Physiologic changes during brain stem death—lessons for management of the organ donor

Primary graft dysfunction in heart transplantation: the challenge to survival

Primary graft dysfunction (PGD) is a life-threatening clinical condition with a high mortality rate, presenting as left, right, or biventricular dysfunction within the initial 24 h following heart transplantation, in the absence of a discernible secondary cause. Given its intricate nature, definitive definition and diagnosis of PGD continues to pose a challenge. The pathophysiology of PGD encompasses numerous underlying mechanisms, some of which remain to be elucidated, including factors like myocardial damage, the release of proinflammatory mediators, and the occurrence of ischemia-reperfusion injury. The dynamic characteristics of both donors and recipients, coupled with the inclination towards marginal lists containing more risk factors, together contribute to the increased incidence of PGD. The augmentation of therapeutic strategies involving mechanical circulatory support accelerates myocardial recovery, thereby significantly contributing to survival. Nonetheless, a universally accepted treatment algorithm for the swift management of this clinical condition, which necessitates immediate intervention upon diagnosis, remains absent. This paper aims to review the existing literature and shed light on how diagnosis, pathophysiology, risk factors, treatment, and perioperative management affect the outcome of PGD.

Effect of Hypertonic Saline Solution on the Ventilatory Mechanics of Lungs Donated After Brain Death

INTRODUCTION

Brain death (BD) compromises the viability of the lung for donation. Hypertonic saline solution (HSS) induces rapid intravascular volume expansion and immunomodulatory action. We investigated its role in ventilatory mechanics (VMs) and in the inflammatory activity of the lungs of rats subjected to BD.

METHODS

Wistar rats were divided into four groups: control, n = 10: intact rats subjected to extraction of the heart-lung block; BD, n = 8 (BD): rats treated with isotonic saline solution (4 mL/kg) immediately after BD; hypertonic saline 0 h, n = 9 (Hip.0'): rats treated with HSS (4 mL/kg) immediately after BD; and hypertonic saline 1 h, n = 9 (Hip.60'), rats treated with HSS (4 mL/kg) 60 min after BD. The hemodynamic characteristics, gas exchange, VMs, inflammatory mediators, and histopathological evaluation of the lung were evaluated over 240 min of BD.

RESULTS

In VMs, we observed increased airway resistance, tissue resistance, tissue elastance, and respiratory system compliance in the BD group (P < 0.037), while the treated groups showed no impairment over time (P > 0.05). In the histological analysis, the BD group showed a greater area of perivascular edema and a higher neutrophil count than the control group and the Hip.60' group (P < 0.05).

CONCLUSIONS

Treatment with HSS was effective in preventing changes in the elastic and resistive pulmonary components, keeping them at baseline levels. Late treatment reduced perivascular and neutrophilic edema in lung tissue.

Management of potential cardiac donors

Heart transplantation (HTx) outcomes have improved with careful donor selection and management; nonetheless, donor shortages remain a major challenge. Optimizing donor management is crucial for improving donor utility rates and post-HTx outcomes. Brain death leads to various pathophysiological changes that can affect multiple organs, including the heart. Understanding these alterations and corresponding management strategies is key to optimizing the donor organ condition. This review assesses several aspects of these pathophysiological changes, including hemodynamic and endocrinological considerations, and emphasizes special consideration for potential cardiac donors, including serial echocardiographic evaluations for reversible cardiac dysfunction and coronary assessments for donors with risk factors.

Later Brain Death Declaration Correlates to Favorable Donor Characteristics but Decreased Heart Acceptance

BACKGROUND

With rates of potential donor heart discard as high as 66% nationally, quality improvement efforts must seek to optimize donor utilization. Whether the timing of donor brain death declaration (BDD) influences organ acceptance is understudied. The authors sought to characterize the impacts of time between donor hospital admission and BDD on heart utilization and posttransplant outcomes.

METHODS

All potential heart donors and recipients in the United Network for Organ Sharing database were identified (2006-2021). Admission-to-BDD cohorts were: 1 to 2 d (n = 52 469), 3 to 4 d (n = 44 033), 5 to 7 d (n = 24 509), and 8 to 10 d (n = 8576). Donor clinical characteristics were compared between cohorts, and donor acceptance was assessed using multivariable binary logistic regression. Recipient posttransplant survival was assessed with the Kaplan-Meier method.

RESULTS

Donor demographics and comorbidity profiles (diabetes and hypertension) were comparable across cohorts. Anoxia/overdose deaths were more common (10% > 21% > 24% > 18%, respectively) and cardiopulmonary resuscitation requirements were higher (37% > 52% > 58% > 47%) when BDD occurred longer after admission. Renal dysfunction (44% > 44% > 35% > 29%) and inotrope requirements (52% > 25% > 36% > 29%) were lower in the later BDD cohorts. Proportions of hepatic dysfunction (18%-21%) and left ventricular ejection fraction <50% (13%-16%) were clinically equivalent. Donor acceptance differed by admission-to-BDD cohort (36% [1-2 d], 34% [3-4 d], 30% [5-7 d], and 28% [8-10 d]). Admission-to-BDD >4 d was independently associated with lower odds of acceptance on multivariable analysis (odds ratio 0.79, P  < 0.001). Recipients experienced equivalent posttransplant survival for all donor admission-to-BDD cohorts ( P  = 0.999 adults and P  = 0.260 pediatrics).

CONCLUSIONS

Heart donors with later BDD were disproportionately discarded despite similar-to-favorable overall clinical profiles, resulting in nearly 3000 fewer transplants during the study. Increased utilization of donors with later BDD and "high-risk" characteristics (eg, anoxia/overdose, cardiopulmonary resuscitation requirement) can improve rates of transplantation without compromising outcomes.

Clinical outcomes of a prospective randomized comparison of bioreactance monitoring versus pulse-contour analysis in a stroke-volume based goal-directed fluid resuscitation protocol in brain-dead organ donors

Eighty percent of brain-dead (BD) organ donors develop hypotension and are frequently hypovolemic. Fluid resuscitation in a BD donor is controversial. We have previously published our 4-h goal-directed stroke volume (SV)-based fluid resuscitation protocol which significantly decreased time on vasopressors and increased transplanting four or more organs. The SV was measured by pulse-contour analysis (PCA) or an esophageal doppler monitor, both of which are invasive. Thoracic bioreactance (BR) is a non-invasive portable technology that measures SV but has not been studied in BD donors. We performed a randomized prospective comparative study of BR versus PCA technology in our fluid resuscitation protocol in BD donors. Eighty-four donors (53.1%) were randomized to BR and 74 donors to PCA (46.8%). The two groups were well matched based on 24 demographic, social, and initial laboratory factors, without any significant differences between them. There was no difference in the intravenous fluid infused over the 4-h study period [BR 2271 ± 823 vs. PCA 2230 ± 962 mL; p = .77]. There was no difference in the time to wean off vasopressors [BR 108.8 ± 61.8 vs. PCA 150.0 ± 68 min p = .07], nor in the number of donors off vasopressors at the end of the protocol [BR 16 (28.6%) vs. PCA 15 (29.4%); p = .92]. There was no difference in the total number of organs transplanted per donor [BR 3.25 ± 1.77 vs. PCA 3.22 ± 1.75; p = .90], nor in any individual organ transplanted. BR was equivalent to PCA in clinical outcomes and provides a simple, non-invasive, portable technology to monitor fluid resuscitation in organ donors.

