The Effect of Fibrin on the Survival of Ischemic Skin Flaps in Rats

Flap Preconditioning with the Cyclic Mode (Triangular Waveform) of Pressure-Controlled Cupping in a Rat Model: An Alternative Mode to the Continuous System

BACKGROUND

Improving flap survival is essential for successful soft-tissue reconstruction. Although many methods to increase the survival of the distal flap portion have been attempted, there has been no widely adopted procedure. The authors evaluated the effect of flap preconditioning with two different modes (continuous and cyclic) of external volume expansion (pressure-controlled cupping) in a rat dorsal flap model.

METHODS

Thirty rats were randomly assigned to the control group and two experimental groups (n = 10 per group). The continuous group underwent 30 minutes of preconditioning with -25 mmHg pressure once daily for 5 days. The cyclic group received 0 to -25 mmHg pressure for 30 minutes with the cyclic mode once daily for 5 days. On the day after the final preconditioning, caudally based 2 × 8-cm dorsal random-pattern flaps were raised and replaced in the native position. On postoperative day 9, the surviving flap area was evaluated.

RESULTS

The cyclic group showed the highest flap survival rate (76.02 percent), followed by the continuous and control groups (64.96 percent and 51.53 percent, respectively). All intergroup differences were statistically significant. Tissue perfusion of the entire flap showed similar results (cyclic, 87.13 percent; continuous, 66.64 percent; control, 49.32 percent). Histologic analysis showed the most increased and organized collagen production with hypertrophy of the attached muscle and vascular density in the cyclic group, followed by the continuous and control groups.

CONCLUSION

Flap preconditioning with the cyclic mode of external volume expansion is more effective than the continuous mode in an experimental rat model.

Flap Preconditioning by Electrical Stimulation as an Alternative to Surgical Delay: Experimental Study

Partial flap failures are unpredictable complications of reconstructive surgery. Electrical stimulation increases blood flow, capillary density, angiogenesis and vascular endothelial growth factor, anti-inflammatory effects while decreasing oxygen tension in tissues. In this study, we investigated these effective properties of electrical stimulation preoperatively on flap surgery instead of the surgical delay procedure.Modified McFarlane flaps were raised on the backs of 50 Sprague-Dawley rats. In the control group, a skin flap was made and flap survival rate was assessed on the seventh day. In the surgical delay group, 14 days after creating the bipedicled flap, the flap was totally elevated and flap survival rate was assessed on the 21st day. In the preconditioning by electrical stimulation group, the flap was created after application of electrical stimulation for 7 days. Flap survival rate was assessed on the 14th day. In the electrically stimulated ischemic flap group, the flap was created and afterward, electrical stimulation was applied for 7 days. After that, flap survival rate was assessed on the seventh day. In the surgical delay plus electrical stimulation group, following the elevation and suturing of the bipedicled flap back into its bed, electrical stimulation was applied in the first 7 days of delay, the flap was created on the 14th day, and then flap survival rate was assessed on the 21st day. In all groups, blood flow was evaluated at particular times. After completing these procedures, the flap vascularities of 5 animals from each group were assessed with microangiography.The flap survival rate of the preconditioning by electrical stimulation group was significantly higher than those of the other groups (P < 0.05). According to the blood flow estimates, except the preconditioning by electrical stimulation group and surgical delay plus electrical stimulation group, blood flow decreased in all the other groups after the postprocedure. In the microangiographic assessment of the preconditioning by electrical stimulation group, there were thin but numerous networks like vascular structures.Electrical stimulation applied to the normal area before flap elevation increased the flap survival. This increase is paramount to surgical delay which is, so far, widely known as the most effective method of improving flap vascularity.