Ultra‐low dose heparin locks perform well on non‐tunnelled temporary haemodialysis catheters

Renaud Claude J et al. recently reported that ultra-low dose heparin solution for early tunnelled dialysis catheter (TDC) did not increase malfunction and catheter-related infection (CRI) rate. Coincidently, we have been applying the ultra-low dose (500 U/mL) heparin locks on patients using non-tunnelled temporary haemodialysis catheters (NTHC) since 2012. Results in our centre showed that ultra-low dose heparin locks also performed well on NTHC, serving as complementary evidence for its clinical application. A pilot study was conducted to assess the effect and safety of ultra-low dose heparin locks on NTHC patients. It was a prospective, single centre, randomized controlled study and gained the institutional ethics permission (NO.B2014-06301). During December 2012 to June 2014, 59 patients who had their dialysis catheter placed in Hemodialysis Unit of Guangdong Provincial Hospital of Chinese Medicine gave their consent to participate. Haemodialysis catheters (12 Fr×16 cm, non-tunnelled, dual lumen, Quinton, NJ, USA) were implanted by experienced nephrologists under ultrasound guidance. After catheter insertion, participants were randomized into ultra-low dose heparin locks group (500 U/mL, n = 30) and a common dose group (3125 U/mL, n = 29) based on the random number chart. The primary outcome was coagulation function and catheter-related infectious (CRI) rate. The coagulation function was checked before catheterization, as well as at 2 h and 4 h after heparin locks. Participants were followed-up until catheter removal. There was no statistical difference in baseline characteristics between the two groups. All patients received Chinese medicine decoction, which were prescribed to promote blood circulation. The decoction mainly consists of Salviae Miltiorrhizae Radix, Angelicae Sinensis Radix, Hirudo whose active components were proved to antiplatelet analogue. Comparing the two groups, results indicated that there was no significant difference in bleeding episodes, malfunction cases and activated partial thromboplastic time (APTT) before catheterization (Table 1). Fourteen patients in the ultra-low dose group and eight in the common dose group used antiplatelet or anticoagulants agents. Linear regression analysis was conducted to detect the confounder effect of antiplatelet and anti-coagulants agents. The independent variables were different dosage and using these agents or not, and the outcome was APTT level in baseline, 2 h and 4 h after dialysis, respectively. After controlling for independent variables, only different dosage had an effect on APTT of 2 h (P = 0.003) and 4 h (P = 0.014) after dialysis. These results were consistent with those of the univariate analysis (Table 1), which meant whether to use agents (antiplatelet and anti-coagulants) did not influence the effect of different dosage. Average follow-up period was 48.3 days. Thirty-day CRIfree catheter survival was comparable (67% vs 62%, P = 0.60), giving a cumulative CRI rate of 0.7/1000 catheter days. This result was lower than that reported in a previous study. This might be the reason that seven cases in the ultra-low dose group and eight cases in the common dose group had NTHCs placed for temporary treatment before peritoneal dialysis initiation or fistula maturation. Our research results showed that concentration of heparin solution could be as low as 500 U/mL without harming the function of NTHC. Due to patients’ concerns on financial burden, bacteriological tests were not routinely carried out in this study. But clinical manifestations of CRI such as fever, pain and secretions at the catheter exit were intensively monitored at each dialysis session. These could have introduced some bias to the results. Clinical evidence suggested that catheter function, CRI rate and bleeding events are acceptable using ultra-low dose heparin locks for both early TDC and NTHC. This could be explained in that heparin concentration was not an exclusive determinant of catheter survival. However, it remains unsolved whether ultra-low dose heparin locks would be suitable for long-term use. Previous publications reported low-concentration heparin lock solutions (1000 U/mL) required a two-fold increase in thrombolytic instillation to maintain long-term patency. Further studies are needed to demonstrate the role of ultra-low dose heparin locks in the long-term application, from both a clinical and economical perspective.