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° increments from 6° leg-down to 12° 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° 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° to legs which were first horizontal and then tilted up 6°; supine, first horizontal then 6° leg-up) showed significant increases in velocity between consecutive positions.