Influence of water on noninvasive hemoglobin measurement by Dynamic Spectrum

Water as the maximum content in whole blood has a great influence on noninvasive hemoglobin measurement. To analyze its influence on Dynamic Spectrum, we chose the analysis window at the wavelength range of 600–1050 nm based on 62 patients data. The spectra from 600.87 to 920.58 nm were first used to develop a calibration model. The spectra affected by water absorption band at 920.58–1050.6 nm were split in nearly 10 nm increments, and then each part of the spectra were gradually added to the spectra at 600.87–920.58 nm to develop different calibration models. Comparing the performances of these models developed by using different wavelength ranges, we find that the spectra covering absorption peaks of non-detected components can improve the signal-to-noise ratio of the calibration model, while the spectra whose boundary is around the absorption peak are exposed to the highest noise level. The results open up an avenue for reducing the non-detected component influence by selecting wavelength range. Moreover, the results demonstrate the feasibility of noninvasive low-level hemoglobin measurements by Dynamic Spectrum.