P6


Topic: Other

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New technology for extracorporeal therapies


Claudio Ronco, S. Bagshaw, C. Ronco

Nephrology and IRRIV, St. Bortolo Hospital, Vicenza, Italy | Division of Critical Care Medicine, University Of Alberta Hospital, Edmonton, AB, United States of America | Nephrology and IRRIV, St Bortolo hospital, Vicenza, Italy

Introduction: From the first application of ContinuousVenoVenousHemofiltration CVVH, the blood flow has been driven by a peristaltic pump. Several attractive alternatives, with both advantages and disadvantages, have been proposed for many years. SAM (Spectral Medical Inc.; Toronto, Canada) is a novel instrument, in which the pumping of whole blood and fluids is performed through the use of pistons, chambers and valves through a plastic cartridge blood circuit system. All is assembled in a basic machine. Hemoperfusion [1], an extracorporeal circuit equipped with a cartridge adsorption column effective in removing endotoxin in the bloodstream, is a short modality that ideally require a dedicated machine.


Objectives: Aim of this investigation is to compare the membrane with peristaltic pumps in terms of hemolysis by measuring the Normalized Index of Hemolysis NIH [2] during in vitro testing. Secondary we evaluate the new pumping system in terms of general usability.


Methods: Three sessions of hemoperfusion with a line inserted in place of a hemofilter were performed both with SAM and Prismaflex (©Baxter International).A single pool of fresh heparinized bovine blood (Heparin 500 u/L,Hb 12‡1 g/dl,Base Excess 0+/5 mmol/L) were split into three aliquots containing 900 mL (Control, SAM, Prismaflex) and circulated for 6 hours/session. Bloo±d samples were drawn at baseline, 30 min and every 1 hour. NIH were calculated as median hourly variation of free hemoglobin and used for comparison. Data was compared with two tailed Student's test based on FTest results. We also set up the machine for CVVH. An 11.5 Fr 20 cm catheter was connected to the lines. We ran the machine for 6 hours in order to characterize the performance of the system

Results: NIH values of 0.12±0.03 and 0.13±0.09 mg/100L for SAM and Prismaflex respectively are lower than those reported in literature due to the simplified circuit used (no vascular access and filter). Creation of hemoglobin between sam and control, and prisma and control are nonsignificant. Slope of the curves that describe the creation of hemolysis are nearly identical with a slow rate of production of free hemoglobin. We did not observe a reduction of blood flow due to a loss of membrane elasticity.

Conclusion: Device compatibility in terms of lethal damage to blood cells, is an important aspect of the development of artificial organs. Since a validation based on dangerous level of free hemoglobin do not exist, an empirical evaluation using comparative test suggest that piston driven membrane is safe from a hemolysis point of view.
Analyzing the pumpingsystem/cassette equipment, we identified potential advantages, in addition to usability, such as: accurate balancing system, blood flow ideally designed to avoid mechanical cell damage, constant blood flow over time, accurate volumetric balancing system, less clotting activations, and an optimal withdrawal flow profile. More tests should be performed in order to validate the device in various aspects and conditions.The use of an 'allintegrated' cassette reduces the number of manual operations, avoiding operator related errors and favoring an easy and time saving set up: precious things especially when a short extracorporeal treatment is required.

References:

1.Early use of polymyxin B hemoperfusion in abdominal septic shock: the EUPHAS randomized controlled trial.