Evaluation of Fractional Blood Saturation in an Aircraft Pilot Under the Influence of Dynamic Flight Factors

The purpose of research is to improve the accuracy in assessing the level of blood oxygen saturation in an aircraft pilot when conducting non-invasive spectrophotometric measurements in transmitted light under the influence of dynamic flight factors.

Methods are based on the basic concepts of the interaction of optical radiation with biological tissue and blood, the theory of pulse oximetry, probability theory, mathematical statistics, signal theory. When developing mathematical models of photoplethysmographic signals, aircraft noise, vibration, as well as for their representation in the frequency domain, the MATLAB 2019b program with a graphical user interface with a built-in Symbolic Math Toolbox package of mathematical functions was used as a tool.

Results. Mathematical models have been developed to assess the level of functional and fractional blood saturation. Model studies of the influence of dynamic flight factors, such as broadband quasi-harmonic vibration and aircraft noise, on the accuracy of estimating the pilot's blood saturation level have been carried out. It has been shown that to assess functional saturation, it is sufficient to use two sources of optical radiation, while for fractional saturation, their minimum number should be equal to four and is determined by the number of hemoglobin fractions taken into account in the blood. The use of four sources of optical radiation of a given spectral composition (660 nm, 805 nm, 880 nm and 940 nm) when performing non-invasive spectrophotometric measurements to assess the level of blood oxygen saturation compared to two sources (660 nm and 940 nm) allows to reduce the absolute error: in under the influence of broadband quasi-harmonic vibration - 3.64 times; under the influence of aircraft noise (70 dB) and (30 dB) - by 7.64 and 2.5 times, respectively; under the influence of the combined effects of vibration and aircraft noise (30 dB) - by 2.22 times.

Conclusion. For an adequate assessment of the pilot's functional state according to the values of his physiological parameters, in particular, the level of blood oxygen saturation, it is necessary to use diagnostic tools based on multiwave pulse oximetry, which allow estimating the level of fractional saturation.

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