How can catheter flow be maintained or improved?

Catheter Flow Maintenance and Improvement

Flush catheters with normal saline using at least twice the catheter volume to maintain patency, as saline is equally effective as heparin for preventing occlusion while avoiding heparin-related complications. 1

Primary Flushing Strategy

Use normal saline (0.9% sodium chloride) as the standard flush solution for maintaining catheter patency. 1 The evidence demonstrates that:

• Saline and heparin are equally effective at preventing thrombotic complications in central venous catheters 1
• Heparin flushing shows only weak evidence for reducing catheter occlusion and no evidence for reducing bloodstream infections 2
• The minimum flush volume should be at least twice the catheter volume to ensure adequate clearance 1

Flushing Technique and Frequency

Perform forceful irrigation with saline when completing infusions, using proper aseptic technique throughout. 1 Key technical points include:

• For peripheral intravenous catheters, flushing once daily (every 24 hours) maintains patency as effectively as twice-daily flushing 3
• Pre-filled saline syringes significantly reduce catheter failure rates (43.4% vs 57%) compared to manually filled syringes 4
• Use a closed flush system rather than open systems requiring syringes and stopcocks to maintain patency 1
• Minimize manipulations and entries into the catheter system 1

Catheter Selection and Placement Factors

Optimize catheter flow by using the fewest lumens necessary and ensuring proper tip placement in the caudal superior vena cava. 1 Evidence shows:

• Risk of thrombosis increases with the number of catheter lumens 1
• Right-sided placements have lower thrombosis rates than left-sided placements 1
• Catheter tip placement in the SVC or right atrium reduces thrombosis compared to subclavian or innominate vein positioning 1
• Use ultrasound guidance for placement to minimize endothelial damage and reduce thrombosis risk 1

Managing Catheter Occlusion

When occlusion occurs, attempt forceful saline irrigation first before escalating to other interventions. 1 The algorithmic approach is:

1. First-line: Forceful irrigation with saline (excludes mechanical obstruction in many cases) 1
2. For lipid occlusion: Use 70% ethanol or sodium hydroxide 1
3. For mineral precipitates: Use 0.1 N hydrochloric acid 1
4. For thrombotic occlusion: Use fibrinolytic drugs (alteplase or urokinase) with at least 30-minute dwell time, repeat if needed 1
5. Refractory cases: Consider guidewire insertion or fibrin sheath stripping (more invasive, use only when necessary) 1

Monitoring for Dysfunction

Proactively monitor catheter performance to detect dysfunction early, before complete occlusion occurs. 1 Warning signs include:

• Blood pump flow rates <300 mL/min 1
• Arterial pressure <-250 mm Hg 1
• Venous pressure >250 mm Hg 1
• Progressive decline in urea reduction ratio <65% 1
• Frequent pressure alarms not responsive to repositioning or flushing 1

Critical Pitfalls to Avoid

Do not use heparin routinely, as risks of thrombocytopenia and bone disease outweigh benefits in most cases. 1 Additional cautions:

• Avoid blood sampling through the catheter when possible, as this increases occlusion risk 1
• Do not administer dextrose-containing solutions or parenteral nutrition through pressure monitoring circuits 1
• Never use topical antibiotic ointments on catheter sites due to fungal infection and resistance risks 1
• Avoid using catheters for infusions when not needed—remove as soon as clinically unnecessary 1

Special Considerations for Long-Term Catheters

For home parenteral nutrition and long-term central venous catheters, use infusion pumps and maintain strict aseptic technique. 1 Additional measures:

• Catheter occlusion incidence in home parenteral nutrition is approximately 0.07 episodes/catheter/year 1
• Consider anticoagulation prophylaxis only after individual risk-benefit assessment for thrombosis versus bleeding 1
• Replace administration sets at 96-hour intervals (or at least every 7 days) for continuously used sets 1
• Replace tubing for blood products or fat emulsions within 24 hours 1