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RESEARCH PRODUCT

Noninvasive Flap Preconditioning by Foam-Mediated External Suction Improves the Survival of Fasciocutaneous Axial-Pattern Flaps in a Type 2 Diabetic Murine Model

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Background Advances in reconstructive surgery are leading to an increased number of flaps at risk for ischemic necrosis, because of either intrinsic (e.g., larger flap size) or extrinsic (e.g., diabetes) factors. Methods to preoperatively improve flap vascularity and limit postoperative ischemia are lacking. Noninvasive suction, using either a macrodeformational silicone cup interface (external volume expansion) or a microdeformational polyurethane foam interface (foam-mediated external volume expansion), has been shown to induce angiogenesis in tissues. The authors investigated whether the preoperative use of external volume expansion/foam-mediated external volume expansion improves flap survival in an obesity-induced diabetic animal model. Methods Db/Db mice underwent either mechanical stimulation with suction for 5 days using either external volume expansion or foam-mediated external volume expansion, or received no stimulation (n = 8 per group). Five days after the last stimulation, a critical-size, axial-pattern, fasciocutaneous flap was raised in all animals. Postoperatively, flap survival was monitored with digital imaging for 10 days. After this period, flaps were harvested to assess tissue survival, angiogenesis, and inflammation, using histology and polymerase chain reaction. Results Foam-mediated external volume expansion preconditioning significantly increased the viable flap area (28 percent), viable flap volume (27 percent), and flap capillary density (36 percent) in comparison to controls; vascular endothelial growth factor was also up-regulated (>300 percent). In contrast, external volume expansion resulted in a severe inflammatory response and increased flap necrosis. Conclusions Foam-mediated external volume expansion improves flap survival in obese diabetic mice. This procedure may allow for improved clinical rates of flap survival in high-risk patients.