What happened if various kinds of postconditioning working on the preconditioned ischemic skin flaps

Abstract

Objective: Ischemic pre-conditioning and post-conditioning are useful manipulations to reduce the undesirable effects of ischemia-reperfusion skin flap each. But the impact of post-conditioning on the pre-conditioning skin flap is not manifested. Here we investigated the influence of ischemic post-conditioning in a preconditioned axial pattern skin flap model.

Method: We used the skin flap in 40 rabbits and divided them into 5 groups randomly. At first we induced the ischemic pre-conditioning of the flap which was applied by 2 periods of 15 minutes of ischemia/15 minutes of reperfusion cycle. Next post-conditioning was performed by 6 cycles of 10 seconds of repeated ischemia/reperfusion periods at different times of just after the reperfusion,5 minutes after the reperfusion,10 minutes after the reperfusion. The animals were allocated into 5 groups: group 1 (Ischemia Group); group 2: (Pre-conditioning Group); group 3: (Pre-conditioning+ Post-conditioning Group); group 4 (Pre-conditioning+ Post-conditioning 5 minutes later Group); group 5 (Pre-conditioning+ Post-conditioning 10 minutes later). The neutrophil count was assessed with histologic analysis before the dissection of the skin flap. Flap viability was assessed 1 week after the operation, and surviving flap area was recorded as a percentage of the whole flap area. LSD test was used for statistical analysis among different groups to evaluate the effects of ischemic pre-conditioning against ischemia.

Result: Among the varying groups, the neutrophil count varied: Group 1 was 50.12 ± 5.91; Group 2, 30.00 ± 2.00, and Group 3, 18.87 ± 3; Group 4, 22.50 ± 1.92; Group 5, 30.12 ± 1.88.The mean ± SD surviving areas of the flaps for groups 1, 2, 3, 4 and 5 were 31.76 ± 4.59, 51.26 ± 3.24,82.18 ± 5.28,66.85 ± 3.87 and 51.13 ± 2.90 respectively. Spearman correlation analysis shows an increase relation between neutrophil count and flap survival rate in the different groups (P <0.05).

Conclusion: Ischemic post-conditioning has protective effect on ischemic preconditioned skin flaps, but the post-conditioning should be performed within 5 minutes after the end of ischemia.

Figure 1. The overview of the elevation of the skin flap.

The red arrow indicates the pedicle which is dissected.

Figure 2. Neutrophil count among different groups.

Data are expressed as mean. ±SD neutrophil count. O (p<0.05) compared between the neighboring groups. ■ (p>0.05) compares with 2/5 groups.

Figure 3. Comparison of the surviving portion of the skin flap.

The red line indicates the necrosis part of the skin flap.

Figure 4. Neutrophil count among different groups.

Data are expressed as mean ±SD neutrophil count. O (p<0.05) compared between the neighboring groups. ■ (p>0.05) compares with 2/5 groups.