#2703 Venous chambers vary in the reduction capacity of air microbubbles: a randomized study of chronic haemodialysis patients

Abstract

Abstract Background and Aims The extracorporeal circuit (ECC) enables haemodialysis (HD) of patients. When the blood passes the ECC air contamination occurs, and consequently microbubbles (MBs) enter into the patient. MBs are verified at autopsy of HD patients and are covered by clots manifested as microemboli that are deposited within the lung, heart and brain tissue. A venous chamber is inserted in the ECC to reduce air contamination. However, venous chambers in clinical use have limited capacity in eliminating MBs from entering the return bloodline. In an in vitro study, the Emboless® chamber showed better results in comparison to models commonly used clinically (the best of the clinical models was the Fresenius 5008). Our aim was to determine if the Emboless® venous chamber differed in its capacity to limit MB exposure compared to the Fresenius 5008 (F5008) during HD and hemodiafiltration (HDF). Method Twenty chronic HD patients were included in a cross-over randomized study to compare the Emboless® to the F5008 venous chamber during HD. Each patient underwent a total of four dialyses divided into two paired series. This resulted in 80 studied dialyses, of which 32 included HDF. Dialyzers, blood-pump speed, HD or HDF, and ultrafiltration was the same between the pairs. MBs (20-500 µm, merged in intervals of 5 µm) were measured with an ultrasound device adjusted for HD (BCC200, GAMPT) at the ‘inlet’ and ‘outlet’ of the venous chamber. Measurements of MBs were done in the HD mode during the first 30 minutes, and if HDF was prescribed the measurement proceeded for another 30 minutes after the switch to the HDF mode (time was extended if fewer than 1000 MBs were detected at the inlet). The percentage of change in the ‘outlet’ versus ‘inlet’ counts was compared (paired Wilcoxon test). A total reduction was equal to −100%, while an increase (+) of MBs (worsening) was expressed as an unlimited percentage. If a diameter of an MB was without counts, it was not included in the analysis. Results For patients during HD, the median change of MBs in the outlet versus the inlet bloodline was −39% with the F5008 (n = 3807) and −76% with the Emboless® (n = 3805) venous chambers (p < 0.001, Fig. 1). For patients during HDF, the median change of MBs in the outlet versus the inlet bloodline was −28% with the F5008 (n = 1549) and −70% with the Emboless® (n = 1517) venous chambers (p < 0.001, Fig. 2). Conclusion Fewer MBs and subsequently fewer microemboli entered the patient using the Emboless® compared to the Fresenius 5008 venous chamber during HD, as well as during HDF. In considering previous autopsy studies, our results support less patient tissue damage when using the Emboless® venous chamber.