Enhanced pulmonary inflammation in organ donors following fatal non-traumatic brain injury

17β-estradiol and methylprednisolone association as a therapeutic option to modulate lung inflammation in brain-dead female rats

Introduction

Brain death (BD) is known to compromise graft quality by causing hemodynamic, metabolic, and hormonal changes. The abrupt reduction of female sex hormones after BD was associated with increased lung inflammation. The use of both corticoids and estradiol independently has presented positive results in modulating BD-induced inflammatory response. However, studies have shown that for females the presence of both estrogen and corticoids is necessary to ensure adequate immune response. In that sense, this study aims to investigate how the association of methylprednisolone (MP) and estradiol (E2) could modulate the lung inflammation triggered by BD in female rats.

Methods

Female Wistar rats (8 weeks) were divided into four groups: sham (animals submitted to the surgical process, without induction of BD), BD (animals submitted to BD), MP/E2 (animals submitted to BD that received MP and E2 treatment 3h after BD induction) and MP (animals submitted to BD that received MP treatment 3h after BD induction).

Results

Hemodynamics, systemic and local quantification of IL-6, IL-1β, VEGF, and TNF-α, leukocyte infiltration to the lung parenchyma and airways, and adhesion molecule expression were analyzed. After treatment, MP/E2 association was able to reinstate mean arterial pressure to levels close to Sham animals (p<0.05). BD increased leukocyte infiltration to the airways and MP/E2 was able to reduce the number of cells (p=0.0139). Also, the associated treatment modulated the vasculature by reducing the expression of VEGF (p=0.0616) and maintaining eNOS levels (p=0.004) in lung tissue.

Discussion

Data presented in this study show that the association between corticoids and estradiol could represent a better treatment strategy for lung inflammation in the female BD donor by presenting a positive effect in the hemodynamic management of the donor, as well as by reducing infiltrated leukocyte to the airways and release of inflammatory markers in the short and long term.

Pathophysiology of acute lung injury in patients with acute brain injury: the triple-hit hypothesis

It has been convincingly demonstrated in recent years that isolated acute brain injury (ABI) may cause severe dysfunction of peripheral extracranial organs and systems. Of all potential target organs and systems, the lung appears to be the most vulnerable to damage after ABI. The pathophysiology of the bidirectional brain-lung interactions is multifactorial and involves inflammatory cascades, immune suppression, and dysfunction of the autonomic system. Indeed, the systemic effects of inflammatory mediators in patients with ABI create a systemic inflammatory environment ("first hit") that makes extracranial organs vulnerable to secondary procedures that enhance inflammation, such as mechanical ventilation (MV), surgery, and infections ("second hit"). Moreover, accumulating evidence supports the knowledge that gut microbiota constitutes a critical superorganism and an organ on its own, potentially modifying various physiological functions of the host. Furthermore, experimental and clinical data suggest the existence of a communication network among the brain, gastrointestinal tract, and its microbiome, which appears to regulate immune responses, gastrointestinal function, brain function, behavior, and stress responses, also named the "gut-microbiome-brain axis." Additionally, recent research evidence has highlighted a crucial interplay between the intestinal microbiota and the lungs, referred to as the "gut-lung axis," in which alterations during critical illness could result in bacterial translocation, sustained inflammation, lung injury, and pulmonary fibrosis. In the present work, we aimed to further elucidate the pathophysiology of acute lung injury (ALI) in patients with ABI by attempting to develop the "double-hit" theory, proposing the "triple-hit" hypothesis, focused on the influence of the gut-lung axis on the lung. Particularly, we propose, in addition to sympathetic hyperactivity, blast theory, and double-hit theory, that dysbiosis and intestinal dysfunction in the context of ABI alter the gut-lung axis, resulting in the development or further aggravation of existing ALI, which constitutes the "third hit."

Uncontrolled Donation after Circulatory Death Only Lung Program: An Urgent Opportunity

Uncontrolled donation after circulatory death (uDCD) represents a potential source of lungs, and since Steen's 2001 landmark case in Sweden, lungs have been recovered from uDCD donors and transplanted to patients in other European countries (France, the Netherlands, Spain and Italy) with promising results. Disparities still exist among European countries and among regions in Italy due to logistical and organizational factors. The present manuscript focuses on the clinical experiences pertaining to uDCD lungs in North America and European countries and on different lung maintenance methods. Existing experiences (and protocols) are not uniform, especially with respect to the type of lung maintenance, the definition of warm ischemic time (WIT) and, finally, the use of ex vivo perfusion (available in the last several years in most centers). In situ lung cooling may be superior to protective ventilation, but this process may be difficult to perform in the uDCD setting and is also time-consuming. On the other hand, the "protective ventilation technique" is simpler and feasible in every hospital. It may lead to a broader use of uDCD lung donors. To date, the results of lung transplants performed after protective ventilation as a preservation technique are scarce but promising. All the protocols comprise, among the inclusion criteria, a witnessed cardiac arrest. The detectable differences included preservation time (240 vs. 180 min) and donor age (<55 years in Spanish protocols and <65 years in Toronto protocols). Overall, independently of the differences in protocols, lungs from uDCD donors show promising results, and the possibility of optimizing ex vivo lung perfusion may broaden the use of these organs.

Prevalence, in-hospital mortality, and factors related to neurogenic pulmonary edema after spontaneous subarachnoid hemorrhage: a systematic review and meta-analysis

Neurogenic pulmonary edema (NPE) is a life-threatening and severe complication in patients with spontaneous subarachnoid hemorrhage (SAH). The prevalence of NPE varies significantly across studies due to differences in case definitions, study populations, and methodologies. Therefore, a precise estimation of the prevalence and risk factors related to NPE in patients with spontaneous SAH is important for clinical decision-makers, policy providers, and researchers. We conducted a systematic search of the PubMed/Medline, Embase, Web of Science, Scopus, and Cochrane Library databases from their inception to January 2023. Thirteen studies were included in the meta-analysis, with a total of 3,429 SAH patients. The pooled global prevalence of NPE was estimated to be 13%. Out of the eight studies (n = 1095, 56%) that reported the number of in-hospital mortalities of NPE among patients with SAH, the pooled proportion of in-hospital deaths was 47%. Risk factors associated with NPE after spontaneous SAH included female gender, WFNS class, APACHE II score ≥ 20, IL-6 > 40 pg/mL, Hunt and Hess grade ≥ 3, elevated troponin I, elevated white blood cell count, and electrocardiographic abnormalities. Multiple studies showed a strong positive correlation between the WFNS class and NPE. In conclusion, NPE has a moderate prevalence but a high in-hospital mortality rate in patients with SAH. We identified multiple risk factors that can help identify high-risk groups of NPE in individuals with SAH. Early prediction of the onset of NPE is crucial for timely prevention and early intervention.

