Ijichi Sonoko, Kusaka Takashi, Isobe Kenich, Islam Fahmida, Okubo Kensuke, Okada Hitoshi, Namba Masanori, Kawada Kou, Imai Tadashi, Itoh Susumu
Kagawa University, Department of Pediatrics, Faculty of Medicine, Mikicho 1750-1, Kitagun, Kagawa 761-0793, Japan.
J Biomed Opt. 2005 Mar-Apr;10(2):024026. doi: 10.1117/1.1899184.
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 (mu(a)) and reduced scattering coefficient (mu(s)') of the head. Measurements of absolute values of mu(a) 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 mu(a) 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(FI(O2)) 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 FI(O2) 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 FI(O2) in the range of 12 to 4%. The SO2 values calculated from the water-only background are higher than those of SaO2 at FI(O2) 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 FI(O2). 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.
近红外光谱（NIRS）已被用于测量新生儿大脑血红蛋白（Hb）浓度，以研究大脑氧合作用和血流动力学。我们通过便携式三波长近红外时间分辨光谱（TRS）在具有不同氧合程度的仔猪缺氧模型中进行测量，以估计头部的吸收系数（μ(a)）和约化散射系数（μ(s)'）。在三个波长处测量μ(a)的绝对值能够估计头部的Hb浓度和Hb氧饱和度（SO2）。然而，存在一个问题，即应该使用哪种背景吸收来根据三个波长处的μ(a)估计头部的Hb浓度，因为这与简单的体外模型不同。因此，我们使用两个不同的背景吸收值，假设背景吸收仅由85%（体积）的水引起，或者背景吸收等于用氟碳化合物（FC）进行血液交换输血后的仔猪头部的吸收，并且我们在几个吸入氧分数（FI(O2)）浓度下，将TRS测量的SO2与用共血氧计测量的动脉Hb氧饱和度（SaO2）和矢状窦静脉Hb氧饱和度（SvO2）进行了比较。我们发现，在15%至100%的FI(O2)范围内，使用FC进行血液交换输血（BET）后的仔猪头部吸收（abs）得到的SO2值与仅使用水背景得到的SO2值没有显著差异，但在4%至12%的FI(O2)范围内，使用FC进行BET后的头部abs得到的值低于仅使用水背景得到的值。在4%至10%的FI(O2)范围内，仅使用水背景计算得到的SO2值高于SaO2值。然而，在整个FI(O2)范围内，使用FC进行BET后的头部abs得到的SO2值介于SaO2和SvO2值之间。因此，使用FC进行BET后的头部abs对于估计仔猪头部氧合血红蛋白和脱氧血红蛋白的绝对值更有用。
