The effect of ischemic preconditioning on secondary ischemia in myocutaneous flaps

We sought to determine the effect of ischemic preconditioning (IPC) on secondary ischemia in myocutaneous flaps in a rat model. Forty rectus abdominis myocutaneous flaps were elevated in 40 rats, and the animals were randomized into control or IPC groups (20 flaps each group). All flaps were then subject to primary ischemia for 2 hours via pedicle clamping. Twenty-four hours later, the control and IPC flaps were randomized to two groups each of 1 or 2 hours of secondary ischemia (4 groups, 10 flaps per group). Flap survival was evaluated on postoperative day 5 by measuring the percentage area of flap survival by a blinded observer. Mean flap survival area and total necrosis rates were compared between the groups. In the 1-hour secondary ischemia groups, IPC improved mean flap survival area from 11 +/- 7% to 36 +/- 22%, and the total necrosis rates from 40 to 0%. These differences were statistically significant (p < 0.006, p < 0.05, respectively). In the 2-hour secondary ischemia groups, differences were not statistically significant (p = 0.2, p = 0.4, respectively). IPC improves the survival of myocutaneous flaps subjected to secondary ischemia of 1 hour in this rat free flap model.