ИСТИНА

A quantitative assessment of edema syndrome that can occur in various diseases, such as chronic heart failure or renal impairment is an urgent and yet unsolved problem. Fluid retention in tissues occurs as a result of an imbalance in transcapillary system, through which water and nutrients are exchanged between the circulatory blood system and other tissues. The study of shallow blood capillaries (lying at a depths of about 50-150 microns in skin) is possible using optical microscopy, and a large number of parameters of the capillary network obtained using an optical microscopy, such as the density of the number of capillaries, their tortuosity, capillary blood flow velocity are diagnostically significant parameters in many diseases [1]. Still, there is lack of parameters that allow one to assess the degree of fluid release and retention in tissues by the parameters of capillaries, though such a relationship should obviously exist. Previously, we demonstrated that the area of viable epidermis around papillary capillary loops can be enlarged significantly in patients with heart failure, and the size of this perivascular area can be quantitatively characterized by optical microscopy and can serve as a diagnostic parameter for estimation of severity of heart failure [2]. In this work, we show that the size of the perivascular zone and the apical diameter of the capillary loop – the capillary section, which separates venous and arterial sections – can change upon changes in fluid flow in tissues and that both these parameters are suitable for assessing the fluid retention in the tissues. We demonstrate the diagnostic value of these parameters both in the model experiments like venous and arterial occlusion, and in real clinical case of patients undergoing treatment with diuretics. We believe these parameters will find its diagnostic application in a clinical setting. [1] Cutolo, Maurizio, Carmen Pizzorni, and Alberto Sulli. "Capillaroscopy." Best practice & research Clinical rheumatology 19.3 (2005): 437-452. [2] Shirshin, Evgeny A., et al. "In vivo optical imaging of the viable epidermis around the nailfold capillaries for the assessment of heart failure severity in humans." Journal of biophotonics 11.9 (2018): e201800066.