Organ-Protective Intensive Care in Organ Donors

Defects in vein valve PROX1/FOXC2 antithrombotic pathway in endothelial cells drive the hypercoagulable state induced by trauma and critical illness

OBJECTIVES

Deep venous thrombosis (DVT) causes significant morbidity and mortality after trauma. Recently, we have shown that blood flow patterns at vein valves induce oscillatory stress genes, which maintain an anticoagulant endothelial phenotype that inhibits spontaneous clotting at vein valves and sinuses, is lost in the presence of DVT in human pathological samples, and is dependent on expression of the transcription factor FOXC2. We describe an assay, modifying our mouse multiple injury system, which shows evidence of clinically relevant microthrombosis and hypercoagulability applicable to the study of spontaneous DVT in trauma without requiring direct vascular injury or ligation. Finally, we investigated whether these model findings are relevant to a human model of critical illness by examining gene expression changes by quantitative polymerase chain reaction and immunofluorescence in veins collected from critically ill.

METHODS

C57/Bl6 mice were subjected to a modified mouse multiple injury model with liver crush injury, crush and pseudofracture of a single lower extremity, and 15% total blood volume hemorrhage. Serum was assayed for d-dimer at 2, 6, 24, and 48 hours after injury by enzyme-linked immunosorbent assay. For the thrombin clotting assay, veins of the leg were exposed, 100 μL of 1 mM rhodamine (6 g) was injected retro-orbitally, and 450 μg/mL thrombin was then applied to the surface of the vein with examination of real-time clot formation via in vivo immunofluorescence microscopy. Images were then examined for percentage area of clot coverage of visible mouse saphenous and common femoral vein. Vein valve specific knockout of FOXC2 was induced with tamoxifen treatment in PROX1 Ert2Cre FOXC2 fl/fl mice as previously described. Animals were then subjected to a modified mouse multiple injury model with liver crush injury, crush and pseudofracture of a single lower extremity, and 15% total blood volume hemorrhage. Twenty-four hours after injury, we examined the valve phenotype in naive versus multiple injury animals, with and without loss of the FOXC2 gene from the vein valve (FOXC2 del ) via the thrombin assay. Images were then examined for proximity of clot formation to the valve present at the junction of the mouse saphenous, tibial, and superficial femoral vein and presence of spontaneous microthrombi present in the veins before exposure to thrombin. Human vein samples were obtained from excess tissue preserved after harvest for elective cardiac surgery and from organ donors after organ procurement. Sections were submitted for paraffin embedding and then assayed by immunofluorescence for PROX1, FOXC2, thrombomodulin, endothelial protein C receptor, and von Willebrand's factor. All animal studies were reviewed and approved by the Institutional Animal Care and Use Committee, and all human studies reviewed and approved by the institutional review board.

RESULTS

After mouse multiple injuries, enzyme-linked immunosorbent assay for d-dimer showed evidence of products of fibrin breakdown consistent with formation of clot related to injury, fibrinolysis, and/or microthrombosis. The thrombin clotting assay demonstrated higher percentage area of vein covered with clot when exposed to thrombin in the multiple injury animals compared with uninjured (45% vs. 27% p = 0.0002) consistent with a phenotype of hypercoagulable state after trauma in our model system. Unmanipulated FoxC2 knockout mice manifest increased clotting at the vein valve as compared with unmanipulated wild type animals. After multiple injuries, wild type mice manifest increase clotting at the vein after thrombin exposure ( p = 0.0033), and equivalent to that of valvular knockout of FoxC2 (FoxC2del), recapitulating the phenotype seen in FoxC2 knockout animals. The combination of multiple injuries and FoxC2 knockout resulted in spontaneous microthrombi in 50% of the animals, a phenotype not observed with either multiple injuries or FoxC2 deficiency alone (χ 2 , p = 0.017). Finally, human vein samples demonstrated the protective vein valve phenotype of increased FOXC2 and PROX1 and showed decreased expression in the critically ill organ donor population by immunofluorescence imaging in organ donor samples.

