Antifactor Xa activity in intensive care patients receiving thromboembolic prophylaxis with standard doses of enoxaparin.
BACKGROUND
Low-molecular-weight heparins (LMWHs) have become increasingly used to prevent thromboembolic complications in intensive care patients. Unlike in medical and surgical patients, no data on the anticoagulant effectiveness of standard LMWH dosages exist in intensive care patients. Therefore, we prospectively investigated antifactor Xa (aFXa) levels after subcutaneous administration of 40 mg of enoxaparin in 89 intensive care patients over a 24-h period.


METHODS
AFXa levels were measured before, 4, 12 and 24 h after subcutaneous administration of enoxaparin. Laboratory parameters including prothrombin time, activated partial thromboplastin time, antithrombin III, fibrinogen as well as platelet count were collected at same intervals. Demographics included age, sex, height, weight, body mass index, admission diagnosis, a thromboembolic risk score and a modified Goris multiple organ dysfunction score.


RESULTS
At 4, 12 and 24 h, 56.5%, 39.3% and 12.6% of the study patients were within recommended antithrombotic aFXa levels (0.1-0.3 U ml(-1)). Presence of multiple organ dysfunction as well as high body weight were significantly correlated with low aFXa levels.


CONCLUSIONS
European standard dosages of 40 mg of enoxaparin once daily proved to be ineffective in achieving recommended antithrombotic aFXa levels in intensive care patients. This was most pronounced in patients with high body weight and presence of multiple organ dysfunction.
Mayr
A J
AJ
Division of General and Surgical Intensive Care Medicine, Department of Anaesthesia and Critical Care Medicine, The Leopold Franzens University of Innsbruck, Anichstrasse 35, Innsbruck 6020, Austria.
Dünser
M
M
Jochberger
S
S
Fries
D
D
Klingler
A
A
Joannidis
M
M
Hasibeder
W
W
Schobersberger
Wolfgang
W
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood / Q000276:immunology*; D003422:Critical Care; D017984:Enoxaparin / Q000008:administration & dosage* / Q000276:immunology; D015951:Factor Xa / Q000276:immunology*; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage* / Q000276:immunology; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
D000906:Antibodies; D017984:Enoxaparin; D005343:Fibrinolytic Agents; D015951:Factor Xa