“Non-invasive flap preconditioning by foam-mediated external suction improves the survival of fascio-cutaneous axial-pattern flaps in a type-2 diabetic murine model”

Background: Advances in reconstructive surgery are leading to an increased number of flaps at risk for ischemic necrosis, either due to intrinsic (e.g., larger flap size) or extrinsic (e.g., diabetes) factors. Yet, methods to pre-operatively improve flap vascularity and limit post-operative ischemia are lacking. Non-invasive suction, using either a macro-deformational silicone-cup interface (External Volume Expansion, EVE) or a micro-deformational polyurethane-foam interface (F-EVE), has shown to induce angiogenesis in tissues. We investigated whether, by increasing the vascular density of flaps, the pre-operative use of EVE/F-EVE (preconditioning) 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 EVE, or F-EVE, or received no stimulation (n = 8 per group). Five days after the last stimulation, a critical-sized, axial-pattern, fascio-cutaneous flap was raised in all animals. Post-operatively, flap survival was monitored with digital imaging for 10 days. Following this period, flaps were harvested to assess tissue survival, angiogenesis, and inflammation, utilizing histology and PCR. Results: F-EVE preconditioning significantly increased the viable flap area (+28%), the viable flap volume (+27%), the flap capillary density (+36%), in comparison to controls; VEGF was also upregulated (>300%). In contrast, EVE resulted in severe inflammatory response and increased flap necrosis. Conclusions: F-EVE improves flap survival in obese diabetic mice. This procedure may allow for improved clinical rates of flap survival in high-risk patients. Acknowledgments, conflict of interest and role of funding sources disclosure statement: Authors are thankful to KCI, Inc. for providing the pumps and the foam-shaped Interface used in this study. Dr. Orgill serves as a consultant and has received sponsored research grants from KCI to Brigham and Women's Hospital. Authors declare no actual or potential conflict of interest: in addition, they disclose no commercial or financial associations, personal or other relationships with other people or organizations that could inappropriately influence the reported manuscript or create a conflict of interest with the information presented. This study was funded by a research grant from the Gillian Reny Stepping Strong Foundation to Brigham and Women's Hospital. Ethics: The displayed study was carried out with respect to high ethical standards. All the studies have been approved, when required, by the appropriate ethics committee and have, therefore, been performed in accordance and in compliance with the World Medical Association Declaration of Helsinki (June 1964) and subsequent amendments. Meetings at which the paper has been presented: None. Corresponding author: Giorgio Giatsidis (* corresponding author), Division of Plastic Surgery, Department of Surgery, Brigham and Women's Hospital - Harvard Medical School, 75 Francis St., Boston MA 02115, T: 617-525-7837, F: 617-730-2855, E: ggiatsidis@bwh.harvard.edu ©2018American Society of Plastic Surgeons

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