Killewich LA, Cahan MA, Hanna DJ, Murakami M, Uchida T, Wiley LA, Hunter GC.
The effect of external pneumatic compression on regional fibrinolysis in a
prospective randomized trial.
J Vasc Surg 2002 Nov;36(5):953-8

Section of Vascular Surgery, Department of Surgery, and the Office of
Biostatistics, University of Texas Medical Branch, Galveston 77555, USA.
lakillew@utmb.edu

INTRODUCTION: External pneumatic compression devices (EPC) prevent deep venous
thrombosis (DVT) by reducing lower extremity venous stasis. Early studies
suggested they also enhance fibrinolytic activity; however, in a recent study,
EPC had no effect on systemic fibrinolysis in patients undergoing abdominal
surgery. The hypothesis of this study was that EPCs enhance regional fibrinolysis
in these subjects. METHODS: Forty-five patients (44 male, one female; mean age,
67 years) undergoing major abdominal surgery (35 bowel procedures, 10 aortic
reconstructions) were prospectively randomized to one of three groups for DVT
prophylaxis: subcutaneous heparin injections (HEP), thigh-length sequential EPC
devices (EPC), or both (HEP+EPC). Prophylaxis was begun immediately before
surgical incision and continued until postoperative day 5 or patient discharge.
Venous blood samples were collected from the common femoral vein for measurement
of regional fibrinolysis after induction of anesthesia but before initiation of
prophylaxis, and on postoperative days 1, 3, and 5. A baseline sample was
collected the day before surgery. Fibrinolysis was quantified with measurement of
the activities of tissue plasminogen activator (tPA; the activator of
fibrinolysis) and its inhibitor plasminogen activator inhibitor-1 (PAI-1) with
amidolytic technique. RESULTS: tPA activity in all groups was normal at baseline;
baseline PAI-1 activity was elevated. Within each prophylaxis group, no
significant changes occurred in either tPA or PAI-1 activities after induction of
anesthesia or after surgery compared with before surgery (P >.05, analysis of
variance with repeated measures). No changes occurred between postoperative
samples and after anesthesia within each group. No significant enhancement of
fibrinolysis, manifested as either increased tPA activity or decreased PAI-1
activity, occurred in either EPC group compared with the HEP group at any time
point (P >.05, analysis of variance with repeated measures). No differences were
noted when surgery was performed for malignant disease versus nonmalignant
disease. CONCLUSION: In this study, enhanced regional fibrinolysis in the lower
extremities could not be detected with the use of EPCs, as measured with tPA and
PAI-1 activity in common femoral venous blood samples. EPC devices do not appear
to prevent DVT with fibrinolytic enhancement; effective and safe prophylaxis is
provided only when the devices are used in a manner that reduces lower extremity
venous stasis.