Development of a NIRS method to quantify cerebral perfusion and oxidative metabolism in preterm infants with post-hemorrhagic ventricle dilation (Conference Presentation)

A complication of intraventricular hemorrhage among preterm neonates is post-hemorrhagic ventricle dilation (PHVD), which is associated with a greater risk of life-long neurological disability. Clinical evidence, including suppressed EEG patterns, suggests that cerebral perfusion and oxygenation is impaired in these patients, likely due to elevated intracranial pressure (ICP). Cerebral blood flow (CBF) and the cerebral metabolic rate of oxygen (CMRO2) can be quantified by dynamic contrast-enhanced NIRS; however, PHVD poses a unique challenge to NIRS since the cerebral mantle can be compressed to 1 cm or less. The objectives of this work were to develop a finite-slab model for the analysis of NIRS spectra, incorporating depth measurements from ultrasound images, and to assess the magnitude of error when using the standard semi-infinite model. CBF, tissue saturation (StO2) and CMRO2 were measured in 9 patients receiving ventricle taps to reduce ICP. Monte Carlo simulations indicated that errors in StO2 could be greater than 20% if the cerebral mantle was reduced to 1 cm. Using the finite-slab model, basal CBF and CMRO2 in the PHVD patients were not significantly different from a control group of preterm infants (14.6 ± 4.2 ml/100 g/min and 1.0 ± 0.4 ml O2/100 g/min), but StO2 was significantly lower (PDA 70.5 ± 9%, PHVD 58.9 ± 12%). Additionally, ventricle tapping improved CBF by 15.6 ± 22%. This work indicates that applying NIRS to PHVD patients is prone to error; however, this issue can be overcome with the appropriate model and using readily available ultrasound images.