Respiratory challenges and ventilatory management in different types of acute brain-injured patients

Acute brain injury (ABI) covers various clinical entities that may require invasive mechanical ventilation (MV) in the intensive care unit (ICU). The goal of MV, which is to protect the lung and the brain from further injury, may be difficult to achieve in the most severe forms of lung or brain injury. This narrative review aims to address the respiratory issues and ventilator management, specific to ABI patients in the ICU.

Bronchial Culture Growth From the Donor and Recipient as Predictive Factors in the Detection of Primary Graft Dysfunction and Pneumonia After Lung Transplant

OBJECTIVES

In this study, our aim was to investigate whether bacterial culture growth from donors and recipients is related to early posttransplant complications and to analyze its role in primary graft dysfunction and posttransplant pneumonia in lung transplant recipients.

MATERIALS AND METHODS

This retrospective cohort study included patients diagnosed with end-stage lung disease who received a lung transplant for treatment. We examined relationships between donor bronchial lavage, pretransplant recipient sputum, and recipient posttransplant serial bronchial lavage culture results, as well as the development of both primary graft dysfunction and pneumonia after lung transplant during the early posttransplant period.

RESULTS

Our study included 77 patients with median age of 48 years (25%-75% IQR, 34-56 years) and who were mostly men (79.2%; n = 61). Donor culture positivity was 62.3% (n = 48), and the positivity of sputum culture from patients before transplant was 20.8% (n = 16). Compared with that shown in those without versus those with primary graft dysfunction, there were significantly more positive sputum cultures from patients before transplant (P = .003). Recipients with donor culture growth had a longer duration of invasive mechanical ventilation (median of 4 days [IQR, 2-13 days] vs 1 day [IQR, 1-2 days]; P = .001, respectively) than those without. Multivariate logistic analysis identified both donor culture positivity (odds ratio: 3.391; 95% CI, 1.12-20.46; P = .0028) and sputum culture positivity in pretransplant recipient candidates (odds ratio: 6.494; 95% CI, 1.80-36.27; P = .004) as independent predictors of primary graft dysfunction.

CONCLUSIONS

Bacterial growth shown in donor bronchial lavage and sputum culture positivity in patients before transplant were found to be independent predictors of primary graft dysfunction in the early posttransplant period. Organism growth in both the donor and the recipient during the pretransplant period are important determinants for the development of primary graft dysfunction.

NLRP3 Knockout Protects against Lung Injury Induced by Cerebral Ischemia–Reperfusion

Background and Purpose. Stroke-associated pneumonia (SAP) is a common complication after stroke that increases the mortality of patients. Although there have been many studies suggesting that stroke can increase patient susceptibility to pneumonia, it is still unknown whether the treatment of stroke can also improve lung injury. We used NLRP3-knockout (NLRP3-KO) mice to verify that an improvement in brain injury would also be beneficial to lung injury and further confirm the relationship between stroke and pneumonia. Methods. C57/BL6 wild-type (WT) and NLRP3-KO mice were used to construct middle cerebral artery occlusion (MCAO) models. 2,3,5-Triphenyltetrazolium chloride (TTC) was used to evaluate brain damage, and neurological deficits were assessed. Then, lung tissue injury was examined in the different groups of mice by hematoxylin-eosin (HE) staining. Inflammation (macrophage and neutrophil infiltration, NLRP3-associated inflammatory molecules) and oxidative stress (reactive oxygen species, ROS) in the lungs were comprehensively examined by immunofluorescence staining and Western blotting. Results. First, our findings demonstrated that NLRP3 knockout had a protective effect against cerebral ischemia–reperfusion injury after MCAO. Second, by reducing brain damage after MCAO, lung inflammation was also alleviated. Immunofluorescence staining showed that NLRP3-KO-MCAO mice had reduced inflammatory effector molecule (caspase-1 and IL-1β) expression and macrophage and neutrophil infiltration in the lung, as well as remissive oxidative stress state in the lung, compared with WT-MCAO mice. We also observed a decrease in phosphorylated p65 (p-p65) (an NF-κB factor) in NLRP3-KO-MCAO mice, suggesting that the NF-κB pathway was involved in the protective effect of NLRP3 gene knockout on stroke-induced lung injury. Conclusions. NLRP3 inflammasome knockout not only is beneficial for cerebral ischemia–reperfusion injury but also reduces the severity of poststroke lung injury by reducing brain damage. It has been confirmed that there is a relationship between central insult and peripheral organ injury, and protecting the brain can prevent peripheral organ damage.

Brain stem death induces pro-inflammatory cytokine production and cardiac dysfunction in sheep model

Introduction

Organs procured following brain stem death (BSD) are the main source of organ grafts for transplantation. However, BSD is associated with inflammatory responses that may damage the organ and affect both the quantity and quality of organs available for transplant. Therefore, we aimed to investigate plasma and bronchoalveolar lavage (BAL) pro-inflammatory cytokine profiles and cardiovascular physiology in a clinically relevant 6-h ovine model of BSD.

Methods

Twelve healthy female sheep (37–42 Kg) were anaesthetized and mechanically ventilated prior to undergoing BSD induction and then monitored for 6 h. Plasma and BAL endothelin-1 and cytokines (IL-1β, 6, 8 and tumour necrosis factor alpha (TNF-α)) were assessed by ELISA. Differential white blood cell counts were performed. Cardiac function during BSD was also examined using echocardiography, and cardiac biomarkers (A-type natriuretic peptide and troponin I were measured in plasma.

Results

Plasma concentrations big ET-1, IL-6, IL-8, TNF-α and BAL IL-8 were significantly (p < 0.01) increased over baseline at 6 h post-BSD. Increased numbers of neutrophils were observed in the whole blood (3.1 × 10⁹ cells/L [95% confidence interval (CI) 2.06–4.14] vs. 6 × 10⁹ cells/L [95%CI 3.92–7.97]; p < 0.01) and BAL (4.5 × 10⁹ cells/L [95%CI 0.41–9.41] vs. 26 [95%CI 12.29–39.80]; p = 0.03) after 6 h of BSD induction vs baseline. A significant increase in ANP production (20.28 pM [95%CI 16.18–24.37] vs. 78.68 pM [95%CI 53.16–104.21]; p < 0.0001) and cTnI release (0.039 ng/mL vs. 4.26 [95%CI 2.69–5.83] ng/mL; p < 0.0001), associated with a significant reduction in heart contractile function, were observed between baseline and 6 h.

