AJP - Regulatory, Integrative and Comparative Physiology, Vol 240, Issue 5 327-R329, Copyright © 1981 by American Physiological Society
Subcutaneous interstitial fluid pressure during external loading
N. P. Reddy, V. Palmieri and G. V. Cochran
Interstitial fluid pressure (IFP) distribution generated as a result of
externally applied pressure (EAP) may play an important role in the
etiology of decubitus ulcers. In the forelimbs of 10 thiopental
sodium-anesthetized Yorkshire pigs, weighing 16-20 kg, we placed wick
catheters 2-5 mm below the skin. After equilibration, we applied a
pediatric cuff and added EAP. With zero EAP, the IFP was -3.9 +/- 1.4 (SD)
mmHg. In each case of EAP, IFP as measured with the wick catheter increased
and reached a plateau within 10-15 min. In normal tissues, IFP reached
approximately 65-75% of EAP. When we created an edematous condition by
preinfusing with excess saline, IFP was found to reach 100% of EAP. The
total normal stress in the tissue, generated as a result of external cuff
pressure, can be considered as a sum of interstitial fluid pressure and
extranormal stress. Integrity of the fibrous network and pore fraction may
be important in transmitting pressure to the fluid.
