Experimental Characterization and Numerical Modeling of the Corrosion Effect on the Mechanical Properties of the Biodegradable Magnesium Alloy WE43 for Orthopedic Applications.

Computational modeling plays an important role in the design of orthopedic implants. In the case of biodegradable magnesium alloys, a modeling approach is required to predict the effects of degradation on the implant's capacity to provide the desired stabilization of fractured bones. In the present work, a numerical corrosion model is implemented to predict the effects of biodegradation on the structural integrity of temporary trauma implants. A non-local average pitting corrosion model is calibrated based on experimental data collected from in vitro degradation experiments and mechanical testing of magnesium WE43 alloy specimens at different degradation stages. The localized corrosion (pitting) model was implemented by developing a user material subroutine (VUMAT) with the program Abaqus®/Explicit. In order to accurately capture both the linear mechanical reduction in specimen resistance, as well as the non-linear corrosion behavior of magnesium WE43 observed experimentally, the corrosion model was extended by employing a variable corrosion kinetic parameter, which is time-dependent. The corrosion model was applied to a validated case study involving the pull-out test of orthopedic screws and was able to capture the expected loss of screw pull-out force due to corrosion. The proposed numerical model proved to be an efficient tool in the evaluation of the structural integrity of biodegradable magnesium alloys and bone-implant assembly and can be used in future works in the design optimization and pre-validation of orthopedic implants.

Fluid Management During Kidney Transplantation: A Consensus Statement of the Committee on Transplant Anesthesia of the American Society of Anesthesiologists.

BACKGROUND: Intraoperative fluid management may affect the outcome after kidney transplantation. However, the amount and type of fluid administered, and monitoring techniques vary greatly between institutions and there are limited prospective randomized trials and meta-analyses to guide fluid management in kidney transplant recipients. METHODS: Members of the American Society of Anesthesiologists (ASA) committee on transplantation reviewed the current literature on the amount and type of fluids (albumin, starches, 0.9% saline, and balanced crystalloid solutions) administered and the different monitors used to assess fluid status, resulting in this consensus statement with recommendations based on the best available evidence. RESULTS: Review of the current literature suggests that starch solutions are associated with increased risk of renal injury in randomized trials and should be avoided in kidney donors and recipients. There is no evidence supporting the routine use of albumin solutions in kidney transplants. Balanced crystalloid solutions such as Lactated Ringer are associated with less acidosis and may lead to less hyperkalemia than 0.9% saline solutions. Central venous pressure is only weakly supported as a tool to assess fluid status. CONCLUSIONS: These recommendations may be useful to anesthesiologists making fluid management decisions during kidney transplantation and facilitate future research on this topic.

Service Requirements of Liver Transplant Anesthesia Teams: Society for the Advancement of Transplant Anesthesia Recommendations.

There are disparities in liver transplant anesthesia team (LTAT) care across the United States. However, no policies address essential resources for liver transplant anesthesia services similar to other specialists. In response, the Society for the Advancement of Transplant Anesthesia appointed a task force to develop national recommendations. The Conditions of Transplant Center Participation were adapted to anesthesia team care and used to develop Delphi statements. A Delphi panel was put together by enlisting 21 experts from the fields of liver transplant anesthesiology and surgery, hepatology, critical care, and transplant nursing. Each panelist rated their agreement with and the importance of 17 statements. Strong support for the necessity and importance of 13 final items were as follows: resources, including preprocedure anesthesia assessment, advanced monitoring, immediate availability of consultants, and the presence of a documented expert in liver transplant anesthesia credentialed at the site of practice; call coverage, including schedules to assure uninterrupted coverage and methods to communicate availability; and characteristics of the team, including membership criteria, credentials at the site of practice, and identification of who supervises patient care. Unstructured comments identified competing time obligations for anesthesia and transplant services as the principle reason that the remaining recommendations to attend integrative patient selection and quality review committees were reduced to a suggestion rather than being a requirement. This has important consequences because deficits in team integration cause higher failure rates in service quality, timeliness, and efficiency. Solutions are needed that remove the time-related financial constraints of competing service requirements for anesthesiologists. In conclusion, using a modified Delphi technique, 13 recommendations for the structure of LTATs were agreed upon by a multidisciplinary group of experts.

Can reporting more lead to less? The role of metrics in assessing liver transplant program performance.

Appropriate metrics for performance analysis is an active topic of debate within the transplant community. This study explores current proposals on metric expansion as well as potential metrics and prospective collaborations that have not received widespread discussion within the transplant community. The premature introduction of additional, nonvalidated metrics risks behaviors that may undermine donor utilization and patient access to transplantation.

The impact of adult-to-adult living donor liver transplantation on transplant center outcomes reporting.

BACKGROUND: The Scientific Registry of Transplant Recipients (SRTR) has released a 5-tier performance ranking system based upon results of deceased-donor and living-donor liver transplantation. MATERIALS AND METHODS: An analysis of Spring 2017 SRTR Program Specific Reports for outcomes of adult living-donor and deceased-donor liver transplantation. RESULTS: Utilizing the current SRTR performance algorithm, living-donor liver transplant results may disproportionately affect transplant center performance ranking. CONCLUSION: Improvements in SRTR performance ranking including transparency in outcomes calculation, a calculating tool for transplant centers, and the potential reporting of living-donor outcomes as a separate report are necessary.

