Experience of calibration of a non-contact laser Doppler flowmeter

Objective: to carry out calibration of a non-contact laser Doppler flowmeter (LDF) with justification for its subsequent use in model experiments and clinical trials. Material and methods. An experimental setup is described for reproducing a given blood flow velocity by simulating a capillary; methods are presented for calibrating the flowmeter in tissue perfusion units using a calibration emulsion fluid to determine the instrument readings' dependence on the concentration of moving particles. A method is provided for measuring the level of “biological zero” tissue perfusion of gastrointestinal tract mucosa. Results. Key parameters for processing signals from the non-contact LDF were established along with their relationship to characteristics of the calibration solution's flow and particle movement speed within it. The average value of the “biological zero” index was determined for gastric mucosal wall at 0.07±0.014 tpu. Conclusion. As a result of the carried out work on calibration of the experimental LDF apparatus which measures microcirculatory blood flow using a contactless method, suitability for measurements of the microcirculatory bed of human tissues was confirmed, basic dependences of the parameters of processing the LDF signal on the volume of the flowing calibration emulsion, its speed and the number of moving microparticles in it were obtained.