A Comparison of a Four Wavelength Analysis and Multicomponent Wavelength Analysis Applied to Determination of Haemoglobin Saturation
Cryomicrospectrophotometry has been used to study haemoglobin (Hb) and myoglobin (Mb) saturation in living tissue (Figulla, Hoffman and Lubbers, 1983). This paper evaluates two possible artefacts in cryomicrospectrometry applied to Hb measurements in small blood vessels. First, microcirculatory vessels may differ in haematocrit compared with systemic vessels (Hoffman et al., 1984). The resulting difference in Hb concentration might influence the spectroscopic signal and hence the calculation of Hb saturation. Second, the freezing rate of the tissue during the sample preparation influences the ice crystal size. Hence, light scattering and measured spectra may vary as a function of depth from a frozen surface. The present study determines the influence of different haemoglobin concentrations and freezing rates on the cryomicrospectrophotometric measurements and calculated saturations. In addition, we compared mouse, man and dog Hb using dog Hb as the standard. Finally, this paper compares the linear, multicomponent, wavelength analysis of Hoffman and Lubbers (1985) with a four wavelength method of Gayeski (1981). The latter method requires intensity measurements at four different wavelengths per saturation calculation over a ‘narrow’ spectral range (547–588 nm) as compared with many wavelengths (up to 500) over a ‘broad’ spectral range (500–600 nm). A simple method of determining haemoglobin saturation allows easier implementation.
KeywordsFreezing Rate Specimen Holder Cold Stage Wavelength Analysis Average Saturation
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