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 th e walking ability and peripheral haemodynamics of claudicants (IPCfoot, IPC foot+calf), largely due to venous outflow enhancement. This cohort study, u sing direct pressure measurements in healthy limbs, determines the optimal combination of frequency (2-4 impulses/minute), applied pressure (60-140mmH g), mode (IPCfoot-IPCcalf-IPCfoot+calf) and decay time of calf-to-foot impu lse (0 s-0.5 s-1 s) that enables IPC to generate an almost complete and sus tained decrease in venous pressure. Results: (a) IPCfoot at 120 and 80 mmHg generated lower venous pressure tha n that with 100 and 60 mmHg (p =0.036) respectively, for 2-4 impulses/minut e; venous pressure differences between applied pressures of 140 and 120 mmH g or between 80 and 100 mmHg were insignificant. (b) Venous pressure with I PCcalf 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 an d 100 mmHg, or between 120 and 80 mmHg were insignificant. (c) At applied p ressures 60-140 mmHg, IPCfoot+calf with one-second delay generated lower ve nous 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 wit h 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 impul ses/minute and one-second delay, provided the optimum intermittent pneumati c stimulus.