Intravenous Levothyroxine for Unstable Brain-Dead Heart Donors

BACKGROUND

Hemodynamic instability and myocardial dysfunction are major factors preventing the transplantation of hearts from organ donors after brain death. Intravenous levothyroxine is widely used in donor care, on the basis of observational data suggesting that more organs may be transplanted from donors who receive hormonal supplementation.

METHODS

In this trial involving 15 organ-procurement organizations in the United States, we randomly assigned hemodynamically unstable potential heart donors within 24 hours after declaration of death according to neurologic criteria to open-label infusion of intravenous levothyroxine (30 μg per hour for a minimum of 12 hours) or saline placebo. The primary outcome was transplantation of the donor heart; graft survival at 30 days after transplantation was a prespecified recipient safety outcome. Secondary outcomes included weaning from vasopressor therapy, donor ejection fraction, and number of organs transplanted per donor.

RESULTS

Of the 852 brain-dead donors who underwent randomization, 838 were included in the primary analysis: 419 in the levothyroxine group and 419 in the saline group. Hearts were transplanted from 230 donors (54.9%) in the levothyroxine group and 223 (53.2%) in the saline group (adjusted risk ratio, 1.01; 95% confidence interval [CI], 0.97 to 1.07; P = 0.57). Graft survival at 30 days occurred in 224 hearts (97.4%) transplanted from donors assigned to receive levothyroxine and 213 hearts (95.5%) transplanted from donors assigned to receive saline (difference, 1.9 percentage points; 95% CI, -2.3 to 6.0; P<0.001 for noninferiority at a margin of 6 percentage points). There were no substantial between-group differences in weaning from vasopressor therapy, ejection fraction on echocardiography, or organs transplanted per donor, but more cases of severe hypertension and tachycardia occurred in the levothyroxine group than in the saline group.

CONCLUSIONS

In hemodynamically unstable brain-dead potential heart donors, intravenous levothyroxine infusion did not result in significantly more hearts being transplanted than saline infusion. (Funded by Mid-America Transplant and others; ClinicalTrials.gov number, NCT04415658.).

Suspected Malignant Hyperthermia in a Brain-Dead Donor During Anesthesia for Organ Procurement Surgery: A Case Report

We report an unusual case of highly suspected malignant hyperthermia after inducing anesthesia in a brain-dead 18-year-old male patient undergoing organ procurement surgery. The patient was administered desflurane (3 vol%) and rocuronium bromide (50 mg) to induce and maintain general anesthesia. He experienced hypercapnia and tachycardia within 5 minutes of anesthesia induction; however, his body temperature rapidly rose only after 15 minutes. The volatile anesthetic was discontinued, and dantrolene was administered at a low dose (1 mg/kg) to avert possible hepatotoxic effects on the donor liver. Fortunately, the clinical course of the brain-dead donor until the organs were harvested and the liver transplantation outcome of the recipient was favorable. A comprehensive understanding of the pathophysiology of brain death, organ transplantation, and malignant hyperthermia is essential to respond promptly and appropriately. Based on our experience, low-dose dantrolene may be clinically used in brain-dead donors while accounting for its potential hepatotoxic effects.

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.

Anesthetic Considerations of Organ Procurement After Brain and Cardiac Death: A Narrative Review

Organ donation procedures have become more frequent in the US as the need for transplants is increasing. Defining the anesthesiologist's role in organ donations after brain and cardiac death is important, as is understanding its ethics and practical physiologic and perioperative implications. Despite this, there are few papers specifically addressing the anesthetic management of organ donors. This review summarizes the preoperative, intraoperative, and postmortem considerations for the anesthesiologist involved in organ donation after either brain or cardiac death. A search of the published literature was performed using PubMed, Excerpta Medica dataBASE (EMBASE), and Google Scholar in March of 2022 for articles addressing anesthetic considerations of organ procurement surgeries after brain and cardiac death. This review demonstrates that anesthesiologists play a significant role in the organ procurement process. Their role in the perioperative management of the donor may affect the outcomes of organ transplantation. The gap between the number of organs harvested and the number of patients awaiting organ transplantation remains high despite continued efforts to increase the number of available organs. Perioperative management of organ donors aims at counteracting the associated unique physiologic derangements and targets optimization of oxygenation of the organs intended for procurement. Optimizing care after death can help ensure the viability of organs and the best outcomes for recipients. As organ donation after cardiac death (DCD) becomes more frequent in the US, anesthesiologists should be aware of the DCD classifications of donors and emerging novel perfusion techniques.

Vasopressin Use in the Support of Organ Donors: Physiological Rationale and Review of the Literature

The objective of this review was to depict the physiological and clinical rationale for the use of vasopressin in hemodynamic support of organ donors. After summarizing the physiological, pharmacological concepts and preclinical findings, regarding vasopressin's pathophysiological impacts, we will present the available clinical data.

DATA SOURCES

Detailed search strategies in PubMed, OVID Medline, and EMBASE were undertaken using Medical Subject Headings and Key Words.

STUDY SELECTION

Physiological articles regarding brain death, and preclinical animal and human studies about the use of vasopressin or analogs, as an intervention in organ support for donation, were considered.

DATA EXTRACTION

Two authors independently screened titles, abstracts, and full text of articles to determine eligibility. Data encompassing models, population, methodology, outcomes, and relevant concepts were extracted.

DATA SYNTHESIS

Following brain death, profound reduction in sympathetic outflow is associated with reduced cardiac output, vascular tone, and hemodynamic instability in donors. In addition to reducing catecholamine needs and reversing diabetes insipidus, vasopressin has been shown to limit pulmonary injury and decrease systemic inflammatory response in animals. Several observational studies show the benefit of vasopressin on hemodynamic parameters and catecholamine sparing in donors. Small trials suggest that vasopressin increase organ procurement and have some survival benefit for recipients. However, the risk of bias is overall concerning, and therefore the quality of the evidence is deemed low.

CONCLUSIONS

Despite potential impact on graft outcome and a protective effect through catecholamine support sparing, the benefit of vasopressin use in organ donors is based on low evidence. Well-designed observational and randomized controlled trials are warranted.

[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.

Alpha-1-Antitrypsin Protects Vascular Grafts of Brain-Dead Rats Against Ischemia/Reperfusion Injury

INTRODUCTION

Endothelial dysfunction is a potential side effect of brain death (BD). Ischemia/reperfusion (IR) injury during heart transplantation may lead to further endothelial damage. Protective effects of alpha-1-antitrypsin (AAT), a human neutrophil serine protease inhibitor, have been demonstrated against IR injury. We hypothesized that AAT protects brain-dead rats' vascular grafts from IR injury.

