Effect of External Sequential Compression Devices on Femoral Venous Blood Flow

David C. Markel, MD, Gary D. Morris, MD


J South Orthop Assoc. 2002;11(1) 

In This Article

Abstract and Introduction

Sequential compression devices are used to reduce venous stasis and deep venous thrombosis after joint replacement. Thigh-length, calf-length, and foot compression devices were compared in using ultrasonography after unilateral knee arthroplasty. Simulated muscle activity via active ankle motion was also evaluated. Blood flow volume and velocity were recorded above and below the saphenous vein bifurcation, the division of the superficial and deep systems, allowing evaluation of each. Volume and velocity increased in the superficial and deep systems with all devices. A control group was evaluated to determine differences related to age and surgery. The devices performed similarly in the volunteers. However, active motion performed better than any device. Thus, unlike young, healthy patients, muscle activity alone in the operative population was unreliable in increasing blood flow. Thigh-length, calf-length, and foot compression devices are are effective at increasing femoral blood flow volume and velocity in the deep and superficial venous systems after total knee arthroplasty.

Deep venous thrombosis is a common complication of total knee replacement. A venous thrombus in the lower extremity may cause pain or lead to a postphlebitic syndrome,[1] pulmonary embolism, or death.[2] The incidence of deep venous thrombosis after total knee arthroplasty has been reported to range from 50% to 84% without the use of anticoagulation prophylaxis.[2,3,4,5,6,7,8,9,10] When pharmacologic prophylaxis is applied, the range falls to 2% to 57%.[2,8,11,12] The incidence of pulmonary embolism decreases as the frequency of deep venous thrombosis decreases.[13]

Current approaches to prevention of deep venous thrombosis can be divided into two methods: pharmacologic and mechanical. Hypercoagulability, venous stasis, and intimal damage (Virchow's triad) are the target areas for both mechanical and pharmacologic prophylaxis. Pharmacologic prophylaxis primarily targets hypercoagulability. Warfarin, heparin, and low-molecular-weight heparins are the mainstays of contemporary pharmacologic prophylaxis. Numerous studies have validated the efficacy of these agents.[2,5,6,7,8,9,12,13,14,15,16,17,18,19,20] External mechanical compression has become popular in recent years.[9,10,21] It does not pose an increased risk of postoperative bleeding or require laboratory monitoring if used without pharmacologic prophylaxis. These devices primarily combat the venous stasis portion of Virchow's triad but may have a beneficial effect on the clotting cascade.[22,23] In fact, the use of external compression, presumably by increasing venous blood flow has been shown to decrease the incidence of thrombus formation in the lower extremity.[11,24,25,26,27,28] Methods that may increase venous blood flow include external pneumatic sequential compression devices, active and passive exercise, and continuous passive motion.[29] External pneumatic sequential compression devices are readily available and are easily applied to postoperative and nonambulatory patients. Thigh-length, calf-length, and foot pumps have all been shown to statistically increase the peak venous blood flow velocity over baseline values.[10,21,23,27,30,31,32,33,34] There are, however, few studies that directly compare devices[9,10,21,23] and few data quantifying the volumetric changes in flow rates that occur in the superficial system compared with the more clinically important deep venous system.[23]

The current study evaluated the efficacy of thigh-length, calf-length, and foot external pneumatic compression devices from a single manufacturer (Kendall, Mansfield, Mass), as well as active motion at the ankle relative to changes in lower extremity venous blood flow volume and velocity after unilateral total knee arthroplasty. Proprietary software was used in conjunction with computed ultrasonography to generate quantitative measurements.


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