Page 11 - REM Medical Solutions - Physicians Guide

Vol. 226 * No. 3 Fibrinolysis with IPC 307
reduction in PAI-1-Act in both normal subjects (p = 0.003) and patients (p = 0.004). There
were no changes in vWF, and alpha-2-antiplasmin-plasmin complexes increased only in
postthrombotic patients (p = 0.021).

Conclusions
Stimulation of endogenous fibrinolytic activity occurs after IPC, both in normal subjects and
postthrombotic patients; however, baseline and overall fibrinolytic response in
postthrombotic patients is reduced. The mechanism of increased fibrinolytic activity is likely
because of a reduction in PAI-1, with a resulting increase of tPA activity.

Prophylaxis for deep venous thrombosis (DVT) is man- nous fibrinolytic activity89 and patients with postthrom-
datory for patients at moderate and high risk for venous botic venous disease are at high risk of DVT after surgical
thromboembolic complications.'-3 Intermittent pneumatic procedures,2 it would be of value to know if the mecha-
compression (IPC) is an effective mechanical method of nisms of enhanced fibrinolysis with IPC are operative in
DVT prophylaxis.' -3 Because IPC stimulates fibrinolytic these patients and whether it is quantifiably different from
activity, its antithrombotic action appears to be due to that in normal subjects.
more than just a mechanical effect on blood flow.46 Inter- The purposes of this study are to quantify the enhanced
mittent pneumatic compression potentially affects two of fibrinolytic activity with IPC, to clarify the mechanisms
the three limbs of Virchow's triad by increasing venous of fibrinolytic enhancement with IPC; and to evaluate
blood flow velocity, thereby reducing stasis, and stimulat- whether postthrombotic patients have the same capacity
ing fibrinolytic activity, thereby altering hypercoagulabil- for fibrinolytic enhancement with IPC as do normal sub-
ity. jects.
Endogenous or stimulated fibrinolysis is the result of
activation of plasminogen to plasmin by one of two en-
dogenous plasminogen activators, tissue plasminogen ac- MATERIALS AND METHODS
tivator (tPA) and urokinase type plasminogen activator Subjects
(uPA). This activation sequence is balanced by inactiva-
tion (binding with inhibitors), especially of tPA by the Twelve volunteers of 2 distinct groups were studied.
rapid acting inhibitor, plasminogen activator inhibitor-i The first consisted of six healthy subjects (4 men, 2
(PAI-1).7 The degree of endogenous fibrinolysis can be women; mean age, 46 years; range, 25-68 years) with no
measured and the components of the fibrinolytic system history or physical findings of venous or arterial disease
can be quantified, thereby allowing one to study the mech- (normal subjects). Routine venous duplex examinations
anism of fibrinolytic response to a given stimulus. were performed to exclude the presence of asymptomatic
Surgical patients at risk of having postoperative DVT DVT or evidence ofpreviously undetected chronic venous
develop and those who have suffered venous thrombotic disease.
complications have measurably reduced fibrinolytic activ- The second group consisted of six subjects (4 men, 2
ity.89 In addition, patients with an inadequate augmen- women; mean age, 48 years; range, 31-66 years) with a
tation of fibrinolytic activity with IPC are most likely to history of proximal DVT treated with long-term anticoag-
have postoperative DVT develop.5 ulation and venous duplex evidence of recanalization and
It appears that there is a link between development of thickened walls of their veins (postthrombotic patients).
DVT and endogenous fibrinolytic activity, and under-
standing this aspect of the patients' endogenous regula-
tory systems is increasingly important, especially in light Devices
of the multiple options for DVT prophylaxis. Because Five IPC devices were studied in random sequence;
patients with postoperative DVT have depressed endoge-
these included thigh length sequential compression (SCD;
Kendal Health Care Products Company, Mansfield, MA),
TSQ; calf-length sequential compression (SCD Kendal
Presented at the 117th Annual Meeting of the American Surgical Associ-
ation, Quebec City, Quebec, Canada, April 17-19, 1997. Health Care Products Company, Mansfield, MA ), CSQ;
Supported in part by NIH Grant K07HL02658, General Clinical Re- thigh-length single-chamber compression (DVT, 30
search Center Grant RR00349, and Unrestricted Research Grants Flowtron; Huntleigh Health Care, Malapan, NJ), TSC;
from Huntleigh Healthcare, Inc, and NuTech, Inc. calf-length single-chamber compression (Huntleigh
Address reprint requests to Anthony J. Comerota, Jr., M.D., Department Health Care, Malapan, NJ), CSC; and the foot pump
of Surgery, Temple University School of Medicine, Broad and On-
tario Streets, Philadelphia, PA 19140. (Plexipulse; NuTech, San Antonio, TX), FP.
Accepted for publication April 23, 1997. Subjects were studied in the Clinical Research Center