Intra-Arterial Heparin Flushing Guidelines
For arterial lines used for continuous blood pressure monitoring and blood sampling, normal saline (0.9% sodium chloride) is equally effective as heparinized saline and should be the preferred flush solution. 1
Primary Recommendation: Use Normal Saline
Sterile 0.9% sodium chloride (normal saline) should be used as the standard flush solution for arterial catheters, with continuous infusion at 3 mL/hour providing equivalent patency compared to heparinized solutions. 2, 1
Multiple meta-analyses demonstrate that intermittent flushing with heparin provides no additional benefit over normal saline alone for maintaining arterial line patency. 2, 3
A randomized controlled trial in ICU patients showed mean arterial line function scores of 83% (normal saline) versus 82% (heparinized saline), with no statistically significant difference at 95% confidence interval. 1
When Heparin May Be Considered
If heparin is used despite lack of proven superiority, specific protocols apply:
For arterial catheters accessed intermittently (not continuously monitored), flushing with 5-10 U/mL heparinized saline 1-2 times weekly can be considered, though evidence supporting this is extrapolated from adult venous catheter studies. 4, 2
When heparin is deemed necessary, use concentrations between 1-10 U/mL for arterial lines, significantly lower than the 50-500 U/mL range used for central venous catheters. 2, 1
Critical Safety Considerations
Heparin carries specific risks that must be weighed against unproven benefits:
Heparin does not reduce platelet counts in critically ill patients when used as arterial catheter flush (mean platelet count 234.6 × 10⁹/L with saline versus 256.6 × 10⁹/L with heparin), but heparin-induced thrombocytopenia remains a theoretical concern. 5
Heparin has numerous drug interactions and potentially serious side effects including hemorrhage, which appears less frequent with continuous infusion versus intermittent injection when therapeutic doses are used. 1, 6
Heparin promotes intraluminal biofilm formation, potentially increasing catheter-related bloodstream infection risk. 2
Practical Implementation Algorithm
Follow this stepwise approach:
Default to normal saline flush at 3 mL/hour continuous infusion for all arterial lines used for monitoring and blood sampling. 1
Maintain strict aseptic technique during any manipulation of the arterial catheter system to reduce infection risk. 2
Use 10 mL or larger syringes for flushing to prevent excessive pressure that could damage the catheter. 2
Employ turbulent push-pause technique when flushing to create turbulence that helps clear the catheter lumen. 2
If occlusion occurs, attempt forceful irrigation with saline first; if this fails, use fibrinolytic drugs (urokinase or alteplase) for thrombotic occlusions. 2
Common Pitfalls to Avoid
Do not assume heparin is necessary based on historical practice patterns—the evidence does not support routine heparinization of arterial lines. 1, 3
Avoid using heparin immediately before or after lipid-containing infusions through the same catheter, as heparin may facilitate lipid precipitation. 2
Do not use heparin concentrations higher than 10 U/mL for arterial line flushing, as this provides no additional benefit and increases risk. 2, 1
Never use syringes smaller than 10 mL for flushing, as excessive pressure can damage the catheter integrity. 2