Impact of locking solutions on conditioning biofilm formation in tunnelled haemodialysis catheters and inflammatory response activation.

INTRODUCTION: The surface of tunnelled cuffed catheters provides an optimal environment for the development of biofilms, which have recently been described as conditioning films because of the presence of adherent biological materials. These biofilms are associated with infection and thrombosis and potentially increase patients' inflammatory response. These complications could be reduced by the use of locking solutions. OBJECTIVE: To analyse biofilm formation, using confocal and electron microscopy, in tunnelled cuffed catheters locked with three different solutions and to determine the relationship between these solutions and inflammatory response. STUDY DESIGN: This prospective study included 35 haemodialysis patients with tunnelled cuffed catheter removal for non-infection-related reasons. The participants were divided into three groups according to the lock solution used: (1) heparin 1: 5000 IU; (2) citrate 4%; and (3) taurolidine 1.35%, citrate 4% and heparin 500 IU (taurolock); in the latter group, 25,000 IU taurolidine-urokinase was used in the last weekly session. All tunnelled cuffed catheters were cultured, and the inner surface was evaluated with confocal and electron microscopy. The inflammatory profile of included patients was determined at tunnelled cuffed catheter removal. RESULTS: There were no differences in clinical or demographic variables between the three subgroups. Biofilm thickness was lower in the taurolidine group than in the citrate 4% and heparin groups (28.85 ± 6.86 vs 49.99 ± 16.56 vs 56.2 ± 15.67 µm, respectively; p < 0.001), as was biofilm volume (1.01 ±1.18 vs 3.7 ± 2.15 vs 5.55 ±2.44, µm3, respectively; p < 0.001). The mean interleukin-6 value was 39%, which was 50% lower than in the citrate and heparin groups, but without significance differences. CONCLUSION: Our results show that biofilms were found in all tunnelled cuffed catheters, but the thickness and volume were significantly lower in tunnelled cuffed catheters locked with taurolidine solution. Therefore, the type of locking solution used in tunnelled cuffed catheters should maintain tunnelled cuffed catheter sterility and prevent catheter-related bloodstream infections. No significant difference was observed in the inflammatory profile according to the type of locking solution.

Oxidative stress and other risk factors for white matter lesions in chronic hemodialysis patients.

BACKGROUND: Chronic kidney disease (CKD) is a risk factor for cardiovascular disease and promotes oxidative tress (OS), which has been implicated in the pathogenesis of white matter lesions (WML), a form of small-vessel cerebrovascular disease. The relationship between OS and WML in chronic hemodialysis (HD) patients has not yet been studied. METHODS: We studied 67 chronic HD patients, aged 40 - 65 years (average 54 years) without known cerebrovascular disease. All patients underwent brain magnetic resonance imaging and subcortical and periventricular WML were evaluated using semiquantitative measures. Patients were classified into two groups depending on the presence or absence of WML (Fazekas classification), and the WML were scored. Carotid ultrasonography was also performed to evaluate the presence of carotid artery plaques and/or stenosis. Markers of protein and lipid oxidation (protein carbonyl and oxLDL antibodies), the glutathione system, enzymatic antioxidants (superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase) and total antioxidant capacity (ORAC) were measured. OS markers were compared to those of a group of 36 healthy subjects. RESULTS: WML were present in 54% of the total population. Patients who had WML were older and had lower predialysis diastolic blood pressure than patients without WML. Other potential cardiovascular risk factors for WML, including obesity, hyperlipidemia, diabetes mellitus, presence of carotid artery plaques or stenosis, and duration and adequacy of HD were not related to the presence of WML. Compared to controls, HD patients had increased OS and decreased antioxidant capacity. However, OS did not differ between patients with WML and those without, and we found no association between OS markers and mean WML scores. After adjusting for several factors, only age and low predialysis diastolic blood pressure independently predicted an increased risk of WML. CONCLUSIONS: Our results confirm that chronic HD patients have increased OS, but this is not related to the presence or severity of WML.