Mittelman JS, Edwards WS, McDonald JB.
Effectiveness of leg compression in preventing venous stasis.
Am J Surg. 1982 Dec;144(6):611-3.

To compare the ability of intermittent calf compression with that of
sequential leg compression to prevent venous stasis, the clearance time of
radiopaque dye, as determined by sequential phleborheograms performed
on anesthetized patients, were compared. Calf compression was
superior to no compression in clearing the dye from the calf alone,
but did not aid clearance from the rest of the leg. Sequential
leg compression was superior to intermittent calf compression
in clearing dye from the calf and popliteal areas.
Since intermittent leg compression has been as effective as small-dose heparin
therapy in preventing postoperative deep venous thrombosis [7], the use of
sequential leg compression may prove to be more effective and have
less complication than heparin administration.