METHODS

Donor rats were subjected to BD by inflation of a subdural balloon. After 5.5 h, aortic rings were immediately mounted in organ baths (BD, n = 6 rats) or preserved in saline, supplemented either with vehicle (BD-IR, n = 8 rats) or AAT (BD-IR + AAT, n = 14 rats) for 24 h. During organ bath experiment, rings from both IR groups were exposed to hypochlorite to simulate warm reperfusion-associated endothelial injury. Endothelial function was measured ex vivo. Immunohistochemical staining for caspases was carried out and DNA-strand breaks were evaluated using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. Data are presented as median (interquartile range).

RESULTS

AAT improved IR-induced decreased maximum endothelium-dependent vasorelaxation to acetylcholine in the BD-IR + AAT aortas compared to the BD-IR group (BD: 83 (9-28) % versus BD-IR: 49 (39-60) % versus BD-IR + AAT: 64 (24-42) %, P < 0.05). Additionally, an increase in the rings' sensitivity to acetylcholine was noted after AAT (pD₂-value: BD-IR + AAT: 7.35 (7.06-7.89) versus BD-IR: 6.96 (6.65-7.21), P < 0.05). Caspase-3, -8, -9, and -12 immunoreactivity and the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells were significantly decreased by AAT.

CONCLUSIONS

AAT alleviates endothelial dysfunction, prevents increased caspase-3, -8, -9, and -12 levels, and decreases apoptotic DNA breakage due to BD and IR injury. This suggests that AAT treatment may be therapeutically beneficial to reduce IR-induced vascular damage.

Therapeutic donor hypothermia following brain death to improve the quality of transplanted organs

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

This review aims to examine the benefits and harms of therapeutic donor hypothermia in recipients or organs donated after brain death.

Endocrine Management and Hormone Replacement Therapy in Cardiac Donor Management: A Retrospective Observational Study

BACKGROUND

Pituitary dysfunction after brainstem death can cause various hormone deficiencies in potential heart donors. The aim of this study was to evaluate the relationship between hormone replacement therapy (HRT; including antidiuretic hormone analog, thyroid hormone, and methylprednisolone) in heart donors and the recipients' outcomes after heart transplantation (HTx).

METHODS

We retrospectively analyzed HTxs performed between January 2012 and October 2018. Donor and recipient characteristics were retrieved with a focus on endocrine parameters and HRT. The primary outcome was primary graft dysfunction (PGD). Secondary outcomes were the 30-day and 2-year mortality of the recipients. Univariate and multivariate Cox regression analyses were applied.

RESULTS

The study included 297 HTxs. PGD occurred in 56 recipients (18.9%). In the multivariable Cox analysis, methylprednisolone and thyroxine treatment in donors were associated with a lower odds for PGD (odds ratio [OR], 0.43; 95% CI, 0.19-1.01; P = .052; and OR,: 0.34; 95% CI, 0.15-0.76; P = .009, respectively). In multivariate analysis, thyroxine treatment in donors was associated with a lower odds of PGD (OR, 0.38; 95% CI, 0.17-0.86; P = .020). Donor thyroxine supplementation also had a beneficial effect on recipients' 2-year survival (OR, 0.53; 95% CI, 0.29-0.96; P = .036).

CONCLUSIONS

Combined thyroxine and methylprednisolone treatment could be a protective factor against PGD. Thyroxine administration was associated with better 2-year survival in recipients.

Evaluating the translational value of postmortem brain reperfusion technology

A novel pulsatile-perfusion technology, dubbed BrainEx, has been shown to restore microcirculation and cellular functions in the pig brain, 4 h postmortem. This technology has generated enthusiasm for its translational value for human neuroresuscitation. I offer a critical analysis of the study and its methodology, providing several reasons for skepticism. This includes: all phenomena were observed at different degrees of hypothermia; the physiological and biochemical milieu of the experimental preparation is radically different than the clinical setting of hypoxic-ischemic brain injury; and the study is confounded by uncontrolled traumatic brain injury and lifelong stress in all the animals.

Inflammatory responses in lungs from donation after brain death: Mechanisms and potential therapeutic targets

The vast majority of lungs used in clinical transplantation are donated after brain death (DBD). The utilization of DBD lungs is low due to brain death-induced lung injury. Moreover, inflammatory responses in DBD lungs used for transplantation contribute to ischemia-reperfusion injury and primary graft dysfunction. Work from human observational studies has demonstrated overexpression of cytokines, activation of endothelial cells, and cell death in DBD lungs, are associated with the activation of signaling pathways. Animal models have characterized the pulmonary injury induced by brain death and identified potential strategies to improve donor management. Interestingly, transcriptomic studies comparing DBD and donated after circulatory death (DCD) lungs have found that inflammatory responses are elevated in DBD lungs, while cell death pathways are elevated in DCD lungs. Development of the ex vivo lung perfusion technique, has made it possible to assess donor lungs using inflammation and cell death biomarkers. In the future, identification of potential therapeutic targets and development of novel treatments strategies may allow for lung repair during EVLP prior to transplantation.

Mesenchymal stem cell-derived conditioned medium protects vascular grafts of brain-dead rats against in vitro ischemia/reperfusion injury

BACKGROUND

Brain death (BD) has been suggested to induce coronary endothelial dysfunction. Ischemia/reperfusion (IR) injury during heart transplantation may lead to further damage of the endothelium. Previous studies have shown protective effects of conditioned medium (CM) from bone marrow-derived mesenchymal stem cells (MSCs) against IR injury. We hypothesized that physiological saline-supplemented CM protects BD rats' vascular grafts from IR injury.

METHODS

The CM from rat MSCs, used for conservation purposes, indicates the presence of 23 factors involved in apoptosis, inflammation, and oxidative stress. BD was induced by an intracranial-balloon. Controls were subjected to a sham operation. After 5.5 h, arterial pressures were measured in vivo. Aortic rings from BD rats were harvested and immediately mounted in organ bath chambers (BD group, n = 7) or preserved for 24 h in 4 °C saline-supplemented either with a vehicle (BD-IR group, n = 8) or CM (BD-IR+CM group, n = 8), prior to mounting. Vascular function was measured in vitro. Furthermore, immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR) have been performed.

RESULTS

BD in donors was associated with significantly impaired hemodynamic parameters and higher immunoreactivity of aortic myeloperoxidase (MPO), nitrotyrosine, caspase-3, caspase-8, caspase-9, and caspase-12 compared to sham-operated rats. In organ bath experiments, impaired endothelium-dependent vasorelaxation to acetylcholine in the BD-IR group compared to BD rats was significantly improved by CM (maximum relaxation to acetylcholine: BD 81 ± 2% vs. BD-IR 50 ± 3% vs. BD-IR + CM 72 ± 2%, p < 0.05). Additionally, the preservation of BD-IR aortic rings with CM significantly lowered MPO, caspase-3, caspase-8, and caspase-9 immunoreactivity compared with the BD-IR group. Furthermore, increased mRNA expression of vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1 in the aortas from the BD-IR rats compared to BD group were significantly decreased by CM.

CONCLUSIONS

The preservation of BD rats' vascular grafts with CM alleviates endothelial dysfunction following IR injury, in part, by reducing levels of inflammatory response and caspase-mediated apoptosis.

