“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 have been attempted to increase the survival of the distal flap portion, there has been no widely adopted procedure. We 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/group). The continuous group underwent 30 min of preconditioning with -25 mmHg pressure once daily for 5 days. The cyclic group received 0 to -25 mmHg pressure for 30 min with the cyclic mode once daily for 5 days. On the day after the final preconditioning, caudally based 2x8-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%), followed by the continuous and control groups (64.96% and 51.53%, respectively). All inter-group differences were statistically significant. Tissue perfusion of the entire flap showed similar results (cyclic, 87.13%; continuous, 66.64%; control, 49.32%). Histologic analysis with hematoxylin and eosin, Masson trichrome, and CD31 staining 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. Conclusions: Flap preconditioning with the cyclic mode of external volume expansion is more effective than the continuous mode in an experimental rat model. Further studies will be necessary for clinical application. Financial Disclosure Statement: None of the authors has a financial interest in any of the products, devices, or drugs mentioned in this manuscript Authors' Contributions: K.S.K. came up with the main idea and its concept of hypothesis in this experiment. He led the process of this study. Y.G.H. mainly conducted the animal experiment and further organized and analyzed histologic results. He wrote the article. S.C.K. supervised and advised the experimental process and participated in the laboratory meeting with the team and gave several opinions during discussion. Ethics Statement: All procedures were conducted in accordance with the Guide for the Care and Use of Laboratory Animals of the Asan Life Science Research Center animal review board (document no. 2017-13-113). Corresponding author: Kyung S. Koh, MD, PhD, Professor, Department of Plastic and Reconstructive Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Sonpa-gu, Seoul 05505, Korea. Tel.: +82-2-3010-3600, Fax: +2-476-7471, E-mail: kskoh@amc.seoul.kr, kyungskoh@gmail.com ©2018American Society of Plastic Surgeons

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