title: External pneumatic compression and fibrinolysis in abdominal surgery.
abstract: BACKGROUND
  External pneumatic compression (EPC) devices prevent lower extremity deep venous thrombosis by increasing venous flow and thereby reducing stasis. Early studies suggested that they also enhance systemic fibrinolytic activity and thus prevent thrombus formation; more recent studies have been conflicting. The hypothesis of this study was that EPC devices enhance systemic fibrinolysis or reduce postoperative fibrinolytic impairment in patients undergoing abdominal surgical procedures.
  
  
  METHODS
  Each of 48 patients (98% male; mean age, 67 years) undergoing major intra-abdominal surgical procedures (36 bowel procedures, 12 aortic reconstructions) was prospectively randomized to one of three treatments for deep venous thrombosis prophylaxis: subcutaneous heparin injections (HEP group), use of a thigh-length sequential EPC device (EPC group), or both (HEP + EPC group). Antecubital venous samples were collected for measurement of systemic fibrinolytic activity on the day before surgery, after induction of anesthesia but before prophylaxis was initiated, and on postoperative days 1, 3, and 5. Fibrinolysis was assessed through measurement of the activities of the rate limiting fibrinolytic activator, tissue plasminogen activator, and its inhibitor plasminogen activator inhibitor-1 with amidolytic methods.
  
  
  RESULTS
  On the day before surgery, plasminogen activator inhibitor-1 activity was elevated in all groups in comparison with that in age-matched and sex-matched controls (20.3 +/- 0.6 AU/mL). In the HEP group, plasminogen activator inhibitor-1 activity was further elevated above the value for the day before surgery on postoperative day 1 (28.5 +/- 4.3 AU/mL; P =.04) and postoperative day 3 (25.1 +/- 1.9 AU/mL; P =.07). No significant decrease in plasminogen activator inhibitor-1 activity occurred in either group treated with EPC devices in comparison with the HEP group at any time. There were no changes in tissue plasminogen activator activity postoperatively in the HEP group and no significant increases in either EPC group at any point.
  
  
  CONCLUSIONS
  Reduced systemic fibrinolytic activity ("fibrinolytic shutdown") occurred in these patients after abdominal surgery; it was manifested as increased plasminogen activator inhibitor-1 activity. EPC devices did not enhance systemic fibrinolysis or prevent postoperative shutdown either by decreasing plasminogen activator inhibitor-1 activity or by increasing tissue plasminogen activator activity. These data suggest that EPC devices do not prevent deep venous thrombosis by fibrinolytic enhancement; effective prophylaxis is achieved only when the devices are used in a manner that reduces lower extremity venous stasis.
authors.affiliation: Division of Vascular Surgery, Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Cahan
authors.forename: D J
authors.initials: DJ
authors.lastname: Hanna
authors.forename: L A
authors.initials: LA
authors.lastname: Wiley
authors.forename: D K
authors.initials: DK
authors.lastname: Cox
authors.forename: L A
authors.initials: LA
authors.lastname: Killewich
mesh_terms: D000368:Aged; D001018:Aortic Diseases / Q000097:blood / Q000601:surgery*; D005260:Female; D005342:Fibrinolysis / Q000502:physiology*; D005770:Gastrointestinal Neoplasms / Q000097:blood / Q000601:surgery*; D005676:Gravity Suits; D006801:Humans; D008297:Male; D008875:Middle Aged; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood; D011183:Postoperative Complications / Q000097:blood / Q000517:prevention & control*; D013924:Thrombophlebitis / Q000097:blood / Q000517:prevention & control*; D010959:Tissue Plasminogen Activator / Q000097:blood
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D010959:Tissue Plasminogen Activator