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AV Access Flow Measurement: Comparing Fresenius Conductivity Method to Transonic Ultrasound Dilution. |
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Janet L. Graham
James Jaffey, Peter Magner Division of Nephrology, The Ottawa Hospital; Kidney Research Center, University of Ottawa; Ottawa Health Research Institute, The Ottawa Hospital, ON, Canada
JASN Abstracts 2005
Transonic Reference #
HD7062A |
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Abstract |
Publication |
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| Monitoring native AV fistulae intra-access blood flow (QA) has become standard for hemodialysis patients. The current gold standard is the ultrasound dilution technique (HD01; Transonic Systems Inc. Ithaca, NY). Another method, available as a standard feature on Fresenius dialysis machines, uses a change in dialysate conductivity. We conducted a large, single centre, prospective, randomized cross-over trial of 145 patients with AV fistulae. Each patient had both Fresenius(FQA) and Transonic(TQA) measurements on the same day during the first half of their hemodialysis treatment on two consecutive weeks. The order of measurements was randomly assigned, and reversed on the second week. These paired measurements were recorded along with BP, pulse, fluid removal target and other parameters. A total of 290 paired readings were analyzed:
____________________ #Readings #(%) F QA Within 10% of T QA #(%) F QA Within 20% of T QA
All 290 124 (42.8) 208 (71.7)
Quartiles of Transonic QA
0-660 73 35 (48.0) 51 (69.9)
661-928 72 27 (35.5) 55 (76.4)
929-1323 73 20 (27.4) 45 (61.6)
1324-2000 72 42 (58.3) 57 (79.2)
Including only patients with <20% difference between Fresenius on weeks 1 2
All 156 82 (52.2) 129 (82.2)
Transonic QA
0-660 41 21 (51.2) 33 (80.5)
661-928 32 13 (40.6) 28 (87.5)
929-1323 38 13 (34.20 25 (67.80
1324-2000 46 35 (76.1) 43 (93.5)
The TQA-FQA difference was significant (p<.001 by paired t test) and not explained by variation in BP or fluid removal target. The majority of measurements of FQA were > 10% different than TQA and 28% of FQA were > 20% different than TQA. In addition 67 patients had FQA that were >20% different on the two weeks. Elimination of these non-reproducible FQA measurements led to only marginal improvement in ability to reproduce TQA. The TQA-FQA difference was large across all quartiles of TQA. We conclude that the Fresenius method of measurement of AV fistula QA does not reliably reproduce the QA measured by the Transonic method.
Procedure: hemodialysis
Key Words : Human, |
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