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Heparin Flush Dosage

Medically reviewed by Last updated on Aug 2, 2023.

Applies to the following strengths: 100 units/mL; 10 units/mL; 2 units/mL-NaCl 0.9%; 0.5 units/mL-NaCl 0.45%; 0.5 unit/mL-D10%; 90 units/mL-NaCl 0.9%; 1 unit/mL-NaCl 0.9%; 1 unit/mL-NaCl 0.225%; 1 unit/mL-NaCl 0.45%; 0.5 units/mL-NaCl 0.9%; 1 unit/mL-D10%; 125 units/250 mL-D10%; 10 units/mL-NaCl 0.9%; 1 unit/mL-D5%; 4 units/mL-NaCl 0.9%; 5 units/mL-NaCl 0.9%; 3 units/mL-NaCl 0.9%; 1 units/mL; 2 units/mL

Usual Adult Dose for Patency Maintenance of Indwelling Intravenous Devices

Heparin flush, 10 or 100 units/mL, is injected as a single dose into an intravenous injection device using a volume of solution equivalent to that of the indwelling venipuncture device.

When using daily flushes of heparin to maintain patency of single and double lumen central catheters, 10 units/mL is commonly used for younger infants (less than 10 kg) while 100 units/mL is used for older infants, children, and adults.

A single dose should be injected following venipuncture when the indwelling device is not to be used immediately. After each use of the indwelling venipuncture device for injection or infusion of medication, or withdrawal of blood samples, another dose should be injected to restore the effectiveness of the heparin lock. The amount of heparin solution is sufficient to prevent clotting within the lumen of indwelling venipuncture devices (usually not holding more than 0.2 to 0.3 mL) for up to twenty-four hours.

When the indwelling device is used to administer a drug which is incompatible with heparin, the entire heparin lock set should be flushed with 0.9% Sodium Chloride Injection, USP before and after the medication is administered. Following the second flush, another dose of heparin solution should be injected to restore the effectiveness of the heparin lock. When the indwelling device is used for repeated withdrawal of blood samples for laboratory analyses and the presence of heparin or saline is likely to interfere with or alter results of the desired blood tests, the in situ heparin flush solution should be cleared from the device by aspirating and discarding 1 mL before the desired blood sample is drawn.

Usual Pediatric Dose for Patency Maintenance of Indwelling Intravenous Devices

Arterial lines: Heparinize with a usual final concentration of 1 unit/mL; range: 0.5 to 2 units/mL; in order to avoid large total doses and systemic effects, use 0.5 unit/mL in low birth weight/premature newborns and in other patients receiving multiple lines containing heparin.

Peripheral arterial catheters in situ: Neonates and Children: Continuous IV infusion of heparin at a final concentration of 5 units/mL at 1 mL/hour.

Umbilical artery catheter (UAC) prophylaxis: Neonates: Low-dose heparin continuous IV infusion via the UAC with a heparin concentration of 0.25 to 1 unit/mL.

Prophylaxis for cardiac catheterization via an artery: Neonates and Children: IV: Bolus: 100 to 150 units/kg; for prolonged procedures, further doses may be required.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available


Benzyl alcohol, a preservative in the multiple-dose vial preparations of Heparin Lock Flush Solution, USP has been associated with toxicity in neonates. Benzyl alcohol has been reported to be associated with a fetal "Gasping Syndrome" in premature infants. Data are unavailable on the toxicity of other preservatives in this age group. Preservative-free Heparin Lock Flush Solution, USP should be used for maintaining patency of intravenous injection devices in neonates.

Many concentrations of heparin are available and range from 1 unit/mL to 20,000 units/mL. Carefully examine each prefilled syringe or vial prior to use to ensure that the correct concentration is chosen. Heparin lock flush solution is intended only to maintain patency of IV devices and is not to be used for anticoagulant therapy.


Data not available

Further information

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