Report of the 22nd Annual Congress of the International Liver Transplantation Society.

The 2016 Annual Congress of the International Liver Transplantation Society was held in Seoul, South Korea in May. The 22nd Congress marked the largest multidisciplinary liver transplantation meeting in Asia since 2010. The principal themes were living donation, allocation, immunosuppression, machine preservation, novel treatment of hepatitis C, and expansion of the deceased-donor allograft pool. This report presents select abstracts from the scientific sessions within the context of the published literature to serve as a quick reference.

Anesthesia for Patients with Concomitant Hepatic and Pulmonary Dysfunction.

Hepatic function and pulmonary function are interrelated with failure of one organ system affecting the other. With improved therapies, patients with concomitant hepatic and pulmonary failure increasingly enjoy a good quality of life and life expectancy. Therefore, the prevalence of such patients is increasing with more presenting for both emergent and elective surgical procedures. Hypoxemia requires a thorough evaluation in patients with end-stage liver disease. The most common etiologies respond to appropriate therapy. Portopulmonary hypertension and hepatopulmonary syndrome are associated with increased perioperative morbidity and mortality. It is incumbent on the anesthesiologist to understand the physiology of liver failure and its early effect on pulmonary function to ensure a successful outcome.

Meeting report of the 2014 joint international congress of the International Liver Transplantation Society, Liver Intensive Care Group of Europe, and European Liver and Intestinal Association.

The 2014 Annual Meeting of the International Liver Transplantation Society was held in London, England. This was the 20th meeting of the Society and was marked by a joint meeting including the European Liver and Intestinal Association as well as the Liver Intensive Care Group of Europe. The meeting included symposia, invited lectures, debates, oral presentations, and posters. The principal themes were living donation, expanding the deceased donor pool, machine preservation, and new oral therapies for hepatitis C virus. This report highlights the scientific discussions of this meeting.

Meeting report of the 19th Annual International Congress of the International Liver Transplantation Society (Sydney Convention and Exhibition Centre, Sydney, Australia, June 12-15, 2013).

The International Liver Transplantation Society held its annual meeting from June 12 to 15 in Sydney, Australia. More than 800 registrants attended the congress, which opened with a conference celebrating 50 years of liver transplantation (LT). The program included series of featured symposia, focused topic sessions, and oral and poster presentations. This report is by no means all-inclusive and focuses on specific abstracts on key topics in LT. Similarly to previous reports, this one presents data in the context of the published literature and highlights the current direction of LT.

Postoperative care/critical care of the transplant patient.

Critical care of the general surgical patient requires synthesis of the patient's physiology, intraoperative events, and preexisting comorbidities. Evaluating an abdominal solid-organ transplant recipient after surgery adds a new dimension to clinical decisions because the transplanted allograft has undergone its own physiologic challenges and now must adapt to a new environment. This donor-recipient interaction forms the foundation for assessment of early allograft function (EAF). The intensivist must accurately assess and support EAF within the context of the recipient's current physiology and preexisting comorbidities. Optimizing EAF is essential because allograft failure is a significant predictor of recipient morbidity and mortality.

Cardiovascular and renal complications in patients receiving a solid-organ transplant.

PURPOSE OF REVIEW: Cardiovascular and renal complications among solid-organ transplant recipients are a frequent source of morbidity. Appropriate management of these complications throughout the perioperative period significantly affects long-term recipient survival. This review details the identification, management, and potential preventive strategies for perioperative cardiovascular and renal complications among solid-organ transplant recipients. RECENT FINDINGS: Abdominal transplant candidates have a significantly higher prevalence of risk factors for obstructive coronary artery disease than the general population. There is no consensus on pretransplant screening for coronary artery disease or determination of perioperative risk in candidates awaiting transplantation. Limitations of noninvasive cardiac screening tests such as dobutamine stress echocardiography and myocardial perfusion scintigraphy complicate preoperative evaluation and cardiac risk stratification. Coronary angiography remains the definitive mechanism for determining the presence and severity of coronary artery disease prior to transplantation; however, the relationship between angiographically documented coronary artery disease and cardiovascular morbidity after transplantation is inconsistent. This has raised speculation that perioperative adverse cardiac events are not principally caused by obstructive coronary artery disease but other acute events related to surgical intervention and allograft function. Current data indicate coronary angiography is safe even with patients demonstrating renal insufficiency. A cardiac screening program should reflect the patient population, dynamics of the transplant program, and institutional expertise. The development of classification schemes for defining and categorizing acute kidney injury reflects the importance of preserved renal function in long-term recipient survival. The potential of serum markers as indicators of acute kidney injury has provided a foundation for understanding the global influence of surgical intervention and allograft function upon recipient survival. SUMMARY: Meticulous attention to all aspects of the transplant process, including operative events and early allograft function, is necessary to minimize morbidity. Further research is necessary to identify mechanisms that support and improve early allograft function to optimize recipient long-term survival.

Survival of Clostridium perfringens sepsis in a liver transplant recipient.

Clostridium perfringens sepsis following orthotopic liver transplantation (OLT) is a rare but reported complication that historically results in mortality or emergent retransplantation (ReTx). Complications from C. perfringens emphysematous gastritis have contributed to the death of a healthy live liver donor as well. Herein, we describe the first documented survivor of C. perfringens sepsis following OLT managed without laparotomy or emergent ReTx.