Optimum intermittent pneumatic compression stimulus for lower-limb venous emptying

Objective: intermittent pneumatic compression (IPC) of the foot (IPCfoot), calf (IPCcalf) or both (IPCfoot+calf) augments calf inflow, and improves the walking ability and peripheral haemodynamics of claudicants (IPCfoot, IPCfoot+calf), largely due to venous outflow enhancement. This cohort study, using direct pressure measurements in healthy limbs, determines the optimal combination of frequency (2-4 impulses/minute), applied pressure (60-140mmHg), mode (IPCfoot-IPCcalf-IPCfoot+calf) and decay time of calf-to-foot impulse (0 s-0.5 s-1 s) that enables IPC to generate an almost complete and sustained decrease in venous pressure. Results: (a) IPCfoot at 120 and 80 mmHg generated lower venous pressure than that with 100 and 60 mmHg (p =0.036) respectively, for 2-4 impulses/minute; venous pressure differences between applied pressures of 140 and 120 mmHg or between 80 and 100 mmHg were insignificant. (b) Venous pressure with IPCcalf at 80 mmHg was lower than that with 60 mmHg (p = 0.036) (2-4 cycles/minute); differences in venous pressure between applied pressures of 140 and 100 mmHg, or between 120 and 80 mmHg were insignificant. (c) At applied pressures 60-140 mmHg, IPCfoot+calf with one-second delay generated lower venous pressure than that with half-second delay (p=0.036), the latter being more efficient than zero delay; increasing applied pressures produced lower venous pressure, but differences were small. Venous pressure decreased with increasing IPC frequency (from 2 to 3-4/minute), at applied pressures 60-140 mmHg. Conclusions: IPCfoot+calf at applied 120-140 mmHg, a frequency of 3-4 impulses/minute and one-second delay, provided the optimum intermittent pneumatic stimulus.