The effect of a mechanical venous pump on the circulation of the feet in the presence of arterial obstruction.

A boot of single layer, flexible vinyl sheeting and a pneumatic cuff encircling its top at the ankle, each independently inflatable, constitute a mechanical venous pump. Inflation of the cuff to the desired boot pressure is followed immediately by inflation of the boot from a reservoir with higher available pressure than that in the cuff. When the boot pressure reaches cuff pressure, the excess air escapes from the boot under the cuff. A low venous pressure at the foot could be maintained by compressing the foot for 2 seconds every 15 seconds with a pressure which is 10 millimeters of mercury above initial venous pressure. In seated patients with arterial obstruction whose supine ankle blood pressure was 60 milimeters of mercury or less, the rate of blood flow in the skin of the forefoot was increased by 104.1 +/- 43.7 per cent S.E.M., p less than 0.05, during venous pumping. In these patients, a change in posture alone from supine to sitting increased the rate of blood flow by 81.7 +/- 19.47 per cent, p less than 0.002. The combined effect of the erect posture and venous pumping was an increase of 185.7 +/- 49.63 per cent, p less than 0.01. Rest pain was relieved by the combined effect.