THE EFFECTS OF ALTERNATE SUCTION AND PRESSURE ON BLOOD FLOW TO THE LOWER EXTREMITIES

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Abstract
As an application of Poiseuille''s law the effects of alternate suction and pressure on the flow of blood through the lower extremities were studied in normal subjects and in patients with peripheral vascular disease. Increased rate of blood flow was identified by rise in skin temp. under carefully controlled conditions. In a circulation schema it was found that alternate suction and pressure increased by 45 to 78% the rate at which fluid flowed past an obstruction. In normal subjects alternate suction and pressure (a) diminished the rate of cooling of an extremity originally warm and (b) in the majority of instances caused an originally cold extremity to become conspicuously warmer. Suction and pressure sometimes failed to affect blood flow in the cold extremity but, as soon as vasoconstrictor tone was diminished slightly, blood flow was conspicuously and preferentially increased in the extremity exposed to external pressure variations. The vasodilator response to warming one forearm was studied in normal subjects with and without the use of external pressure changes. Alternate suction and pressure caused the vasodilator response to definitely higher in the extremity exposed to such changes. In patients with peripheral vascular disease alternate suction and pressure increased blood flow even though organic obstruction had advanced to such a stage that no rise in skin temp. was obtained when vaso-constrictor tone was completely abolished by immersing both forearms in warm water or by anesthetizing the posterior tibial nerve. The effects of suction and pressure on cyanosis associated with peripheral vascular disease are briefly discussed. To obtain maximal effects on blood flow it is apparently advisable to have (1) rela-tively brief periods of suction, (2) intermittent, brief periods of pressure and (3) diminished vasoconstrictor tone.

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