Microbiological quality and quality control of purified water and ultrapure dialysis fluids for online hemodiafiltration in routine clinical practice.

During online hemodiafiltration, patients are directly infused with sterile substitution solutions to maintain fluid balance. Adequate water treatment and a well-organized quality control process are essential to provide non-pyrogenic fluids with consistent optimal quality. We sought to assess water quality, the water treatment system, and the methods for surveillance of microbiological water quality in 10 Dutch dialysis centers that routinely treat patients with hemodiafiltration. Microbiological monitoring results (micro-organisms and endotoxins) were collected over a 1-year period representing 11,258 hemodiafiltration sessions covering 97 patients. In all centers, water purification was based on a reverse osmosis module in combination with a second reverse osmosis and/or an electrodeionizer. All centers regularly and routinely monitored the microbiological purity of the dialysis water with adequate analytical methods but with variable monitoring frequency. Microbiological assessments were compliant with reference quality levels in 3923 of 3961 samples. Our study suggests that non-pyrogenic substitution fluids can be produced online for a prolonged period of time. It is likely that the current Dutch Quality of Care Guideline has contributed to high-quality water treatment and a well-organized control process.

Plasma dimethylarginine levels in chronic hemodialysis patients are independent of the type of dialyzer applied.

BACKGROUND: Asymmetric dimethylarginine (ADMA) levels are increased in hemodialysis (HD) patients. Reports on the effect of various dialysis strategies on ADMA, symmetric dimethylarginine (SDMA) and L-arginine levels are inconclusive. PATIENTS/METHODS: In this randomized crossover study, 15 patients were dialyzed for 4 weeks with 4 dialyzers, differing in biocompatibility and flux. Dimethylarginine and L-arginine levels were assessed at baseline, and after 4 weeks both before and after HD. RESULTS: During HD, ADMA and SDMA levels decreased significantly with all dialyzers. Dimethylarginine and L-arginine levels remained stable after 4 weeks of HD with each membrane. After pooling all data, values were mainly explained by variation between time points and patients, not by the type of dialyzer. CONCLUSION: Despite an intradialytic decrease in dimethylarginines, no changes occurred after 4 weeks of HD with either membrane. Furthermore, the variability of AMDA, SDMA and L-arginine levels was far more dependent on patient-related factors than on the type of dialyzer applied.

Patient characteristics rather than the type of dialyser predict the variability of endothelial derived surface molecules in chronic haemodialysis patients.

BACKGROUND: Cardiovascular disease (CVD) is a frequent complication in chronic haemodialysis (HD) patients. Endothelial dysfunction, as measured by soluble cellular adhesion molecules (sCAM) and von Willebrand factor (vWf) in plasma, is an early manifestation of CVD. Today, it is unknown if, and to what extent, their levels are influenced by the type of dialyser. METHODS: Four dialysers, low-flux cuprammonium (CU); high-flux and low-flux polysulfone and super-flux polyethersulfone, were compared in 15 chronic HD patients in a randomized cross-over fashion. sCAM and vWf were measured at baseline as well as after 4 weeks, and both intra-dialytical and after 24 h (t24 h). Twenty healthy subjects served as controls. RESULTS: Baseline levels were considerably higher in chronic HD patients than in controls (soluble intercellular adhesion molecule-1: sICAM-1 732+/-216 vs 572+/-259 ng/ml, P = 0.06; soluble vascular cell adhesion molecule-1: sVCAM-1 1917+/-492 vs 1126+/-338 ng/ml, P<0.001; vWF: 205+/-55% vs 98+/-52%, P<0.001). After 4 weeks, no changes were observed. During and after HD, sCAM did not change, except in the case of CU (sICAM-1: 719+/-259 to 772+/-261 ng/ml, P = 0.04). CU induced a rise in vWF directly after HD (t4 h; from 188+/-48% to 255+/-92%, P<0.01), whereas all modalities induced a significant increase at t24 h (mean 228+/-54%, P = 0.02). The levels of sCAM and vWf appeared to be dependent on the individual patients rather than on the type of dialyser (explained variance by different patients: 66%-91%, P<0.001; by type of dialyser 0.4-1.2%). CONCLUSIONS: Baseline levels of sCAM and vWf were markedly higher in chronic HD patients than in controls and did not change after 4 weeks with any dialyser. All membranes induced a marked rise in vWf at t24 h, whereas sICAM-1 increased only in the case of CU at t4 h. As sCAM showed no marked changes during HD with any other modality, our study suggests activation of blood cells rather than endothelial cells. As pre-dialysis levels of sCAM and vWf varied noticeably between individual patients, endothelial dysfunction seems to be far more dependent on patient-related factors than on the HD treatment itself.