Towards Optimizing Sub-Normothermic Machine Perfusion in Fasciocutaneous Flaps: A Large Animal Study.

Machine perfusion has developed rapidly since its first use in solid organ transplantation. Likewise, reconstructive surgery has kept pace, and ex vivo perfusion appears as a new trend in vascularized composite allotransplants preservation. In autologous reconstruction, fasciocutaneous flaps are now the gold standard due to their low morbidity (muscle sparing) and favorable functional and cosmetic results. However, failures still occasionally arise due to difficulties encountered with the vessels during free flap transfer. The development of machine perfusion procedures would make it possible to temporarily substitute or even avoid microsurgical anastomoses in certain complex cases. We performed oxygenated acellular sub-normothermic perfusions of fasciocutaneous flaps for 24 and 48 h in a porcine model and compared continuous and intermittent perfusion regimens. The monitored metrics included vascular resistance, edema, arteriovenous oxygen gas differentials, and metabolic parameters. A final histological assessment was performed. Porcine flaps which underwent successful oxygenated perfusion showed minimal or no signs of cell necrosis at the end of the perfusion. Intermittent perfusion allowed overall better results to be obtained at 24 h and extended perfusion duration. This work provides a strong foundation for further research and could lead to new and reliable reconstructive techniques.

The Superficial Inferior Epigastric Artery Axial Flap to Study Ischemic Preconditioning Effects in a Rat Model.

Fasciocutaneous flaps (FCF) have become the gold standard for complex defect reconstruction in plastic and reconstructive surgery. This muscle-sparing technique allows transferring vascularized tissues to cover any large defect. FCF can be used as pedicled flaps or as free flaps; however, in the literature, failure rates for pedicled FCF and free FCF are above 5%, leaving room for improvement for these techniques and further knowledge expansion in this area. Ischemic preconditioning (I.P.) has been widely studied, but the mechanisms and the optimization of the I.P. regimen are yet to be determined. This phenomenon is indeed poorly explored in plastic and reconstructive surgery. Here, a surgical model is presented to study the I.P. regimen in a rat axial fasciocutaneous flap model, describing how to safely and reliably assess the effects of I.P. on flap survival. This article describes the complete surgical procedure, including suggestions to improve the reliability of this model. The objective is to provide researchers with a reproducible and reliable model to test various ischemic preconditioning regimens and assess their effects on flap survivability.

Microvascular assessment of fascio-cutaneous flaps by ultrasound: A large animal study.

Objectives: Blood perfusion quality of a flap is the main prognostic factor for success. Microvascular evaluation remains mostly inaccessible. We aimed to evaluate the microflow imaging mode, MV-Flow, in assessing flap microvascularization in a pig model of the fascio-cutaneous flap. Methods: On five pigs, bilateral saphenous fascio-cutaneous flaps were procured on the superficial femoral vessels. A conventional ultrasound evaluation in pulsed Doppler and color Doppler was conducted on the ten flaps allowing for the calculation of the saphenous artery flow rate. The MV-Flow mode was then applied: for qualitative analysis, with identification of saphenous artery collaterals; then quantitative, with repeated measurements of the Vascularity Index (VI), percentage of pixels where flow is detected relative to the total ultrasound view area. The measurements were then repeated after increasing arterial flow by clamping the distal femoral artery. Results: The MV-Flow mode allowed a better follow-up of the saphenous artery's collaterals and detected microflows not seen with the color Doppler. The VI was correlated to the saphenous artery flow rate (Spearman rho of 0.64; p = 0.002) and allowed to monitor the flap perfusion variations. Conclusion: Ultrasound imaging of microvascularization by MV-Flow mode and its quantification by VI provides valuable information in evaluating the microvascularization of flaps.