THE EFFECTS OF VENOUS OBSTRUCTION UPON INTERSTITIAL PRESSURE IN ANIMAL AND HUMAN SKIN.

The changes of intracutaneous pressure in the limbs of mice and human beings have been followed during and after periods of venous obstruction with almost unhindered arterial flow. During the first 30 minutes of obstruction the interstitial pressure in the tense skin of the lower legs of mice, a pressure which is slightly higher than that in the loose skin of the ears, backs, and thighs (21), rose from 2.6 to 4.6 cm. of water to about 32 cm., thereafter remaining constant. It would appear that the escape of fluid from the capillaries is checked at this pressure. In the skin of the arm and leg of man the interstitial pressure rose from 2.5-3.7 cm. of water to 15.0-23.0, within 15 to 27 minutes after venous obstruction had been produced, mounting no higher during the period of observation. When venous obstruction had existed for about 20 minutes or more the subjects sometimes experienced sensations of relief from congestion as if some tissue adjustment or the opening of some venous by-pass in the marrow had occurred, preventing a further rise of pressure. However this may be, the pressures still appeared to be great enough to prevent further escape of fluid from the capillaries, at least for the time being.