Sodium citrate 4% locking solution for central venous dialysis catheters--an effective, more cost-efficient alternative to heparin.

Background: Thrombosis of the central venous haemodialysis catheter compromises dialysis adequacy and catheter survival. Heparin containing catheter-locking solution has been associated with bleeding, interferes with INR (prothrombin time/international normalized ratio) measurements and is costly. Sodium citrate has been used successfully as a catheter-locking solution, but long-term experience with its use as the exclusive locking solution has not been published.

Methods: Our haemodialysis unit converted to locking all central venous haemodialysis catheters with sodium citrate 4% instead of heparin 10 000 U/ml. A retrospective analysis compared the outcomes of the year prior and after the conversion. Flow-related catheter exchange rate, prevalence of INR assay interference, tissue plasminogen activator (rt-PA) utilization rate, rate of bacteraemias and annual cost of locking agent were examined.

Results: During the study period, 30 925 and 37 139 catheter days were identified during the heparin and citrate years, respectively. The rate of flow-related catheter exchange was not different during the two periods (1.81 vs 1.88 per 1000 catheter days, P = 0.89). Falsely elevated INR values were eliminated with citrate and the rate of rt-PA treatments was similar during the two periods (4.1 vs 3.23 per 1000 catheter days respectively, P = 0.07). The number of bacteraemias was similar during the two periods (0.77 vs 0.94 per 1000 catheter days respectively, P = 0.36) There was an 85% reduction in the costs associated with catheter-locking therapy during the citrate period.

Conclusions: The pharmaco-economic benefits of sodium citrate 4% are well supported by this analysis. Furthermore, citrate offers several clinical advantages over concentrated heparin: citrate lock avoids heparin-associated bleeding complications, improves reliability of INR assays and provides an effective alternative for patients with suspected or confirmed heparin-induced thrombocytopenia.