Complications during inpatient thrombosis prophylaxis - Experience from 40 patients with heparin-induced thrombocytopenia type II (HIT II)

Heparin-induced thrombocytopenia Type II (HIT II) is based on a hypersensitivity to heparin and results in serious thromboembolic complications with a lethality of up to 23%. Due to its various manifestations - with or without thrombosis and/or a reduced number of thrombocytes-, a reliable diagnosis proves difficult and can only be made by a combination of clinical signs, thrombocytic behavior and antibody screening. From January 1993 to March 2000, 40 cases of HIT II were observed amongst a total of 25,331 patients presenting at 2 surgical clinics, one of which being specialized in emergency surgery. These patients were analyzed according to clinical and laboratory parameters, at first in retrospect and from 1995 prospectively. In 96.8%, thrombosis prophylaxis was done with unfractionated heparin (incidence of HIT II, 0.16%) and in 3.2% using low molecular weight heparin (incidence, 0%). All HIT II cases occurred following treatment with unfractionated heparin (in 40% subcutaneous, in 47.5% combined subcutaneous/intravenous, and in 12.5% intravenous administration). A positive result in the antibody (AB) tests was obtained on average on day 15.4 (10 to 27) SD ± 3.91. For AB testing, the HIPA and/or ELISA test or the agglutination test were used. Average age of the 27 female and 13 male patients was 62.8 SD ± 15.47 years (27 to 85). HIT II was diagnosed in 24 patients (60%) following an accident (group I) and in 16 patients (40%) after endoprosthetic joint replacement (group II). Group I was subdivided into patients suffering from single trauma (14 patients, 58.3%), multiple injury (6 patients, 25%) with an average ISS of 9.7 (4 to 15), and polytrauma (4 patients, 16.7%) with an average ISS of 24.4 (20 to 36). All accident patients sustained injury to at least 1 joint. A marked reduction in the number of thrombocytes was observed in 80%, a reduction < 50% in 10%. 10% showed no reduction or even an increase. Primary thromboembolic complications were clinically manifest - partly overlapping - on average on day 13.6 (11 to 21) SD ± 3.63, the complications being venous thromboses (42.5%), pulmonary emboli (35%), arterial thromboses (27.5%), and mesenteric artery thromboses (10%). Amputation was necessary in 7-5%, death occurred in 10% of the patients.