Conclusions

BSD induced systemic pro-inflammatory responses, characterized by increased neutrophil infiltration and cytokine production in the circulation and BAL fluid, and associated with reduced heart contractile function in ovine model of BSD.

Brain-lung interactions and mechanical ventilation in patients with isolated brain injury

During the last decade, experimental and clinical studies have demonstrated that isolated acute brain injury (ABI) may cause severe dysfunction of peripheral extracranial organs and systems. Of all potential target organs and systems, the lung appears to be the most vulnerable to damage after brain injury (BI). The pathophysiology of these brain–lung interactions are complex and involve neurogenic pulmonary oedema, inflammation, neurodegeneration, neurotransmitters, immune suppression and dysfunction of the autonomic system. The systemic effects of inflammatory mediators in patients with BI create a systemic inflammatory environment that makes extracranial organs vulnerable to secondary procedures that enhance inflammation, such as mechanical ventilation (MV), surgery and infections. Indeed, previous studies have shown that in the presence of a systemic inflammatory environment, specific neurointensive care interventions—such as MV—may significantly contribute to the development of lung injury, regardless of the underlying mechanisms. Although current knowledge supports protective ventilation in patients with BI, it must be born in mind that ABI-related lung injury has distinct mechanisms that involve complex interactions between the brain and lungs. In this context, the role of extracerebral pathophysiology, especially in the lungs, has often been overlooked, as most physicians focus on intracranial injury and cerebral dysfunction. The present review aims to fill this gap by describing the pathophysiology of complications due to lung injuries in patients with a single ABI, and discusses the possible impact of MV in neurocritical care patients with normal lungs.

Beyond the Brain: Peripheral Interactions after Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability, and there are currently no pharmacological treatments known to improve patient outcomes. Unquestionably, contributing toward a lack of effective treatments is the highly complex and heterogenous nature of TBI. In this review, we highlight the recent surge of research that has demonstrated various central interactions with the periphery as a potential major contributor toward this heterogeneity and, in particular, the breadth of research from Australia. We describe the growing evidence of how extracranial factors, such as polytrauma and infection, can significantly alter TBI neuropathology. In addition, we highlight how dysregulation of the autonomic nervous system and the systemic inflammatory response induced by TBI can have profound pathophysiological effects on peripheral organs, such as the heart, lung, gastrointestinal tract, liver, kidney, spleen, and bone. Collectively, this review firmly establishes TBI as a systemic condition. Further, the central and peripheral interactions that can occur after TBI must be further explored and accounted for in the ongoing search for effective treatments.

New models for donor-recipient matching in lung transplantations

Objective

One of the main problems of lung transplantation is the shortage of organs as well as reduced survival rates. In the absence of an international standardized model for lung donor-recipient allocation, we set out to develop such a model based on the characteristics of past experiences with lung donors and recipients with the aim of improving the outcomes of the entire transplantation process.

Methods

This was a retrospective analysis of 404 lung transplants carried out at the Reina Sofía University Hospital (Córdoba, Spain) over 23 years. We analyzed various clinical variables obtained via our experience of clinical practice in the donation and transplantation process. These were used to create various classification models, including classical statistical methods and also incorporating newer machine-learning approaches.

Results

The proposed model represents a powerful tool for donor-recipient matching, which in this current work, exceeded the capacity of classical statistical methods. The variables that predicted an increase in the probability of survival were: higher pre-transplant and post-transplant functional vital capacity (FVC), lower pre-transplant carbon dioxide (PCO2) pressure, lower donor mechanical ventilation, and shorter ischemia time. The variables that negatively influenced transplant survival were low forced expiratory volume in the first second (FEV1) pre-transplant, lower arterial oxygen pressure (PaO2)/fraction of inspired oxygen (FiO2) ratio, bilobar transplant, elderly recipient and donor, donor-recipient graft disproportion requiring a surgical reduction (Tailor), type of combined transplant, need for cardiopulmonary bypass during the surgery, death of the donor due to head trauma, hospitalization status before surgery, and female and male recipient donor sex.

Conclusions

These results show the difficulty of the problem which required the introduction of other variables into the analysis. The combination of classical statistical methods and machine learning can support decision-making about the compatibility between donors and recipients. This helps to facilitate reliable prediction and to optimize the grafts for transplantation, thereby improving the transplanted patient survival rate.

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.

Crosstalk between brain, lung and heart in critical care

Extracerebral complications, especially pulmonary and cardiovascular, are frequent in brain-injured patients and are major outcome determinants. Two major pathways have been described: brain-lung and brain-heart interactions. Lung injuries after acute brain damages include ventilator-associated pneumonia (VAP), acute respiratory distress syndrome (ARDS) and neurogenic pulmonary œdema (NPE), whereas heart injuries can range from cardiac enzymes release, ECG abnormalities to left ventricle dysfunction or cardiogenic shock. The pathophysiologies of these brain-lung and brain-heart crosstalk are complex and sometimes interconnected. This review aims to describe the epidemiology and pathophysiology of lung and heart injuries in brain-injured patients with the different pathways implicated and the clinical implications for critical care physicians.

Comparison of outcomes in lung and heart transplant recipients from the same multiorgan donor

BACKGROUND

Primary graft dysfunction (PGD) and acute cellular rejection (ACR) are important causes of early morbidity and mortality following lung and heart transplantation. While many studies have elucidated donor-related risk factors of PGD and ACR, these complications often occur even with "ideal" donors. Therefore, we investigated potential associations of PGD and ACR between bilateral lung and heart transplant recipients from the same multiorgan donor, respectively.

METHODS

Between 2011 and 2017, 100 donors contributed 100 bilateral lung transplants and 100 heart transplants performed. Logistic regression analysis for PGD and Cox proportional hazards regression analysis for ACR were used to estimate the relationship of heart and lung transplants.

RESULTS

The incidence of PGD was 33% among lung and 17% among heart transplant recipients. Similarly, the incidence of ACR grade ≥ A2 for lung recipients was 38% (30/80), and the incidence of ACR grade ≥ 2R for heart recipients was 19% (15/80). There was no association between the development of PGD and ACR in lung and heart transplant recipients from the same donor, respectively.

CONCLUSIONS

These findings suggest that inherent donor factors are not critical to the development of PGD and ACR after lung and heart transplantation.

