The effect of topical epidermal growth factor(EGF) on random flap survi̇val in rats

Aim: For the repair of skin defects, random axis skin flaps are used frequently in Plastic and Reconstructive Surgery. Aspect ratios are limited in random flaps that do not have a specific feeding vessel system. This situation causes tissue loss in the distal of the flap. Therefore, increasing flap survival is among the main research topics of Plastic and Reconstructive Surgery. In our study, we aimed to investigate the level of increasing the viability of random flaps in rats by using EGF, which is known to have angiogenic, anti-inflammatory and anti-apoptotic effects. Materials and Methods: In the study, 20 rats were divided into 2 groups with 10 rats per group. The first 10 days; in the experimental group, transcutaneous EGF was applied to the area to be flap removed. No procedure was done in the control group. On the 10th day, a 9x3 cm caudal pedicle random flap was removed from the back area in both groups. All flaps were photographed by translumination. EGF was applied to the lower face of the flap removed in the experimental group. Then, flaps were sutured on own place in both groups. In the next 10 days, transcutaneous EGF was continued to be applied to the experimental group, no additional application was applied to the control group other than dressing. On the 20th day of the experiment, photographs were taken to calculate the necrosis areas. Then the same flaps were lifted again and photographed by translumination. Tissue samples were taken along a 3x1 cm horizontal line at a distance of 3 cm from the proximal of pedicle from each flap, and vessel scoring was made by histopathological examination. In the photos taken by translumination, vessel density was calculated using the "image j" program. Results: On the 10th day of the experiment, at the first flap removal phase, the vascular density measurement was found significantly higher in the experimental group (p = 0.045). However, no statistically significant difference was found in the vessel density measurement on the 20th day (p = 0.12). There was no statistically significant difference in the vessel scoring in biopsies taken on the 20th day (p = 0.16). At the end of the experiment, there was no statistically significant difference in the percentage of necrosis area (p = 0.65). Conclusion: We attribute the fact that the data were in favor of the experimental group in terms of flap survival on the 10th day of the study, and then lost its statistical significance to the fact that EGF was also applied to the lower surface of the flap on the 10th day. Because when the flap was lifted on the 20th day, an excessive granulation tissue thickening was observed on the lower surface of the flap in the experimental group. We think that this situation has consequences that will adversely affect flap nutrition. Therefore, in order to investigate the effect of EGF on viability in random flaps, it would be appropriate to conduct a new study with only transcutaneous application without applying EGF on the lower face of the flap.