Hemodynamics of the lower extremity with pneumatic foot compression. The effect of the position of the limb

External pneumatic compression of the foot is being used more and more to i ncrease the venous blood flow in the lower limbs and thus reduce the risk o f postoperative deep venous thrombosis. We have investigated the efficacy o f the foot pump pneumatic compression device (A-V Impulse, Novamedix, Andov er, England) in 10 healthy subjects and in 10 patients undergoing total hip arthroplasty. The velocity of venous blood flow in the common femoral arte ry was measured in the horizontal, Trendelenburg (head-down, foot-up) and r everse Trendelenburg (head-up and foot-down) positions using a duplex ultra sound unit (Sonoline Elegra, Siemens, Erlangen, Germany) with a 5 MHz linea r array probe. Application of the foot pump produced an increase in venous blood flow velocity in all healthy subjects and in all patients. In healthy subjects the mean increase in the horizontal position was 31.18% (SD = 15. 86%), and in the Trendelenburg position 20.72 (SD = 15.69%) (right Limb). I n the reverse Trendelenburg position, the foot pump produced a mean increas e of 94.08% (SD = 55.00%). The difference is statistically significant (p < 0.005). In patients with a total hip arthroplasty, the mean increase in th e horizontal position was 28.67% (SD = 9.95%), and in the Trendelenburg pos ition 20.34% (SD = 17.85%) (operated limb). In the reverse Trendelenburg, t he foot pump produced a mean increase of 91.55% (SD = 42.38%). The differen ce is statistically significant (p < 0.005). There was no noteworthy differ ence in results between the controls and patients. Pneumatic compression de vices designed to reduce venous stasis are effective in decreasing the rate of deep venous thrombosis after surgery on the lower Limb. The results of the present study show that the efficiency of the foot pump in increasing v enous return is improved by adopting the reverse Trendelenburg position. Th is may increase its thromboprophylactic effect.