Neural-respiratory inflammasome axis in traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality. Approximately 20-25% of TBI subjects develop Acute Lung Injury (ALI), but the pathomechanisms of TBI-induced ALI remain poorly defined. Currently, mechanical ventilation is the only therapeutic intervention for TBI-induced lung injury. Our recent studies have shown that the inflammasome plays an important role in the systemic inflammatory response leading to lung injury-post TBI. Here, we outline the role of the extracellular vesicle (EV)-mediated inflammasome signaling in the etiology of TBI-induced ALI. Furthermore, we evaluate the efficacy of a low molecular weight heparin (Enoxaparin, a blocker of EV uptake) and a monoclonal antibody against apoptosis speck-like staining protein containing a caspase recruitment domain (anti-ASC) as therapeutics for TBI-induced lung injury. We demonstate that activation of an EV-mediated Neural-Respiratory Inflammasome Axis plays an essential role in TBI-induced lung injury and disruption of this axis has therapeutic potential as a treatment strategy.

An observational study of Donor Ex Vivo Lung Perfusion in UK lung transplantation: DEVELOP-UK

BACKGROUND

Many patients awaiting lung transplantation die before a donor organ becomes available. Ex vivo lung perfusion (EVLP) allows initially unusable donor lungs to be assessed and reconditioned for clinical use.

OBJECTIVE

The objective of the Donor Ex Vivo Lung Perfusion in UK lung transplantation study was to evaluate the clinical effectiveness and cost-effectiveness of EVLP in increasing UK lung transplant activity.

DESIGN

A multicentre, unblinded, non-randomised, non-inferiority observational study to compare transplant outcomes between EVLP-assessed and standard donor lungs.

SETTING

Multicentre study involving all five UK officially designated NHS adult lung transplant centres.

PARTICIPANTS

Patients aged ≥ 18 years with advanced lung disease accepted onto the lung transplant waiting list.

INTERVENTION

The study intervention was EVLP assessment of donor lungs before determining suitability for transplantation.

MAIN OUTCOME MEASURES

The primary outcome measure was survival during the first 12 months following lung transplantation. Secondary outcome measures were patient-centred outcomes that are influenced by the effectiveness of lung transplantation and that contribute to the health-care costs.

RESULTS

Lungs from 53 donors unsuitable for standard transplant were assessed with EVLP, of which 18 (34%) were subsequently transplanted. A total of 184 participants received standard donor lungs. Owing to the early closure of the study, a non-inferiority analysis was not conducted. The Kaplan-Meier estimate of survival at 12 months was 0.67 [95% confidence interval (CI) 0.40 to 0.83] for the EVLP arm and 0.80 (95% CI 0.74 to 0.85) for the standard arm. The hazard ratio for overall 12-month survival in the EVLP arm relative to the standard arm was 1.96 (95% CI 0.83 to 4.67). Patients in the EVLP arm required ventilation for a longer period and stayed longer in an intensive therapy unit (ITU) than patients in the standard arm, but duration of overall hospital stay was similar in both groups. There was a higher rate of very early grade 3 primary graft dysfunction (PGD) in the EVLP arm, but rates of PGD did not differ between groups after 72 hours. The requirement for extracorporeal membrane oxygenation (ECMO) support was higher in the EVLP arm (7/18, 38.8%) than in the standard arm (6/184, 3.2%). There were no major differences in rates of chest radiograph abnormalities, infection, lung function or rejection by 12 months. The cost of EVLP transplants is approximately £35,000 higher than the cost of standard transplants, as a result of the cost of the EVLP procedure, and the increased ECMO use and ITU stay. Predictors of cost were quality of life on joining the waiting list, type of transplant and number of lungs transplanted. An exploratory model comparing a NHS lung transplant service that includes EVLP and standard lung transplants with one including only standard lung transplants resulted in an incremental cost-effectiveness ratio of £73,000. Interviews showed that patients had a good understanding of the need for, and the processes of, EVLP. If EVLP can increase the number of usable donor lungs and reduce waiting, it is likely to be acceptable to those waiting for lung transplantation. Study limitations include small numbers in the EVLP arm, limiting analysis to descriptive statistics and the EVLP protocol change during the study.

CONCLUSIONS

Overall, one-third of donor lungs subjected to EVLP were deemed suitable for transplant. Estimated survival over 12 months was lower than in the standard group, but the data were also consistent with no difference in survival between groups. Patients receiving these additional transplants experience a higher rate of early graft injury and need for unplanned ECMO support, at increased cost. The small number of participants in the EVLP arm because of early study termination limits the robustness of these conclusions. The reason for the increased PGD rates, high ECMO requirement and possible differences in lung injury between EVLP protocols needs evaluation.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44922411.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 85. See the NIHR Journals Library website for further project information.

Profiling inflammation and tissue injury markers in perfusate and bronchoalveolar lavage fluid during human ex vivo lung perfusion

OBJECTIVES: Availability of donor lungs suitable for transplant falls short of current demand and contributes to waiting list mortality. Ex vivo lung perfusion (EVLP) offers the opportunity to objectively assess and recondition organs unsuitable for immediate transplant. Identifying robust biomarkers that can stratify donor lungs during EVLP to use or non-use or for specific interventions could further improve its clinical impact.

METHODS: In this pilot study, 16 consecutive donor lungs unsuitable for immediate transplant were assessed by EVLP. Key inflammatory mediators and tissue injury markers were measured in serial perfusate samples collected hourly and in bronchoalveolar lavage fluid (BALF) collected before and after EVLP. Levels were compared between donor lungs that met criteria for transplant and those that did not.

RESULTS: Seven of the 16 donor lungs (44%) improved during EVLP and were transplanted with uniformly good outcomes. Tissue and vascular injury markers lactate dehydrogenase, HMGB-1 and Syndecan-1 were significantly lower in perfusate from transplanted lungs. A model combining IL-1β and IL-8 concentrations in perfusate could predict final EVLP outcome after 2 h assessment. In addition, perfusate IL-1β concentrations showed an inverse correlation to recipient oxygenation 24 h post-transplant.

CONCLUSIONS: This study confirms the feasibility of using inflammation and tissue injury markers in perfusate and BALF to identify donor lungs most likely to improve for successful transplant during clinical EVLP. These results support examining this issue in a larger study.

The role of interleukin-1β as a predictive biomarker and potential therapeutic target during clinical ex vivo lung perfusion

Background

Extended criteria donor lungs deemed unsuitable for immediate transplantation can be reconditioned using ex vivo lung perfusion (EVLP). Objective identification of which donor lungs can be successfully reconditioned and will function well post-operatively has not been established. This study assessed the predictive value of markers of inflammation and tissue injury in donor lungs undergoing EVLP as part of the DEVELOP-UK study.

Methods

Longitudinal samples of perfusate, bronchoalveolar lavage, and tissue from 42 human donor lungs undergoing clinical EVLP assessments were analyzed for markers of inflammation and tissue injury. Levels were compared according to EVLP success and post-transplant outcomes. Neutrophil adhesion to human pulmonary microvascular endothelial cells (HPMECs) conditioned with perfusates from EVLP assessments was investigated on a microfluidic platform.

