Overspill of Catheter Locking Solution: Safety and Efficacy Aspects :

A direct broad-based comparison of vascular access use and survival in Europe (EUR) and the United States (US) has not been performed previously. Case series reports suggest that vascular access practices differ substantially in the US and EUR. We report on a representative study (DOPPS) which has used the same data collection protocol for> 6400 hemodialysis (HD) patients to compare vascular access use at 145 US dialysis units and 101 units in five EUR countries (France, Germany, Italy, Spain, and the United Kingdom). Logistic analysis evaluated factors associated with native arteriovenous fistula (AVF) versus graft use or permanent access versus catheter use for prevalent and incident HD patients. Times to failure for AVF and graft were analyzed using Cox proportional hazards regression. AVF was used by 80% of EUR and 24% of US prevalent patients, and was significantly associated with younger age, male gender, lower body mass index, non-diabetic status, lack of peripheral vascular disease, and no angina. After adjusting for these factors, AVF versus graft use was still much higher in EUR than US (AOR=21, P 30 days prior to ESRD compared with 74% in the US (P < 0.0001); pre-ESRD care was associated with increased odds of AVF versus graft use (AOR=1.9, P=0.01). New HD patients had a 1.8-fold greater odds (P=0.002) of starting HD with a permanent access if a facility's typical time from referral to access placement was < or =2 weeks. AVF use when compared to grafts was substantially lower (AOR=0.61, P=0.04) when surgery trainees assisted or performed access placements. When used as a patient's first access, AVF survival was superior to grafts regarding time to first failure (RR=0.53, P=0.0002), and AVF survival was longer in EUR compared with the US (RR=0.49, P=0.0005). AVF and grafts each displayed better survival if used when initiating HD compared with being used after patients began dialysis with a catheter. Large differences in vascular access use exist between EUR and the US, even after adjustment for patient characteristics. The results strongly suggest that a facility's preferences and approaches to vascular access practice are major determinants of vascular access use.

The indwelling venous catheter such as Dual-Cath or Twin-Cath is widely used in haemodialysis. Although the manufacturer recommends filling the catheter lumen with heparin after the dialysis session to prevent clotting, little is known about the systemic effects of such a procedure. Twenty haemodialysis patients with Dual-Cath were studied. Dialysis anticoagulation was achieved by injecting a bolus of dalteparin. The patient/control ratio of activated partial thromboplastin time (aPTT) was determined at the end of the session immediately before and 10 min after locking with 2 ml of undiluted heparin (10,000 U/catheter). We also determined the catheter volume for each patient and measured aPTT immediately before and 10 min after heparin locking with this patient-specific volume. Catheter patency was followed over a 2-week period. The aPTT values determined at the end of two consecutive dialysis sessions were nearly normal, respectively 1.29 (+/-0.17) and 1.33 (+/-0.22), whereas all patients had uncoagulable blood (aPTT >3.75) 10 min after locking with 2 ml of heparin. When catheter volumes were individually calculated, they were found to be substantially lower than 2.0 ml (1.21+/-0.12 for the arterial branch and 1.27+/-0.13 for the venous branch). aPTT was only 2.42+/-0.73 10 min after locking with the estimated volumes except in one patient (aPTT >3.75). No catheter clotting was observed despite these smaller locking volumes. A risk of inducing serious bleeding does indeed exist with Dual-Cath heparin locking, especially in postoperative patients. This risk can be reduced by measuring catheter length at the time of placement in order to ensure an appropriate lock volume. Sodium citrate, polygeline, or urokinase are possible alternatives to heparin.

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.