Low-dose fondaparinux in suspected heparin-induced thrombocytopenia in the critically ill.
BACKGROUND
In critically ill patients, heparin-induced thrombocytopenia (HIT) is estimated to account for approximately 1 to 10% of all causes of thrombocytopenia. HIT exerts a strong procoagulant state. In case of suspected HIT, it is an important clinical decision to stop heparin and start treatment with alternative nonheparin anticoagulation, awaiting the results of laboratory testing for the final diagnosis of HIT (bridging therapy). Fondaparinux acts by factor Xa inhibition and expresses no cross-reactivity with HIT antibodies. Excretion of fondaparinux is mainly renal. We describe our early experience with fixed low-dose fondaparinux bridging therapy and monitoring of anticoagulant activity for safety reasons.


METHODS
This retrospective cohort study was conducted in a closed format general intensive care unit in a teaching hospital. Consecutive critically ill patients suspected of HIT were treated with fondaparinux after discontinuation of unfractionated heparin or nadroparin. Anti-Xa levels were determined afterwards.


RESULTS
Seven patients were treated with fondaparinux 2.5 mg/day for 1.8 to 6.5 days. Anti-Xa levels varied from 0.1 to 0.6 U/ml. A negative correlation was found between creatinine clearance and mean and maximum anti-Xa levels. No thromboembolic complications occurred. Bleeding complications were only minor during fondaparinux treatment. Transfusion requirements did not differ significantly between treatment episodes with fondaparinux or with heparin anticoagulants.


CONCLUSIONS
In this small sample of critically ill patients suspected of HIT, bridging therapy with fixed low-dose fondaparinux resulted in prophylactic and therapeutic anti-Xa levels. Monitoring of anticoagulant activity is advised in patients with renal insufficiency.
Wester
J P J
JP
Department of Intensive Care Medicine, Onze Lieve Vrouwe Gasthuis, PO Box 95500, 1090 HM Amsterdam, the Netherlands. j.p.j.wester@olvg.nl
Leyte
A
A
Oudemans-van Straaten
H M
HM
Bosman
R J
RJ
van der Spoel
J I
JI
Haak
E A F
EA
Porcelijn
L
L
Zandstra
D F
DF
D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects / Q000494:pharmacology; D018890:Chemoprevention; D003422:Critical Care / Q000379:methods*; D016638:Critical Illness; D004305:Dose-Response Relationship, Drug; D016903:Drug Monitoring; D005260:Female; D000077425:Fondaparinux; D006493:Heparin / Q000009:adverse effects*; D006784:Hospitals, Teaching; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011134:Polysaccharides / Q000008:administration & dosage* / Q000009:adverse effects / Q000494:pharmacology; D012189:Retrospective Studies; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced*
D000925:Anticoagulants; D011134:Polysaccharides; D006493:Heparin; D000077425:Fondaparinux