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Background: During hemodialysis (HD), blood passes through an extracorporeal circuit (ECC). To prevent air administration to the patient, a venous chamber (chamber) is located before the blood return. Microbubbles (MBs) may pass through the chamber and end up as microemboli in organs such as the brain and heart. This in vitro study investigated the efficacy of various chambers in MB removal. Materials and Methods: The in vitro recirculated setting of an ECC included an FX10 dialyzer, a dextran‐albumin solution to mimic blood viscosity and chambers with different flow characteristics in clinical use (Baxter: AK98 and Artis, Fresenius: 5008 and 6008) and preclinical test (Embody: Emboless®). A Gampt BCC200 device measured the presence and size of MBs (20–500 μm). Percentage change of MBs was calculated: ΔMB% = 100*(outlet–inlet)/inlet for each size of MB. Blood pump speed (Qb) was 200 (Qb200) or 300 (Qb300) ml/minute. Wilcoxon paired test determined differences. Results: With Qb200 median ΔMB% reduction was: Emboless −58%, AK98 −24%, Fresenius 5008 −23%, Artis −8%, and Fresenius 6008 ± 0%. With Qb300 ΔMB% was: Emboless −36%, AK98 ± 0%, Fresenius 5008 ± 0%, Artis +25%, and Fresenius 6008 + 21%. The Emboless was superior to all other chambers with Qb200 and Qb300 (p < 0.001). Further, the Emboless with Qb300 still eliminated more MBs than all other chambers with Qb200 (p ≤ 0.003). Conclusion: The results from the present study indicate that flow characteristics of the chamber and the Qb are important factors to limiting exposure of MB to the return bloodline. The Emboless chamber reduced MBs more effective than those chambers in clinical use investigated. [ABSTRACT FROM AUTHOR]

We previously showed, in vitro, that micro bubbles pass the air trap without inducing an alarm. The aim was to investigate if micro bubbles bypass the detector during hemodialysis (HD). During HD (40 patients, 47 HD sessions, 231 measurements), an ultrasound detector was fixed just after the venous air trap. Micro bubble size was measured in the range from 5 µm up to >42.5 µm. Blood flow was at a mean 346 mL/min (SD ± 57). The mean of all micro bubbles per minute, without inducing an alarm, was at start 128 (range 0–769). Measurements revealed the presence of micro bubbles in all of the series and in 90% of the measurements. There was no difference between start and end of the same dialyses. There was a correlation between blood flow and extent of micro bubbles for the smaller sizes and the sum of all bubbles ( r ≥ 0.29, P ≤ 0.026). Micro bubbles passed the air trap without alarming. Most bubbles were approximately 5 µm. [ABSTRACT FROM AUTHOR]

During hemodialysis microembolic findings have been noted after the venous chamber (subclavian vein). The aim of this study was to evaluate if air could pass the venous chamber and, if so, if it passes the safety-system detector for air-infusion without triggering an alarm.Various in vitro dialysis settings were performed using regular dialysis devices. A dextran fluid was used instead of blood to avoid the risk of development of emboli. Optical visualization as well as recirculation and collection of eventual air into an intermediate bag were investigated. In addition, a specifically designed ultrasound monitor was placed after the venous air trap to measure the presence of eventual microbubbles. Speed of dialysis fluid was changed, as was the level of the fluid in the air trap. Thereby a fluid level was considered “high” if it was close to the top of the air trap and “low” if it was around the mid part of the air trap. By optical vision microbubbles were seen at the bottom of the air trap and could pass the air trap towards the venous line without alarming. During recirculation several mL of air were collected in an intermediate bag after the venous line. Ultrasound monitoring exhibited the presence of microbubbles of the size of approximately 5 µm upwards passing to the venous line in all runs performed. Amount of bubbles differed between devices and in general an increased fluid speed correlated significantly with the increased counts of microbubbles/min. No alarming of the detector occurred. A more concentrated fluid allowed higher counts/min when flow was increased to 600 mL/min. Data revealed that air passes the safety-sensor in the air trap without alarming. The presence of air increased in general with fluid speed and a lower fluid level in the air trap. Differences were present between devices. If this affects the patients has to be elucidated. [ABSTRACT FROM AUTHOR]