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J Neurosurg Anesthesiol · Apr 2023
Correlation Between Cerebral Tissue Oxygen Saturation and Oxygen Extraction Fraction During Anesthesia: Monitoring Cerebral Metabolic Demand-supply Balance During Vasopressor Administration.
- Klaus U Koch, Xu Zhao, Irene K Mikkelsen, Ulrick S Espelund, Joel Aanerud, Mads Rasmussen, and Lingzhong Meng.
- Department of Anesthesiology, Section of Neuroanesthesia.
- J Neurosurg Anesthesiol. 2023 Apr 1; 35 (2): 238242238-242.
BackgroundThe speculation that cerebral tissue oxygen saturation (SctO 2 ) measured using tissue near-infrared spectroscopy reflects the balance between cerebral metabolic rate of oxygen and cerebral oxygen delivery has not been validated. Our objective was to correlate SctO 2 with cerebral oxygen extraction fraction (OEF) measured using positron emission tomography; OEF is the ratio between cerebral metabolic rate of oxygen and cerebral oxygen delivery and reflects the balance between these 2 variables.Materials And MethodsThis cohort study was based on data collected in a previously published trial assessing phenylephrine versus ephedrine treatment in anesthetized patients undergoing brain tumor surgery. The variables of interest were measured twice over the healthy hemisphere before surgery: the first measurement performed after anesthesia induction and the second measurement performed after induction of a ∼20% increase in blood pressure using either phenylephrine or ephedrine.ResultsData from 24 patients were analyzed. The overall vasopressor-induced relative changes in SctO 2 (ΔSctO 2 ) and OEF (ΔOEF) were 3.16% [interquartile range, -0.73% to 6.04%] and -12.5% [interquartile range, -24.0% to -6.19%], respectively. ΔSctO 2 negatively correlated with ΔOEF after phenylephrine treatment (Spearman rank correlation coefficient [ rs ]=-0.76; P =0.007), ephedrine treatment ( rs =-0.76; P =0.006), and any treatment ( rs =-0.79; P <0.001). ΔSctO 2 significantly associated with ΔOEF based on multivariable analysis with ΔOEF, relative changes in mean arterial pressure, arterial blood oxygen tension, and the bispectral index as covariates ( P =0.036).ConclusionsThe negative correlation between changes in SctO 2 and OEF suggests that SctO 2 may reflect the cerebral metabolic demand-supply balance during vasopressor treatment. The generalizability of our findings in other clinical scenarios remains to be determined.Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.
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