What are the best practice recommendations for irrigating urinary catheters and central venous catheters, including appropriate solutions, flush volumes, dwell times, indications, and use of adjuncts such as chlorhexidine, urokinase, or heparin?

Best Practice Recommendations for Irrigating Catheters

For central venous catheters (CVCs), routine flushing with sterile 0.9% normal saline is recommended for frequently accessed lines, while heparin flushing may be reserved for infrequently accessed devices like implanted ports. For urinary catheters, routine irrigation is not recommended as a preventive measure against infection, and should only be used when continuous irrigation is needed to prevent obstruction (such as after urologic surgery with bleeding).

Central Venous Catheter Flushing

Frequently Accessed CVCs

Use sterile 0.9% normal saline for routine flushing and locking of catheter lumens that are in frequent use 1. This applies to:

• CVCs used for hemodialysis
• CVCs for parenteral nutrition with continuous infusion
• Any CVC accessed daily or multiple times per day

The evidence supporting saline over heparin for frequently accessed lines is strong (Grade A) 1. Proper saline flushing technique is more important than heparin concentration itself 1.

Infrequently Accessed CVCs

For catheters accessed infrequently, the approach differs:

• Implanted ports not in active use: Flush every 4 weeks 2
• Tunneled cuffed catheters and PICC lines: Flush weekly 2
• Heparin concentration: When manufacturer recommends heparin, use 50-500 units/mL (Grade C) 1

Important caveat: Close-ended valve catheters should be flushed and locked with saline only, following manufacturer instructions 1.

Lipid-Containing Solutions

When administering parenteral nutrition with lipids, always flush with saline before any heparin administration to prevent lipid precipitation 1. Heparin should never be used immediately before or after lipid-containing admixtures.

Hemodialysis Catheter Protocol

For hemodialysis CVCs, follow this specific sequence 3:

Connecting to dialysis:

1. Disinfect hub with chlorhexidine ("scrub the hub") 3
2. Aspirate 2-5 mL of blood and locking solution
3. Optional: Flush with 5-10 mL normal saline using turbulent technique
4. Initiate dialysis

Disconnecting from dialysis:

1. Flush lumen with 5-10 mL normal saline
2. Instill locking solution per protocol
3. Close clamp and apply sterile cap

Managing CVC Occlusion

When a CVC becomes occluded, the approach depends on the suspected cause 1:

Thrombotic Occlusion

Use urokinase 5,000 U/mL for clot-related occlusions 4:

NKF-K/DOQI Protocol 4:

1. Aspirate occluded lumen to remove heparin
2. Inject urokinase (1 mL or volume to fill lumen) using 3 mL syringe
3. Add 0.3 mL saline every 10 minutes to advance active urokinase distally
4. Aspirate catheter after dwell time
5. Repeat if necessary

Alternative protocol: Fill entire lumen with urokinase 5,000 U/mL, allow 30-minute dwell, then aspirate 4.

Critical safety point: Always use a 10 mL or larger syringe to avoid excessive pressure that may damage the catheter 1.

Non-Thrombotic Occlusion

Match the clearing solution to the obstruction type 1:

• Lipid aggregates: Ethanol
• Drug precipitates: NaOH or HCl
• Contrast medium: NaHCO₃

Urinary Catheter Management

Routine Care

Routine bladder irrigation is NOT recommended for infection prevention 5. The evidence does not support prophylactic irrigation in most clinical scenarios.

Standard catheter maintenance includes 5:

• Routine hygiene with soap and water
• Chlorhexidine for meatal cleaning before insertion (avoid alcohol-based products on mucosa)
• Maintain closed drainage system
• No routine catheter changes

When Irrigation IS Indicated

Bladder irrigation should only be used for:

1. Continuous irrigation to prevent obstruction (e.g., post-TURP with hematuria) - maintain closed system 5
2. Manual irrigation for documented obstruction - use sterile technique 6

One study showed daily irrigation with 450 mL normal saline (in three 150-mL doses) for 3 days reduced CAUTI risk in comatose ICU patients 7, but this is not standard practice and routine irrigation remains generally not recommended 5.

Critical Safety Warnings

Heparin Use

Do NOT use Heparin Sodium Injection as a catheter lock flush product 8. Fatal hemorrhages have occurred in pediatric patients when high-concentration heparin vials were confused with catheter lock flush solutions 8.

Infection Prevention

• Chlorhexidine with alcohol should be used for skin preparation before CVC insertion and dressing changes 9
• Scrub the hub with chlorhexidine before each access 3
• Replace dressings when damp, loose, or soiled 9, 10
• Gauze dressings: change every 2 days
• Transparent dressings: change every 7 days 9, 10

Avoiding Complications

Common pitfalls to avoid:

• Using scissors near catheters during dressing changes 3
• Applying organic solvents to silicone catheters 1
• Using power injectors on non-certified catheters 1
• Leaving Huber needles in ports >1 week 1
• Routine antimicrobial prophylaxis (not recommended) 2