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.