Preventive effect of inhaled nitric oxide and pentoxifylline on ischemia/reperfusion injury after lung transplantation

Pentoxifylline protects against cerebral ischaemia-reperfusion injury through ferroptosis regulation via the Nrf2/SLC7A11/GPX4 signalling pathway

OBJECTIVE

To investigate whether pentoxifylline (PTX) attenuates cerebral ischaemia-reperfusion injury (IRI) in rats by inhibiting ferroptosis and to explore the underlying molecular mechanisms.

METHODS

Cerebral IRI was induced in male Sprague-Dawley (SD) rats using middle cerebral artery occlusion (MCAO). The effects of PTX on cerebral ischaemia-reperfusion brain samples were detected through neurological deficit score, staining and electron microscopy; levels of ferroptosis biomarkers from brain samples were detected using kits. Additionally, the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2), transferrin receptor protein 1, divalent metal transporter 1, solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) were determined by immunohistochemistry, real-time quantitative polymerase chain reaction and western blotting.

RESULTS

Pre-treatment with PTX was found to improve neurological function, evidenced by reduced neurological deficit scores, decreased infarct volume and alleviated pathological features post-MCAO. This improvement was accompanied by reduced lipid peroxidation levels and mitigated mitochondrial damage. Notably, PTX's inhibitory effect on ferroptosis was characterised by enhanced Nrf2 nuclear translocation and regulation of ferroptosis-related proteins. Moreover, inhibition of Nrf2 using ML385 (an Nrf2-specific inhibitor) reversed PTX's neuroprotective effect on MCAO-induced ferroptosis via the SLC7A11/GPX4 signalling pathway.

CONCLUSIONS

Ferroptosis is evident following cerebral ischaemia-reperfusion in rats. Pentoxifylline confers protection against IRI in rats by inhibiting ferroptosis through the Nrf2/SLC7A11/GPX4 signalling pathway.

Therapeutic benefits of nitric oxide in lung transplantation

Lung transplantation is an evolutionary procedure from its experimental origin in the twentieth century and is now recognized as an established and routine life-saving intervention for a variety of end-stage pulmonary diseases refractory to medical management. Despite the success and continuous refinement in lung transplantation techniques, the widespread application of this important life-saving intervention is severely hampered by poor allograft quality offered from donors-after-brain-death. This has necessitated the use of lung allografts from donors-after-cardiac-death (DCD) as an additional source to expand the pool of donor lungs. Remarkably, the lung exhibits unique properties that may make it ideally suitable for DCD lung transplantation. However, primary graft dysfunction (PGD), allograft rejection and other post-transplant complications arising from unavoidable ischemia-reperfusion injury (IRI) of transplanted lungs, increase morbidity and mortality of lung transplant recipients annually. In the light of this, nitric oxide (NO), a selective pulmonary vasodilator, has been identified as a suitable agent that attenuates lung IRI and prevents PGD when administered directly to lung donors prior to donor lung procurement, or to recipients during and after transplantation, or administered indirectly by supplementing lung preservation solutions. This review presents a historical account of clinical lung transplantation and discusses the lung as an ideal organ for DCD. Next, the author highlights IRI and its clinical effects in lung transplantation. Finally, the author discusses preservation solutions suitable for lung transplantation, and the protective effects and mechanisms of NO in experimental and clinical lung transplantation.

Primary graft dysfunction: what we know

Many advances in lung transplant have occurred over the last few decades in the understanding of primary graft dysfunction (PGD) though effective prevention and treatment remain elusive. This review will cover prior understanding of PGD, recent findings, and directions for future research. A consensus statement updating the definition of PGD in 2016 highlights the growing complexity of lung transplant perioperative care taking into account the increasing use of high flow oxygen delivery and pulmonary vasodilators in the current era. PGD, particularly more severe grades, is associated with worse short- and long-term outcomes after transplant such as chronic lung allograft dysfunction. Growing experience have helped identify recipient, donor, and intraoperative risk factors for PGD. Understanding the pathophysiology of PGD has advanced with increasing knowledge of the role of innate immune response, humoral cell immunity, and epithelial cell injury. Supportive care post-transplant with technological advances in extracorporeal membranous oxygenation (ECMO) remain the mainstay of treatment for severe PGD. Future directions include the evolving utility of ex vivo lung perfusion (EVLP) both in PGD research and potential pre-transplant treatment applications. PGD remains an important outcome in lung transplant and the future holds a lot of potential for improvement in understanding its pathophysiology as well as development of preventative therapies and treatment.

