Rinsing time and disinfectant release of reused dialyzers: comparison of formaldehyde, hypochlorite, warexin, and renalin.

The influence of disinfecting agent (DA) type on the rinsing time of reused dialyzers and DA rebound release after rinsing is unknown. We compared 10 groups of five dialyzers each: cellulose acetate capillaries and AN69 plates disinfected with formaldehyde (F), polysulfone and cuprophane capillaries disinfected with 3.5% Renalin (R; Renal Systems, Minneapolis, MN), polysulfone capillaries and AN69 plates disinfected with 0.5% R, and AN69 capillaries and plates disinfected with Hypochlorite (H; Solvay, Brussels, Belgium) or Warexin (W; Guardian Chemical, Division of United Guardian Inc, Hauppage, NY), respectively. Formaldehyde, R, H, and W were detected by standard tests. The rinsing time required to reach undetectable levels of DA is shortest for H and W, intermediate for R 0.5% and 3.5%, and longest for F (F v R, H, and W; R v H and W; and H v W: P < 0.001). The rebound release 30 minutes after completion of rinsing is the highest for F (average 6 ppm), intermediate for R 0.5% and 3.5% (mean 1.4 ppm, P < 0.002 compared with F and mean 2.95 ppm, P < 0.05 compared with F, respectively), and low (< or = 1 ppm) for W and H (P < 0.001 compared with F and P < 0.01 compared with R 3.5% and 0.5%). We conclude that the dialyzer rinsing time needed to obtain undetectable levels of DA depends on the DA type. In addition, we demonstrate that like F, R is released from reused dialyzers after "adequate rinsing." The potential clinical consequences of this phenomenon require further investigation.