STRAIN-GAUGE PLETHYSMOGRAPHY AND DUPLEX ULTRASOUND STUDY OF VENOUS-BLOOD FLOW CHANGES DURING APPLICATION OF THE A-V IMPULSE SYSTEM(R) FOOT PUMP AND TED(R) ANTI-EMBOLISM STOCKINGS

Objective. To study the combined effect of two methods of preventing d eep vein thrombosis on the physiology of blood flow in the lower limb. Design. Single volunteer group. Setting. Teaching hospital vascular l aboratory. Subjects. Twenty volunteers with no evidence of lower limb venous or arterial disease. Interventions. Blood flow was measured wit h the individual or combined application of a T.E.D.(R) stocking and A V Impulse System(R) foot pump. The subjects lay supine, sat in the 45 degrees recumbent position and also sat upright with the legs dependen t. Outcome measures. Venous flow velocity and diameters were assessed by duplex ultrasonography measuring the superficial femoral vein, medi al gastrocnemius vein and the posterior tibial vein. Changes in calf v olume were assessed by strain gauge plethysmography. Results. In the 4 5 degrees recumbent position strain gauge measurements showed that the net decrease in calf volume was greater with the combined use of the foot-pump and T.E.D. stockings. In the sitting position the calf volum e increased during the treatment period. This was least when both stoc king and foot pump were applied. Duplex ultrasonography showed that th e combined use of stockings and foot pump resulted in a considerable i ncrease flow velocity and volumetric flow in all three veins and each study position. Conclusions. The combined use of the A-V Impulse Syste m(R) foot pump and T.E.D. stockings resulted in increased venous now v elocity without causing venodilation.