Hypothalamic function in patients diagnosed as brain dead and its practical consequences

Some patients who have been diagnosed as "dead by neurologic criteria" continue to exhibit certain brain functions, most commonly, neuroendocrine functions. In this chapter, we review the pathophysiology of brain death that can lead either to neuroendocrine failure or to preserved neuroendocrine functioning. We review the evidence on continued hypothalamic functioning in patients who have been declared "brain dead," examine potential mechanisms that would explain these findings, and discuss how these findings create additional confounds for brain death testing. We conclude by reviewing the evidence for the management of hypothalamic-pituitary failure in the setting of brain death and organ transplantation.

Ventilation in the prone position improves oxygenation and results in more lungs being transplanted from organ donors with hypoxemia and atelectasis

BACKGROUND

Hypoxemia is the most common barrier to lungs being transplanted from eligible organ donors who are brain dead (BD). Atelectasis is the principal reversible contributing factor to hypoxemia after brain death. We evaluated prospectively whether ventilation in the prone position in donors who are BD would reverse atelectasis, improve oxygenation, and result in more lungs being transplanted.

METHODS

Organ donors managed at the recovery center of 1 organ procurement organization over a 2-year period who exhibited hypoxemia (partial pressure of arterial oxygen [PaO₂]/fraction of inspired oxygen of <300 mm Hg) and had evidence of atelectasis were ventilated in the prone position for 12 hours or longer during donor management. A subset underwent computed tomography (CT) imaging to quantify the degree of atelectasis before and after prone positioning. Outcomes were compared with those of a control group with hypoxemia and atelectasis managed similarly but in the supine position in the previous 2 years.

RESULTS

A total of 40 lung-eligible donors who were BD with hypoxemia and atelectasis were managed in a prone position and compared with 79 donors in supine position. Baseline PaO₂ was similar between the prone and the supine groups (194 ± 78 vs 177 ± 77 mm Hg, p = 0.26) but increased more in the prone group at 4 hours (by 113 vs 54 mm Hg, p = 0.001) and remained 74-mm Hg higher at 12 hours (340 vs 266 mm Hg, p = 0.0006). CT-graded atelectasis was significantly reduced after ventilation in the prone position but persisted in the supine group (p = 0.001). Final PaO₂ was not significantly higher (344 vs 306, p = 0.12), but lungs were more often transplanted in the prone group (45% vs 24%, p = 0.03).

CONCLUSIONS

Ventilation in the prone position reverses atelectasis and rapidly and sustainably improves oxygenation in organ donors who are BD with hypoxemia. This effect appears to translate into more lungs being transplanted.

Impact of donor sodium levels on clinical outcomes in liver transplant recipients: a systematic review

We performed a systematic review of the literature to examine the effects of donor sodium levels on liver graft function and recipient survival, as well as to identify the optimal serum sodium target in donors. We searched MEDLINE, Cochrane, and trial registries from 1946 to May 2019 for studies that evaluated the effect of serum sodium levels in neurologically deceased liver donors on transplant outcomes. We used a two-step review process with four independent reviewers to identify relevant articles based on inclusion/exclusion criteria. We summarize the results narratively, assess the risk of bias, and apply the Grading of Recommendations Assessment, Development, and Evaluation methods to evaluate the certainty in the evidence. We included 25 cohort studies were in our final analysis (total n = 19 389). Twenty-two reported on graft function and survival. Summary data suggest an association between donor serum sodium and recipient liver graft dysfunction, with very low certainty in evidence due to serious concerns with risk of bias, inconsistency, indirectness, and imprecision. Seven studies reported on recipient mortality, with results suggesting no association between donor sodium and recipient survival. The certainty in evidence for this outcome was also very low due to serious concerns with imprecision, indirectness, and risk of bias. Donor sodium dysregulation is associated with liver graft dysfunction, but not recipient mortality. Further research is needed to determine the effects of correcting donor sodium levels on transplant outcomes, quantify the dose-response curve, and identify liver recipients most vulnerable to sodium dysregulation.

Review 1: Lung transplant-from donor selection to graft preparation

For various end-stage lung diseases, lung transplantation remains one of the only viable treatment options. While the demand for lung transplantation has steadily risen over the last few decades, the availability of donor grafts is limited, which have resulted in progressively longer waiting lists. In the early years of lung transplantation, only the 'ideal' donor grafts are considered for transplantation. Due to the donor shortages, there is ongoing discussion about the safe use of 'suboptimal' grafts to expand the donor pool. In this review, we will discuss the considerations around donor selection, donor-recipient matching, graft preparation and graft optimisation.

Deceased Donor Predictors for Pediatric Liver Allograft Utilization

BACKGROUND

The number of pediatric deceased organ donors has recently declined, and the nonutilization of pediatric liver allografts has limited the development of liver transplantation. We determined the utilization rate of pediatric livers and identified risk factors for graft discard.

METHODS

We used data from the Scientific Registry of Transplant Recipients database from January 1, 2000, to December 31, 2012. The trends of pediatric liver donors and utilization rates were analyzed. Donor risk factors that impacted the graft use of pediatric livers were measured. Logistic regression modelling was performed to evaluate graft utilization and risk factors.

RESULTS

A total of 11,934 eligible pediatric liver donors were identified during this period. A total of 1191 authorized liver grafts did not recover or recovered without transplantation. Factors including pediatric donors >1 year of age (odds ratio [OR] = 2.956, 95% confidence interval [CI] 2.494-3.503, P < .001), nonhead trauma (OR = 2.243, 95% CI 1.903-2.642, P < .001), lack of heartbeat (OR = 7.534, 95% CI 5.899-9.623, P < .001), hepatitis B surface antigen positivity (OR = 4.588, 95% CI 1.021-20.625, P = .047), anti-hepatitis C virus positivity (OR = 4.691, 95% CI 1.352-16.280, P = .015), total bilirubin >1 mg/dL (OR = 1.743, 95% CI 1.469-2.068, P < .001), and blood urea nitrogen >21 mg/dL (OR = 1.941, 95% CI 1.546-2.436, P < .001) were significantly related to graft nonutilization. Steroids or diuretics administered prerecovery were significantly related to graft utilization (OR = 0.684, 95% CI 0.581-0.806, P < .001; OR = 0.744, 95% CI 0.634-0.874, P < .001; respectively).

CONCLUSIONS

The pediatric liver allograft utilization rate and risk factors for nonutilization of grafts were determined.

Donor hearts in the Sydney Heart Bank: reliable control but is it 'normal' heart?

Human heart samples from the Sydney Heart Bank have become a de facto standard against which others can be measured. Crucially, the heart bank contains a lot of donor heart material: for most researchers this is the hardest to obtain and yet is necessary since we can only study the pathological human heart in comparison with a control, preferably a normal heart sample. It is not generally realised how important the control is for human heart studies. We review our studies on donor heart samples. We report the results obtained with 17 different donor samples collected from 1994 to 2011 and measured from 2005 to 2015 by our standard methodology for in vitro motility and troponin I phosphorylation measurements. The donor heart sample parameters are consistent between the hearts, over time and with different operators indicating that Sydney Heart Bank donor hearts are a valid baseline control for comparison with pathological heart samples. We also discuss to what extent donor heart samples are representative of the normal heart.