Primary Graft Dysfunction

Primary graft dysfunction (PGD) is a form of acute lung injury after transplantation characterized by hypoxemia and the development of alveolar infiltrates on chest radiograph that occurs within 72 hours of reperfusion. PGD is among the most common early complications following lung transplantation and significantly contributes to increased short-term morbidity and mortality. In addition, severe PGD has been associated with higher 90-day and 1-year mortality rates compared with absent or less severe PGD and is a significant risk factor for the subsequent development of chronic lung allograft dysfunction. The International Society for Heart and Lung Transplantation released updated consensus guidelines in 2017, defining grade 3 PGD, the most severe form, by the presence of alveolar infiltrates and a ratio of PaO₂:FiO₂ less than 200. Multiple donor-related, recipient-related, and perioperative risk factors for PGD have been identified, many of which are potentially modifiable. Consistently identified risk factors include donor tobacco and alcohol use; increased recipient body mass index; recipient history of pulmonary hypertension, sarcoidosis, or pulmonary fibrosis; single lung transplantation; and use of cardiopulmonary bypass, among others. Several cellular pathways have been implicated in the pathogenesis of PGD, thus presenting several possible therapeutic targets for preventing and treating PGD. Notably, use of ex vivo lung perfusion (EVLP) has become more widespread and offers a potential platform to safely investigate novel PGD treatments while expanding the lung donor pool. Even in the presence of significantly prolonged ischemic times, EVLP has not been associated with an increased risk for PGD.

Morbidity and mortality related to pneumonia and TRACHEOBRONCHITIS in ICU after lung transplantation

Background

Bacterial respiratory infections (BRI) are major complications contributing to increased morbidity and mortality after lung transplantation (LT). This study analyzed epidemiology and outcome of 175 consecutive patients developing BRI in ICU after LT between 2006 and 2012.

Methods

Three situations were described: colonization determined in donors and recipients, pneumonia and tracheobronchitis during the first 28 postoperative days. Severity score, demographic, bacteriologic and outcome data were collected.

Results

26% of donors and 31% of recipients were colonized. 92% of recipients developed BRI, including at least one episode of pneumonia in 19% of recipients. Only 21% of recipients developed BRI with an organism cultured from the donor’s samples, while 40% of recipients developed BRI with their own bacteria cultured before LT. Purulent sputum appears to be an important factor to discriminate tracheobronchitis from pneumonia. When compared to patients with tracheobronchitis, those with pneumonia had longer durations of mechanical ventilation (13 [3–27] vs 3 [29], p = 0.0005) and ICU stay (24 [16–34] vs 14 [9-22], p = 0.002). Pneumonia was associated with higher 28-day (11 (32%) vs 9 (7%), p = 0.0004) and one-year mortality rates (21 (61%) vs 24 (19%), p ≤ 0.0001).

Conclusions

These data confirm the high frequency of BRI right from the early postoperative period and the poor prognosis of pneumonia after LT.

Anesthesia for Lung Transplantation

Lung transplantation is the only therapeutic option for more than 3,000 individuals in the United States with end-stage lung disease. Innovations in anesthetic and surgical techniques have expanded the indications for lung transplantation. Presently, the major limiting factor in the number of lung transplantations that are performed is the availability of suitable donor organs. Lung transplantation includes a number of surgical procedures, including single-lung, double-lung, bilateral-sequential-single-lung, heart-lung, and lobar transplantation. Patients undergoing lung transplantation present a variety of challenges to the anesthesia team. Critical periods include induction of anesthesia, initiation of positive pressure ventilation, establishment and maintenance of one-lung ventilation, pulmonary artery clamping, pulmonary artery unclamping, and reperfusion of the transplanted lung. Pharmacologic advances have been an important factor in the continued development and success of lung transplantation. Newer immunosuppressive agents have improved the prevention and management of post-transplant rejection. Selective pulmonary vasodilators that are administered via inhalation affect the anesthetic management during the surgical procedure. Technologic advances in monitoring have also been valuable in lung transplantation. Transesophageal echocardiography is commonly used to evaluate intraoperative ventricular function. Continuous cardiac output, mixed venous oxygen saturation, continuous arterial blood gas monitoring, and the bispectral index have also been used to monitor the patient during lung transplantation. Anesthetic management of lung transplantation requires a thorough understanding of end-stage lung disease and pharmacologic and technical considerations that may not be applicable in any other part of anesthetic practice.