Results

The most effective markers to differentiate between in-hospital survival and non-survival post-transplant were perfusate interleukin (IL)-1β (area under the curve = 1.00, p = 0.002) and tumor necrosis factor-α (area under the curve = 0.95, p = 0.006) after 30 minutes of EVLP. IL-1β levels in perfusate correlated with upregulation of intracellular adhesion molecule-1 in donor lung vasculature (R² = 0.68, p < 0.001) and to a lesser degree upregulation of intracellular adhesion molecule-1 (R² = 0.30, p = 0.001) and E-selectin (R² = 0.29, p = 0.001) in conditioned HPMECs and neutrophil adhesion to conditioned HPMECs (R² = 0.33, p < 0.001). Neutralization of IL-1β in perfusate effectively inhibited neutrophil adhesion to conditioned HPMECs (91% reduction, p = 0.002).

Conclusions

Donor lungs develop a detectable and discriminatory pro-inflammatory signature in perfusate during EVLP. Blocking the IL-1β pathway during EVLP may reduce endothelial activation and subsequent neutrophil adhesion on reperfusion; this requires further investigation in vivo.

Airway management and mechanical ventilation in acute brain injury

Patients with acute neurologic disease often develop respiratory failure, the management of which profoundly affects brain physiology and long-term functional outcomes. This chapter reviews airway management and mechanical ventilation of patients with acute brain injury, offering practical strategies to optimize treatment of respiratory failure and minimize secondary brain injury. Specific concerns that are addressed include physiologic changes during intubation and ventilation such as the effects on intracranial pressure and brain perfusion; cervical spine management during endotracheal intubation; the role of tracheostomy; and how ventilation and oxygenation are utilized to minimize ischemia-reperfusion injury and cerebral metabolic distress.

Increasing the Quantity of Lungs for Transplantation Using High-Frequency Chest Wall Oscillation: A Proposal

The use of chest physiotherapy in donor patient management occupies an established place in most lung procurement protocols. Although its merits remain controversial and uncorroborated by direct data, some studies support the efficacy of chest physiotherapy in a variety of pulmonary patient populations. Comparative studies have shown that an airway clearance technology utilizing high-frequency chest wall oscillation clears pulmonary secretions as well as or better than chest physiotherapy, but has few of its contraindications and disadvantages. The implementation of high-frequency chest wall oscillation as part of the donor lung procurement protocol may increase rates of successful lung recovery by providing effective clearance of obstructing pulmonary secretions containing destructive by-products of inflammation and entrapped pathogens. High-frequency chest wall oscillation may also improve arterial blood gas values, a critical factor in increasing lung procurement rates. Although speculative, the benefits of high-frequency chest wall oscillation on donor lungs might improve perfusion and oxygenation of other organs for possible transplantation.

Brain-lung crosstalk: Implications for neurocritical care patients

Major pulmonary disorders may occur after brain injuries as ventilator-associated pneumonia, acute respiratory distress syndrome or neurogenic pulmonary edema. They are key points for the management of brain-injured patients because respiratory failure and mechanical ventilation seem to be a risk factor for increased mortality, poor neurological outcome and longer intensive care unit or hospital length of stay. Brain and lung strongly interact via complex pathways from the brain to the lung but also from the lung to the brain. Several hypotheses have been proposed with a particular interest for the recently described “double hit” model. Ventilator setting in brain-injured patients with lung injuries has been poorly studied and intensivists are often fearful to use some parts of protective ventilation in patients with brain injury. This review aims to describe the epidemiology and pathophysiology of lung injuries in brain-injured patients, but also the impact of different modalities of mechanical ventilation on the brain in the context of acute brain injury.

[Post-mortem organ donation]

In Germany approximately 3000 body organs are transplanted annually. In general, all artificially ventilated patients with diagnosed brain death are potential organ donors. All German hospitals are obliged to report potential organ donors and be actively involved in the organ donation process. These matters lie under the jurisdiction of the German transplantation act. An essential prerequisite for organ donation is the diagnosis of brain death according to the guidelines of the German Medical Association. Brain death is associated with complex pathophysiological changes in cardiopulmonary function as well as fluid, electrolyte and metabolic homeostasis. In the case of diagnosed brain death and with permission for organ donation, a precise organ-protective therapy is initiated, essentially focussing on optimal organ perfusion and oxygenation. The quality of organ protection has a direct influence on the outcome of transplantation.

A standardized model of brain death, donor treatment, and lung transplantation for studies on organ preservation and reconditioning

BACKGROUND

We set a model of brain death, donor management, and lung transplantation for studies on lung preservation and reconditioning before transplantation.

METHODS

Ten pigs (39.7 ± 5.9 Kg) were investigated. Five animals underwent brain death and were treated as organ donors; the lungs were then procured and cold stored (Ischemia). Five recipients underwent left lung transplantation and post-reperfusion follow-up (Graft). Cardiorespiratory and metabolic parameters were collected. Lung gene expression of cytokines (tumor necrosis factor alpha (TNFα), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interferon gamma (IFNγ), high mobility group box-1 (HMGB-1)), chemokines (chemokine CC motif ligand-2 (CCL2-MCP-1), chemokine CXC motif ligand-10 (CXCL-10), interleukin-8 (IL-8)), and endothelial activation markers (endothelin-1 (EDN-1), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), selectin-E (SELE)) was assessed by real-time polymerase chain reaction (PCR).

RESULTS

Tachycardia and hypertension occurred during brain death induction; cardiac output rose, systemic vascular resistance dropped (P < 0.05), and diabetes insipidus occurred. Lung-protective ventilation strategy was applied: 9 h after brain death induction, PaO2 was 192 ± 12 mmHg at positive end-expiratory pressure (PEEP) 8.0 ± 1.8 cmH2O and FiO2 of 40%; wet-to-dry ratio (W/D) was 5.8 ± 0.5, and extravascular lung water (EVLW) was 359 ± 80 mL. Procured lungs were cold-stored for 471 ± 24 min (Ischemia) at the end of which W/D was 6.1 ± 0.9. Left lungs were transplanted and reperfused (warm ischemia 98 ± 14 min). Six hours after controlled reperfusion, PaO2 was 192 ± 23 mmHg (PEEP 8.7 ± 1.5 cmH2O, FiO2 40%), W/D was 5.6 ± 0.4, and EVLW was 366 ± 117 mL. Levels of IL-8 rose at the end of donor management (BD, P < 0.05); CCL2-MCP-1, IL-8, HMGB-1, and SELE were significantly altered after reperfusion (Graft, P < 0.05).

