Neonatal cerebral hemodynamics under elevated intracranial pressure: a near-infrared spectroscopy study in piglets.

Abstract

Elevated intracranial pressure (ICP) is a common postnatal complication in premature infants, particularly those with very low birth weight, and it is associated with hemodynamic impairments. Continuous monitoring of cerebral blood flow (CBF) and oxygenation may enable early detection and inform clinical management. We hypothesized that non-invasive, bedside optical spectroscopy measurements of CBF and oxygenation are sensitive to abrupt increases in ICP. A hybrid optical system combining broadband near-infrared spectroscopy (bNIRS) and diffuse correlation spectroscopy (DCS) was used to monitor cerebral oxygenation and blood flow in 7 newborn piglets. ICP was gradually increased through saline infusion into the ventricles, and changes in CBF, oxygen saturation (StO₂), oxyhemoglobin (HbO₂), deoxyhemoglobin (Hb), and the oxidation state of cytochrome-c-oxidase (oxCCO) were continuously monitored with the hybrid optical device. Elevated ICP was associated with decreased StO₂ and CBF, while oxCCO remained stable, indicating unchanged cerebral oxygen metabolism. Across all parameters, segmented linear regression revealed a breakpoint at which ICP alterations led to steeper slopes and in turn, larger hemodynamic changes. This study demonstrates that bNIRS/DCS can effectively detect ICP-induced changes in cerebral hemodynamics and shows promise as a non-invasive neuromonitoring tool for neonatal critical care. Tissue optical spectroscopy can detect the hemodynamic effects of elevated ICP and could be used to guide interventions aimed at mitigating these effects. Breakpoints identified in hemodynamics highlight a compensatory mechanism, after which ICP changes lead to a larger impact on cerebral hemodynamics. Elevated ICP leads to distinct hemodynamic changes that may precede injury. This study supports the use of tissue optical spectroscopy for non-invasive neonatal neuromonitoring.