Neonatal NIRS monitoring: recommendations for data capture and review of analytics

Abstract

Brain injury is one of the most consequential problems facing neonates, with many preterm and term infants at risk for cerebral hypoxia and ischemia. To develop effective neuroprotective strategies, the mechanistic basis for brain injury must be understood. The fragile state of neonates presents unique research challenges; invasive measures of cerebral blood flow and oxygenation assessment exceed tolerable risk profiles. Near-infrared spectroscopy (NIRS) can safely and non-invasively estimate cerebral oxygenation, a correlate of cerebral perfusion, offering insight into brain injury-related mechanisms. Unfortunately, lack of standardization in device application, recording methods, and error/artifact correction have left the field fractured. In this article, we provide a framework for neonatal NIRS research. Our goal is to provide a rational basis for NIRS data capture and processing that may result in better comparability between studies. It is also intended to serve as a primer for new NIRS researchers and assist with investigation initiation.

Fig. 1. Absorption coefficients of oxy- and deoxyhemoglobin in the infrared and near-infrared spectrum.

Note the marked difference at ~700 nm, a difference leveraged in NIRS monitoring.

Fig. 2. Examples of two different device configurations.

On the left, an INVOS 5100c is integrated with a Moberg CNS monitor. On the right, a ForeSight Elite is integrated with a laptop computer. Both setups utilize portable rolling stands, allowing easy movement between patients.

Fig. 3. The result of two different interpolation methods.

First, 80% of the original signal is randomly removed. Moving mean and spline interpolation approaches are applied; note the significantly more continuous results of spline interpolation.

Fig. 4. Autoregulation methods.

Example plots of four different methods for quantifying autoregulatory function including time correlation (A), cerebrovascular reactivity (B), coherence (C), and transfer function analysis (D).