Flush Volume for Continuous Infusion Pumps
For continuous infusion pumps and central venous catheters in frequent use, sterile 0.9% normal saline should be used for flushing, with volumes of 5-10 mL being adequate for maintaining patency. 1
Standard Flushing Volumes by Clinical Context
Central Venous Catheters (CVCs) in Active Use
- 5-10 mL of normal saline is the recommended flush volume for CVCs being accessed regularly 1
- For hemodialysis CVCs specifically, use a 5-10 mL syringe with 0.9% normal saline and employ a turbulent flushing technique to ensure blood is cleared from the lumen 1
- No heparin is needed for catheters in daily use during continuous infusion, as saline alone is equally effective 1
Pediatric Emergency Medication Administration
- 5-10 mL of normal saline should be used as an immediate rapid flush after IV medication administration in children 1
- For adenosine specifically, a larger flush of up to 20 mL may be helpful in older children to ensure the medication reaches central circulation 1
- A 2-syringe technique is preferred, using the most proximal IV site possible 1
Parenteral Nutrition Lines
- After lipid emulsion administration, flush with ≥10 mL of saline immediately, then flow >240 mL of primary PN solution to minimize residual lipid in standard infusion sets 2
- For infusion sets with small inner diameter (1.0 mm), ≥20 mL of saline immediately after lipid administration is effective 2
Key Principles for Continuous Pumping
Heparin vs. Saline Controversy
- Saline is preferred over heparin for catheters in frequent use (accessed daily or with continuous infusion) 1
- Three meta-analyses have concluded that intermittent flushing with heparin provides no additional benefit over normal saline alone 1
- Heparin may facilitate precipitation of lipids, making saline mandatory during parenteral nutrition with lipids 1
When Heparin May Be Considered
- For CVCs accessed intermittently (not daily), flushing with 5-10 U/mL heparinized saline 1-2 times weekly can help maintain patency 1
- For implanted ports or open-ended catheter lumens scheduled to remain closed for >8 hours, heparinized solutions (50-500 units/mL) may be used after proper saline flushing 1
Critical Flushing Technique Considerations
Proper Technique
- Use a turbulent flushing technique (push-pause method) rather than continuous pressure to ensure adequate clearance of blood and medications from the catheter lumen 1
- Always flush with saline before any heparinization to prevent drug interactions and precipitation 1
- Ensure the flush volume is adequate to clear the entire catheter dead space plus the hub 1
Common Pitfalls to Avoid
- Insufficient flush volume may leave residual blood or medication in the catheter, increasing occlusion risk 1
- Omitting saline flush before heparin when using lipid-containing solutions can cause precipitation 1
- Using flush volumes <5 mL may not adequately clear the catheter lumen in adult patients 1
- Failing to use turbulent flushing technique reduces effectiveness of clearing the catheter 1
Volume Resuscitation Context (Distinct from Line Flushing)
For anaphylaxis requiring aggressive fluid resuscitation through continuous infusion, 1-2 L of normal saline should be administered to adults at a rate of 5-10 mL/kg in the first 5 minutes, with crystalloids up to 7 L potentially necessary 1. This represents therapeutic fluid administration rather than catheter maintenance flushing.