral white matter results in injury detectable by brain MRI as white matter hyperintensities (WMH). We hypothesized that rScO 2 as assessed by NIRS correlates with the degree of WMH progression in patients admitted to a neurocritical care unit (NCCU). Materials and Methods: Retrospective study of eight comatose patients (Glasgow Coma Scale ≤8) in the NCCU who were continuously monitored for three days after their coma onset with NIRS to assess rScO 2, and who had a brain MRI upon admission and before their hospital discharge. Semi-automated volumetry based on intensity thresholding was used to quantify the WMH volume on FLAIR sequences. The degree of WMH progression was calculated by subtracting the WMH volume of the admission MRI from discharge MRI. Spearman rank correlation was used to determine the strength of association between the rScO 2 (averaged over the monitoring period) and the degree of WMH progression. Results: The median averaged rScO 2 was 61 (IQR (48-73) and the lowest 45. Overall, rScO 2 inversely correlated with WMH progression (rho -.738, p= 0.037); i.e., a lower rScO 2 was associated with greater WMH progression (Figure 1). Patients with greater WMH progression had a worse modified Rankin Scale on discharge (rho .769, p= 0.026). Interpretation: Our study provides proof of principle that rScO 2 as assessed by non-invasive NIRS monitoring may aid detection of cerebral white matter injury.