Subcutaneous Heparin Not Absorbed Sufficiently Following Abdominal Surgery

A new study suggests that subcutaneously administered heparin might not provide optimal protection against venous thromboembolism (VTE) for patients who have undergone major abdominal surgery, as absorption appears to be decreased in these patients.

Researchers at the University of Colorado at Denver School of Medicine (Aurora, USA) randomized 50 intensive care unit (ICU) patients immediately after major abdominal surgery to receive subcutaneous heparin (5000 U) 3 times daily--the standard of care--or an intravenous (IV) heparin infusion titrated to a target activated partial thromboplastin time range of 40-45 seconds. The patients were matched demographically, and had a similar body mass index (BMI) of 27 kg/m² and an average acute physiology and chronic health evaluation (APACHE) score of 13. Daily blood heparin-activity levels, daily whole blood coagulation parameters, and screening of the lower extremities with ultrasound for 10 days after surgery were performed.

The researchers found that patients receiving subcutaneous heparin had no detectable levels of antifactor Xa activity 5 days after surgery. In contrast, patients receiving IV heparin showed statistically significant increases in antifactor Xa activity on day 3 and day 4. Using a whole blood coagulation device, the researchers found that the patients who received subcutaneous heparin had a hypercoagulable profile for up to 5 days after surgery, but that patients who received IV heparin had a normal profile. No lower-extremity deep vein thrombosis (DVT) was found on screening ultrasounds in either group, nor were there any episodes of major bleeding or heparin-induced thrombocytopenia. The study was presented at the Society of Critical Care Medicine 40th Critical Care congress, held during January 2011 in San Diego (CA, USA).

"There were no differences in ICU length of stay or 28-day mortality, and we are confident that we are not overtly hurting people,” concluded study presenter and lead author Sara Cheng, MD. "This allows us to push forward and study the efficacy of IV heparin for the prevention of postoperative VTE in surgical intensive care patients. A larger phase 3 study is definitely warranted.”

Related Links:
University of Colorado at Denver School of Medicine