GUIDELINES [ back to index ]
25. Identification and management of tunneled catheter complications
*1 Patient with catheter dysfunction
Haemodialysis vascular access catheters have a significantly higher rate of thrombotic and infectious complications than grafts or native A/V fistulas 1.
*2 Decreased catheter flow
Permanent tunneled catheters should provide a blood flow of > 300 ml/min to allow for adequate haemodialysis.
Blood flow should not be measured by roller pump revolution, as this might overestimate blood flow by up to 33 % in the presence of highly negative inflow pressure (- 400 mm Hg) 2.
Blood flow depends on the size of the catheter and its positioning (see algorithm Placement and Routine Management of Permanent Tunneled Catheter for details) and obstruction / thrombosis of the catheter.
In cases of insufficient blood flow, differentiation between extrinsic and intrinsic catheter thrombosis should be made. The former may be caused by central vein thrombus, atrial thrombus or mural thrombus, and the latter due to intraluminal thrombus, catheter tip thrombus or fibrin sheath.
*3 Signs of infection
Catheter-related sepsis is largely based on clinical suspicion. Due to the fact, that dialysis patients frequently present with non-catheter-related infection, it is important to identify the source of any infection in order to avoid unnecessary catheter exchanges 3. Kite et al. used an endoluminal brush, which allows for sampling of the endoluminal surface of the catheter in situ 4. The sensitivity and specificity for the diagnosis of catheter-related sepsis was 95 % and 84 %, respectively. However, this procedures is considered by some to be potentially dangerous, due to the risk of disruption of the biofilm.
Catheter-related infection might also present only with minor signs such as insidious onset of low-grade fever, hypothermia, hypotension, hypoglycaemia, distant abscesses, endocarditis or by symptoms of lethargy and confusion.
*4 Mural or atrial thrombus
Both types of thrombi are rare but can interfere with catheter function5.
It is assumed that the movement of the catheter tip causes damage to the inner wall of the vessel resulting in formation of a thrombus. In such instances, three months of anticoagulation should follow the removal of the catheter 1.
*5 Catheter malposition
Insufficient blood flow can also be caused by catheter malposition. This can be diagnosed by radiology . In these cases, the catheter should be repositioned or exchanged over a guidewire, the correct positioning should be confirmed by X-ray.
*6 Poor catheter blood flow
In case of reduced catheter flow or obstruction, fibrinolytic agents like urokinase and tissue plasminogen activator (tPA) can be injected into the catheter (locking the catheter) for 30 minutes in the predialysis period, locking the catheter for 24 hours between dialysis sessions or by infusion of the agent for 2-3 hours during the dialysis session.
If the dysfunction of the catheter cannot be resolved, catheterogram and/or venography is indicated to identify precisely the cause of the catheter dysfunction.
Relapsing catheter dysfunction may indicate a prothrombotic state of the patient caused by inflammation, latent infection, hyperfibrinogenaemia, high platelet count or other abnormalities of the coagulation cascade. The underlying cause must be treated accordingly. Oral anticoagulation may maintain patency of the catheter in this situation.
*7 Urokinase lock
Urokinase lock and urokinase infusion have been successfully used to reopen a catheter or to restore catheter flow 6 7 8 9.
Catheters presenting with low flow high pressures may be locked for 30 minutes with 10,000 units of urokinase (5,000 units per branch), then, re-aspirated and flushed with saline (see appendix for protocol).
A second protocol is infusion of 50,000 or 100,000 units of urokinase for 20-30 minutes through each catheter lumen.
Suhocki et al. described successful restoration of catheter flow to > 300 ml/min in 74 % of the cases using urokinase instillation 10.
Catheters with persisting low flow and high resistance despite short urokinase lock can be infused for 3 hours continuously with urokinase at 100,000 units per hour (50000 units per lumen). The catheter should then be flushed with saline and flow resistance tested.
Twardowski compared effectiveness of a urokinase lock to an infusion of urokinase 8. While the urokinase lock was only partly successful in 21 out of 286 occluded catheters, an infusion of 20-40,000 IU urokinase lead to a partial restoration of blood flow in 10 out of 25 patients. Best results were achieved by infusion of 250,000 IU urokinase over 3 hours during dialysis. If necessary, this procedure was repeated during the following dialysis session. Full restoration of catheter flow was achieved at the first attempt in 132 out of 162 catheters with reduced flow.
