D-DIMERS - D-Dimers are fibrin cross-links that are cleaved and released into the circulation by the action of the enzyme plasmin during fibrinolysis (clot breakdown). This process normally begins one hour after blood clot formation and can be detected in the circulation using a variety of antigen-antibody assays. The easiest to perform is the SimpliRED whole blood assay that can be performed quickly at the bedside on two drops of whole blood. Studies show this test may be a good screening tool for those who are thought to have clinical evidence for pulmonary embolism or deep venous thrombosis.