MO764AVF VOLUME BLOOD FLOW REDUCTION AS THE FIRST STAGE OF TREATMENT OF CENTRAL VEIN STENOSIS IN HD PATIENTS

Background and Aims It is well-known that central vein stenosis (CVS) significantly reduces the time of AVF functioning. At the same time, according to current guidelines (KDIGO, European Vascular Surgery Society, European Best Clinical Practice), only clinically significant CVS should be treated. Often, CVS becomes clinically manifest due to a significant increase of AVF volume blood flow (Qa) through the matured dialysis access. Aim: to assess the effect of Qa reduction on the CVS clinical course. Method We performed a retrospective study included 56 patients who underwent Qa reduction as the first step of treatment, and 62 patients who received endovascular interventions without Qa reduction (balloon angioplasty supplemented with stenting if necessary). Blood flow reduction was performed using banding under intraoperative ultrasound control. Results Surgical banding leads to a clinically obvious and statistically significant decrease in Qa in all patients – fig. 1. In contrast, after endovascular intervention most of the patients show a modest but statistically significant increase in Qa - fig. 2. All surgeries were performed to reduce the severity of clinical manifestations of CVS. AVF was better available for immediate cannulation after endovascular interventions than after banding: RR=4,537 [95%CI 1,416; 14,84], p=0,0116. However, the probability of successful cannulation at the third postoperative HD session did not differ between groups: RR=3.024 [95%CI 0.674; 13.67], p=0.2126. Taking in consideration these findings, we can conclude that the short-term results of Qa reduction are satisfactory. After Qa reduction in case of recurrence of CVS symptoms or absence of their complete resolving, we supplemented the treatment with endovascular interventions. Both primary and secondary patency were significantly better than in the case of endovascular interventions without Qa reduction – fig. 3. Moreover, in patients who underwent endovascular interventions without Qa reduction, higher Qa values were associated with decrease of the primary and secondary patency – fig. 4. So, increasing or maintaining large Qa values after endovascular intervention may be an important risk factor for CVS relapse and AVF function loss. Conclusion Qa is an important factor of CVS clinical manifestation. When determining treatment strategy, it is necessary to evaluate Qa first and reduce it, if necessary. Manage of Qa allows to transfer manifest CVS into its subclinical course, which itself leads to improved treatment results. Endovascular interventions are the preferred treatment of CVS with clinical manifestations in a case of underlying normal or suboptimal Qa.

FEATURES OF REGULATION OF BREATH

In modern physiology, very simplified perceptions of such an essential system for the body as the respiratory system have taken root. The system analysis showed that at a physical load of more than 50 W, the tissue respiratory subsystem is activated, providing a volume blood flow rate adequate to the amount of oxygen consumed, and in the external respiratory subsystem the regulation on oxygen voltage in arterial blood is activated, and the regulation on carbon dioxide voltage is deactivated. The role of respiratory frequency in increasing the rate of diffusion through the alveolar capillary membrane is shown. For physiologists, medical professionals and trainers.

P1330ACCURACY OF CARDIOPULMONARY RECURCULATION ASSESSEMENT IN HD PATIENTS

Background and Aims cardiopulmonary recirculation (CRP) is one of the most informative instrumental parameters, which are widely used to predict adverse cardiovascular events. The CRP is calculated on the basis of two indirectly measured estimates. We observe a significant variability in CRP, the reason for which we have tried to explain. Method The prospective study included 88 patients with native AVF. At the first stage, we evaluated the inter- and inner-observer agreement of AVF volume blood flow (Qa) measurement with color duplex ultrasound. Two specialists with 5-7 years of experience measured Qa twice on the brachial artery, twice on fistula vein, after that - twice measured cardiac output before HD and one time after HD. Ultrafiltration during HD was 1.9±0,5 l. Results We observed good concordance between measurements on the brachial arteria by one specialist (fig 1A) and by two specialists (fig. 1B). There was poor concordance between the brachial artery and the fistula vein, even if the measurement was performed by one specialist (fig. 1C). Qa measurement on the fistula vein has a low repeatability, even if the measurement was performed by one specialist: the variance is very high (fig. 1 D). We observed a good concordance between measurements (fig. 2A) and between specialists (fig. 2B) in CO assessment. The main pitfalls of CPR-based cardiovascular risk stratification are related to the fact that CO changes significantly after HD (fig. 3A), while Qa values remain relatively stable (fig. 3B): the QA before and after HD difference is statistically significant, but it is minimal. Median CO decrease was 13.4% (maximum 26.6%), while median of Qa decrease was 1.7% (maximum 6.1%). This leads to a significant increase of the CPR value after HD, which can reach 40%(!) in some patients (absolute increase – 0.11). Conclusion Qa assessment should be performed on the brachial artery. After HD, there is a significant decrease in cardiac output (even with moderate ultrafiltration) with relatively stable AVF volume blood flow. This leads to a significant increase of CPR value after HD in some patients. Assessment of CPR before HD may lead to underestimation of cardiovascular risk.

ANALYSIS OF THE CARDIOVASCULAR SYSTEM IN SIMULATED CONDITIONS

Aim. The article deals with establishing the correlations between the anthropometric, hemodynamic, and vegetative tone indicators in first and second-year students during their adaptation to university conditions. The morphophysiological status of students was corrected by Selenes+ and additional physical load. Materials and methods. Students aged 17–20 years (n = 60) participated in a longitudinal study. The following physiological methods were used: body length and mass measurement; BMI calculation; detection of selenium in blood serum; systolic and diastolic pressure measurement; heart rate calculation; average dynamic pressure calculation; pulse pressure calculation; stroke volume calculation using Starr’s equation; minute volume blood flow calculation; endurance coefficient calculation according to Kvass’ equation; functional changes index calculation; Kerdo vegetative index calculation. Results. It was established that application of selenium depending on physical load in first-year female students influenced significantly the following indicators: arterial pressure (F = 4.21), heart rate (F = 3.42), minute volume blood flow (F = 3.80), functional changes index (F = 10.65), systolic pressure (F = 4.72; P < 0.05); selenium concentration (F = 93.97; P < 0.001). At the end of the IV stage, statistically significant F-criteria for arterial pressure (F = 3.50), heart rate (F = 4.33), endurance coefficient (F = 4.78; Р < 0.05), systolic pressure (F = 5.92), pulse pressure (F = 5.50; P < 0.01), functional changes index (F = 10.65), selenium concentration (F = 41.11; P < 0.001) were registered. Conclusion. The correlations revealed between the anthropometric, hemodynamic, and vegetative tone indicators in first and second-year students allowed to make a conclusion about the efficiency of the Selenes+ supplement during adaptation to university conditions. The Selenes+ supplement combined with physical exercises contributes to less pronounced stress in the cardiovascular system and provides the physiological optimum of the body.