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Journal of Biomedical Optics

Quantification of cerebral hemoglobin as a function of oxygenation using near-infrared time-resolved spectroscopy in a piglet model of hypoxia
Author(s): Sonoko Ijichi; Takashi Kusaka; Kenich Isobe; Fahmida Islam; Kensuke Okubo; Hitoshi Okada; Masanori Namba; Kow Kawada; Tadashi Imai; Susumu Itoh
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Paper Abstract

Near-infrared spectroscopy (NIRS) has been used for measurement of cerebral hemoglobin (Hb) concentrations in neonates to study cerebral oxygenation and hemodynamics. We perform measurements by portable three-wavelength NIR time-resolved spectroscopy (TRS) in a piglet hypoxia model with various degrees of oxygenation to estimate the absorption coefficient (µa) and reduced scattering coefficient (µs') of the head. Measurements of absolute values of µa at three wavelengths enable estimation of Hb concentration and Hb oxygen saturation in the head (SO2). However, there is a problem concerning which background absorption should be used to estimate Hb concentration in the head derived from µa at three wavelengths because it is different from a simple in vitro model. Therefore, we use two different background absorption values with the assumption that background absorption is due only to 85% (by volume) water or that background absorption is equal to absorption of the piglet head with blood exchange transfusion by fluorocarbon (FC), and we compared SO2 measured by TRS with arterial Hb oxygen saturation (SaO2) and sagittal sinus venous Hb oxygen saturation (SvO2) measured by a co-oximeter at several inspired fractional O2(FIO2) concentrations. We find that SO2 values using the absorption (abs) of the piglet head with blood exchange transfusion (BET) by FC are not significantly different from SO2 values using the water-only background at FIO2 in the range of 15 to 100%, but that the values using abs of the head with BET by FC are lower than the values using the water-only background at FIO2 in the range of 12 to 4%. The SO2 values calculated from the water-only background are higher than those of SaO2 at FIO2 in the range of 10 to 4%. However, SO2 values using the abs of the head with BET by FC are between those of SaO2 and SvO2 over the whole range of FIO2. Therefore, abs of the head with BET by FC is more useful for estimation of the absolute values of oxyHb and deoxyHb of the piglet head.

Paper Details

Date Published: 1 March 2005
PDF: 9 pages
J. Biomed. Opt. 10(2) 024026 doi: 10.1117/1.1899184
Published in: Journal of Biomedical Optics Volume 10, Issue 2
Show Author Affiliations
Sonoko Ijichi, Kagawa Univ. (Japan)
Takashi Kusaka, Kagawa Univ. (Japan)
Kenich Isobe, Kagawa Medical Univ. (Japan)
Fahmida Islam, Kagawa Univ. (Japan)
Kensuke Okubo, Kagawa Univ. (Japan)
Hitoshi Okada, Kagawa Univ. (Japan)
Masanori Namba, Kagawa Univ. (Japan)
Kow Kawada, Kagawa Medical Univ. (Japan)
Tadashi Imai, Kagawa Univ. (Japan)
Susumu Itoh, Kagawa Medical Univ. (Japan)

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