Impact of Skull Thickness on Cerebral NIRS Oximetry in Neonates: An in silico Study

Monitoring of cerebral tissue oxygen saturation (StO₂) by near-infrared spectroscopy (NIRS oximetry) has great potential to reduce the incidence of hypoxic and hyperoxic events and thus prevent long-term disabilities in preterm neonates. Since the light has to penetrate superficial layers (bone, skin and cerebrospinal fluid) before it reaches the brain, the question arises whether these layers influence cerebral StO₂ measurement. We assessed this influence on the accuracy of cerebral StO₂ values. For that purpose, we simulated light propagation with 'N-layered medium' software. It was found that with a superficial layer thickness of ≤6 mm, typical for term and preterm neonates, StO₂ accurately reflects cerebral tissue oxygenation.