Oral Preconditioning of Donors After Brain Death With Calcineurin Inhibitors vs. Inhibitors of Mammalian Target for Rapamycin in Pig Kidney Transplantation

Background: The systemic inflammatory cascade triggered in donors after brain death enhances the ischemia-reperfusion injury after organ transplantation. Intravenous steroids are routinely used in the intensive care units for the donor preconditioning. Immunosuppressive medications could be potentially used for this purpose as well. Data regarding donor preconditioning with calcineurin inhibitors or inhibitors of mammalian target for Rapamycin is limited. The aim of this project is to investigate the effects of (oral) donor preconditioning with a calcineurin inhibitor (Cyclosporine) vs. an inhibitor of mammalian target for Rapamycin (Everolimus) compared to the conventional administration of steroid in the setting of donation after brain death in porcine renal transplantation.

Methods: Six hours after the induction of brain death, German landrace donor pigs (33.2 ± 3.9 kg) were randomly preconditioned with either Cyclosporine (n = 9) or Everolimus (n = 9) administered via nasogastric tube with a repeated dose just before organ procurement. Control donors received intravenous Methylprednisolone (n = 8). Kidneys were procured, cold-stored in Histidine-Tryptophane-Ketoglutarate solution at 4°C and transplanted in nephrectomized recipients after a mean cold ischemia time of 18 h. No post-transplant immunosuppression was given to avoid confounding bias. Blood samples were obtained at 4 h post reperfusion and daily until postoperative day 5 for complete blood count, blood urea nitrogen, creatinine, and electrolytes. Graft protocol biopsies were performed 4 h after reperfusion to assess early histological and immunohistochemical changes.

Results: There was no difference in the hemodynamic parameters, hemoglobin/hematocrit and electrolytes between the groups. Serum blood urea nitrogen and creatinine peaked on postoperative day 1 in all groups and went back to the preoperative levels at the conclusion of the study on postoperative day 5. Histological assessment of the kidney grafts revealed no significant differences between the groups. TNF-α expression was significantly lower in the study groups compared with Methylprednisolone group (p = 0.01) Immunohistochemistry staining for cytochrome c showed no difference between the groups.

Conclusion: Oral preconditioning with Cyclosporine or Everolimus is feasible in donation after brain death pig kidney transplantation and reduces the expression of TNF-α. Future studies are needed to further delineate the role of oral donor preconditioning against ischemia-reperfusion injury.

Impact of Deceased Donor Management on Donor Heart Use and Recipient Graft Survival

BACKGROUND

Current risk-adjusted models used to predict donor heart use and cardiac graft survival from organ donors after brain death (DBDs) do not include bedside critical care data. We sought to identify novel independent predictors of heart use and graft survival to better understand the relationship between donor management and transplantation outcomes.

STUDY DESIGN

We conducted a prospective observational study of DBDs managed from 2008 to 2013 by 10 organ procurement organizations. Demographic data, critical care parameters, and treatments were recorded at 3 standardized time points during donor management. The primary outcomes measures were donor heart use and cardiac graft survival.

RESULTS

From 3,433 DBDs, 1,134 hearts (33%) were transplanted and 969 cardiac grafts (85%) survived after 684 ± 392 days of follow-up. After multivariable analysis, independent positive predictors of heart use included standard criteria donor status (odds ratio [OR] 3.93), male sex (OR 1.68), ejection fraction > 50% (OR 1.64), and partial pressure of oxygen to fraction of inspired oxygen ratio > 300 (OR 1.31). Independent negative predictors of heart use included donor age (OR 0.94), BMI > 30 kg/m² (OR 0.78), serum creatinine (OR 0.83), and use of thyroid hormone (OR 0.78). As for graft survival, after controlling for known recipient risk factors, thyroid hormone dose was the only independent predictor (OR 1.04 per μg/h).

CONCLUSIONS

Modifiable critical care parameters and treatments predict donor heart use and cardiac graft survival. The discordant relationship between thyroid hormone and donor heart use (negative predictor) vs cardiac graft survival (positive predictor) warrants additional investigation.

Optimisation of the organ donor and effects on transplanted organs: a narrative review on current practice and future directions

Mortality remains high for patients on the waiting list for organ transplantation. A marked imbalance between the number of available organs and recipients that need to be transplanted persists. Organs from deceased donors are often declined due to perceived and actual suboptimal quality. Adequate donor management offers an opportunity to reduce organ injury and maximise the number of organs than can be offered in order to respect the donor's altruistic gift. The cornerstones of management include: correction of hypovolaemia; maintenance of organ perfusion; prompt treatment of diabetes insipidus; corticosteroid therapy; and lung protective ventilation. The interventions used to deliver these goals are largely based on pathophysiological rationale or extrapolations from general critical care patients. There is currently insufficient high-quality evidence that has assessed whether any interventions in the donor after brain death may actually improve immediate post-transplant function and long-term graft survival or recipient survival after transplantation. Improvements in our understanding of the underlying mechanisms following brain death, in particular the role of immunological and metabolic changes in donors, offer promising future therapeutic opportunities to increase organ utilisation. Establishing a UK donor management research programme involves consideration of ethical, logistical and legal issues that will benefit transplanted patients while respecting the wishes of donors and their families.

Vascular Signaling in Allogenic Solid Organ Transplantation - The Role of Endothelial Cells

Graft rejection remains the major obstacle after vascularized solid organ transplantation. Endothelial cells, which form the interface between the transplanted graft and the host’s immunity, are the first target for host immune cells. During acute cellular rejection endothelial cells are directly attacked by HLA I and II-recognizing NK cells, macrophages, and T cells, and activation of the complement system leads to endothelial cell lysis. The established forms of immunosuppressive therapy provide effective treatment options, but the treatment of chronic rejection of solid organs remains challenging. Chronic rejection is mainly based on production of donor-specific antibodies that induce endothelial cell activation—a condition which phenotypically resembles chronic inflammation. Activated endothelial cells produce chemokines, and expression of adhesion molecules increases. Due to this pro-inflammatory microenvironment, leukocytes are recruited and transmigrate from the bloodstream across the endothelial monolayer into the vessel wall. This mononuclear infiltrate is a hallmark of transplant vasculopathy. Furthermore, expression profiles of different cytokines serve as clinical markers for the patient’s outcome. Besides their effects on immune cells, activated endothelial cells support the migration and proliferation of vascular smooth muscle cells. In turn, muscle cell recruitment leads to neointima formation followed by reduction in organ perfusion and eventually results in tissue injury. Activation of endothelial cells involves antibody ligation to the surface of endothelial cells. Subsequently, intracellular signaling pathways are initiated. These signaling cascades may serve as targets to prevent or treat adverse effects in antibody-activated endothelial cells. Preventive or therapeutic strategies for chronic rejection can be investigated in sophisticated mouse models of transplant vasculopathy, mimicking interactions between immune cells and endothelium.

Influence of donor brain death duration on outcomes following heart transplantation: A United Network for Organ Sharing Registry analysis

OBJECTIVES

We hypothesized that an increased duration of donor brain death may worsen survival following orthotopic heart transplantation.

