Investıgatıon of the effect of surgıcal delay on reperfusıon ınjury ın free flaps under dıfferent ıschemıa tımes

INTRODUCTION: Reconstruction of large tissue defects is still a major problem. Flaps play a prominent role in reconstruction of such tissue defects. The increase in flap survival leads to earlier recovery of the patient, resulting in decreased physical and psychological stress, which is also cost effective. Many studies have been performed to find out the appropriate method to increase flap survival, but studies on enchancement of free flap survival are in smaller number. The purpose of this study is to investigate the effect of warm ischemia time on free flap survival following surgical delay.MATERIALS and METHODS: The study was carried out using 48 rats. These rats divided in to 6 groups, 8 in each. Free flap model was performed on abdominal skin island flap measuring 6 x 3.5 cm. Surgical delay was performed by undermining the flap after insicing it?s longitudinal borders parallely. Surgical delay was performed in groups 1, 2 and 3. Flaps were followed for 2 weeks. Then, abdominal skin island flap were raised in all rats based on femoral artery and vein. In groups 1 and 4 the flaps were subjected to 120 minutes of warm ischemia, in groups 2 and 5 flaps were subjected to 240 minutes of warm ischemia. In groups 3 and 6, flaps were performed without subjecting to ischemia. All the flaps were resutured to their original places. Twenty-four hours after the flaps were resutured, skin biopsies were taken at standart points. Biochemical measurements of the tissue malonedialdehyde, glutathione, glutathione peroxidase, super oxide dismutase levels were carried out. All the flaps were observed for 1 week following resuturation to their original places. Then all rat sacrified and surviving areas of flaps were measured by planimetric technique.RESULTS : Surviving areas in flaps were found to be %16.4, %13.2, %16.4, %13.2, %9.6, %16.3 in groups 1,2,3,4,5 and 6 respectively. The survival in the flaps with 120 minutes of ischemia time with surgical delay was significantly higher than flaps with 120 minutes of ischemia time without surgical delay (p= 0.001). Similary, the survival was also higher in flaps with 240 minutes of ischemia time, which underwent surgical delay compared to the flaps of the same ischemia time but without surgical delay (p= 0.001). In control groups (groups 3 and 6), in which no ischemia were applied, the survival was higher in flaps with surgical delay (p= 0.001). The difference in surviving area in groups 1 and 4 was higher than the difference between groups 2 and 5 (p= 0.001). It was found that biochemical results combatible with all of these findings. One comparison (Differences of glutatione levels between groups 1 and 4., and between groups 2. and 5.) was found not statisticaly significant (p= 0.051)CONCLUSION: The delay procedure is an effective method for improving free flap survival. As the flap's ischemia time prolonges, ischemia reperfusion damage causes decreased flap survival at an increasing rate. Application of ``surgical delay?? prior to surgery on a free flap is a beneficial procedure for increasing flap survival and this benefit is more with flaps having shorter ischemia durations.Key words: Ischemia- reperfusion injury, surgical delay, free flap model