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We present the results of measuring the volume of polyvinyl alcohol polymer granules crosslinked with epichlorohydrin in water and in aqueous solutions of KCl, MgCl2 and their mixtures, obtained by optical micrometry, and consider the main sources of errors in the measurement errors. The purpose of this study is to analyze and evaluate the effect of the main sources of errors on the accuracy of determining the relative volumes of granules, as well as to search for techniques that can minimize the resulting measurement errors. The diameters of the granules were determined using specialized software implementing machine vision algorithms from the images obtained by optical microscopy. Their volumes were calculated using the formula for the volume of the ellipsoid of revolution. The maximum accuracy of volume determination is known to be achieved when the measured granule has a sphere shape. It is shown that deviation from this shape, for example, in case of an ellipsoid, gives errors in determining the third axis of the ellipsoid, invisible in the image, which creates an error in determining the relative volume of the granule. The instrument error is determined and a statistical estimate of the error attributed to the non-sphericity of the granules is given. It is shown that a typical instrument error in determining the relative volumes of granules is 0.4%. The non-sphericity of the measured granules increases the measurement error up to 3.5%. The error for a single granule can be reduced to 2.3% by combination of methodological techniques and statistical processing of the results, whereas and for an ensemble of at least 5 granules — up to 1.5%. The reproducibility of the properties of polymer granules in cyclic measurements was studied. It is shown that the degree of swelling the granules is reproduced with an error of 1%, which allows the sensor to be used repeatedly. The results obtained can be used in experiments and data processing for analytical applications.

Aim.To analyze the frequency of resumption of anticoagulant therapy (ACT) after major and clinically significant bleeding among AF patients who received oral anticoagulants and were observed in the Department of clinical problems of atherothrombosis from 1999 to 2019 within the retro-prospective register Regata-2, and to search for clinical factors associated with recurrence of hemorrhagic complications among patients who resumed anticoagulant therapy after a bleeding episode. Materials and methods.In cohort study of patients with high-risk AF with absolute indications for ACT we enrolled 290 AF patients (130 women and 160 men) aged 32 to 85 years (the average age was 65.188.89 years). During the follow-up period, 92 patients developed hemorrhagic complications, and 73 of them resumed ACT. 35 of the 73 patients who resumed ACT developed a relapse of major/clinically significant bleeding. Results.The frequency of resuming ACT after the first hemorrhagic complication increased over time from 75% in the period from 19992003 to 90% in the period 20152019. We were not able to establish an exact relationship between the presence of concomitant pathology and the decision to resume the ACT after bleeding. The only reliable reason for refusing to resume the ACT was the patients categorical reluctance. Among patients who had recurrent hemorrhagic complications, the total score on the Charleson comorbidity scale was significantly higher (4.232.01vs3.521.43;p=0.0425). Patients with recurrent bleeding were significantly more likely to suffer from CKD with a decrease in GFR less than 60 ml/min/1.73 sq. m, and also had a history of erosive and ulcerative lesions of the gastrointestinal tract. There was also a significant Association of recurrent bleeding with the use of proton pump inhibitors. Subgroups of patients who switched from warfarin to taking direct oral anticoagulants after the first bleeding and subsequent recurrent bleeding did not differ in basic clinical characteristics from patients without bleeding after changing the anticoagulant. According to multiple regression analysis, NSAIDs showed a tendency to develop a relapse of B/C bleeding on the background of direct oral anticoagulants in patients who underwent GO on the background of warfarin therapy (b=0.4524,p=0.0530). Conclusion.During the 20-year follow-up, the frequency of all major and clinically significant bleeding was 2.6/100 patients-years, the frequency of first bleeding was 5.86/100 patients-years, while the frequency of repeated hemorrhagic complications was 7.06/100 patients-years. Patients with a high thromboembolic risk should receive anticoagulants, provided that the modifiable risk factors for bleeding are carefully corrected.