For chronic central venous dialysis catheters, the standard method for maintaining catheter patency between treatments is to instill (lock) catheters with 5000 - 10 000 units of heparin in each lumen. Sodium citrate (citrate) is an anticoagulant with intrinsic antibacterial activity (at 20% concentration or higher). Citrate has only transient anticoagulant effects if accidentally infused to the patient. Prior studies of citrate as a catheter lock solution have utilized citrate concentrations of 1% in combination with 27 mg/mL gentamicin. We changed clinical protocols for catheter locks using various solutions, including concentrated citrate, in a dialysis unit with 50% of patients having chronic central venous catheters [40 catheters total, mostly Ash Split Cath (Medcomp, Harleysville, PA, U.S.A.) but some Tesio (Medcomp) and Hickman (BARD, Salt Lake City, UT, U.S.A.) catheters]. At 3- to 4-month intervals, the standard catheter lock solution for the unit was varied on the following schedule: heparin; 10% citrate with 3 mg/mL gentamicin; 20% citrate with 3 mg/mL gentamicin; heparin; and 23% citrate. Catheters were not routinely removed during treatment of bacteremia. Incidence of bacteremia in patients with catheters using heparin as catheter lock was 4.32 episodes per 3000 patient-days (equivalent to percent of patients with catheters having bacteremia per month). The incidence of bacteremia decreased to 1.68 using 20% citrate/gentamicin as catheter lock (p < 0.05) and to 0% with 47% citrate (p < 0.05). Incidence of bacteremia increased on return to heparin and decreased again with use of 23% citrate to 1.79 (p < 0.05). Use of urokinase for occluded catheters also significantly decreased with citrate during the time that it was available (p = 0.02). Life table analysis indicated an 83% survival of Ash Split Cath catheters at 1 year, in this unit. Concentrated citrate is an effective catheter lock solution that may provide prolonged central venous catheter use with a diminution in catheter-related infections and occlusion.
Keywords: Central venous catheters; bacteremia; sodium citrate.