Abstract
Near-infrared spectroscopy (NIRS) is increasingly used in neonatal intensive care. We investigated the impact of skin, bone, and cerebrospinal fluid (CSF) layer thickness in term and preterm infants on absorption-(μa) and/or reduced scattering coefficients (μs') measured by multidistance frequency-domain (FD)-NIRS. Transcranial ultrasound was performed to measure the layer thicknesses. Correlations were only statistically significant for μa at 692 nm with bone thickness and μs' at 834 nm with skin thickness. There is no evidence that skin, bone, or CSF thickness have an important effect on μa and μs'. Layer thicknesses of skin, bone, and CSF in the range studied do not seem to affect cerebral oxygenation measurements by multidistance FD-NIRS significantly.
Highlights
Near-infrared spectroscopy (NIRS) is a tool to evaluate tissue oxygenation noninvasively
We investigated the impact of skin, bone, and cerebrospinal fluid (CSF) layer thickness in term and preterm infants on absorption(μa) and/or reduced scattering coefficients measured by multidistance frequency-domain (FD)-NIRS
The measured thicknesses of skin, bone, and CSF are shown in Table 2, and absorption coefficients and reduced scattering coefficients at the two wave lengths are depicted in Table 3 along with intra- and inter-individual coefficients of variation
Summary
Near-infrared spectroscopy (NIRS) is a tool to evaluate tissue oxygenation noninvasively. As reported previously,[1,2,3] there are several instruments commercially available which use different techniques to measure tissue oxygenation, e.g., in the brain. The NIRS quantifies the interaction of near-infrared photons with biological tissue, which can be described by two different properties: the absorption and reduced scattering coefficient (μa and μs0).[4,5] Deoxygenated hemoglobin (HHb) and oxygenated hemoglobin (O2Hb) are the most relevant chromophores absorbing light of the near-infrared spectrum and their concentrations can be calculated using the modified law of Lambert and Beer if the optical path length and geometrical factors are known.[6].
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