THE FALLIBILITY OF RECIRCULATION MEASUREMENTS USING PERIPHERAL VEIN AND LOW-FLOW TECHNIQUES IN MONITORING HEMODIALYSIS ACCESS FUNCTION

For quite a while now, measurement of recirculation has been used to a ssess the function of a hemodialysis vascular access. However, the con clusions of prior studies based on the peripheral vein method are, in the main, probably invalid due to the fact that peripheral solute leve ls ave always higher than the respective values in arterialized blood The present study was designed to evaluate the accuracy and reproducib ility of recirculation measurements. In 26 randomly selected hemodialy sis patients, all with native arteriovenous fistulae, recirculation wa s determined (at a mean blood flow rate of 300 +/- 8 ml/min) on 2 sepa rate occasions, at an interval of 1 to 2 weeks. Each recirculation mea surement was performed using, at first, the peripheral vein method, fo llowed immediately by the low-flow method at 20 and 60 seconds respect ively. For each measurement, recirculation was calculated using 3 test solutes urea, uric acid, and creatinine. The percent recirculation wa s essentially similar irrespective of the test solute used. Recirculat ion using a peripheral vein was, at all times, significantly, higher t han that measured using the low-flow technique; 15.4% of the recircula tion measurements registered a negative value. There was no correlatio n between the recirculation values determined at an interval of 1 to 2 weeks. We conclude that the reproducibility of recirculation measurem ents using the above test solutes and methodology is too low to accura tely monitor the progression of function of a hemodialysis vascular ac cess.