A Guide to the Implementation and Design of Ex Vivo Perfusion Machines for Vascularized Composite Allotransplantation.

Background: Ex vivo machine perfusion (EVMP) is a versatile platform utilized in vascularized composite allotransplantation (VCA) to prolong preservation, salvage tissue, and evaluate graft viability. However, there is no consensus on best practices for VCA. This article discusses the common components, modifications, and considerations necessary for a successful VCA perfusion. Methods: A systematic literature review was performed in several databases (PubMed, Scopus, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov) to identify articles published on VCA EVMP (face, limb, abdominal wall, uterus, penis, and free flaps) before August 2022. Graft type and animal model, general perfusion parameters, core components of the circuit, and optional components for enhanced monitoring were extracted from the articles. Results: A total of 1370 articles were screened, and 46 articles met inclusion criteria. Most articles (84.8%) were published in the last 10 years. Pigs were the main model used, but 10 protocols used human grafts. Free flaps were the most common graft type (41.3%), then upper extremities/forelimbs (28.3%), uteruses (17.4%), and hindlimbs (13.0%). Postperfusion replantation occurred in 15.2% of studies. Normothermic perfusion predominated (54.1%), followed by hypothermic (24.3%), and subnormothermic (21.6%). The majority of studies (87.0%) oxygenated their systems, most commonly with carbogen. Conclusions: EVMP is a rapidly growing area of research. Leveraging EVMP in VCA can optimize VCA procedures and allow for expansion into replantation, flap salvage, and other areas of plastic surgery. Currently, VCA EVMP is achieved through a variety of approaches, but standardization is necessary to advance this technology and attain clinical translation.