METHODS

The United Network for Organ Sharing Registry was queried for first-time, adult recipients of heart transplant from 2006 to 2018. Cox proportional hazards with penalized smooth splines was used to stratify patients based on donor brain death interval: shorter (<22 hours), reference (22-42 hours), and longer (>42 hours). Overall survival was estimated using Kaplan-Meier and Cox proportional hazards models.

RESULTS

A total of 22,960 patients met study criteria (9.2% shorter, 55.0% reference, and 35.8% longer). Longer brain death duration recipients were more likely to have a later year of transplant and have a mechanical bridge to transplant, whereas longer duration donors were more likely to be black and die of anoxia compared with shorter duration and reference donors. Compared with reference, neither shorter (hazard ratio, 1.02; 95% confidence interval, 0.94-1.12) nor longer donor brain death interval (hazard ratio, 1.01; 95% CI, 0.94-1.08) was associated with posttransplant survival in either unadjusted or multivariable analyses (both P values >0.6).

CONCLUSIONS

Longer duration of brain death was not associated with worse survival following heart transplantation. Donors with prolonged interval of brain death should not necessarily be excluded based on brain death period alone.

A stroke volume-based fluid resuscitation protocol decreases vasopressor support and may increase organ yield in brain-dead donors

Brain-dead donors are frequently hypovolemic and hypotensive requiring vasopressor support. We studied a stroke volume-based fluid resuscitation and vasopressor weaning protocol prospectively on 64 hypotensive donors, with a recent control cohort of 30 hypotensive donors treated without a protocol. Stroke volume was measured every 30 minutes for 4 hours by pulse contour analysis or esophageal Doppler. A 500 mL saline fluid bolus was infused over 30 minutes and repeated if the stroke volume increased by 10%. No fluid was infused if the stroke volume did not increase by 10%. Vasopressors were weaned every 10 minutes if the mean arterial pressure was greater than 65 mm Hg. The protocol group received 1937 ± 906 mL fluid compared to 1323 ± 919 mL in the control group (P = .003). Mean time on vasopressors was decreased from 957.6 ± 586.2 to 176.3 ± 82.2 minutes (P<.001). Donors in the protocol group were more likely to donate four or more organs than donors in the control group (OR = 4.114, 95% Confidence Interval (CI) = 1.003-16.876). While more organs were transplanted per donor in the protocol group (3.39 ± 1.52) than in the control group (2.93 ± 1.44) (P = .268), the difference did not reach statistical significance. A goal-directed fluid resuscitation protocol decreased organ ischemia and may increase organs transplanted.

Brainstem dysfunction in critically ill patients

The brainstem conveys sensory and motor inputs between the spinal cord and the brain, and contains nuclei of the cranial nerves. It controls the sleep-wake cycle and vital functions via the ascending reticular activating system and the autonomic nuclei, respectively. Brainstem dysfunction may lead to sensory and motor deficits, cranial nerve palsies, impairment of consciousness, dysautonomia, and respiratory failure. The brainstem is prone to various primary and secondary insults, resulting in acute or chronic dysfunction. Of particular importance for characterizing brainstem dysfunction and identifying the underlying etiology are a detailed clinical examination, MRI, neurophysiologic tests such as brainstem auditory evoked potentials, and an analysis of the cerebrospinal fluid. Detection of brainstem dysfunction is challenging but of utmost importance in comatose and deeply sedated patients both to guide therapy and to support outcome prediction. In the present review, we summarize the neuroanatomy, clinical syndromes, and diagnostic techniques of critical illness-associated brainstem dysfunction for the critical care setting.

A Novel Method to Improve Perfusion of Ex Vivo Pumped Human Kidneys

OBJECTIVE

To determine if addition of the S-nitrosylating agent ethyl nitrite (ENO) to the preservation solution can improve perfusion parameters in pumped human kidneys.

BACKGROUND

A significant percentage of actively stored kidneys experience elevations in resistance and decreases in flow rate during the ex vivo storage period. Preclinical work indicates that renal status after brain death is negatively impacted by inflammation and reduced perfusion-processes regulated by protein S-nitrosylation. To translate these findings, we added ENO to the preservation solution in an attempt to reverse the perfusion deficits observed in nontransplanted pumped human kidneys.

METHODS

After obtaining positive proof-of-concept results with swine kidneys, we studied donated human kidneys undergoing hypothermic pulsatile perfusion deemed unsuitable for transplantation. Control kidneys continued to be pumped a 4°C (ie, standard of care). In the experimental group, the preservation solution was aerated with 50 ppm ENO in nitrogen. Flow rate and perfusion were recorded for 10 hours followed by biochemical analysis of the kidney tissue.

RESULTS

In controls, perfusion was constant during the monitoring period (ie, flow rate remained low and resistance stayed high). In contrast, the addition of ENO produced significant and sustained reductions in resistance and increases in flow rate. ENO-treated kidneys had higher levels of cyclic guanosine monophosphate, potentially explaining the perfusion benefits, and increased levels of interleukin-10, suggestive of an anti-inflammatory effect.

CONCLUSIONS

S-Nitrosylation therapy restored the microcirculation and thus improved overall organ perfusion. Inclusion of ENO in the renal preservation solution holds promise to increase the number and quality of kidneys available for transplant.

Direct Peritoneal Resuscitation Alters Leukocyte Infiltration in the Lung After Acute Brain Death

BACKGROUND

Brain death is associated with significant lung injury and inflammation. This has been associated with worse long-term outcomes for transplanted lungs. Direct peritoneal resuscitation (DPR) reduces systemic inflammation in brain death and improves lung procurement rate. The effect of DPR on macrophage and neutrophil infiltration in the lungs is not known.

METHODS

Male Sprague-Dawley rats had a 4F Fogarty catheter inserted into the skull and the balloon inflated until brain death was achieved. Rats were resuscitated with normal saline to maintain a mean arterial pressure of 80 mmHg (targeted intravenous fluid, TIVF) and DPR animals received an intraperitoneal injection of commercial peritoneal dialysis solution. Rats were sacrificed at 0, 2, 4, and 6 h after brain death. Protein levels were assessed using quantitative ELISA. Leukocytes were quantified using flow cytometry and immunohistochemistry.

RESULTS

At all time points, DPR downregulated multiple inflammatory cytokines including IFN-γ, TNF-α, IL-1α, and IL-6. Adhesion molecules ICAM, E-selectin, and P-selectin were increased above sham at 4 and 6 h after brain death and reduced with DPR, whereas VCAM was reduced at 2 and 6 h. Infiltration of macrophages and neutrophils were trended downward at 6 h with DPR, though this difference was not statistically significant.

CONCLUSIONS

Animals that received TIVF alone had significant increases in inflammatory cytokines within the lung tissue, leading to adhesion molecule expression and ultimately leukocyte infiltration. Each stage of inflammation was affected by DPR. Using DPR in brain dead organ donors shows promise as a way to reduce lung injury and inflammation.

Impact of Donor Brain Death Duration on Outcomes After Lung Transplantation

BACKGROUND

Donor brain death duration (BDD) may impact posttransplant graft function and survival in lung transplant.

