University of Ottawa Eye Institute, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada.
Analyst. 2011 Apr 21;136(8):1637-43. doi: 10.1039/c0an00996b. Epub 2011 Feb 22.
It is well known that red blood cell scattering has an impact on whole blood oximetry as well as in vivo retinal oxygen saturation measurements. The goal of this study was to quantify the impact of small angle forward scatter on whole blood oximetry for scattering angles found in retinal oximetry light paths. Transmittance spectra of whole blood were measured in two different experimental setups: one that included small angle scatter in the transmitted signal and one that measured the transmitted signal only, at absorbance path lengths of 25, 50, 100, 250 and 500 µm. Oxygen saturation was determined by multiple linear regression in the 520-600 nm wavelength range and compared between path lengths and experimental setups. Mean calculated oxygen saturation differences between setups were greater than 10% at every absorbance path length. The deviations to the Beer-Lambert absorbance model had different spectral dependences between experimental setups, with the highest deviations found in the 520-540 nm range when scatter was added to the transmitted signal. These results are consistent with other models of forward scatter that predict different spectral dependences of the red blood cell scattering cross-section and haemoglobin extinction coefficients in this wavelength range.
众所周知，红细胞的散射会对全血血氧测定以及活体视网膜血氧饱和度测量产生影响。本研究的目的是定量评估小角度前向散射对视网膜血氧测量光路中发现的散射角的全血血氧测定的影响。在两种不同的实验设置中测量了全血的透射光谱：一种设置中包括在透射信号中存在小角度散射，另一种设置仅测量透射信号，在吸收路径长度为 25、50、100、250 和 500 µm 时。在 520-600nm 波长范围内通过多元线性回归确定氧饱和度，并在路径长度和实验设置之间进行比较。在每个吸收路径长度下，设置之间的平均计算氧饱和度差异均大于 10%。在实验设置之间，与 Beer-Lambert 吸光度模型的偏差具有不同的光谱依赖性，当向透射信号中添加散射时，在 520-540nm 范围内发现的偏差最大。这些结果与前向散射的其他模型一致，这些模型预测在该波长范围内红细胞散射截面和血红蛋白消光系数的不同光谱依赖性。
