Enhancing venous outflow in the lower limb with intermittent pneumatic compression. A comparative haemodynamic analysis on the effect of foot vs. calf vs. foot and calf compression.

OBJECTIVES: intermittent pneumatic compression (IPC), an established method of deep-vein thrombosis prophylaxis, is also an effective means of leg inflow enhancement, improving the walking capacity and ankle pressure of claudicants, long-term. This study, using duplex ultrasonography, compares the haemodynamic effect of IPC of the (a) foot (at 120 mmHg [IPC(foot/120 mmHg)], and 180 mmHg [IPC(foot/180 mmHg)]), (b) calf (IPC(calf), 120 mmHg) and (c) both simultaneously (IPC(foot+calf), 120 mmHg), on the venous outflow of 20 legs of normals and 25 legs of claudicants.

RESULTS: the peak and mean velocities, volume flow and pulsatility index in the superficial femoral and popliteal veins of both groups increased significantly with all IPC modes (p<0.001). IPC(foot+calf)produced the highest enhancement followed by IPC(calf)(p<0.01), which was more effective (p<0.001) than either IPC(foot/180 mmHg)or IPC(foot/120 mmHg). The venous volume expelled with IPC(calf)and IPC(foot+calf)was 2-2.5 and 3-3.5 times that with IPC(foot/180 mmHg)respectively. Velocity enhancement with IPC was similar between groups and the superficial femoral and popliteal veins. IPC(foot/180 mmHg)produced higher (p<0. 01) flow velocities than IPC(foot/120 mmHg)in both groups and veins examined; however, differences were limited.

CONCLUSIONS: all IPC modes proved effective, IPC(foot+calf)generating the highest venous outflow enhancement. Higher venous volumes expelled with IPC(foot+calf)explain its reported superiority on leg inflow over the other modes. Increase of applied pressure from 120 to 180 mmHg with IPC(foot)offered only a small outflow improvement. Venous haemodynamics at rest and with IPC in claudicants do not differ significantly from those in healthy subjects.