Heparin Dwelling for PICC Lines: Concentration and Frequency
For PICC lines that are accessed intermittently (not in continuous use), flush with 5-10 units/mL heparinized saline 1-2 times weekly to maintain patency. 1
Key Recommendations by Clinical Context
For Regularly Used PICC Lines (Daily Access)
- Use normal saline (0.9% sodium chloride) only - no heparin is needed when catheters are in frequent use 2
- Heparin provides no proven benefit over saline for catheters accessed regularly 1
For Intermittently Accessed PICC Lines
- Concentration: 5-10 units/mL heparin in saline
- Frequency: 1-2 times weekly 1
- This recommendation is extrapolated from adult studies but represents the best available evidence
For Closed/Unused Lines >8 Hours
- Concentration: 50-500 units/mL (most commonly 100 units/mL) 2
- Always flush with saline first before heparin lock
- For small caliber catheters (≤5 Fr): flush weekly
- For large caliber catheters (≥6 Fr): flush every 3-4 weeks 2
Important Clinical Nuances
Valve-Tipped Catheters: Use saline only - never heparin 2
Lipid-Containing Parenteral Nutrition: Always interpose a saline flush between PN and heparin, as heparin facilitates lipid precipitation 2
Pediatric Considerations:
- In newborns, evidence shows heparin (1 unit/mL) reduces PICC occlusion, but potential risks haven't been fully defined 1
- For infants <10 kg: 10 units/kg is frequently used 1
Evidence Quality and Practical Reality
The evidence base reveals significant uncertainty. Multiple meta-analyses show heparin is no more beneficial than saline alone for maintaining catheter patency in regularly accessed lines 2, 3. However, manufacturer recommendations and clinical practice often favor heparin for infrequently accessed devices.
Critical caveat: The most important factor is proper saline flushing technique before any heparinization - this matters more than the heparin itself or its concentration 2.
Common Pitfalls to Avoid
- Never use heparin immediately before or after lipid-containing solutions - always flush with saline between 2
- Don't use heparin in valve-tipped catheters - manufacturer instructions specify saline only 2
- Avoid high concentrations unnecessarily - studies show 10 units/mL may be as effective as 100 units/mL 1, 4
- Don't assume heparin prevents thrombosis - it maintains lumen patency but doesn't reduce catheter-related thrombosis risk 1
When Heparin May Be Most Justified
- Implanted ports that are accessed infrequently
- Open-ended catheter lumens per manufacturer recommendation
- Home parenteral nutrition patients (with careful attention to lipid precipitation risk) 2
The 2018 pediatric guidelines provide the most current specific recommendation: for intermittently accessed CVCs including PICCs, use 5-10 units/mL heparinized saline 1-2 times weekly 1. This represents a conditional recommendation based on extrapolated adult evidence, acknowledging the lack of high-quality pediatric data.