Thrombocytopenia associated with heparin-coated catheters in patients with heparin-associated antiplatelet antibodies

Article Abstract:

Pulmonary artery catheters are important in the care of critically ill patients. Unfortunately use of these catheters carries with it the risk of a wide range of complications, including catheter sepsis, skin infection, pulmonary artery rupture, and thrombosis. Catheters coated with the anticoagulant heparin can reduce catheter-related thrombosis, formation of clots around the catheter. Heparin-associated antibodies against platelets in the blood, which are responsible for clotting, form in approximately 0.4 percent of the patients catheterized. Twelve cases of thrombocytopenia, an abnormal decrease in the number of blood platelets, were reviewed to evaluate the use of heparin- coated pulmonary artery catheters in patients who had developed heparin-associated antiplatelet antibodies. Heparin can become separated from the catheter, and it is likely that heparin-coated catheters release heparin into solutions they come in contact with. Heparin results in heparin-induced thrombocytopenia syndrome in an average of five to six percent of patients, but to date no risk factors have been identified for this syndrome, making it very difficult to predict which patients will be at risk for heparin-induced thrombocytopenia. Symptoms usually begin to appear about the eighth day of heparin administration in those patients receiving heparin for the first time, and on the first or second day in those with previous exposure to the substance. The mortality rate for heparin-induced thrombocytopenia is 12 percent and the morbidity rate is 22.5 percent. Patients who develop complications due to this syndrome have a mortality rate close to 55 percent. The mortality and morbidity linked to heparin-associated thrombocytopenia can be greatly reduced by daily monitoring of the blood platelet level following the completion of heparin therapy if there is a decrease in the platelet count. Aspirin may be used as an anticoagulant in patients who develop heparin-associated platelet antibodies. In the 12 patients studied, platelet counts approached normal levels following the removal of heparin-coated catheters. It is concluded that patients with heparin-associated antiplatelet antibodies should not receive heparin or heparin-coated pulmonary catheters.

Case studies, Risk factors, Anticoagulants (Medicine), Anticoagulants, Arterial catheterization, Blood platelet disorders, Platelet function disorders

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Heparin-induced thrombocytopenia and thrombosis syndrome: a case study

Article Abstract:

Heparin is commonly used in critical care patients to prevent the formation of blood clots (thrombi). Thrombi result from the aggregation of blood platelets and minimize blood loss from the body. A recent case study described a 36-year-old, obese, non-smoking woman who was treated with heparin and developed thrombi and a decreased number of blood platelets (thrombocytopenia). The patient was initially admitted to the hospital for chest pain, and received heparin in the coronary care unit while being evaluated and during heart surgery. The patient was discharged nine days following the operation, but was readmitted the next day for severe pain in her left leg. To prevent the further development of thrombi in her legs, the patient was given more heparin, but developed blood clots in her right leg that were surgically removed. Twelve hours later, the patient lost sensation in her right foot and was diagnosed with heparin-induced thrombocytopenia and thrombosis syndrome (HITTS). The right leg was amputated above the knee to prevent deterioration of the patient's condition. All heparin therapy was discontinued and the patient's platelet count began to rise. A mild form of heparin-induced thrombocytopenia occurs in almost 25 percent of patients receiving heparin therapy and typically lasts only a few days. This patient had a severe form of HITTS that may have been caused by an allergic reaction to heparin. In support of this theory, circulating antibodies against heparin have been observed in patients with HITTS. Antibodies are proteins produced by the immune system of the body that bind and inactivate foreign substances. HITTS is occurring more frequently with the widespread use of heparin. Clinicians should be aware of this syndrome and should be suspicious if thrombi occur and platelet numbers decrease after heparin therapy. (Consumer Summary produced by Reliance Medical Information, Inc.)

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Low incidence of thrombocytopenia with porcine mucosal heparin: a prospective multicenter study

Article Abstract:

Two hundred patients were treated either intravenously or by subcutaneous (under the skin) injection for five days with porcine intestinal mucosa heparin, a substance which inhibits blood clotting and is derived from the intestinal tissue of pigs. The patients subsequently had frequent platelet (cells in the blood which are necessary for blood clotting) counts to determine if thrombocytopenia (an abnormal decrease in the number of platelets) or arterial thrombosis (the formation of a blood clot in an artery) had occurred as a result of the heparin. None of the patients developed severe thrombosis or arterial thrombosis. The lowest platelet count occurred on the fourth day. It was concluded that the incidence of heparin-related severe thrombocytopenia and arterial thrombosis is low in patients treated with porcine mucosal heparin.

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