CONCLUSIONS

We have set a standardized, reproducible pig model resembling the entire process of organ donation that may be used as a platform to test in vivo and ex vivo strategies of donor lung optimization before transplantation.

Brain death-induced inflammatory activity in human pancreatic tissue: a case-control study

BACKGROUND

Long-term insulin independence after islet transplantation depends on engraftment of a large number of islets. However, the yield of pancreatic islets from brain-dead donors is negatively affected by the up-regulation of inflammatory mediators. Brain death is also believed to increase tissue factor (TF) expression, contributing to a low rate of engraftment.

METHODS

We conducted a case-control study to assess brain death-induced inflammatory effects in human pancreas. Seventeen brain-dead patients and 20 control patients undergoing pancreatectomy were studied. Serum tumor necrosis factor (TNF), interleukin (IL) 6, IL-1β, interferon (IFN) γ, and TF were measured using enzyme-linked immunosorbent assay kits. Gene expressions of these cytokines and TF were evaluated by reverse transcriptase quantitative polymerase chain reaction. Protein quantification was performed by immunohistochemistry in paraffin-embedded pancreas sections.

RESULTS

Brain-dead patients had higher serum concentrations of TNF and IL-6 and increased TNF protein levels compared to controls. The groups had similar TNF, IL-6, IL-1β, and IFN-γ messenger RNA levels in pancreatic tissue. Reverse transcriptase quantitative polymerase chain reaction revealed TF messenger RNA up-regulation in controls. Immunohistochemical analyses showed that brain-dead patients had increased TNF protein levels compared to controls.

CONCLUSIONS

Brain death induces inflammation evidenced by the up-regulation of TNF in serum and pancreatic tissue. Blocking the expression of key inflammatory mediators in brain-dead donors should be evaluated as a new approach to improve the outcomes of islet transplantation.

Preclinical pulmonary capillary endothelial dysfunction is present in brain dead subjects

Pulmonary endothelium is a major metabolic organ affecting pulmonary and systemic vascular homeostasis. Brain death (BD)-induced physiologic and metabolic derangements in donors’ lungs, in the absence of overt lung pathology, may cause pulmonary dysfunction and compromise post-transplant graft function. To explore the impact of BD on pulmonary endothelium, we estimated pulmonary capillary endothelium-bound (PCEB)-angiotensin converting enzyme (ACE) activity, a direct and quantifiable index of pulmonary endothelial function, in eight brain-dead patients and ten brain-injured mechanically ventilated controls. No subject suffered from acute lung injury or any other overt lung pathology. Applying indicator-dilution type techniques, we measured single-pass transpulmonary percent metabolism (%M) and hydrolysis (v) of the synthetic, biologically inactive, and highly specific for ACE substrate ³H-benzoyl-Phe-Ala-Pro, under first order reaction conditions, and calculated lung functional capillary surface area (FCSA). Substrate %M (35 ± 6.8%) and v (0.49 ± 0.13) in BD patients were decreased as compared to controls (55.9 ± 4.9, P = 0.033 and 0.9 ± 0.15, P = 0.033, respectively), denoting decreased pulmonary endothelial enzyme activity at the capillary level; FCSA, a reflection of endothelial enzyme activity per vascular bed, was also decreased (BD patients: 1,563 ± 562 mL/min vs 4,235 ± 559 in controls; P = 0.003). We conclude that BD is associated with subtle pulmonary endothelial injury, expressed by decreased PCEB-ACE activity. The applied indicator-dilution type technique provides direct and quantifiable indices of pulmonary endothelial function at the bedside that may reveal the existence of preclinical lung pathology in potential lung donors.

Effects of traumatic brain injury on intestinal contractility

BACKGROUND

Patients with traumatic brain injury (TBI) often suffer from gastrointestinal dysfunction including intolerance to enteral feedings. However, it is unclear how TBI affects small intestinal contractile activity. The purpose of this study was to determine if TBI affects intestinal smooth muscle function.

METHODS

Sprague-Dawley rats were subjected to controlled cortical impact injury (TBI). Sham animals underwent a similar surgery but no injury (SHAM). Animals were sacrificed 1, 3, and 7 days after TBI and intestinal smooth muscle tissue was collected for measurement of contractile activity and transit, NF-kB activity, and cytokine levels. Brains were collected after sacrifice to determine volume loss due to injury.

KEY RESULTS

Contractile activity decreased significantly in ileum, but not jejunum, in the TBI group 7 days after injury compared with SHAM. Brain volume loss increased significantly 7 days after injury compared with 3 days and correlated significantly with the contractile activity 1 day after injury. In the intestinal smooth muscle, NF-kB activity increased significantly in the TBI group 3 and 7 days after injury vs SHAM. Wet to dry weight ratio, indicating edema, also increased significantly in the TBI group. Interleukin-1α, -1β, and -17 increased significantly in the TBI group compared with SHAM.

CONCLUSIONS & INFERENCES

Traumatic brain injury causes a delayed but significant decrease in intestinal contractile activity in the ileum leading to delayed transit. The decreased intestinal contractile activity is attributed to secondary inflammatory injury as evidenced by increased NF-kB activity, increased edema, and increased inflammatory cytokines in the intestinal smooth muscle.

Critical care of the potential organ donor

Organ transplantation represents one of the great success stories of 20th century medicine. However, its continued success is greatly limited by the shortage of donor organs. This has led to an increased focus within the critical care community on optimal identification and management of the potential organ donor. The multi-organ donor can represent one of the most complex intensive care patients, with numerous competing physiological priorities. However, appropriate management of the donor not only increases the number of organs that can be successfully donated but has long-term implications for the outcomes of multiple recipients. This review outlines current understandings of the physiological derangements seen in the organ donor and evaluates the available evidence for management strategies designed to optimize donation potential and organ recovery. Finally, emerging management strategies for the potential donor are discussed within the current ethical and legal frameworks permitting donation after both brain and circulatory death.

Management of the Potential Organ Donor in the ICU

There is a major gap between supply and demand of organs for transplantation. Organ donation after neurological death is increasing in the United States, and there is potential for this gap to be minimized by focused medical management of the potential donor in the ICU. Increasing organ yield requires early potential donor identification and early referral to organ procurement organizations, and understanding the medical issues specific to the brain-dead patient, such as hemodynamic instability requiring vasopressors, coagulopathy, diabetes insipidus, renal failure, and acute lung injury/acute respiratory distress syndrome. Intensive care with treatment focused on these issues has the potential to increase both the number of potential donors and the number of organs transplanted per donor.

