Ischemic preconditioning of a rat adipomusculocutaneous flap: which duration of ischemia/reperfusion works best?

In this study a comparison was made to the efficacy of three cycles of vari ous duration of ischemic preconditioning (IPC) on flap survival after the c ritical ischemic time, Method: In the first study, 20 Sprague-Dawley rats w ere used (6 groups of rats; flap ischemia ranging from 6 to 14 h) to determ ine the critical ischemia time for the rat groin flap (6x3 cm). In the seco nd study the rats (n=31 were divided into nine groups; ischemia and reperfu sion times being 5, 10 or 15 min) a groin flap was elevated. Thereafter IPC was induced to the flap by clamping its pedicle prior to the critical isch emic time (14 h). Three cycles of IPC were applied. After seven days, the f lap was retraced for viability assessment and the surviving flap area was c alculated with planimetry. Results: Without pretreatment with IPC flap surv ival after 8, 10, 12, 13, and 14 h global ischemia was respectively 100%, 7 7+/-13%, 78+/-15%, 42+/-16%, and 2+/-4%. When the flaps were treated with t hree cycles of IPC before 14 h global ischemia the significant flap surviva l was noted in the 10/5 min and 15/10 min IPC groups (p<0.05). Overall, the 5 min reperfusion groups increased flap survival (38+/-26%; p<0.05), and h ad fewer total flap losses (2/9) than the 10 or 15 min reperfusion groups. Only if ischemia time was longer than reperfusion time the flaps had increa sed survival area (40+/-22%, p<0.05). Conclusion: This study demonstrated t he efficacy of IPC to improve the viability of a composite flap even after a long critical ischemic time. The optimal IPC duration was 10/5 min combin ation, yet the 15/10 schedule was also acceptable.