On expander pressure and skin blood flow during tissue expansion in the pig

The structural and circulatory dynamics of expanded skin in connection with expander fillings were assessed in pigs following 7, 14, and 21 days of expansion by measuring the pressure of te fluid in the expander (Pexp) and the dermal blood flow. The results differed consistently on thoracic and abdominal sites. It was suggested that the stimulus to expansion be defined as the relative increase in extensible surface area of the expander. When plotting this value against Pexp, as measured at the end of injection, there was a good fit to an exponential curve. The area/Pexp relation was used to assess the connective tissue reaction around the expander; the reaction was most pronounced at 21 days. The decrease in Pexp after injection of fluid to 100 mm Hg showed that the tissue adapted rapidly during the first hour. Blood flow in the skin covering the expander was lower than on adjacent normal skin, and there was no increase during the three weeks of expansion. The decreases in blood flow were moderate even after injection of fluid until Pexp reached 100 mm Hg. It was suggested that the connective tissue capsule might protect the dermis from flow decrease.