ASSESSMENT OF CUTANEOUS BLOOD FLOW IN LOWER EXTREMITIES BY IMAGING PHOTOPLETHYSMOGRAPHY METHOD

Subject of Research. The paper presents effective application of the novel imaging photoplethysmography method for receiving data on reaction of peripheral blood flow in lower extremities on venous occlusion. Method. Four digital cameras were used to record synchronously videos of all-around view of the subject's lower limb illuminated by green light (525 nm). For blood flow reactivity assessment, four consecutive venous occlusions were applied for 10 s by rapid increase of the pressure up to 60 mm Hg in an occlusal cuff situated at the lower third of the thigh followed by 20-second recovery period. Two techniques were used and compared for processing of experimental data: by averaging of camera matrix pixel values in arbitrary chosen regions of interest and by component analysis of camera video signals. It was found out that the technique of the pixel value averaging provides a more reliable quantitative assessment of peripheral blood flow parameters in lower extremities. The data processing algorithm was optimized. Main Results. The study involved 16 healthy volunteers. Data analysis has shown that dynamics of changes in the intensity of light interacting with the lower leg during occlusion was successfully obtained in all subjects. The shape of the optically measured response on venous occlusion was found out to be the same as the curves of classical air plethysmography applied to evaluation of musculocutaneous blood flow in the forearm. Practical Relevance. Taking into account the simplicity and contactless nature of the study, the imaging photoplethysmography method can be widely introduced into clinical practice for research of the functional state of the lower extremity vessels in a wide range of diseases.