Critical Care Aspects of Lung Transplant Patients

Major strides have been made in lung transplantation during the 1990s and it has become an established treatment option for patients with advanced lung disease. Due to improvements in organ preservation, surgical techniques, postoperative intensive care, and immunosuppression, the risk of perioperative and early mortality (less than 3 months after transplantation) has declined [1]. The transplant recipient now has a greater chance of realizing the benefits of the long and arduous waiting period.

Despite these improvements, suboptimal long-term outcomes continue to be shaped by issues such as opportunistic infections and chronic rejection. Because of the wider use of lung transplantation and the longer life span of recipients, intensivists and ancillary intensive care unit (ICU) staff should be well versed with the care of lung transplant recipients.

In this clinical review, issues related to organ donation will be briefly mentioned. The remaining focus will be on the critical care aspects of lung transplant recipients in the posttransplant period, particularly ICU management of frequently encountered conditions. First, the groups of patients undergoing transplantation and the types of procedures performed will be outlined. Specific issues directly related to the allograft, including early graft dysfunction from ischemia-reperfusion injury, airway anastomotic complications, and infections in the setting of immunosuppression will be emphasized. Finally nonpulmonary aspects of posttransplant care and key pharmacologic points in the ICU will be covered.

Pentoxifylline Alleviates Perinatal Hypoxic-Ischemia-Induced Short-term Memory Impairment by Suppressing Apoptosis in the Hippocampus of Rat Pups

Purpose:

Perinatal hypoxic-ischemic brain damage is a major cause of acute mortality and chronic neurologic morbidity in infants and children. We investigated the effects of pentoxifylline, a methylxanthine derivative and type-4 phosphodiesterase inhibitor, on short-term memory and apoptotic neuronal cell death in the hippocampus following perinatal hypoxic-ischemia in newborn rats.

Methods:

We used a step-down avoidance task to evaluate short-term memory and 3ʹ-5ʹ-cyclic adenosine monophosphate (cAMP) assay to detect cAMP levels. We evaluated apoptosis using a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay for evidence of DNA fragmentation, immunohistochemistry for caspase-3 levels, and western blot for Bcl-2 and Bax.

Results:

Perinatal hypoxic-ischemic injury increased apoptotic cell death in the hippocampus, resulting in impaired short-term memory with decreased cAMP levels. Pentoxifylline treatment improved short-term memory by suppressing apoptotic cell death in the hippocampus with elevated cAMP levels.

Conclusions:

Pentoxifylline ameliorated perinatal hypoxic-ischemia in rat pups. This alleviating effect could be ascribed to the inhibition apoptosis due to increased cAMP production by pentoxifylline.

Pharmacology of Ischemia-Reperfusion. Translational Research Considerations

Ischemia-reperfusion (IRI) is a complex physiopathological mechanism involving a large number of metabolic processes that can eventually lead to cell apoptosis and ultimately tissue necrosis. Treatment approaches intended to reduce or palliate the effects of IRI are varied, and are aimed basically at: inhibiting cell apoptosis and the complement system in the inflammatory process deriving from IRI, modulating calcium levels, maintaining mitochondrial membrane integrity, reducing the oxidative effects of IRI and levels of inflammatory cytokines, or minimizing the action of macrophages, neutrophils, and other cell types. This study involved an extensive, up-to-date review of the bibliography on the currently most widely used active products in the treatment and prevention of IRI, and their mechanisms of action, in an aim to obtain an overview of current and potential future treatments for this pathological process. The importance of IRI is clearly reflected by the large number of studies published year after year, and by the variety of pathophysiological processes involved in this major vascular problem. A quick study of the evolution of IRI-related publications in PubMed shows that in a single month in 2014, 263 articles were published, compared to 806 articles in the entire 1990.

Primary graft dysfunction: lessons learned about the first 72 h after lung transplantation

PURPOSE OF REVIEW

In 2005, the International Society for Heart and Lung Transplantation published a standardized definition of primary graft dysfunction (PGD), facilitating new knowledge on this form of acute lung injury that occurs within 72 h of lung transplantation. PGD continues to be associated with significant morbidity and mortality. This article will summarize the current literature on the epidemiology of PGD, pathogenesis, risk factors, and preventive and treatment strategies.

RECENT FINDINGS

Since 2011, several manuscripts have been published that provide insight into the clinical risk factors and pathogenesis of PGD. In addition, several transplant centers have explored preventive and treatment strategies for PGD, including the use of extracorporeal strategies. More recently, results from several trials assessing the role of extracorporeal lung perfusion may allow for much-needed expansion of the donor pool, without raising PGD rates.

