Development of a combined broadband near-infrared and diffusion correlation system for monitoring cerebral blood flow and oxidative metabolism in preterm infants

Abstract

Neonatal neuromonitoring is a major clinical focus of near-infrared spectroscopy (NIRS) and there is an increasing interest in measuring cerebral blood flow (CBF) and oxidative metabolism (CMRO2) in addition to the classic tissue oxygenation saturation (StO2). The purpose of this study was to assess the ability of broadband NIRS combined with diffusion correlation spectroscopy (DCS) to measured changes in StO2, CBF and CMRO2 in preterm infants undergoing pharmaceutical treatment of patent ductus arteriosus. CBF was measured by both DCS and contrast-enhanced NIRS for comparison. No significant difference in the treatment-induced CBF decrease was found between DCS (27.9 ± 2.2%) and NIRS (26.5 ± 4.3%). A reduction in StO2 (70.5 ± 2.4% to 63.7 ± 2.9%) was measured by broadband NIRS, reflecting the increase in oxygen extraction required to maintain CMRO2. This study demonstrates the applicability of broadband NIRS combined with DCS for neuromonitoring in this patient population.

Keywords: (170.3660) Light propagation in tissues; (170.3880) Medical and biological imaging; (170.6510) Spectroscopy, tissue diagnostics.

Figures

Fig. 1

(left) Brain ICG concentration curves measured by DCE NIRS before (blue) and after (red) indomethacin infusion and (right) corresponding DCS intensity autocorrelation curves measured pre (blue symbols) and post (red symbols) infusion. The solid lines in the DCS graphs represent the best fit of the diffusion equation with flow modeled as pseudo-Brownian motion.

Fig. 2

Time course of CBF from one infant during indomethacin infusion. Intensity autocorrelation curves were acquired continuously with a temporal resolution of 30 s. Their corresponding BFi values have been scaled to the baseline CBF value measured by DCE NIRS.

Fig. 3

Correlation between the treatment-induced change in BFi measured by DCS and the corresponding CBF change measured DCE NIRS (N = 8). Each symbol represents data from one of eight infants, the solid line is the best linear fit, and the blue lines are the 95% confidence intervals.

Fig. 4

First (a) and second (b) spectral derivatives of reflectance spectra acquired before (red) and after (blue) indomethacin infusion. Spectra were de-noised and averaged over a 10-s interval.

Fig. 5

Average absorption spectrum (top) and the corresponding 1st and 2nd derivative spectra (bottom) (N = 13). In each graph, the mean value is represented by the red line and the standard deviation by the error bars.