Tissue Viability of Free Flaps after Extracorporeal Perfusion Using a Modified Hydroxyethyl Starch Solution

Abstract

Background: In free flap surgery, tissue is stored under hypothermic ischemia. Extracorporeal perfusion (EP) has the potential to extend storage time and the tissue’s perspective of survival. In the present study, the aim is to improve a recently established, simplified extracorporeal perfusion system. Methods: Porcine musculus rectus abdominis were stored under different conditions. One group was perfused continuously with a simplified one-way perfusion system for six hours, while the other received only a single flush but no further treatment. A modified hydroxyethyl starch solution was used as a perfusion and flushing solution. Vitality, functionality, and metabolic activity of both groups were analyzed. Results: Perfused muscles, in contrast to the ischemically stored ones, showed no loss of vitality and significantly less functionality loss, confirming the superiority of storage under continuous perfusion over ischemic storage. Furthermore, in comparison to a previous study, the results were improved even further by using a modified hydroxyethyl starch solution. Conclusion: The use of EP has major benefits compared to the clinical standard static storage at room temperature. Continuous perfusion not only maintains the oxygen and nutrient supply but also removes toxic metabolites formed due to inadequate storage conditions.

The Future of Microsurgery: Vascularized Composite Allotransplantation and Engineering Vascularized Tissue

“…16 Using a modified heart-lung machine, Slater et al were able to provide ECP to porcine myocutaneous rectus abdominis flaps for 24 hours with no signs of necrosis using oxygenated histidine-tryptophan-ketoglutarate. [17][18][19] Fichter et al reported promising results in humans, demonstrating the feasibility and safety of short-term ECP (►Fig. 1) for up to 4 hours to salvage eight human critically perfused and congested-free radial forearm flaps.…”

Review of machine perfusion studies in vascularized composite allotransplant preservation

“…For mid-thermic and subnormothermic conditions, perfusion without an oxygen carrier has been attempted by Pendexter ( 34 ), Veraza ( 37 ), and Kruit ( 42 ) in limb models and by Taeger et al in multiple studies ( 65 , 67 , 69 ) ( Tables 1 , 2 ). Most of these studies do not include SCS controls except for that of Kruit et al in which they report worse outcomes after 18 h of perfusion in histology vs. SCS controls yet preserved muscle contractility after replantation.…”

“…Taeger et al ( 65 , 67 , 68 ), in their multiple studies, reported a wide range of weight gain (49.5%–99%) after 6 h of perfusion in swine rectus abdomins flaps. They reported better tissue preservation with perfusion.…”