SUMMARY

This article will highlight the current state of the science regarding PGD, focusing on recent advances, and set a framework for future preventive and treatment strategies.

Inhaled nitric oxide in cardiac surgery: Evidence or tradition?

Inhaled nitric oxide (iNO) therapy as a selective pulmonary vasodilator in cardiac surgery has been one of the most significant pharmacological advances in managing pulmonary hemodynamics and life threatening right ventricular dysfunction and failure. However, this remarkable story has experienced a roller-coaster ride with high hopes and nearly universal demonstration of physiological benefits but disappointing translation of these benefits to harder clinical outcomes. Most of our understanding on the iNO field in cardiac surgery stems from small observational or single centre randomised trials and even the very few multicentre trials fail to ascertain strong evidence base. As a consequence, there are only weak clinical practice guidelines on the field and only European expert opinion for the use of iNO in routine and more specialised cardiac surgery such as heart and lung transplantation and left ventricular assist device (LVAD) insertion. In this review the authors from a specialised cardiac centre in the UK with a very high volume of iNO usage provide detailed information on the early observations leading to the European expert recommendations and reflect on the nature and background of these recommendations. We also provide a summary of the progress in each of the cardiac subspecialties for the last decade and initial survey data on the views of senior anaesthetic and intensive care colleagues on these recommendations. We conclude that the combination of high price tag associated with iNO therapy and lack of substantial clinical evidence is not sustainable on the current field and we are risking loosing this promising therapy from our daily practice. Overcoming the status quo will not be easy as there is not much room for controlled trials in heart transplantation or in the current atmosphere of LVAD implantation. However, we call for international cooperation to conduct definite studies to determine the place of iNO therapy in lung transplantation and high risk mitral surgery. This will require new collaboration between the pharmaceutical companies, national grant agencies and the clinical community. Until these trials are realized we should gather multi-institutional experience from large retrospective studies and prospective data from a new international registry. We must step up international efforts if we wish to maintain the iNO modality in the armamentarium of hemodynamic tools for the perioperative management of our high risk cardiac surgical patients.

Clinical perspectives with long-term pulsed inhaled nitric oxide for the treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic, progressive disease of the pulmonary vasculature with a high morbidity and mortality. Its pathobiology involves at least three interacting pathways – prostacyclin (PGI₂), endothelin, and nitric oxide (NO). Current treatments target these three pathways utilizing PGI₂ and its analogs, endothelin receptor antagonists, and phosphodiesterase type-5 (PDE-5) inhibitors. Inhaled nitric oxide (iNO) is approved for the treatment of hypoxic respiratory failure associated with pulmonary hypertension in term/near-term neonates. As a selective pulmonary vasodilator, iNO can acutely decrease pulmonary artery pressure and pulmonary vascular resistance without affecting cardiac index or systemic vascular resistance. In addition to delivery via the endotracheal tube, iNO can also be administered as continuous inhalation via a facemask or a pulsed nasal delivery. Consistent with a deficiency in endogenously produced NO, long-term pulsed iNO dosing appears to favorably affect hemodynamics in PAH patients, observations that appear to correlate with benefit in uncontrolled settings. Clinical studies and case reports involving patients receiving long-term continuous pulsed iNO have shown minimal risk in terms of adverse events, changes in methemoglobin levels, and detectable exhaled or ambient NO or NO₂. Advances in gas delivery technology and strategies to optimize iNO dosing may enable broad-scale application to long-term treatment of chronic diseases such as PAH.

Lung ischemia-reperfusion injury: a molecular and clinical view on a complex pathophysiological process

Lung ischemia-reperfusion injury remains one of the major complications after cardiac bypass surgery and lung transplantation. Due to its dual blood supply system and the availability of oxygen from alveolar ventilation, the pathogenetic mechanisms of ischemia-reperfusion injury in the lungs are more complicated than in other organs, where loss of blood flow automatically leads to hypoxia. In this review, an extensive overview is given of the molecular and cellular mechanisms that are involved in the pathogenesis of lung ischemia-reperfusion injury and the possible therapeutic strategies to reduce or prevent it. In addition, the roles of neutrophils, alveolar macrophages, cytokines, and chemokines, as well as the alterations in the cell-death related pathways, are described in detail.

