Salzman EW, McManama GP, Shapiro AH, Robertson LK, Donovan AS,
Blume HW, Sweeney J, Kamm RD, Johnson MC, Black PM.
Effect of optimisation of hemodynamics on fibrinolytic activity and
antithrombotic efficacy of external pneumatic calf compression.
Ann Surg 1987 Nov;206(5):636-41

External pneumatic calf compression is effective but imperfect for antithrombotic
prophylaxis in surgical patients. In preliminary studies, sequential filling of
multisegmented leggings with graded pressure decreasing from ankle to knee
increased venous flow velocity and wall shear stress, decreased residual venous
volume, and enhanced postoperative fibrinolysis more than uniform compression. To
determine if improved hemodynamics also increased antithrombotic activity, we
performed a prospective randomized trial in neurosurgical patients comparing
sequential application of graded pressure with uniform pressure applied to either
a segmented bladder or to a single bladder. Deep vein thrombosis was diagnosed by
leg scanning and impedance plethysmography and confirmed by phlebography. Venous
thrombosis developed in 3 of 45 patients with graded-sequential filling, 6 of 50
with uniform compression-multiple compartments, and 3 of 41 with uniform pressure
single bladder (differences not significant). These results suggest either that
uniform compression offers all that can be expected of external pneumatic calf
compression in prevention of venous thrombosis, or that even if a study with
greater statistical power showed graded-sequential filling to be superior, the
benefit/cost ratio of the more complex latter system is not likely to be large.