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Calculating IV Heparin Sodium Protocol

Because patient vary significantly in weight, the IV heparin sodium dosage is individualized based on patient weight. Many institutions have standard protocols related to IV heparin administration. Note that the bolus or loading dosage and the initial infusion dosage of heparin sodium are based on the patient's weight.


Standard Weight-Based Heparin Sodium Protocol

For all patients on heparin sodium drips:

1. Weight in KILOGRAMS: Required for order to be processed: ______ Kg

2. Heparin sodium 25 000 units in 250 mL of 1/2 NS. Boluses to be given as 1000 units/mL.

3. aPTT q6h or 6 hours after rate change; daily after two consecutive therapeutic aPTTs.

4. CBC initially and repeat every _____ day (s).

5. Obtain aPTT and PT/INR on day 1 prior to initiation of therapy.

6. Guaiac stool initially then every _____ day (s) until heparin sodium discontinued. Notify if positive (+).

7. Neuro checks every _____ hours while on heparin sodium. Notify physician of any changes.

8. Discontinue aPTT and CBC once heparin sodium drip is discontinued, unless otherwise ordered.

9. Notify physician of any bleeding problems.

10. Bolus with 80 units/kg. Start drip at 18 units/kg/h.

11. If aPTT is less than 35 secs: Rebolus with 80 units/kg and increase rate by 4 units/kg/h

12. If aPTT is 36-44 secs: Rebolus with 40 units/kg and increase rate by 2 units/kg/h

13. If aPTT is 45-75 secs: Continue current rate

14. If aPTT is 76-90 secs: Decrease rate by 2 units/kg/h

15. If aPTT is more than 90 secs: Hold heparin sodium for 1 h and decrease rate by 3 units/kg/h


#10 indicates that this protocol, the standard heparin sodium dosage is 80 units/kg and the infusion rate is 18 units/kg/h. When the patient's response to heparin therapy changes, as measured by the activated partial thromboplastin time (aPTT) measured in seconds, the heparin sodium dosage is adjusted as indicated in #11 to #15. These orders are based on patient weight rounded to the nearest 10 kilograms. Some institutions use the patient's exact weight in kilograms. It is important to know the protocol for your clinical setting. Let us work through some examples of calculation of heparin sodium dosage based on patient weight and a standardized heparin sodium dosage protocol.


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Dosage calculation by Gloria D. Pickar, Beth Swart, Hope Graham, and Margaret Swedish


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