Non heart-beating donors in England

When transplantation started all organs were retrieved from patients immediately after cardio-respiratory arrest, i.e. from non heart-beating donors. After the recognition that death resulted from irreversible damage to the brainstem, organ retrieval rapidly switched to patients certified dead after brainstem testing. These heart-beating-donors have become the principal source of organs for transplantation for the last 30 years. The number of heart-beating-donors are declining and this is likely to continue, therefore cadaveric organs from non-heart-beating donor offers a large potential of resources for organ transplantation. The aim of this study is to examine clinical outcomes of non-heart-beating donors in the past 10 years in the UK as an way of decreasing pressure in the huge waiting list for organs transplantation.

Post-ischemic treatment of pentoxifyline reduces cortical not striatal infarct volume in transient model of focal cerebral ischemia in rat

Previous studies reported that pentoxifylline (PTX) have a neuroprotective effect in the brain trauma and the global cerebral ischemia in the experimental models. However, the effect of PTX in transient model of focal cerebral ischemia has not been investigated yet. Therefore, this study was designed to investigate the effect of post-ischemic treatment of PTX on ischemic injuries in focal cerebral ischemic. Male Wistar rats (n=32) were assigned to control or PTX- (60 mg/kg i.p.) treated groups. PTX at dose 60 mg/kg i.p. administered at the beginning, or 1, or 3 h after ischemia. Focal cerebral ischemia was induced by middle cerebral artery occlusion, followed by 24-h reperfusion. At the end of 24 h ischemia, neurological dysfunction score was tested and infarct volumes were determined using triphenyltetrazolium chloride staining. Administration of PTX (60 mg/kg) at the beginning of ischemia, or 1, or 3 h after ischemia significantly reduces cortical infarct volumes by 43%, 40% and 41%, respectively. However, PTX did not significantly affect striatal infarct volumes and neurological dysfunction. The findings of the present study indicate that administration of PTX at least 3 h post-transient focal stroke reduces cortical brain ischemic damage in the rat model of transient focal cerebral ischemia.

Clinical indication for use and outcomes after inhaled nitric oxide therapy

BACKGROUND

Inhaled nitric oxide (iNO) use is widespread, but the long-term outcomes after therapy in adult patients remain unknown.

METHODS

All 376 patients receiving perioperative iNO (excluding pediatric and interventional cardiology procedures) at Columbia University Medical Center were prospectively followed from 2000 to 2003. Survival data were collected from chart review.

RESULTS

Inhaled nitric oxide was used to treat pulmonary and right ventricular failure in patients undergoing orthotopic heart transplantation (OHT, n = 67), orthotopic lung transplantation (n = 45), cardiac surgery (n = 105), and ventricular assist device placement (n = 66), and for hypoxemia in other surgery (n = 34) and medical patients (n = 59). Average follow-up was 2.9 +/- 1.0 years. Overall mortality was lowest when iNO was used after OHT (25.4%) and orthotopic lung transplantation (37.8%), intermediately after cardiac surgery (61%), ventricular assist device (62%), and other surgery patients (75%), and highest among medical patients (90%; all p < 0.005). The cost of iNO therapy was lower in transplantation versus medical patients, with a trend toward shorter duration of use. In multivariate analysis, respiratory failure and use in non-OHT were independent predictors of mortality (both p = 0.001). A risk score greater than 1 (score = non-OHT use 1, plus right ventricular failure 1) predicted a mortality of 76.5% versus 37.2% (p < 0.001).

CONCLUSIONS

Use of iNO for pulmonary hypertension in patients undergoing OHT and orthotopic lung transplantation was associated with a significantly lower overall mortality rate compared with its use after cardiac surgery or for hypoxemia in medical patients. Inhaled nitric oxide does not appear to be cost effective when treating hypoxemia in medical patients with high-risk scores and irreversible disease.

Inhaled Nitric Oxide Does Not Prevent Pulmonary Edema After Lung Transplantation Measured By Lung Water Content

STUDY OBJECTIVE

In order to assess the effects of inhaled nitric oxide (iNO) in preventing early-onset lung edema from occurring after lung transplantation, we measured extravascular lung water (EVLW) in a group of lung transplant recipients who were at high risk for developing ischemia-reperfusion-induced lung injury.

DESIGN

Prospective, randomized study.

SETTINGS

Surgical ICU in a teaching hospital.

PATIENTS

Thirty double-lung transplant recipients.

INTERVENTIONS

Patients were randomized to receive or not receive 20 ppm iNO at the time of reperfusion (ie, before any occurrence of lung edema). In the NO group, iNO was then administered for a 12-h period. A double-dilution technique was used for the serial assessment of EVLW, intrathoracic blood volume, and cardiac index. Standard hemodynamic and pulmonary parameters were also recorded during the first 3 postoperative days.