Management of the heartbeating brain-dead organ donor

The main factor limiting organ donation is the availability of suitable donors and organs. Currently, most transplants follow multiple organ retrieval from heartbeating brain-dead organ donors. However, brain death is often associated with marked physiological instability, which, if not managed, can lead to deterioration in organ function before retrieval. In some cases, this prevents successful donation. There is increasing evidence that moderation of these pathophysiological changes by active management in Intensive Care maintains organ function, thereby increasing the number and functional quality of organs available for transplantation. This strategy of active donor management requires an alteration of philosophy and therapy on the part of the intensive care unit clinicians and has significant resource implications if it is to be delivered reliably and safely. Despite increasing consensus over donor management protocols, many of their components have not yet been subjected to controlled evaluation. Hence the optimal combinations of treatment goals, monitoring, and specific therapies have not yet been fully defined. More research into the component techniques is needed.

Acute lung injury in patients with severe brain injury: a double hit model

The presence of pulmonary dysfunction after brain injury is well recognized. Acute lung injury (ALI) occurs in 20% of patients with isolated brain injury and is associated with a poor outcome. The "blast injury" theory, which proposes combined "hydrostatic" and "high permeability" mechanisms for the formation of neurogenic pulmonary edema, has been challenged recently by the observation that a systemic inflammatory response may play an integral role in the development of pulmonary dysfunction associated with brain injury. As a result of the primary cerebral injury, a systemic inflammatory reaction occurs, which induces an alteration in blood-brain barrier permeability and infiltration of activated neutrophils into the lung. This preclinical injury makes the lungs more susceptible to the mechanical stress of an injurious ventilatory strategy. Tight CO2 control is a therapeutic priority in patients with acute brain injury, but the use of high tidal volume ventilation may contribute to the development of ALI. Establishment of a therapeutic regimen that allows the combination of protective ventilation with the prevention of hypercapnia is, therefore, required. Moreover, in patients with brain injury, hypoxemia represents a secondary insult associated with a poor outcome. Optimal oxygenation may be achieved by using an adequate FiO2 and by application of positive end-expiratory pressure (PEEP). PEEP may, however, affect the cerebral circulation by hemodynamic and CO2-mediated mechanisms and the effects of PEEP on cerebral hemodynamics should be monitored in these patients and used to titrate its application.

Special issues in the management and selection of the donor for lung transplantation

Lung transplantation is a viable treatment option for select patients with end-stage lung disease. Two issues hamper progress in transplantation: first, donor shortage is a major limitation to increasing the number of transplants performed. Secondly, recipient outcomes remain disappointing when compared with other solid organ transplant results. Outcomes are limited by primary graft dysfunction (PGD), the posttransplant acute lung injury that increases both short-and long-term mortality. Attempts to overcome donor shortage have included aggressively managing solid organ donors to increase the number of donor lungs suitable for transplantation. Yet, the quality of the lung donor is likely to be related to the probability of the recipient experiencing PGD. PGD is the culmination of a series of insults, hemodynamic, metabolic, and inflammatory, that begin with the brain dead donor and result in poor recipient outcomes. Understanding the mechanism of donor lung injury resulting from brain death and the possible treatment strategies for its inhibition could help to increase the number of usable lungs and decrease the rate of PGD in the recipient. Here we present a review of the key pathways which result in donor lung injury, and follow this with a brief review of recent biomarkers that are proving to be instrumental to our ability to predict truly unsuitable lungs, and our ability to predict and hopefully prevent or treat recipients with subsequent lung injury.

How I manage the adult potential organ donor: donation after neurological death (part 1)

The need for organ donation has become a growing concern over that last decade as the gap between organ donors and those awaiting transplant widens. According to UNOS, as of 8/2009, there were 102,962 patients on the transplant waiting list and only 6,004 donors in 2009 (UNOS.org. Accessed 4/8/2009). In 2008, an estimated 17 patients died each day awaiting transplant (OPTN.org). Though currently most organ donations come after brain death (DND or donation after neurological death), tissue donation (cornea, skin, bone, and musculoskeletal tissue), and donation after cardiac death (DCD) and are also possible. The term "extended criteria donor" refers to potential donors over 60 years of age or age 50-59 years plus 2 of the 3 following criteria: stroke as the cause of death, creatnine > 1.5 meq/dl, or a history of hypertension. Historically, extended criteria donors have had a lower organ yield per donor. In order to preserve the choice of organ donation for the family, intensive management of the potential organ donor is necessary. Since each potential donor could save seven lives or more, nihilism in the care of such patients can have far reaching ramifications. This article describes intensive care management practices that can optimize organ donation.

Regulated gene expression in cultured type II cells of adult human lung

Alveolar type II cells have multiple functions, including surfactant production and fluid clearance, which are critical for lung function. Differentiation of type II cells occurs in cultured fetal lung epithelial cells treated with dexamethasone plus cAMP and isobutylmethylxanthine (DCI) and involves increased expression of 388 genes. In this study, type II cells of human adult lung were isolated at approximately 95% purity, and gene expression was determined (Affymetrix) before and after culturing 5 days on collagen-coated dishes with or without DCI for the final 3 days. In freshly isolated cells, highly expressed genes included SFTPA/B/C, SCGB1A, IL8, CXCL2, and SFN in addition to ubiquitously expressed genes. Transcript abundance was correlated between fetal and adult cells (r = 0.88), with a subset of 187 genes primarily related to inflammation and immunity that were expressed >10-fold higher in adult cells. During control culture, expression increased for 8.1% of expressed genes and decreased for approximately 4% including 118 immune response and 10 surfactant-related genes. DCI treatment promoted lamellar body production and increased expression of approximately 3% of probed genes by > or =1.5-fold; 40% of these were also induced in fetal cells. Highly induced genes (> or =10-fold) included PGC, ZBTB16, DUOX1, PLUNC, CIT, and CRTAC1. Twenty-five induced genes, including six genes related to surfactant (SFTPA/B/C, PGC, CEBPD, and ADFP), also had decreased expression during control culture and thus are candidates for hormonal regulation in vivo. Our results further define the adult human type II cell molecular phenotype and demonstrate that a subset of genes remains hormone responsive in cultured adult cells.

