Is heparin (anticoagulant) flush or saline lock used to maintain patency in ports?

Flushing Ports and Saline Locks: Current Evidence-Based Recommendations

Most central venous access devices, including saline locks, can be safely flushed and maintained with normal saline solution alone, without the need for heparin in most clinical scenarios. 1

General Recommendations for Port and Saline Lock Maintenance

• Sterile 0.9% sodium chloride (normal saline) should be used to flush and lock catheter lumens that are in frequent use (Grade A evidence) 1
• For catheters accessed frequently or closed for short periods (<8 hours), normal saline flushing alone is sufficient to maintain patency 1
• Three different meta-analyses have concluded that intermittent flushing with heparin is no more beneficial than flushing with normal saline alone for most central venous access devices 1

When Heparin Should Be Used

• Heparinized solutions should be used as a lock (after proper flushing with saline) in the following specific situations:
  • When recommended by the manufacturer 1
  • For implanted ports that will remain closed for more than 8 hours 1
  • For open-ended catheter lumens scheduled to remain closed for more than 8 hours 1
• For intermittently accessed devices, flushing with 5-10 U/mL heparinized saline 1-2 times weekly can help maintain patency 1

Heparin Concentration and Frequency

• When heparin is indicated, most authors suggest using a concentration between 50 and 500 units per mL (Grade C evidence) 1
• For devices that remain unused for prolonged periods:
  • Small caliber devices (5 Fr or less): flush weekly 1
  • Large caliber devices (6 Fr or more): flush every 3-4 weeks 1

Special Considerations

• Close-ended valve catheters should be flushed and locked with saline only, following manufacturer's instructions 1
• Heparin should not be used immediately before or after administration of lipid-containing parenteral nutrition admixtures, as heparin may facilitate lipid precipitation 1
• If heparin must be used after lipid administration, a saline flush should always be interposed between the lipid infusion and heparin (Grade B evidence) 1
• Do not use concentrated heparin solutions labeled for IV use as "catheter lock flush" products, as fatal hemorrhages have occurred due to medication errors 2

Clinical Evidence Supporting Normal Saline

• A randomized, non-inferiority trial with 802 cancer patients found that normal saline is a safe and effective locking solution in implantable ports when combined with a strict protocol for device insertion and maintenance 3
• A retrospective study of 610 implanted ports showed no statistically significant differences in port occlusion rates between heparinized solution and normal saline 4
• Studies in both adult surgical patients and neonates have demonstrated that normal saline alone is effective for maintaining catheter patency 5, 6

Practical Algorithm for Port/Saline Lock Maintenance

1. Identify the type of central venous access device:

   • If close-ended valve catheter: use saline only 1
   • If open-ended catheter or implanted port: proceed to next step

2. Determine frequency of access:

   • If accessed frequently (multiple times daily) or closed <8 hours: use saline only 1
   • If infrequently accessed or closed >8 hours: check manufacturer recommendations

3. If manufacturer recommends heparin for infrequently accessed device:

   • Flush with saline first (critical step) 1
   • Then lock with appropriate heparin concentration (typically 50-500 units/mL) 1
   • For parenteral nutrition lines: always interpose saline flush between lipid-containing solutions and heparin 1

4. Follow appropriate flushing schedule:

   • Frequently used devices: flush with saline after each use 1
   • Infrequently used small devices (<5 Fr): flush weekly 1
   • Infrequently used large devices (>6 Fr): flush every 3-4 weeks 1