MEASUREMENTS AND RESULTS

Patients who received iNO did not have a different lung water content compared to control subjects (p = 0.61 [by analysis of variance (ANOVA)]). Blood oxygenation (ie, Pao(2)/fraction of inspired oxygen [Fio(2)] ratio) did not differ between the two groups (p = 0.61 [by ANOVA]). In both groups, EVLW and Pao(2)/Fio(2) ratio dropped significantly over time, regardless of the use of iNO (p < 0.01 [by ANOVA]).

CONCLUSIONS

In the population studied, prophylactic iNO that was administered at 20 ppm had no effect on pulmonary edema formation and resolution following lung transplantation.

Risk factors for reperfusion injury after lung transplantation

OBJECTIVE

To assess the influence of recipient's and donor's factors as well as surgical events on the occurrence of reperfusion injury after lung transplantation.

DESIGN AND SETTING

Retrospective study in the surgical intensive care unit (ICU) of a university hospital.

METHODS

We collected data on 60 lung transplantation donor/recipient pairs from June 1993 to May 2001, and compared the demographic, peri- and postoperative variables of patients who experienced reperfusion injury (35%) and those who did not.

RESULTS

The occurrence of high systolic pulmonary pressure immediately after transplantation and/or its persistence during the first 48 h after surgery was associated with reperfusion injury, independently of preoperative values. Reperfusion injury was associated with difficult hemostasis during transplantation (p=0.03). Patients with reperfusion injury were more likely to require the administration of catecholamine during the first 48 h after surgery (p=0.014). The extubation was delayed (p=0.03) and the relative odds of ICU mortality were significantly greater (OR 4.8, 95% CI: 1.06, 21.8) in patients with reperfusion injury. Our analysis confirmed that preexisting pulmonary hypertension increased the incidence of reperfusion injury (p<0.01).

CONCLUSIONS

Difficulties in perioperative hemostasis were associated with reperfusion injury. Occurrence of reperfusion injury was associated with postoperative systolic pulmonary hypertension, longer mechanical ventilation and higher mortality. Whether early recognition and treatment of pulmonary hypertension during transplantation can prevent the occurrence of reperfusion injury needs to be investigated.

Ischemia-reperfusion injury in cadaveric nonheart beating, cadaveric heart beating and live donor renal transplants

PURPOSE

Ischemia-reperfusion injury is gaining importance in transplantation as being responsible for allograft dysfunction. Ischemia occurs during kidney procurement, which is shortest in LDs, and prolonged in cadaveric HBDs and NHBDs.

MATERIALS AND METHODS

Renal transplants from 17 LDs, 15 HBDs and 19 NHBDs were assessed during reperfusion for biochemical markers of ischemia-reperfusion injury and assessed clinically. Central venous blood sampling was assayed for free radicals using electron spin resonance and tissue injury biomarkers, namely lactate dehydrogenase, fatty acid binding protein, alanine aminopeptidase, lactate and total antioxidants.

RESULTS

The return to stable renal function was more rapid in LD renal transplants, while recovery continued from 3 months after hospital discharge in NHBD renal transplants. Injury markers, such as lactate dehydrogenase, fatty acid binding protein, alanine aminopeptidase and lactate, were raised at the time of reperfusion, especially in NHBD renal transplants. Free radical release measured by electron spin resonance showed 2 phase release, that is early (0 to 10-minute) and late (20 to 40-minute) release. In NHBD, HBD and LD renal transplants the index of free radical release in the early phase was 1.43, 1.36 and 1.20, and in the late phase it was 1.43, 1.38 and 0.97, respectively (each ANOVA p <0.05).

CONCLUSIONS

NHBD renal transplants were accompanied by a greater release of free radicals at reperfusion (NHBD > HBD > LD), which was associated with an increase in tissue injury markers at reperfusion. This was reflected in a slower return to stable renal function in NHBD compared to HBD and LD renal transplants.

Inhaled nitric oxide therapy in adults: European expert recommendations

BACKGROUND

Inhaled nitric oxide (iNO) has been used for treatment of acute respiratory failure and pulmonary hypertension since 1991 in adult patients in the perioperative setting and in critical care.

METHODS

This contribution assesses evidence for the use of iNO in this population as presented to a expert group jointly organised by the European Society of Intensive Care Medicine and the European Association of Cardiothoracic Anaesthesiologists.

CONCLUSIONS

Expert recommendations on the use of iNO in adults were agreed on following presentation of the evidence at the expert meeting held in June 2004.

