How often should intravenous (IV) lines be flushed?

IV Flushing Frequency Recommendations

Flush peripheral IV lines after each use and at least once every 24 hours when not actively infusing; flush central venous catheters after each use, with weekly flushes for tunneled catheters/PICCs and monthly flushes for implanted ports when not in active use.

Peripheral IV Lines

For peripheral intravenous catheters, flush with normal saline after each infusion or blood sampling, and maintain patency with once-daily flushing when the line is not in active use 1.

• Research demonstrates that flushing peripheral IVs once every 24 hours is non-inferior to more frequent flushing (every 12 hours), with occlusion rates of 4.5% versus 7.6% respectively 2.
• More frequent flushing (2-3 times daily) actually increases complication rates to 75% compared to 39.4% with once-daily flushing 3.
• Use normal saline (0.9% sodium chloride) rather than heparin for peripheral IV flushing, as saline is equally effective and avoids heparin-related complications 2, 4.

Central Venous Catheters (CVCs)

Active Use

• Flush with saline immediately after completion of any infusion or blood sampling 1.

When Not in Active Use

The flushing frequency depends on catheter type:

Subcutaneous ports (implanted devices):

• Flush every 4 weeks (monthly) when not in active use 1.

Tunneled cuffed catheters and PICC lines:

• Flush weekly when not in active use 1.

Evidence supports extending flushing intervals: A meta-analysis of totally implantable venous access devices showed no increase in catheter occlusions with prolonged flushing intervals compared to shorter intervals (RR 0.81,95% CI 0.41-1.61) 5.

Flushing Technique

• Use 10 mL or larger syringes to prevent excessive pressure that can damage the catheter 6.
• Employ a turbulent push-pause technique for optimal catheter clearance 6.
• Clean injection ports with 70% alcohol or iodophor before accessing the system 1.
• Maintain strict aseptic technique during all catheter manipulations 1.

Heparin Considerations

Routine heparin use is not necessary for most IV lines:

• For peripheral IVs, normal saline is as effective as heparin and avoids potential complications 2, 4.
• For central lines in oncology patients, the American Society of Clinical Oncology recommends routine saline flushing rather than prophylactic heparin 1.
• In pediatric patients, evidence is mixed: heparin (0.5-1.0 U/mL) may reduce CVC occlusion but studies are underpowered to assess risks 1.
• If heparin is used, concentrations of 10-100 U/mL are typical, though evidence shows no difference between these concentrations in pediatric oncology patients 1.

Administration Set Replacement

• Replace administration sets every 72 hours unless catheter-related infection is suspected 1.
• Replace tubing for blood products or lipid emulsions within 24 hours 1.
• Change needleless components at least as frequently as administration sets (every 72 hours) 1.

Critical Pitfall to Avoid

Do not flush more frequently than necessary, as excessive manipulation increases infection risk and, paradoxically, increases complication rates for peripheral IVs 3. The evidence clearly shows that less frequent flushing (once daily for peripheral IVs) results in better outcomes than the traditional every-8-hour protocols.