Bioengineered Approach to the Design of a Fat Graft Based on Mathematical Modeling that Predicts Oxygen Delivery.

BACKGROUND: Fat grafting is a common procedure in plastic surgery. A major limitation is unpredictable graft retention, in part caused by inadequate oxygen delivery during the early posttransfer period. METHODS: The authors present a bioengineered approach to the design of a fat graft based on mathematical theory, which can estimate the limitations of oxygen delivery. To simplify the problem, four variables were defined: (1) recipient-site oxygen partial pressure; (2) adipose tissue oxygen permeability; (3) adipose tissue oxygen consumption rate; and (4) fat graft size. Recipient-site oxygen partial pressure and adipose tissue oxygen permeability were estimated from literature, whereas adipose tissue oxygen consumption rate was measured using stirred microchamber technology. Calculations were performed in both spherical and planar geometry to calculate the maximum allowable fat graft size from an oxygen delivery standpoint. RESULTS: As expected, planar geometry is less favorable for oxygenation but represents a realistic configuration for a fat graft. Maximum allowable fat graft thickness is only approximately 1 to 2 mm at external oxygen partial pressures of 10 to 40 mm Hg; any thicker and an anoxic or necrotic core likely develops. Given a reasonably large surface area and assuming several planes of injection, the maximum allowable fat graft volume is tens of milliliters. CONCLUSIONS: A systematic bioengineered approach may help better design a fat graft. Applying principles of mass transfer theory can predict whether a fat graft has a favorable chance of surviving from an oxygen delivery standpoint and can direct the development of strategies for improved fat graft oxygenation.

Characterization of Adipose Tissue Product Quality Using Measurements of Oxygen Consumption Rate.

BACKGROUND: Fat grafting is a common procedure in plastic surgery but associated with unpredictable graft retention. Adipose tissue (AT) "product" quality is affected by the methods used for harvest, processing and transfer, which vary widely amongst surgeons. Currently, there is no method available to accurately assess the quality of AT. OBJECTIVES: In this study, we present a novel method for the assessment of AT product quality through direct measurements of oxygen consumption rate (OCR). OCR has exhibited potential in predicting outcomes following pancreatic islet transplant. Our study aim was to reapportion existing technology for its use with AT preparations and to confirm that these measurements are feasible. METHODS: OCR was successfully measured for en bloc and postprocessed AT using a stirred microchamber system. OCR was then normalized to DNA content (OCR/DNA), which represents the AT product quality. RESULTS: Mean (±SE) OCR/DNA values for fresh en bloc and post-processed AT were 149.8 (± 9.1) and 61.1 (± 6.1) nmol/min/mg DNA, respectively. These preliminary data suggest that: (1) OCR and OCR/DNA measurements of AT harvested using conventional protocol are feasible; and (2) standard AT processing results in a decrease in overall AT product quality. CONCLUSIONS: OCR measurements of AT using existing technology can be done and enables accurate, real-time, quantitative assessment of the quality of AT product prior to transfer. The availability and further validation of this type of assay could enable optimization of fat grafting protocol by providing a tool for the more detailed study of procedural variables that affect AT product quality.

Characterization of adipose tissue for autologous fat grafting.

Fat grafting is a common procedure in aesthetic and reconstructive plastic surgery, but variable graft retention limits its utility. Unpredictable clinical outcomes with fat grafting can be explained in part by the lack of standardized protocols for harvesting, processing, and transplanting adipose tissue (AT). Historically, plastic surgeons have relied on trial and error and their clinical experience to develop fat grafting protocols. Optimization of fat grafting protocols requires systematic assessment of the impact that key variables have on the quality of the AT preparation at each step of the procedure. In this article, we review recent findings regarding the composition and quality of AT prepared for fat grafting and the strengths and limitations of existing AT characterization assays. We discuss the need for an assessment of the viability of intact AT (ie, conventionally harvested AT that has not been disrupted further) by means of an operator-independent, quantitative assay that can be performed in real time and generates reproducible data. Promising assays for the characterization of cell product quality have been developed for other therapeutic applications, such as transplantation of pancreatic islet cells. The development or adaptation of a gold-standard assay to determine the quality of an AT preparation may help to standardize fat grafting protocols and improve clinical outcomes.

Volunteers in plastic surgery guidelines for providing surgical care for children in the less developed world.

BACKGROUND: A significant need is met by volunteer groups who provide free reconstructive plastic surgery for underserved children in developing countries. However, at present there are no consistent guidelines for volunteer groups in plastic surgery seeking to provide high-quality and safe care. METHODS: With these quality and safety standards in mind, in 2006, the Volunteers in Plastic Surgery Committee of the American Society of Plastic Surgeons/Plastic Surgery Educational Foundation undertook a project to develop a detailed set of guidelines for volunteer groups from developed countries seeking to provide plastic surgery services to children in developing countries. To make the guidelines include both surgical and anesthetic needs, they were developed in conjunction with the Society for Pediatric Anesthesia. RESULTS: Guidelines for the delivery of plastic surgery care by volunteer groups to developing countries have been reviewed and approved by the boards of both organizations (the American Society of Plastic Surgeons/Plastic Surgery Educational Foundation and the Society for Pediatric Anesthesia). These include guidelines for the initial site visit, site and patient selection, staff and equipment that should be available, and procedures that can be safely performed based on the site and available facilities. Guidelines for assessment of outcomes, dealing with adverse outcomes, and quality improvement are also provided. CONCLUSIONS: Any plastic surgery group undertaking an international mission trip should be able to go to one source to find a detailed discussion of the perceived needs in providing high-quality, safe care for children. The present document was created to satisfy this need.

Management of vasospastic disorders with botulinum toxin A.

BACKGROUND: Surgical digital artery sympathectomy is indicated when medical management has failed to control rest pain, impending infarction of digits, or healing of ischemic ulcerations caused by profound vasospasm that is associated with other systemic diseases. After digital artery sympathectomy, recurrence or persistence of vasospasm may compromise hand function and ultimately result in amputation of all or portions of both lower and upper extremities. METHODS: The authors present a case series of 11 patients with vasospasm producing intractable rest pain, digital ulcerations, and digit infarctions that failed aggressive medical therapy and that were then treated by perivascular injections of botulinum toxin A (Botox). Before Botox injection, the level of pain, cutaneous temperatures, color, and ulcerations and infarctions were documented RESULTS: The authors' longest follow-up was 30 months. All patients reported highly significant pain reduction, 10 of 10 to 0 to 2 of 10, within 24 to 48 hours after injection, persisting for months after the injection. Nine of 11 patients with nonhealing ulcers spontaneously healed small ulcers and areas of infarction after surgical debridement. Two cases required small skin grafts. Nine of 11 patients reported decreased severity and frequency of vasospastic episodes. CONCLUSIONS: Hand injection of botulinum toxin A appears to be an effective treatment for intractable digital ulcerations and rest pain in patients with severe vasospastic disorders. Because of the complexity of surgical digital artery sympathectomy along with its associated high risk of persistent symptoms, the authors conclude that the therapeutic use of botulinum toxin A injections represents an attractive alternative therapy.