In cases of persistent dysfunction a catheterogram and/or a venography is indicated.
Occluded catheters may be reopened by a combination of mechanical intervention and fibrinolysis based on a continuous urokinase infusion of 100,000 units per hour during 3 hours.
Urokinase use is not recommended in all situations, and is no longer prescribable in the United States due to safety concerns 7.
*8 tPA lock
Recombinant tissue plasminogen activator (tPA) is a safe and very effective fibrinolytic agent to dissolve catheter clots and re-establish adequate blood flow 11 12 13 14 15. Efficacy of tPA seems to be superior or at least equivalent to urokinase in reopening catheters. One mg of tPA was seen to be as equally as effective as 36,000 units of urokinase 7.
tPA can also be used either as a catheter lock or as a continuous infusion. Partial catheter obstruction with low flow and high resistance may be resolved either by a tPA catheter infusion for a short period of 2-3 hours 16 or by a catheter lock for a long duration of an interdialysis period of 24-48 hours) 17. In the latter case it seems appropriate to have a mixture of tPA and heparin as a locking solution.
Occluded catheters might be reopened by locking each catheter line with 2mg/2mL of tPA with a dwell time of 2 hours, leading to a 74 % success rate of restoring catheter function. If only partial flow recovery occurs, the procedure may be repeated a second time, increasing the success rate to 90 % 15.
Little et al. investigated the long-term outcome of catheters treated with tPA to restore adequate blood flow 18. They found the clinical benefit and cost-effectiveness of treating recurrent catheter malfunction with tPA to be limited, since this only allowed for a median of five to seven additional dialysis sessions.
*9 If necessary, treat with prolonged incubation time
When catheter treatment is unsuccessful (relapsing dysfunction or persistent occlusion) catheter imaging (catheterogram and venography) is indicated.
In cases of partial catheter thrombosis or fibrin sheath formation around the catheter tip, a prolonged thrombolysis of the catheter may be attempted (see urokinase *6 or tPA *7).
*10 Fibrin sheath
A fibrin sheath (also called fibrin sleeve) surrounding the catheter tip requires the prolonged infusion of fibrinolytic agent to dissolve the clot. However, this sheath may not only consist of fibrin alone, but also of a tissue, formed by the migration of small muscle cells into the fibrin layer.
If thrombolysis is not successful in catheters with fibrin sheaths, fibrin sheath stripping by means of a snare catheter, led up from the femoral vein, may be indicated. This procedure has a success rate of 79 % 19 20. However, this procedure does not provide a durable benefit, as blood flow rates decreased by the 5th session 21. No significant difference has been found between fibrin sheath stripping and urokinase infusion 22.
Suhocki et al. increased mean catheter survival to 12.7 months by using thrombolysis and percutaneous mechanical techniques 10.
*11 Exchanging catheters over guidewire Replace at new venotomy site
Persisting dysfunction requires the replacement of the catheter. Depending on the type of catheter, exchange may be performed over a guidewire 23. However, when a fibrin sheath is the cause of reduced blood flow, this sheath may recur around the new catheter also 1. In addition, infectious complications may be better prevented by insertion of a new catheter at a new venous site. Therefore, new catheter insertion is preferred by some experts to exchange over a guidewire.
*12 Mechanical method to regain catheter patency
Catheter brushing is a new therapeutic option to re-open the catheter 24. Beleed et al. temporarily restored blood flow in 3 out of 13 patients 25. The main advantage is to save time for both patient and care providers 26. However, the use of such a mechanical device is associated with potentially serious hazards that may be underestimated. These include clot embolism with potential lung injury, bacteraemia, trauma of the host vein, perforation of the superior vena cava, right atrium or the ventricle, arrhythmia, or rupture of the catheter. Catheter brushing must, therefore, be carefully performed only by trained physicians under strict fluoroscopy control.
*13 Monitor catheter
Catheter exit site should be examined for signs of infection at each haemodialysis session.