Venous Pressure in the Saphenous Vein at the Ankle in Man during Exercise and Changes in Posture

Abstract

Venous pressure in the great saphenous vein at the ankle was studied in 11 normal subjects in the recumbent, seated and quiet standing positions as well as during contraction of the leg muscles produced by standing on the toes and while walking on a treadmill. Heart rate, heel position and pressure of a column of water extending from the 3d thoracic interspace to the tip of the catheter at the ankle were recorded simultaneously. The venous pressure at the ankle averaged 11.7 mm.Hg (7-16) in the recumbent position, 56 mm. Hg (45.-67.5) in the sitting position and 86.8 mm. Hg (78.5-92.6) in the resting standing position. Venous pressure at the ankle in the resting sitting or standing positions was sufficient to support a column of blood to approx. the level of the 3d thoracic interspace at the sternum. The changes in venous pressure produced by a single step were studied in 10 subjects. There was an avg. rise in pressure of 10 mm. Hg from the standing control level before the heel was lifted from the floor at the beginning of the step. An avg. fall of 52 mm. Hg (28.0-80.5) occurred with the foot off the floor. As the heel touched the floor there was a slight rise in pressure, followed by another fall to the previous low level while the heel settled on the floor and the body wt. was redistributed. The pressure returned to the control level in an avg. time of 22.9 sec. (11-37) as the subject resumed the quiet standing position. Subjects exercised on a level treadmill at i.7, 2.6 and 3.3 miles per hr. Each step in the walk produced changes in venous pressure resembling the effect produced by a single step. The mean venous pressure decreased in every instance during the first 3 to 12 steps to an avg. stable value of 22.3 (11-30.6), 24.3 (8.5-38), and 23.6 (10-43.2) mm.Hg, respectively, which was maintained for the duration of the walk. After cessation of the walk the venous pressure returned to the previous standing control level in about 30 sec. No significant difference was demonstrated in the avg. mean pressures at the ankle during walking at the different speeds. The avg. decrease in pressure was approx. 60 mm. Hg, so that the mean venous pressure during walking was sufficient to support a column of blood approx. up to the level of the knee. Inclining the treadmill to 20[degree] did not significantly alter the avg. decrease in pressure produced by walking. The recorded mean pressure of a column of water extending from the outside of the ankle up to the 3d interspace was not changed during walking. Contraction of the calf muscles by standing On the toes, without walking, caused a fall in venous pressure at the ankle. This decrease in pressure occurred without shortening of the hydrostatic distance from the catheter tip to the level of the right side of the heart and without occurrence of significant accelerative forces on the manometer system.