Postoperative monitoring of low molecular weight heparin prophylaxis in high-risk patients

The alterations of the laboratory assays described for heparin monitoring in low molecular weight and unfractionated heparin prophylaxis groups did not correlate with the clinical outcome. Current laboratory techniques failed to detect an increased need for a higher dose of unfractionated or low molecular weight heparin to prevent DVT in these high-risk patients. The parameters commonly associated with thrombosis, that is, decreases in protein C and AT III were correlated with an increased incidence of DVT, but there was no difference in the assay values between the low molecular weight heparin and unfractionated heparin groups. Fibrinolysis activation is known to be associated with surgery; however, our data suggest an additional activation due to low molecular weight heparin compared with the unfractionated heparin group. Most interestingly, elevated PAI levels appear to correlate with thrombosis.