Assessment of survival and microscopic changes in porcine skin flaps undergoing immediate intraoperative tissue expansion.

The technique of rapid intraoperative tissue expansion has been used with increasing frequency in the clinical setting over the last several years. This technique takes advantage of the skin's ability to immediately stretch and increase in surface area when expanded under a constant load. Sixteen random-pattern, rapidly expanded skin flaps on 10 domestic male pigs were studied to assess the predictive value of the fluorescein test for flap viability after rapid intraoperative tissue expansion. Partial fluorescence was found to be a more accurate predictor of flap survival in the experimental rapidly expanded flaps when compared to full fluorescence. Partial fluorescence was found to under-predict flap survival by 0.3 to 0.5 cm, whereas full fluorescence was found to under-predict flap survival by 2.5 cm. Additionally, histologic and ultrastructural changes were examined in rapidly expanded skin from the hip region in three pigs. The only microscopic change noted between control and experimental flaps was dilated capillaries in the dermis of expanded skin, which was noted by electron microscopy. Collagen and elastic tissue changes were not demonstrated in rapidly expanded pig skin by electron microscopy, direct immunofluorescence, collagen, and elastic tissue stains.