Estimation of trisodium citrate (Citra-Lock) remaining in central venous catheters after the interdialytic interval.

Infection of central venous catheters used for haemodialysis remains an important cause of morbidity and mortality [1]. Patency of the catheters can be maintained between dialyses by a heparin lock, but this has no antibacterial activity. Sodium citrate, especially at higher concentrations, is an anticoagulant with intrinsic antibacterial activity [2]. However, citrate inadvertently entering the circulation of the patient will chelate calcium ions and depress the ionized calcium level. This may prolong the QT interval [3], which may lead to ventricular dysrhythmias and torsade de pointes. We investigated the amount of citrate remaining in dialysis catheters after the interdialytic interval in order to assess the risk of this amount entering the circulation.