Heparin-Induced Thrombocytopenia - Use of Heparin Flushes: Rx Update: Virtual Hospital

Rx Update: November 2004

Heparin-Induced Thrombocytopenia - Use of Heparin Flushes

Joan Murhammer, R.Ph., Mary Ross, R.Ph., M.B.A., Kevin Bebout, R.Ph.
Peer Review Status: Internally Reviewed

Heparin-induced thrombocytopenia (HIT) is a potentially life- and limb-threatening immunologic reaction caused by platelet activation, which is accompanied by an intense hypercoagulable state. The incidence of HIT is estimated to be up to 5% in patients exposed to heparin. HIT generally occurs between 5 and 10 days after initiation of heparin therapy; however, the onset of HIT may be more rapid and occur within 12 hours of heparin exposure if the patient has been exposed to heparin previously within the past 100 days. HIT may also occur after heparin has been discontinued. This is known as “delayed-onset HIT” and it generally occurs an average of nine days after heparin is stopped. Delayed-onset HIT should be considered prior to heparin administration in patients who present with thromboembolism and have recently been hospitalized. HIT can occur with any heparin exposure, including heparin flushes, heparin-coated catheters, and heparin given via the intravenous or subcutaneous route. For this reason, all use of heparin must be documented in the medical record.

The clinical characteristics of HIT generally include a decrease in platelet count by 30% to 50% compared to baseline or a platelet count nadir of 20,000 to 100,000/mm³. It is important to recognize that HIT is not associated with bleeding, but rather it is associated with thrombosis. HIT is also associated with skin lesions or necrosis, fever, chills, respiratory distress, hypertension and myocardial infarction.

The initial diagnosis and treatment of HIT is based on clinical observation. When HIT is suspected, all sources of heparin exposure must be removed immediately and it is necessary to begin alternative anticoagulation, as the risk of thrombosis with heparin discontinuation alone may be as high as 50%. Direct thrombin inhibitors are considered the agents of choice for the treatment of HIT. Argatroban is the direct thrombin inhibitor on the UIHC Formulary. Warfarin may be initiated while the patient is still on argatroban and once the platelet count is > 150,000/mm³. Argatroban should be continued until the platelet counts have fully recovered.

When a diagnosis of HIT is suspected, it is important to ensure that heparin exposure from any source (including flushes) is completely avoided. Due to the severe outcomes if a patient with HIT receives any form of heparin, the Pharmacy and Therapeutics Subcommittee has approved several safety measures for preventing heparin from being administered to a patient with suspected HIT.

Physician orders are required for any administration of heparin; this includes all therapeutic heparin, heparin flushes, and heparinized normal saline.

Use of all forms of heparin must be documented (e.g., the Medication Administration Record [MAR], clinic drug doctor’s order forms).

Effective November 23, 2004, orders for heparin products, including flushes, must be reviewed and dispensed by Pharmacy. Heparin will not be over-rideable in the Pyxis Medstation.

Title Page