Janssen H, Trevino C, Williams D.
Hemodynamic alternations in venous blood flow produced by external pneumatic
compression.
J Cardiovac Surg (Torino) 1993 Oct;34(5):441-7

Department of Orthopaedic Surgery, Texas Tech University Health Sciences Center, Lubbock 79430.

Venous stasis associated with prolonged bed rest can enhance the risk of deep
venous thrombosis (DVT). Pneumatic compression of the lower extremities can
reduce this risk by preventing venous stasis. When selecting a method of leg
compression for their patients, physicians must chose between two distinctly
different types of compression devices. One device applies pressure with a
single-chambered sleeve to the below knee region while the other applies pressure
in a sequential gradient fashion from the ankle to the thigh. The current
prospective study was designed to evaluated the ability of two such devices to
increase blood flow in the profunda femoral vein. Venous blood flow velocity,
compression time, and vein diameter were measured in nine normal experimental
subjects using an Accuson duplex-Doppler before, during and after leg
compression. Compression with the single-chambered device produced a significant
rise in venous blood flow velocity; however, this could not be maintained and our
results indicate a higher average velocity was achieved with the sequential
gradient device. The sequential gradient device also moved a greater volume of
blood and achieved a higher average blood flow rate. The time between deflation
of the sleeve and return of a phasic respiratory signal was greater after
compression with the sequential gradient device. These results suggest that
sequential gradient compression produces the type of hemodynamic alterations
needed to reduce the risk of DVT by achieving a sustained increase in venous
blood flow and more completely emptying of the veins in the leg.