Increased cerebral blood volume and oxygen consumption in neonatal brain injury

Abstract

With the increasing interest in treatments for neonatal brain injury, bedside methods for detecting and assessing injury status and evolution are needed. We aimed to determine whether cerebral tissue oxygenation (StO(2)), cerebral blood volume (CBV), and estimates of relative cerebral oxygen consumption (rCMRO(2)) determined by bedside frequency-domain near-infrared spectroscopy (FD-NIRS) have the potential to distinguish neonates with brain injury from those with non-brain issues and healthy controls. We recruited 43 neonates < or =15 days old and >33 weeks gestational age (GA): 14 with imaging evidence of brain injury, 29 without suspicion of brain injury (4 unstable, 6 stable, and 19 healthy). A multivariate analysis of variance with Newman-Keuls post hoc comparisons confirmed group similarity for GA and age at measurement. StO(2) was significantly higher in brain injured compared with unstable neonates, but not statistically different from stable or healthy neonates. Brain-injured neonates were distinguished from all others by significant increases in CBV and rCMRO(2). In conclusion, although NIRS measures of StO(2) alone may be insensitive to evolving brain injury, increased CBV and rCMRO(2) seem to be useful for detecting neonatal brain injury and suggest increased neuronal activity and metabolism occurs acutely in evolving brain injury.

Figure 1

(A) Average (±95% confidence interval) of StO₂ for each clinical group, with significant P-value. (B) Average (±95% confidence interval) of CBV for each clinical group, with significant P-values. (C) Average (±95% confidence interval) of rCMRO₂ for each clinical group, for β = 2.6 and with significant P-values.

Figure 2

Scatterplot of rCMRO₂ against CBV for each clinical group, for β = 2.6. The black line represents the cutoff for sensitivity and specificity calculation.