Guidelines for Heparin Therapy

Guidlelines

Heparin Dose

2.  Initial doses

3.  Adjust heparin to maintain PTT at 60-85 seconds as follows:
 
 

4.  The rate changes suggested above are to be calculated as a fraction of the total infusion, that is, in units/kg/hour and not simply in the number of cc/hour at which the IV is infusing.

5.  The solution for maintenance heparin therapy is prepared at concentrations of 80 units/ml for children less than or equal to 10 kg or 40 units/ml for children over 10 kg.  Fluid restricted patients (such as renal patients or neonates) may receive more concentrated heparin solutions upon request.

6.  Dedicated IV for heparin administration not to be stopped.  This IV must not be stopped or interrupted for other medication.

Monitoring of Therapy

2.  Once patients have achieved a therapeutic aPTT, obtain blood for CBC, PT, aPTT daily.

3.  Measure heparin level during the first 48 hours to ensure that the aPTT is reflecting the heparin concentration.  Level should be between 0.2 and 0.4 units/mL by anti-factor II_a assay or 0.35 to 0.6 units/mL by anti-factor X_a assay.

4.  If the infusion of heparin during the maintenance phase is interrupted for more than one hour, obtain blood for a stat aPTT and reestablish the pheparing maintenance infusion at the previous rate.  Once the aPTT result is available, adjust the infusion rate as indicated above.

5.  Measure platelet counts daily.  If the platelet count drops below 150 x 10⁹/L determine if the decrease in platelet count likely related to the underlying disorder or is potemntially secondary to the heparing therapy.  If the latter, consider discontinuing heparing therapy and instituting alternative therapy.  The risk of heparin-induced thromboctopenia is greater after 5 days of therapy. (3).

6.  Avoid IM injections, and, where possible, arterial punctures during anticoagulation therapy.  Clinical situations may warrant the use of arterial punctures (for example, ventilated patients).  Appropriate precausts, including the use of extended periods of external pressure should be used.

7.  The duration of heparin therapy is dependent upon the primary problem.  For DVT in children, heparin is usually administered for a minimum of 7 days.  Maintenance warfarin therapy should be instituted on day 1 or 2 of heparin therapy.  Note: if the thrombus is extensive or massive PE is present, administer heparing for 7 to 14 days and begin coumadin therapy on day 5 (4).  Neonates may be treated for 10 to 14 days without coumadin.  This decision should be individualized following consultation with the hematology service.

8. Avoid aspirin or other antiplatelet drugs during heparin therapy.  if analgesia is required, prescribe acetaminophen.

Ongoing Follow-Up

2.  If platelet count is less than 150,000 x 10⁹/L or bleeding occurs, notify M.D. immediately.

3.  As soon as a patient is administed for heparin therapy, arrange for hematology consult and clinical follow-up

Heparin Antidote

Protamine sulphate neutralized heparin activity by virtue of its positive charge.  Following IV administration, neutralization occurs within 5 minutes.  The dose of protamine sulphate required to neutralize heparin is based on the amount of the heparin received in the previous 2 hours as follows:
 
 

The maximum dose of protamine sulphate, regardless of the amount of heparin received, is 50 mg.  Protamine sulphate should be administered in a concentration of 10 mg/mL at a rate not to exceed 5 mg/minute.  If administered too quickly protamine sulphate may cause cardiovascular collapse.  Patients with known hypersensitivity reactions to fish, and those who have received protamine containing insulin or previous protamine therapy may be at risk of hypersensitivity reactions to protamine sulphate.  Obtain blood for aPTT and PT, 15 minutes after the administration of protamine.

References

2.  Andrew, M, Marzinotto, V, Massicotte, P, Blanchette, V, Ginsberg, J, Brill-Edwards, P, Burows, P, Benson, L, Williams, W, David, A, Poon, A, Sparling, K.  Heparin therapy in pediatric patients: A prospective cohort study.  Pediatr Res 35(1):78-83, 1994

3.  Warkentin, TE, Levine, MN, Hirsh, J, horsewood, P, Roberts, RS, Gent, M, Kelton, JG.  Heparin-induced thrombocytopenia in patients treated with low-molecular weight heparin or unfractionated heparin. N Engl J Med 332:1330-1335, 1995.

4.  Hull, RD, Raskob, GE, Rosenbloom, D, Panju, AAP, Brill-Edwards, P, Ginsberg, JS, Hirsh, J, Martin, GJ, Green, D.  Heparin for 5 days as compared with 10 days in the initial treatment of proximal vein thrombosis. N Engl J Med 322:1260-1264, 1990.

5.  Hirsh, J.  Heparin.  N Engl J Med 324(22):1565-1574, 1991.

6.  Nieuwenhuis, HK, Albada, J, Banga, JD, Sixma, JJ.  Identification of risk factors for bleeding during treatment of acute venous thromboembolism with heparin or low molecular weight heparin. Blood 78(9):2337-2343, 1991.

7.  Brandjes, DPM, Heiboer, J, Buller, HR, De Rijk, M, Jagt, H, Ten Cate, JW.  Acenocoumarol and heparin compared with acenocoumarol alone in the initial treatment of proximal vein thrombosis. N Engl J Med 327:1485, 1992.

8.  Einhaupl, KJ, Willringer, A, Meister, W, Mehraein, S, Garner, C, Pellkofer, M., Haberl, RL, Pfister, HW, Schmiedek, P.  Heparin treatment in sinus venous thrombosis.  Lancet 338:597-600, 1991.

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