CONCLUSION

We have established a novel model of posttrauma hypercoagulation that does not require direct restriction of venous flow or direct injury to the vessel endothelium to assay for hypercoagulability and can generate spontaneous microthrombosis when combined with valve-specific FOXC2 knockout. We find that multiple injuries induce a procoagulant phenotype that recapitulates the valvular hypercoagulability seen in FOXC2 knockout and, in critically ill human specimens, find evidence for loss of oscillatory shear stress-induced gene expression of FOXC2 and PROX1 in the valvular endothelium consistent with potential loss of DVT-protective valvular phenotype.

[Anaesthesiological management of postmortem organ donors - What Evidence is Out There?]

The transplantation of organs from postmortem organ donors has been a lifesaving and quality-of-life-improving therapy for patients with irreversible organ failure for many years. In Germany, however, there has been an imbalance between the number of organs donated postmortem and the number of patients on the waiting list for years. The anesthesiological management of multiple organ harvesting (MOE) in postmortem organ donors is not an everyday challenge for various reasons: A lack of practical expertise due to the small number of MOE, even at university hospitals (usually < 20 per year), complex pathophysiological changes in the cardiovascular system and other organ functions of the postmortem organ donor and the lack of guidelines complicate anesthesiological management. This paper compiles the existing literature and reviews whether evidence-based recommendations can be derived for anesthesiologic management for MOE.

[Perioperative management of the brain-dead organ donor : Anesthesia between ethics and evidence]

Hintergrund

Die Anzahl postmortal gespendeter Organe ist in Deutschland weit geringer als der Bedarf. Dies unterstreicht die Wichtigkeit einer optimalen Versorgung während des gesamten Prozesses der Organspende.

Fragestellung

Es existieren internationale Leitlinien und nationale Empfehlungen zu intensivmedizinischen organprotektiven Maßnahmen beim Organspender. Für das anästhesiologische Management fehlen evidenzbasierte Empfehlungen. Ziel dieser Übersichtsarbeit ist es, anhand der vorhandenen Evidenz die pathophysiologischen Veränderungen des irreversiblen Hirnfunktionsausfalls zu rekapitulieren und sich kritisch mit den empfohlenen Behandlungsstrategien und therapeutischen Zielgrößen auseinanderzusetzen. Auch auf ethische Aspekte der Betreuung des postmortalen Organspenders wird eingegangen.

Methode

Diese Übersichtsarbeit basiert auf einer selektiven Literaturrecherche in PubMed (Suchwörter: „brain dead donor“, „organ procurement“, „organ protective therapy“, „donor preconditioning“, „perioperative donor management“, „ethical considerations of brain dead donor“). Internationale Leitlinien und nationale Empfehlungen wurden besonders berücksichtigt.

Ergebnisse

Insgesamt ist die Evidenz für optimale intensivmedizinische und perioperative organprotektive Maßnahmen beim postmortalen Organspender sehr gering. Nationale und internationale Empfehlungen zu Zielwerten und medikamentösen Behandlungsstrategien unterscheiden sich teilweise erheblich: kontrollierte randomisierte Studien fehlen. Der Stellenwert einer Narkose zur Explantation bleibt sowohl unter pathophysiologischen Gesichtspunkten als auch aus ethischer Sicht ungeklärt.

Schlussfolgerungen

Die Kenntnisse über die pathophysiologischen Prozesse im Rahmen des irreversiblen Hirnfunktionsausfalls und die organprotektiven Maßnahmen sind ebenso Grundvoraussetzung wie die ethische Auseinandersetzung mit dem Thema postmortale Organspende. Nur dann kann das Behandlungsteam in dieser herausfordernden Situation sowohl dem Organempfänger als auch dem Organspender und seinen Angehörigen gerecht werden.

Elements of a successful hospital-based deceased donation programme in India: Zero to eighty-five in two years

Background

Legislation has made organ donation after brain death (DBD) possible in India since 1994. However, no organs are donated in most parts of the country; the national organ donation rate is estimated at between 0.08 and 0.34 donors per million population-one of the lowest in the world.