Primary graft dysfunction and other selected complications of lung transplantation: A single-center experience of 983 patients

OBJECTIVES

We sought to review the incidence and outcome of lung transplantation complications observed over 15 years at a single center.

METHODS

We performed a retrospective review from our databases, tracking outcomes after adult and pediatric lung transplantation. The 983 operations between July 1988 and September 2003 included 277 pediatric and 706 adult recipients. Bilateral (74%), unilateral (19%), and living lobar transplants (4%) comprised the bulk of this experience. Retransplantations accounted for 44 (4.5%) of the operations.

RESULTS

The groups differed by indication for transplantation. The adults included 57% with emphysema and 17% with cystic fibrosis, and the children included no patients with emphysema and 50% with cystic fibrosis. Hospital mortality was 96 (9.8%) of 983, including 46 (17%) of 277 of the children and 50 (7%) of 706 of the adults. The overall survival curves did not differ between adults and children ( P = .56). Freedom from bronchiolitis obliterans syndrome at 5 and 10 years was 45% and 18% for adults and 48% and 30% for children, respectively ( P = .53). The causes of death for adults included bronchiolitis obliterans syndrome (40%), respiratory failure (17%), and infection (14%), whereas the causes of death in children included bronchiolitis obliterans syndrome (35%), infection (28%), and respiratory failure (21%) ( P < .01). Posttransplantation lymphoproliferative disease occurred in 12% of pediatric recipients and 6% of adults ( P < .01). The frequency of treated airway complications did not differ between adults and children (9% vs 11%, P = .48). The frequency of primary graft dysfunction did not differ between children (22%) and adults (23%), despite disparity in the use of cardiopulmonary bypass.

CONCLUSION

These results highlight major complications after lung transplantation. Despite differences in underlying diagnoses and operative techniques, the 2 cohorts of patients experienced remarkably similar outcomes.

Effects of Short-Term Inhaled Nitric Oxide on Interleukin-8 Release After Single-Lung Transplantation in Pigs

BACKGROUND

Lung transplantation has evolved to become an effective treatment for a variety of end-stage lung diseases. However, severe reperfusion injury is still a major cause for postoperative morbidity and mortality. Although lung reperfusion injury is complex and has not been fully comprehended yet, neutrophil infiltration and cytokine activation have been postulated to play a main role. Recent studies showed that nitric oxide (NO) therapy has salutary effects on lung chronic and acute pathologies because it inhibits interleukin-8 (IL-8) release, but no data have been found on its effects during organ harvest. The aim of this study was to assess whether low doses of inhaled NO pre-treatment at the time of harvesting improves allograft function during early reperfusion in a porcine model.

METHODS

Twenty-two Landrace pigs were randomly assigned to NO-treated and control groups. In NO-treated pigs, NO at 20 ppm was administered 30 min before harvest. During the early allograft reperfusion period IL-8 content, dynamic and static compliance and gas exchange (Pa/FiO2 and PaO2) were measured in both control and NO-treated lungs.

RESULTS

Pre-treatment with NO at the time of harvesting showed improvement of allograft function in terms of dynamic (92 +/- 8% in NO vs 72 +/- 7% in the control group, p < .05) and static (83 +/- 8% in NO vs 63 +/- 7% in the control group, p < 0.05) compliance and gas exchange (PaO2: 96 +/- 4% in NO vs 74 +/- 4.5% in the control group, p < 0.01; Pa/FiO2: 97 +/- 5% in NO vs 74 +/- 5% in the control group, p < 0.01) by diminishing IL-8 (66.5 +/- 4.7 pg/ml in NO versus 208 +/- 43 pg/ml in the control group, p < 0.05) release in pigs.

CONCLUSION

These results show for the first time that NO pre-treatment at the time of harvesting reduces allograft reperfusion injury in part due to its effects on IL-8 release.

High central venous pressure is associated with prolonged mechanical ventilation and increased mortality after lung transplantation

BACKGROUND

Poor oxygenation might occur in transplanted lungs as a result of reperfusion injury and lack of lymphatic drainage. Low central venous and pulmonary capillary wedge pressures are advocated to reduce pulmonary edema and maximize oxygenation but might adversely affect cardiac index, circulation, and renal function.

METHODS

Histories, intensive care unit charts, and donor data on 118 lung transplantations performed between 1999 and 2002 were retrospectively assessed. Multiple logistic regression analysis was performed on donor, recipient, operative, and intensive care unit parameters to determine the relationship of filling pressure (central venous and pulmonary capillary wedge pressures) to prolonged mechanical ventilation and outcome. The mean central venous pressure was used to divide patients into high and low central venous pressure groups, which were then compared to determine differences in outcome and complication rates.

