RESUMO
BACKGROUND: To assess the adequacy of dialysis, serial urea kinetic modeling (single-pool Kt/V) is used. The main problems that lead to impaired delivery of dialysis prescriptions are inadequate blood flow, reduced treatment time and recirculation. If it is true that the shorter distance between two needles induces the more recirculation, short needle distance would reduce Kt/V. But, usually there is no access recirculation, because upstream access supply exceeds the demand of the blood pump. So we have a question about the relationship between recirculation and needle distance. METHODS: Thirty five chronic dialysis patients were enrolled. We measured access recirculation (a two-needle, slow/stop flow method) and Kt/V with needle distance of 2 cm, 5 cm, and 11 cm in each patient. Three dialysis session were done with each needle distance. Treatment time, dialyzer and blood flow rate were fixed during the study period. RESULTS: Access recirculation with needle distance of 2 cm was 5.37+/-7.53%, with needle distance of 5 cm, 4.26+/-5.69%, and with needle distance of 11 cm, 4.30+/-5.69%. There was no difference of recirculation between three distance. Kt/V with needle distance of 2 cm was 1.27+/-0.19, with needle distance of 5 cm was 1.26+/-0.19, and with needle distance of 11 cm was 1.23+/-0.18. There was no difference of Kt/V between three distance. CONCLUSION: There is no relationship between access recirculation and needle distance. We suggest that short distance between two needles does not increase recirculation and may not a cause of impaired delivery of dialysis prescription.