METHODS

We queried the 2007 to 2018 United Network for Organ Sharing Registry for adult recipients undergoing first-time isolated lung transplant. Cox proportional hazard modeling with splines enabled identification of 3 donor brain death intervals for subsequent analysis: short (<24 hours), reference (24-60 hours), and long (>60 hours). The primary outcome was posttransplant survival.

RESULTS

In total, 19,721 donors and recipients met inclusion criteria. Median time from donor brain death until cross-clamp was 36.6 hours (interquartile range, 19.5). Unadjusted overall survival between cohorts was equivalent (log-rank P = .42); however, longer BDD was associated with improved bronchiolitis obliterans syndrome (BOS)-free survival (log-rank P < .001). On multivariable Cox proportional hazards regression, BDD was not associated with recipient survival (P > .05). Similarly, logistic regression did not identify an independent association between BDD and primary graft dysfunction (P > .05). Increased BDD was, however, associated with a decreased risk of acute rejection (long vs reference; adjusted odds ratio, 0.78; 95% confidence interval, 0.64-0.94) and improved BOS-free survival (long vs reference; adjusted hazard ratio, 0.88; 95% confidence interval, 0.81-0.96).

CONCLUSIONS

Donor BDD is not associated with posttransplant survival or primary graft dysfunction. Long donor BDD, however, is associated with a decreased risk for acute rejection and improved BOS-free survival. Therefore, lung allografts from donors with a prolonged length of time from brain death until explant should not be viewed less favorably by donor selection centers.

Management of the Pediatric Organ Donor

Management of the pediatric organ donor necessitates understanding the physiologic changes that occur preceding and after death determination. Recognizing these changes allows application of the therapeutic strategies designed to optimize hemodynamics and metabolic state to allow for preservation of end-organ function for maximal organ recovery and minimal damage to the donor grafts. The pediatric pharmacist serves as the medication expert and may collaborate with the organ procurement organizations for provision of pharmacologic hemodynamic support, hormone replacement therapy, antimicrobials, and nutrition for the pediatric organ donor.

A Canadian survey of critical care physicians' hemodynamic management of deceased organ donors

PURPOSE

We sought to characterize Canadian physicians' perspectives and stated practices regarding their hemodynamic care of deceased organ donors.

METHODS

We designed a 24-item electronic survey that was independently pretested for relevance, clarity, and intra-rater reliability by ten critical care clinicians. With the help of provincial organ donation organizations (ODO), we identified intensive care units (ICUs) with a high volume of adult deceased donors (defined by the management of five or more donors per year for two consecutive years). Medical directors of these high-volume ICUs helped identify ICU physicians to whom our survey was emailed.

RESULTS

Of the 448 ICU physicians from 37 centres in nine provinces that were emailed, 184/448 (41.1%) responded to one or more survey questions. Respondents identified specialist nurses from ODOs as their primary source of guidance in donor care (107/165; 60%). They typically diagnosed an autonomic storm according to a rise in blood pressure (159/165; 96.4%) and/or heart rate (135/165; 81.8%); nevertheless, their stated management varied substantially. After termination of the autonomic storm, preferred first-line vasopressors were norepinephrine (93/164; 56.7%) and vasopressin (68/164; 41.5%). Twenty-one respondents (21/162; 13.0%) reported that they never administer inotropes to donors. Corticosteroid and thyroid hormone prescriptions for all donors was reported by 62/161 (37.6%) and 50/161 (31.1%) respondents, respectively. Respondents perceived an influence from ODO nurses or transplant physicians when prescribing corticosteroids (77/161; 47.8%) and/or thyroid hormones (33/161; 20.5%) CONCLUSION: We observed important variability in self-perceived practices of ICU physicians in the hemodynamic management of deceased donors, particularly in the treatment of the autonomic storm, in the prescription of hormone therapy, and in the administration of inotropes.

Brain death interval and relationship to outcomes of pediatric cardiac transplantation

BACKGROUND

We sought to analyze brain death interval and outcomes of pediatric cardiac transplantation using national registry data.

METHODS

We retrospectively evaluated a pediatric cohort from the UNOS registry from 2005 to 2014. We restricted the donor cohort to those with a primary central nervous system event as the cause of hospitalization. Brain death interval (BDI) was defined as the time between hospital admission and organ procurement. Primary outcomes were recipient and graft survival time. Logistical regression modeling was used for multivariable analysis.

RESULTS

The donor cohort included 2565 cases. Multivariable analysis demonstrated no relationship between BDI and recipient or graft survival time. For patient survival time, the lowest HR was 0.94 (0.63-1.39), P = 0.531; for graft survival time, the lowest HR was 0.89 (0.53-1.49), P = 0.563. We obtained similar results using a non-restricted donor cohort.

CONCLUSIONS

There was no clear relationship between BDI and recipient or graft survival after pediatric cardiac transplantation.

Catastrophic Non-Survivable Brain Injury Care-Role 2/3

A catastrophic brain injury is defined as any brain injury that is expected to result in permanent loss of all brain function above the brain stem level. These clinical recommendations will help stabilize the patient so that they may be safely evacuated from theater. In addition to cardiovascular and hemodynamic goals, special attention must be paid to their endocrine dysfunction and its treatment-specifically steroid, insulin and thyroxin (t4) replacement while evaluating for and treating diabetes insipidus. Determining the futility of care coupled with resource management must also be made at each echelon. Logistical coordination and communication is paramount to expedite these patients to higher levels of care so that there is an increased probability of reuniting them with their family.

Proposed safe apnea test using positive end-expiratory pressure valve and short-term blood gas analysis: Observational study

The apnea test is an essential examination for the determination of brain death; however, hypotension, hypoxemia, and other complications during the apnea test can affect the stability of brain-dead patients, as well as organ function for recipients. Therefore, it is necessary to establish standard guidelines for apnea testing.The modified apnea test (MAT) comprises delivery of 100% oxygen through the endotracheal tube connected to manual resuscitator (Ambu bag) with the positive end-expiratory pressure (PEEP) valve after disconnection of the mechanical ventilator for maintenance of PEEP. Forty-nine instances of the conventional apnea test (CAT) were performed in 25 brain-dead patients; 77 instances of the MAT were performed in 39 brain-dead patients.The mean duration of the apnea test was 3.5 ± 1.4 minutes in the CAT group and 3.0 ± 1.2 minutes in the MAT group. There were no significant changes in PaCO2, PaO2, or pH between the CAT and MAT groups (P = .341, .593, and .503, respectively). In overweight patients (body mass index ≥ 23 kg/m), MAT prevented dramatic reductions in PaO2 and SaO2 (P < .05 for both). In the patients who had hypoxic brain injury due to hanging, differences in PaO2 and SaO2 in the MAT group were significantly smaller than in the CAT group (P < .05).Although MAT, which was invented to maintain PEEP, was not efficient for all brain-dead patients, it could be helpful in selected patient groups, such as overweight patients or those who had hypoxic injury due to hanging. And clinicians should consider short-term apnea test to avoid unnecessarily prolonged hypoxemia.

