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BACKGROUND: Low-molecular-weight heparins offer several advantages over standard heparins, but their use for maintenance hemodialysis has been limited in North America because of their higher cost. Our objective was to compare tinzaparin to standard heparin during maintenance hemodialysis over an 8-week period, in regard to the visual aspect of the extracorporeal circuit, filter reuse, bleeding and time for compression of vascular access at the end of hemodialysis session, nursing time devoted to anticoagulation administration, level of satisfaction of patients and nurses, and relative cost. METHODS: Thirty-two chronic hemodialysis adult patients with peripheral accesses were randomly divided into two groups in a cross-over design: tinzaparin for 4 weeks followed by standard heparin for 4 weeks, or vice versa. Hemodialysis was performed thrice weekly over 3.5-4 h using large surface reused filters. Standard heparin was administered as an initial bolus of 50-75 units per kilogram followed by an infusion to maintain an activated clotting time (ACTESTER) between 150 and 200 s and discontinued 30-45 min before the end of the session. The initial dose of tinzaparin was 3,500 IU anti-Xa for patients usually receiving 7,500 units or less of standard heparin, or 4,500 IU anti-Xa for patients receiving more than 7,500 units of standard heparin, and it was injected as a bolus in the arterial line at the beginning of hemodialysis. Dosage adjustments were made by increments or decrements of 500 IU. RESULTS: A total of 6 patients did not require any adjustment in their dose of tinzaparin and remained at the initial dose, while the remaining 26 necessitated adjustments of the initial dose of tinzaparin: 20 patients required increments from the initial dose whereas 6 required reductions. For most patients, 27 of them, the standard heparin dose was kept at the same level throughout the study period (since it was their usual regimen and they were in stable medical conditions). According to the monitoring scale, the visual aspects of the tubing of the extracorporeal circuit and of the dialyzers at the end of the session were similar for both tinzaparin and standard heparin. The time of compression of the vascular access at the end of the hemodialysis sessions was not significantly different with tinzaparin than with standard heparin. However, as indicated below, most patients noted less bleeding (or oozing) from their access (during compression and thereafter, in the few hours after hemodialysis) with tinzaparin than with standard heparin. Clotting was observed more frequently in the arterial and venous bubble traps with tinzaparin than with standard heparin. The presence of clot(s) was observed in the arterial and venous bubble traps in, respectively, 18 +/- 12 and 10 +/- 6% of the sessions with tinzaparin, while in, respectively, 3 +/- 4 and 2 +/- 4% of the sessions with standard heparin (p < 0.005). Despite a tendency for a reduced reuse number of the dialyzers, the difference did not reach statistical significance. Among the 30 patients who completed the study, 2 reported excessive bleeding from their vascular access with tinzaparin whereas 8 reported such an excessive bleeding with standard heparin. The level of satisfaction of patients and nurses for tinzaparin was extremely good. The main reasons stated by the patients was reduced bleeding from their access after dialysis. The nurses preferred tinzaparin because of the simplicity and the rapidity of its administration, the lack of monitoring required, and the decreased bleeding/oozing tendency from the vascular access sites. The time spent for anticoagulation during a hemodialysis session was reported as 5 min with standard heparin (if no ACTESTER monitoring), 25-30 min with standard heparin (if ACTESTER monitoring required), and 1 min with tinzaparin. The cost analysis revealed that although tinzaparin is more than six times more expensive than standard heparin, the use of tinzaparin becomes similar to the use of standard heparin (USD 7.33 vs. USD 7.62 Canadian dollars for one hemodialysis session) if ACTESTER monitoring is performed (assuming that 22% of the sessions are routinely monitored and that one ACTESTER device is necessary for 8-10 dialysis stations, as applied in our unit). CONCLUSION: Our experience with tinzaparin was positive: it represents a simple and easy way to offer anticoagulation during maintenance hemodialysis, it seems associated with less postdialysis bleeding, it saves precious nursing time and is widely appreciated by patients and staff.