1 March 2005 Quantification of cerebral hemoglobin as a function of oxygenation using near-infrared time-resolved spectroscopy in a piglet model of hypoxia
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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.
© (2005) Society of Photo-Optical Instrumentation Engineers (SPIE)
Sonoko Ijichi, Sonoko Ijichi, Takashi Kusaka, Takashi Kusaka, Kenich Isobe, Kenich Isobe, Fahmida Islam, Fahmida Islam, Kensuke Okubo, Kensuke Okubo, Hitoshi Okada, Hitoshi Okada, Masanori Namba, Masanori Namba, Kow Kawada, Kow Kawada, Tadashi Imai, Tadashi Imai, Susumu Itoh, Susumu Itoh, } "Quantification of cerebral hemoglobin as a function of oxygenation using near-infrared time-resolved spectroscopy in a piglet model of hypoxia," Journal of Biomedical Optics 10(2), 024026 (1 March 2005). https://doi.org/10.1117/1.1899184 . Submission:
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