Methods

A 350-bedded private hospital in Kochi started its DBD programme in September 2013 with a structured approach based on counselling of family members of critically ill individuals. A counsellor trained to diagnose family dynamics, and recognize different stages of the grieving process, chose the right time, and the correct family member to whom the donation request could be made. Regular debriefing sessions of the core team consisting of a transplant surgeon, a transplant coordinator, an ICU counsellor and a unit administrator resulted in setting up systems that supported families of patients with catastrophic brain injury, and created an environment conducive to obtaining consent.

Results

A total of 85 organ donations took place in the first 24 months (September 2013 to September 2015) of instituting the programme.

Conclusion

It is possible with hospital-based teamwork and a structured approach to consistently elicit organ donation.

[Decision-making support in Intensive Care to facilitate organ donation : Position paper of the Ethics Section and the Organ Donation and Transplantation Section of the German Interdisciplinary Association of Critical Care and Emergency Medicine (DIVI) in collaboration with the Ethics Section of the German Society of Medical Intensive Care Medicine and Emergency Medicine (DGIIN)]

BACKGROUND AND CHALLENGE

Injuries, especially traumatic brain injury, or specific illnesses and their respective sequelae can result in the demise of the patients afflicted despite all efforts of modern intensive care medicine. If in principle organ donation is an option after a patient's death, intensive therapeutic measures are regularly required in order to maintain the homeostasis of the organs. These measures, however, cannot benefit the patient afflicted anymore-which in turn might lead to an ethical conflict between dignified palliative care for him/her and expanded intensive treatment to facilitate organ donation for others, especially if the patient has opted for the limitation of life-sustaining therapies in an advance directive.

METHOD

The Ethics Section and the Organ Donation and Transplantation Section of the German Interdisciplinary Association of Critical Care and Emergency Medicine (DIVI) have convened several meetings and a telephone conference and have arrived at a decision-making aid as to the extent of treatment for potential organ donors. This instrument focusses first on the assessment of five individual dimensions regarding organ donation, namely the certitude of a complete and irreversible loss of all brain function, the patient's wishes as to organ donation, his or her wishes as to limiting life-sustaining therapies, the intensity of expanded intensive treatment for organ protection and the odds of its successful attainment. Then, the combination of the individual assessments, as graphically shown in a {Netzdiagramm}, will allow for a judgement as to whether a continuation or possibly an expansion of intensive care measures is ethically justified, questionable or even inappropriate.

RESULT

The aid described can help mitigate ethical conflicts as to the extent of intensive care treatment for moribund patients, when organ donation is a medically sound option. NOTE: Gerald Neitzke und Annette Rogge contributed equally to this paper and should be considered co-first authors.

Medical Management of Brain-Dead Organ Donors

With improving healthcare services, the demand for organ transplants has been increasing daily worldwide. Deceased organ donors serve as a good alternative option to meet this demand. The first step in this process is identifying potential organ donors. Specifically, brain-dead patients require aggressive and intensive care from the declaration of brain death until organ retrieval. Currently, there are no specific protocols in place for this, and there are notable variations in the management strategies implemented across different transplant centers. Some transplant centers follow their own treatment protocols, whereas other countries, such as Bangladesh, do not have any protocols for potential organ donor care. In this review, we discuss how to identify brain-dead donors and describe the physiological changes that occur following brain death. We then summarize the management of brain-dead organ donors and, on the basis of a review of the literature, we propose recommendations for a treatment protocol to be developed in the future.

Management of the brain-dead donor in the ICU: general and specific therapy to improve transplantable organ quality

PURPOSE

To provide a practical overview of the management of the potential organ donor in the intensive care unit.

METHODS

Seven areas of donor management were considered for this review: hemodynamic management; fluids and electrolytes; respiratory management; endocrine management; temperature management; anaemia and coagulation; infection management. For each subchapter, a narrative review was conducted.

