The effect of dialysis needle size on hemodialysis adequacy

Abstract

Objective: Dialysis adequacy indexed by Kt/V in hemodialysis (HD) patients is recommended as a single pool Kt/V at least 1.2 per session thrice weekly. But many patients cannot achieve this adequacy target. Although dialysis time is the most important factor influencing Kt/V, it is difficult to prolong dialysis time in practice because of its economic impact and poor patient compliance. This study was performed to investigate the effect of increasing dialysis needle size on dialysis adequacy in HD patients. Methods: This study enrolled 73 patients receiving HD thrice weekly for more than 3 months with arteriovenous fistula (AVF) or graft in a single center. Dialysis blood flow rate was 200 ml/min in 12 patients, 250 ml/min in 32 patients, and 300 ml/min in 29 patients. Surface area of dialyzer was 1.2 m2 in 56 patients and 1.6 m2 in 17 patients. We first performed HD using a 16‐gauge needle. Then we increased needle size up to 15‐gauge without change of any other dialysis conditions such as blood and dialysate flow rates, dialysis time, or distance between needle insertion sites. We compared compression time after removing the needles, venous dialysis pressure (VDP), Kt/V, and urea reduction ratio (URR) between these two methods. Results: The mean age was 54 ± 13 years and the number of patients with diabetes mellitus was 27 (37%). Fifty‐eight patients (79.5%) have native AVF. Mean Kt/V at HD method using a 15‐gauge needle was higher than at HD method using a 16‐gauge needle (1.30 ± 0.18 vs. 1.23 ± 0.18, p < 0.001). URR at HD method using a 15‐gauge needle was also higher than at HD method using a 16‐gauge needle. In contrast, VDP at HD method using a 15‐gauge needle was lower than at HD method using a 16‐gauge needle (88 ± 22 mmHg vs. 118 ± 28 mmHg, p < 0.001). There was no difference in compression time between the two methods. Conclusion: This study suggests that increasing dialysis needle size is a safe and effective method in improving dialysis adequacy without increasing blood flow rate or dialysis time.