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Open Access Research article

Effect of different assumptions for brain water content on absolute measures of cerebral oxygenation determined by frequency-domain near-infrared spectroscopy in preterm infants: an observational study

Anja Demel1*, Martin Wolf2, Christian F Poets1 and Axel R Franz1

Author Affiliations

1 Department of Neonatology, University Children’s Hospital Tuebingen, Tuebingen, Germany

2 Biomedical Optics Research Laboratory, Division of Neonatology, University Hospital Zurich, Zurich, Switzerland

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BMC Pediatrics 2014, 14:206  doi:10.1186/1471-2431-14-206

Published: 19 August 2014

Abstract

Background

Brain-water content (BWC) decreases with maturation of the brain and potentially affects parameters of cerebral oxygenation determined by near-infrared spectroscopy (NIRS). Most commercially available devices do not take these maturational changes into account. The aim of this study was to determine the effect of different assumptions for BWC on parameters of cerebral oxygenation in preterm infants.

Methods

Concentrations of oxy-, deoxy- and total hemoglobin and regional cerebral oxygen saturation (rcStO2) were calculated based on absolute coefficients of absorption and scattering determined by multi-distance Frequency-Domain-NIRS assuming BWCs of 75-95%, which may be encountered in newborn infants depending on gestational and postnatal age.

Results

This range of BWC gave rise to a linear modification of the assessed NIRS parameters with a maximum change of 10%. This may result in an absolute overestimation of rcStO2 by (median (range)) 4 (1–8)%, if the calculation is based on the lowest BWC (75%) in an extremely preterm infant with an anticipated BWC of 95%.

Conclusion

Clinicians wishing to rely on parameters of cerebral oxygenation determined by NIRS should consider that maturational changes in BWC not taken into account by most devices may result in a deviation of cerebral oxygenation readings by up to 8% from the correct value.

Keywords:
Brain water content; Regional cerebral oxygen saturation; Near-infrared spectroscopy; Preterm infant