[Hormone modulation of organ donor. Utility of the steroids]

Recently, the work group made up of the National Transplant Organization (Organización Nacional de Trasplantes, ONT), Spanish Society of Intensive, Critical Medicine and Coronary Units (Sociedad Española de Medicina Intensiva, Crítica y de Unidades Coronarias, SEMICYUC) and other Scientific Societies have recommended using 15 mg/kg of methyl prednisolone during the management of lung donors after brain death. This recommendation is based on descriptive and retrospective studies. However, the review of different experimental and clinical studies also suggests a potential benefit of using steroids in either thoracic or abdominal organ donors during management strategies. In brain death management, early steroid administration may decrease cytokine production and also may prevent alterations induced by proinflammatoy mediators, stabilize cell membranes, reduce expression of cell surface adhesion molecules and avoid lipid peroxidation after the ischemic period. This could be beneficial in increasing number and quality of organs harvested and in decreasing rejection episodes after transplant. It would be very recommendable to carry out prospective and comparative studies to demonstrate these potential utilities. Meanwhile and knowing the deleterious effects of inflammatory activity arising during and after brain death, we recommend using 15 mg/kg of methyl prednisolone in the organ donor management, as soon as possible. The potential benefit of its immunomodulation effects, its low cost and the absence of major side effects can justify this recommendation.

Extended donor criteria in lung transplantation

PURPOSE OF REVIEW

Despite improvements in respiratory care and lung transplant organ allocation algorithms, waiting lists continue to grow worldwide. Attempts at improving organ donation rates have generally had little impact on the increase in the number of transplants performed. Improved use of the available pool of cadaveric organ donors, therefore, represents one of few immediately available strategies to alleviate organ shortages.

RECENT FINDINGS

The once-strict lung donor selection criteria have, of necessity, been relaxed and, in many instances, this situation has been to no apparent detrimental effect on posttransplant outcome. There is, however, some evidence that extension of donor acceptability in some respects leads to poorer early outcomes, mainly by increasing the rate of early graft dysfunction. The extension of selection criteria to allow the maximum number of safe lung transplants, coupled with aggressive and appropriate donor management is, therefore, of particular current relevance to the lung transplantation community.

SUMMARY

Although the available evidence for and against the commonly used lung donor selection criteria leaves many questions unanswered, it can help decrease the large number of uncertainties that be falls the practice of lung donor selection and recipient matching.

Acute lung injury in patients with severe brain injury: a double hit model

The presence of pulmonary dysfunction after brain injury is well recognized. Acute lung injury (ALI) occurs in 20% of patients with isolated brain injury and is associated with a poor outcome. The "blast injury" theory, which proposes combined "hydrostatic" and "high permeability" mechanisms for the formation of neurogenic pulmonary edema, has been challenged recently by the observation that a systemic inflammatory response may play an integral role in the development of pulmonary dysfunction associated with brain injury. As a result of the primary cerebral injury, a systemic inflammatory reaction occurs, which induces an alteration in blood-brain barrier permeability and infiltration of activated neutrophils into the lung. This preclinical injury makes the lungs more susceptible to the mechanical stress of an injurious ventilatory strategy. Tight CO2 control is a therapeutic priority in patients with acute brain injury, but the use of high tidal volume ventilation may contribute to the development of ALI. Establishment of a therapeutic regimen that allows the combination of protective ventilation with the prevention of hypercapnia is, therefore, required. Moreover, in patients with brain injury, hypoxemia represents a secondary insult associated with a poor outcome. Optimal oxygenation may be achieved by using an adequate FiO2 and by application of positive end-expiratory pressure (PEEP). PEEP may, however, affect the cerebral circulation by hemodynamic and CO2-mediated mechanisms and the effects of PEEP on cerebral hemodynamics should be monitored in these patients and used to titrate its application.

Systemic inflammation in the brain-dead organ donor

Brain death itself impairs organ function in the potential donor, thereby limiting the number of suitable organs for transplantation. In addition, graft survival of kidneys obtained from brain-dead (BD) donors is inferior to that of kidneys obtained from living donors. Experimental studies confirm an inferior graft survival for the heart, liver and lungs from BD compared with living donors. The mechanism underlying the deteriorating effect of brain death on the organs has not yet been fully established. We know that brain death triggers massive circulatory, hormonal and metabolic changes. Moreover, the past 10 years have produced evidence that brain death is associated with a systemic inflammatory response. However, it remains uncertain whether the inflammation is induced by brain death itself or by events before and after becoming BD. The purpose of this study is to discuss the risk factors associated with brain death in general and the inflammatory response in the organs in particular. Special attention will be paid to the heart, lung, liver and kidney and evidence will be presented from clinical and experimental studies.

Risk factors for early primary graft dysfunction after lung transplantation: a registry study

BACKGROUND

Primary graft dysfunction (PGD) is a leading cause of early morbidity and mortality in lung transplantation. We sought to identify risk factors for PGD using the United Network for Organ Sharing/International Society for Heart and Lung Transplant (UNOS/ISHLT) Registry.

METHODS

A total of 6984 lung transplants between 1994 and 2002 were available for analysis. Potential risk factors were tested for association with PGD and multivariable logistic regression was applied to adjust for confounding.

RESULTS

The overall incidence of PGD was 10.7% (95% CI 9.9-11.4). In multivariable analyses, factors independently associated with PGD were donor age >45 yr (p < 0.001); donor head trauma (p = 0.03); recipient body mass index >25 kg/m(2) (p = 0.005); recipient female gender (p = 0.001); use of Eurocollins preservation solution (p = 0.001); single lung transplant (p = 0.005); increased ischemic time (p < 0.001); and elevated recipient pulmonary artery systolic pressure at transplant (p < 0.001). Recipient transplant diagnosis was strongly associated with PGD, with primary or secondary pulmonary hypertension (p < 0.001 for both), and idiopathic (p < 0.001) or secondary pulmonary fibrosis (p = 0.011) as significant and independent risk factors for PGD.

CONCLUSIONS

Risk factors for PGD in the UNOS/ISHLT registry are consistent with prior smaller studies. Recipient, donor, and therapy variables are independently associated with PGD, as defined in a large registry.

Stereotactic biopsy complicated by pneumocephalus and acute pulmonary edema

BACKGROUND

The aim of this study was to describe pneumocephalus as a rare complication of stereotactic biopsy and as a possible cause of acute neurogenic pulmonary edema.

CASE DESCRIPTION

A case of frameless stereotactic biopsy complicated by pneumocephalus presenting with acute lung injury 48 hours after the procedure. A frameless stereotactic procedure was performed in the standard fashion. Immediate postoperative CT showed no intracranial air except for a gas inclusion at the biopsy site within the lesion. The skin staple placed at the end of surgery on the skin incision was removed 36 hours later. A CT scan performed 48 hours postoperatively showed new pneumocephalus. The patient exhibited acute respiratory distress but no new neurologic symptoms. There was no detectable systemic cause for the pulmonary edema. The patient received supportive respiratory treatment and fully recovered.

CONCLUSION

Pneumocephalus is apparently a rare complication of stereotactic brain biopsy and one that may result from early removal of the skin staple or suture. The occurrence of acute neurogenic pulmonary edema may be attributed to the pneumocephalus.