Zahir K S, Syed S A, Zink J R, Restifo R J, Thomson J G
Section of Plastic Surgery at Yale University School of Medicine, New Haven, Conn 06520-8041, USA.
Plast Reconstr Surg. 1998 Jul;102(1):140-50; discussion 151-2. doi: 10.1097/00006534-199807000-00022.
Inadequate blood supply of pedicle flaps results in partial necrosis, and prolonged ischemia during free-tissue transfer can result in partial or complete flap necrosis. Recent research in the field of cardiovascular surgery has shown that ischemic preconditioning (repeated brief episodes of coronary artery occlusion followed by reperfusion) improves myocardial muscle survival when the heart is subsequently subjected to prolonged ischemia. Preconditioning of skin or myocutaneous flaps as either pedicle or free flap models has never been studied. The goal of this investigation was to measure the effect of ischemic preconditioning on myocutaneous and skin flap survival areas and total necrosis rates after variable periods of global ischemia. In 220 rats, 100 transverse rectus abdominis myocutaneous flaps and 120 dorsal cutaneous flaps were randomized into treatment and control groups. The treatment flaps underwent preconditioning by three cycles of 10 minutes of pedicle clamping followed by 10 minutes of reperfusion for a total preconditioning period of 1 hour. The control flaps were perfused without clamping for 1 hour. Both control and treatment flaps then underwent global ischemia for 0, 2, 4, 6, 10, or 14 hours by pedicle clamping. Flap survival area was measured on the fifth postoperative day. Statistical analysis was performed with analysis of variance, student's t tests, and probit analysis. Preconditioning improved survival areas of pedicle myocutaneous flaps (0-hour group) from 47 +/- 16 percent (mean percent area surviving +/- SD) to 63 +/- 5 percent. This difference was statistically significant (t test, p < 0.04). There was no statistically significant improvement in pedicle skin flap survival. For free flap models (flaps undergoing global ischemia), preconditioning increased the survival areas of skin and myocutaneous flaps (analysis of variance, p < 10(-5)). For the skin flap model, statistical significance of the survival area difference was reached at 6, 10, and 14 hours of ischemia (t test, p < 10(-4)). The magnitude of this effect was higher in the myocutaneous flap model and reached statistical significance at 2, 4, 6, and 10 hours of ischemia (p < 10(-3)). Preconditioned flap survival areas were increased by two to five times that of non-preconditioned flaps at these ischemia times. Preconditioning lowered total necrosis rates at all ischemia times for both flap models. The critical ischemia time when 50 percent of skin flaps became totally necrotic (CIT50) improved from 6.9 to 12.4 hours by preconditioning. Similarly, preconditioning improved the CIT50 of myocutaneous flaps from 3.6 to 9.2 hours. For the first time, statistically significant improvements of partial necrosis areas and total necrosis rates have been demonstrated through intraoperative ischemic preconditioning of skin and myocutaneous flaps. In clinical practice, application of this technique may lead to improved survival during pedicled or free transfer of myocutaneous flaps and free transfer of skin flaps.
带蒂皮瓣血供不足会导致部分坏死，而游离组织移植过程中长时间缺血会导致皮瓣部分或完全坏死。心血管外科领域的最新研究表明，缺血预处理（冠状动脉反复短暂闭塞后再灌注）可在心脏随后遭受长时间缺血时提高心肌的存活率。作为带蒂或游离皮瓣模型的皮肤或肌皮瓣的预处理从未被研究过。本研究的目的是测量缺血预处理对在不同时长的整体缺血后肌皮瓣和皮瓣存活面积及总坏死率的影响。在220只大鼠中，将100个腹直肌横断肌皮瓣和120个背部皮瓣随机分为治疗组和对照组。治疗组皮瓣通过三个周期的预处理，即每次夹蒂10分钟后再灌注10分钟，总预处理时间为1小时。对照组皮瓣不夹蒂灌注1小时。然后通过夹蒂对对照组和治疗组皮瓣进行0、2、4、6、10或14小时的整体缺血。在术后第五天测量皮瓣存活面积。采用方差分析、学生t检验和概率分析进行统计分析。预处理使带蒂肌皮瓣（0小时组）的存活面积从47±16%（平均存活面积百分比±标准差）提高到63±5%。这种差异具有统计学意义（t检验，p<0.04）。带蒂皮瓣存活情况无统计学意义上的改善。对于游离皮瓣模型（经历整体缺血的皮瓣），预处理增加了皮肤和肌皮瓣的存活面积（方差分析，p<10⁻⁵）。对于皮瓣模型，在缺血6、10和14小时时存活面积差异具有统计学意义（t检验，p<10⁻⁴）。这种效应在肌皮瓣模型中更大，在缺血2、4、6和10小时时具有统计学意义（p<10⁻³）。在这些缺血时间，预处理后的皮瓣存活面积增加到未预处理皮瓣的两到五倍。预处理降低了两种皮瓣模型在所有缺血时间的总坏死率。50%的皮肤皮瓣完全坏死时的临界缺血时间（CIT50）通过预处理从6.9小时提高到12.4小时。同样，预处理将肌皮瓣的CIT50从3.6小时提高到9.2小时。首次通过术中对皮肤和肌皮瓣进行缺血预处理，证明了部分坏死面积和总坏死率有统计学意义的改善。在临床实践中，应用该技术可能会提高肌皮瓣带蒂或游离移植以及皮肤皮瓣游离移植过程中的存活率。