Direct Peritoneal Resuscitation Reduces Lung Injury and Caspase 8 Activity in Brain Death

Background: Acute brain death (ABD) is associated with inflammation and lung injury. Direct peritoneal resuscitation (DPR) improves blood flow to the vital organs after ABD. DPR reduces lung injury, but the mechanism for this is unknown. Methods: Male Sprague-Dawley rats were randomized to five groups (n = 8/group): (1) Sham (no ABD); (2) Targeted intravenous fluid (TIVF) (ABD plus enough IVF to maintain a MAP of 80 mmHg) at 2 hours post-resuscitation (RES); (3) ABD + TIVF + DPR (TIVF and 30 cc intraperitoneal 2.5% Delflex) at 2 hours post-RES; (4) ABD + TIVF at 4 hours post-RES; and (5) ABD + TIVF + DPR at 4 hours post-RES. Messenger RNA (mRNA) levels were measured using Qiagen qRT PCR. Protein levels were assessed using quantitative ELISAs and the Luminex MagPix system. Results: Use of DPR caused 5.8-fold downregulation of mRNA expression for TNF-α and 2.7-fold decrease for the TNF receptor compared to TIVF alone. Caspase 8 mRNA was also downregulated. Protein levels for TNF-α, TNF receptor, caspase 8, NFκB, and NFκB inhibitor kinase, which promotes dissociation of NFκB inhibitor, were reduced by DPR. Cell death markers M30 and M65 were also decreased with DPR. Conclusions: Use of DPR caused changes in the expression of multiple mRNAs and proteins in the caspase 8 apoptotic pathway. These data represent a mechanism through which DPR exerts its beneficial effects within the lung tissue.

Death by neurologic criteria: pathophysiology, definition, diagnostic criteria and tests

Death by neurologic criteria is an irreversible sequence of events culminating in permanent cessation of cerebral functions. In this context, there are no responses arising from the brain, no cranial nerve reflexes nor motor responses to pain stimuli, and no respiratory drive. The diagnosis of death by neurologic criteria implies that there is clinical evidence of the complete and irreversible cessation of brainstem and cerebral functions. The diagnosis, confirmation, and certification of death are core skills for medical practitioners. The aim of this review is to discuss the pathophysiology and definition of death by neurological criteria, describing the clinical assessment, and the use of ancillary tests for the diagnosis of brainstem death.

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.

A Single-Center Experience with an Intensivist-Led Brain-Dead Donor Management Program

Background

The aim of this study is to report our experience of brain-dead donor management by a dedicated intensivist who had wide experience in treatment of hemodynamically unstable patient and to suggest a role for intensivists in organ donation.

Material/Methods

The management of brain-dead donors was performed by experienced intensivists. The hospital medical records and data from the Korean Network of Organ Sharing from August 2013 to December 2016 were reviewed retrospectively.

Results

Fifty-four brain death patients (3.2% of KONOS nationwide data) donated organs in our institution during 41 months. Dedicated intensivists managed deceased patients for the whole duration (2.81±1.21 days) of management, not only with conservative therapies like fluid resuscitation, vasopressor, or hormonal replacement, but also with pulmonary artery catheter insertion for cardiac output monitoring (n=47, 87.0%) and continuous renal replacement therapy (n=22, 40.7%). The number of donors increased each year. The mean number of retrieved organs in each deceased donor was 3.98±1.55, more than the national average (3.26) and comparable to the higher level among the recent worldwide data. The number of donations by organ was: 23 hearts (4.9% of nationwide data), 17 lungs (7.5% of nationwide data), 102 kidneys (3.3% of nationwide data), 47 livers (3.1% of nationwide data), 6 pancreases (2.9% of nationwide data), 1 pancreatic duct (11.1% of nationwide data), and 1 small intestine (12.5% of nationwide data).

Conclusions

Management by dedicated intensivists will improve not only the number of actual organ donors, but also the number of harvested organs.

The Impact of l-Thyroxine Treatment of Donors and Recipients on Postoperative Outcomes After Heart Transplantation

OBJECTIVE

The effect of thyroid dysfunction on adverse outcomes has been studied in many different patient populations. The objective of this study was to investigate the effect of thyroid hormone supplementation of donors and recipients on postoperative outcomes after orthotopic heart transplantation.

DESIGN

Retrospective.

SETTING

Single center, university hospital.

PARTICIPANTS

Two-hundred and sixty-six consecutive patients undergoing heart transplantation.

INTERVENTIONS

No interventions.

MEASUREMENTS AND MAIN RESULTS

Demographic, hemodynamic, and clinical characteristics; donor and recipient United Network for Organ Sharing scores; and information on thyroid hormone support of donors and recipients were recorded. During the median follow-up of 4.59 years (interquartile range 4.26-4.92 y), 70 patients (26.3%) died. After adjustments were made for the United Network for Organ Sharing score, recipients who were treated preoperatively with l-thyroxine had a lower risk for all-cause mortality (adjusted hazard ratio [HR] 0.24, 95% confidence interval [CI] 0.06-0.98; p = 0.047) compared with recipients who were not treated with l-thyroxine. In addition, l-thyroxine treatment of donors was associated with a better recipient survival (HR 0.31, 95% CI 0.11-0.87; p = 0.025).

CONCLUSIONS

Pretransplantation thyroid hormone supplementation of donors and recipients was associated with improved long-term survival after heart transplantation.

Frequency of use of the religious exemption in New Jersey cases of determination of brain death

BACKGROUND

The 1981 Uniform Determination of Death Act (UDDA) established the validity of both cardio-respiratory and neurological criteria of death. However, many religious traditions including most forms of Haredi Judaism (ultra-orthodox) and many varieties of Buddhism strongly disagree with death by neurological criteria (DNC). Only one state in the U.S., New Jersey, allows for both religious exemptions to DNC and provides continuation of health insurance coverage when an exception is invoked in its 1991 Declaration of Death Act (NJDDA). There is yet no quantitative or qualitative data on the frequencies of religious exemptions in New Jersey. This study gathered information about the frequency of religious exemptions and policy in New Jersey that was created out of respect for religious beliefs.

METHODS

Literature and internet searches on topics related to religious objections to DNC were conducted. Fifty-three chaplains and heads of bioethics committees in New Jersey hospitals were contacted by phone or email requesting a research interview. Respondents answered a set of questions about religious exemptions to DNC at the hospital where they worked that explored the frequency of such religious exemptions in the past five years, the religious tradition indicated, and whether any request for a religious exemption had been denied. This study was approved by the Northeastern University Institutional Review Board (IRB #: 16-03-15).

RESULTS

Eighteen chaplains and bioethics committee members participated in a full research interview. Of these, five reported instances of religious exemptions to DNC occurring at the hospital at which they worked for a total of approximately 30-36 known exemptions in the past five years. Families sought religious exemptions because of faith in an Orthodox Judaism tradition and nonreligious reasons. No failed attempts to obtain an exemption were reported.

CONCLUSIONS

Religious exemptions to DNC in New Jersey do occur, although very infrequently. Prior to this study, there was no information on their frequency. Considering religious exemptions do occur, there is a need for national or state policies that addresses both religious objections to DNC and hospital resources. More information is needed to better understand the impact of granting religious exemptions before new policy can be established.