RESULTS AND CONCLUSIONS

Most elements in the current recommendations and guidelines are based on pathophysiological reasoning, epidemiological observations, or extrapolations from general ICU management strategies, and not on evidence from randomized controlled trials. The cardiorespiratory management of brain-dead donors is very similar to the management of critically ill patients, and the same applies to the management of anaemia and coagulation. Central diabetes insipidus is of particular concern, and should be diagnosed based on clinical criteria. Depending on the degree of vasopressor dependency, it can be treated with intermittent desmopressin or continuous vasopressin, intravenously. Temperature management of the donor is an area of uncertainty, but it appears reasonable to strive for a core temperature of > 35 °C. The indications and controversies regarding endocrine therapies, in particular thyroid hormone replacement therapy, and corticosteroid therapy, are discussed. The potential donor should be assessed clinically for infections, and screening tests for specific infections are an essential part of donor management. Although the rate of infection transmission from donor to receptor is low, certain infections are still a formal contraindication to organ donation. However, new antiviral drugs and strategies now allow organ donation from certain infected donors to be done safely.

[Organ donation: Lessons to be learned from abroad?]

The profound and ongoing crisis of organ donation and transplantation medicine in Germany urges for swift and sustainable improvement. Over the last few decades, various European countries have introduced national action plans and have efficiently begun to tap into their national potential for organ donation. Our paper sheds light on a variety of measures that have proven successful in different countries. Careful evaluation and comprehensive debate in public and professional bodies may warrant a tailor-made approach towards successful, albeit fundamental, changes in Germany's organ donation system.

[Critical care management of the potential organ donor : Current recommendation for adults]

The shortage of donor organs has not improved in recent years. To increase the number and success of transplantation it is crucial to optimize the processes of early identification of potential organ donors and structured critical care management. The therapy starts long before brain death is diagnosed. Structured in-house organ donor management protocols ensure a highly qualified critical care that has a direct impact on the transplantation outcome. The therapy is based on the established standards. The main focus is on differentiated catecholamine and volume therapy. Vasopressin, in combination with norepinephrine, is effective for both treating vasoplegia and electrolyte disturbances. Despite poor evidence, steroids are useful for stabilizing hemodynamics and treating the consequences of neuroendocrine dysfunction. Overall, prospective studies are required to give general recommendations for critical care.

[Organ donation : Update 2019]

The number of organ donors in Germany has been falling since 2010. In 2017, it reached its lowest level in 20 years with 797 organ donors. With 9.7 organ donors per million inhabitants, Germany lags far behind other European countries. The development of the donor numbers has long been an issue of concern for the Deutsche Stiftung Organtransplantation (DSO). Together with the donor hospitals, DSO has carried out extensive analyses on the possible causes. Though causes are multiple and complex, one important lever for improving the situation is seen in better detection and consistent reporting of possible organ donors. This is considered the best way to meet the patient's desire regarding organ donation. With reference to the dramatic development, DSO calls for a broad social debate and a joint initiative involving medical associations, contractors, patient associations and policymakers. Getting organ donation back on track in Germany for the benefit of patients on the waiting lists can only be achieved by a joint effort.

[Therapy escalation for the potential organ donor : Are all intensive care measures also ethically justifiable?]

The gap between the number of organs needed and the number available has dramatically increased in Germany in the last decade-for intensivists and transplantation specialists, it is challenging to cover the demand responsibly. It is therefore increasingly important to identify potential organ donors in order to realize organ donation. An escalation of intensive care measures is often required, which raises critical ethical questions. In Germany, organ donation is only allowed after brain death with prior informed consent from the deceased or his/her relatives. Determining the willingness of the potential organ donor and adapting the subsequent intensive care to it requires experience and empathy. Therapy escalation for the realization of organ donation is not opposed to the basic ethical principles of medicine, but remains an individual decision. A time limitation of this last intensive therapy phase to achieve optimal conditions for transplantation should be discussed with the relatives and adapted to the medical requirements. This article would like to highlight ethical questions that are relevant in the context of therapy escalation of potential organ donors and, thus, support the decision-making process.