AJP - Heart and Circulatory Physiology, Vol 261, Issue 2 349-H353, Copyright © 1991 by American Physiological Society
Effect of skin concavity on subcutaneous tissue fluid pressure
T. H. Adair, G. A. Vance, J. P. Montani and A. C. Guyton
Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson 39216-4505.
We tested the hypothesis that mechanical factors associated, with a skin
concavity can cause the local tissue fluid pressure to become more
negative. Perforated Teflon collars, 26 mm in diameter and having various
heights (5, 10, 13, and 16 mm), were implanted into the fascial plane of
the inguinal and abdominal areas of six sheep. After several weeks, visible
signs of edema were no longer apparent, and the skin formed a concavity
within the center of each collar. The depth of each concavity was measured
using an electronic micrometer, and the tissue fluid pressure beneath the
concavity was measured using a needle method. Over the entire range of
collar heights, the average depth of the concavities ranged from 1.1 to 4.7
mm in the abdominal tissues and from 1.8 to 5.5 mm in the inguinal tissues.
The respective values of tissue fluid pressure averaged -4.6 to -13.0 and
-5.7 to -12.8 mmHg. The results therefore indicate that implanting deeper
collars leads to the formation of deeper concavities in the skin and also
to greater negativity in the free tissue fluid pressure beneath the skin.
Linear regression extrapolation to a collar height of 0 mm corresponded to
a tissue fluid pressure of -1.0 mmHg in the abdominal tissue and -2.4 mmHg
in the inguinal tissues. A model based on excessive pumping of the
lymphatic system in the vicinity of a concavity is provided to explain this
newly described phenomenon. We conclude that mechanical factors associated
with the formation of a skin concavity cause or permit the tissue fluid
pressure to reach levels of negativity far greater than those that exist in
the absence of a concavity.
