Standard subcutaneous dosing of unfractionated heparin for venous thromboembolism prophylaxis in surgical ICU patients leads to subtherapeutic factor Xa inhibition.
OBJECTIVE
To assess coagulation status and factor Xa inhibition in surgical intensive care unit (ICU) patients administered prophylactic unfractionated heparin for venous thromboembolism (VTE) prophylaxis.


METHODS
We conducted a randomized, single-blind study at a tertiary academic medical center. Included were patients 18 years and older admitted to the surgical ICU directly after major abdominal surgery. Exclusion criteria included significant bleeding risk, preoperative anticoagulation, or history of heparin-induced thrombocytopenia. Patients were randomized to two regimens for VTE prophylaxis: standard of care unfractionated heparin, 5,000 units subcutaneously three times daily (SQH) versus unfractionated heparin via intravenous infusion, titrated to an activated partial thromboplastin time of 40-45 s (IVH). Blood samples were taken prior to surgical incision on day 0 and daily for 5 days after surgery. Samples were analyzed for factor Xa inhibition and viscoelastic whole blood clotting parameters (Sonoclot analyzer).


RESULTS
A total of 50 patients were randomized to either SQH or IVH. The majority of patients had cancer. Patients in the SQH group had no detectable peak anti-factor Xa (aFXa) activity for 5 days after surgery, while patients in the IVH group had statistically elevated levels compared to the SQH group on days 3-5. SQH patients demonstrated a hypercoagulable profile on Sonoclot, while IVH patients displayed a normal profile.


CONCLUSIONS
Standard of care subcutaneous dosing of unfractionated heparin for VTE prophylaxis in surgical ICU patients leads to subtherapeutic levels of factor Xa inhibition.
Department of Anesthesiology, University of Colorado School of Medicine, Mail Stop B113, 12401 E. 17th Avenue, Aurora, CO 80045, USA. sara.cheng@ucdenver.edu
Sara S
SS
Cheng
Kristen
K
Nordenholz
David
D
Matero
Nathan
N
Pearlman
Martin
M
McCarter
Csaba
C
Gajdos
Christine
C
Hamiel
Angela
A
Baer
Elizabeth
E
Luzier
Zung Vu
ZV
Tran
Timothy
T
Olson
Kelly
K
Queensland
Ryan
R
Lutz
Paul
P
Wischmeyer
D018806:APACHE; D000704:Analysis of Variance; D000925:Anticoagulants / Q000008:administration & dosage*; D001780:Blood Coagulation Tests; D003422:Critical Care; D065427:Factor Xa Inhibitors; D005260:Female; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000517:prevention & control; D011446:Prospective Studies; D016037:Single-Blind Method; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000517:prevention & control*
D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D006493:Heparin