Haemodialysis catheter dysfunction is reduced by catheter restricted filling with gentamicin and heparin.

H Pitt, W Priestman, R Fluck, C McIntyre, M Taal

Derby City General Hospital

PROBLEM. Use of tunnelled catheters as vascular access for haemodialysis (HD) is commonly limited by catheter related infection (CRI) and catheter dysfunction (associated with either intra-lumenal thrombosis or thrombus/fibrin sheath formation).

PURPOSE. To study the outcome of catheter restricted filling with gentamicin and heparin on haemodialysis catheter dysfunction.

DESIGN. We have recently completed a randomized controlled trial of gentamicin locking of newly inserted catheters and have demonstrated a 90% reduction in CRI. We report the effects of the introduction of antibiotic locking to all prevalent catheters on CRI incidence and catheter dysfunction rates.

We studied catheter dysfunction over a 30 month period. The initial period related to lines being locked with heparin alone. The second segment was during the RCT on newly inserted catheters only, and the third 10 months was after full adoption of antibiotic locking. Catheter malfunction was defined as a blood flow rate <200 ml/min, with a delivered Kt/V of <1.0. Catheters were initially treated with urokinase locks and subsequently patients received systemic thrombolysis with urokinase 250,000 i.u on dialysis.

FINDINGS. The mean number of tunnelled catheters in use throughout the trial period was similar (pre RCT 43± 0.6 (41-48), during RCT 47± 0.46 (45-49) and post RCT 44.6± 1.2 (38-51).

CRI rates fell from 4/1000 (pre RCT) to 0.3/1000 catheter days for patients within the RCT and 0.76/1000 catheter days for all patients post RCT. This was associated with a significant lowering of CRP levels following the introduction of gentamicin locking (31.6 cf 20.4 mg/l p<0.05).

Catheter malfunction was halved by the introduction of antibiotic locking: pre RCT 0.06± 0.02 (0-0.18), during RCT 0.02± 0.007 (0-0.065) and post RCT 0.03± 0.008 (0-0.07) urokinase infusions per catheter per month (48 infusions in total), p=0.05.

CONCLUSION. Catheter related sepsis might play a role in the development of catheter dysfunction and is reduced by the use of antibiotic locking with gentamicin and heparin.

RELEVANCE. This study shows that the simple measure of gentamicin and heparin locking of haemodialysis catheters has the benefit of not only reducing CRI but may also help prolong the lifespan of tunneled dialysis catheters by reducing catheter malfunction, thereby improving patient outcome on haemodialysis.