Posture, blood velocity in common femoral vein, and prophylaxis of venous thromboembolism.

Might leg elevation and avoidance of poor postures provide better prophylaxis against venous thromboembolism than heparin or mechanical methods? 12 supine subjects tilted in 3 degrees increments from 6 degrees leg-down to 12 degrees leg-up showed linear increase in mean peak blood velocity and reduction in calibre in the common femoral vein (colour-duplex ultrasound). Between horizontal and 6 degrees leg-up, velocity was increased by 17% and diameter reduced by 14%. A ranking of mean peak velocities in six postures (sitting; standing; trunk raised 35 degrees to legs which were first horizontal and then tilted up 6 degrees; supine, first horizontal then 6 degrees leg-up) showed significant increases in velocity between consecutive positions.