RESULTS

A high central venous pressure was found to be associated with prolonged mechanical ventilation (odds ratio, 1.57; 95% confidence interval, 1.13-2.20; P = .008). After removing the effect of poor myocardial function by excluding patients with low cardiac index (< 2.2 L x min -1 x m(-2) ) and high inotrope requirement (> 10 microg/min), central venous pressure remained associated with prolonged mechanical ventilation (odds ratio, 2.31; 95% confidence interval, 1.31-4.07; P = .004). Duration of ventilation (P < .001), intensive care unit mortality (P = .02), hospital mortality (P = .09), and 2-month mortality (P = .02) were higher in patients with central venous pressures of greater than 7 mm Hg. There was no evidence of complications caused by hypovolemia in the low (< or = 7 mm Hg) central venous pressure group, who had lower inotrope requirements (P = .02) and lower creatinine levels (P = .013). Conclusions A high central venous pressure was associated with adverse outcomes after lung transplantation.

Anesthetic Considerations for Lung Volume Reduction Surgery and Lung Transplantation

Anesthetic considerations for lung transplantation and LVRS have been reviewed, with an emphasis on critical intraoperative junctures and decision points. Cognizance of these issues promotes coordinated and optimal care and provides the potential to improve outcome in this particularly high-risk population.

Lung preservation

Better understanding of the mechanisms of ischemia-reperfusion injury, improvement in the technique of lung preservation, and the recent introduction of a new preservation solution specifically developed for the lungs have helped to reduce the incidence of primary graft dysfunction after lung transplantation. Currently, the limitation in extending the ischemic time is more often related to the increasing use of non-ideal lung donors rather than to poor lung preservation. In this review, we have focused our attention on the experimental and clinical work performed to optimize the methods of lung preservation from the time of retrieval to the period of reperfusion after graft implantation.

Anesthetic implications for lung transplantation

Anesthetic challenges regarding lung transplantation are related to the expanded spectrum of diseases for which lung transplantation is offered and to the interval changes in health status likely to occur as patients wait longer for an organ to become available. Particular attention to avoiding or reducing the impact of increases in pulmonary vascular resistance and right heart failure are important and may necessitate cardiopulmonary bypass. Intraoperative and postoperative ventilator management should account for differences in pulmonary compliance after the new lung is implanted. Minimizing intravenous fluids without compromising end organ perfusion may avoid or reduce postoperative respiratory insufficiency.

Pentoxifylline Prevents Spontaneous Brain Ischemia in Stroke-Prone Rats

Anti-inflammatory properties of pentoxifylline (PTX) have recently been described. Spontaneously hypertensive stroke-prone rats (SHRSP) constitute an animal model that develops an inflammatory condition that precedes the appearance of brain abnormalities. The aim of the present investigation was to assess: 1) the efficacy of PTX treatment in protecting the neural system in SHRSP, and 2) how its anti-inflammatory properties might be involved in this effect. Male SHRSP fed with a permissive diet received no drug or PTX (100 or 200 mg/kg/day). Brain abnormalities detected by magnetic resonance imaging developed spontaneously in control rats after 42 +/- 3 days, whereas in rats treated with 100 mg/kg/day PTX, abnormalities developed in only 80% of the animals and only after 70 to 80 days. Treatment with a higher dose of PTX (200 mg/kg/day) completely protected the brain from abnormal development. The drug treatment prevented the accumulation of macrophages or CD4+ positive cells, the activation of glia in brain tissues, and the appearance of inflammatory proteins and thiobarbituric acid-reactive substances in body fluids. PTX treatment did induce a greater increase of serum tumor necrosis factor-alpha (TNF-alpha), but not of interleukin (IL)-1beta and IL-6 induced by in vivo administration of lipopolysaccharide (LPS), which suggests a protective role for TNF-alpha. PTX also exerted protective effects when it was administered after the first occurrence of proteinuria (>40 mg/day). These data indicate that PTX treatment dose-dependently prevents the occurrence of spontaneous brain damage by reducing inflammatory events. We also hypothesize that the increase of TNF-alpha by PTX treatment represents a protective mechanism in SHRSP.

Lung transplantation. Lung preservation

Over the past decade, improvements in the technique of lung preservation have led to significant reduction in the incidence of ischemia-reperfusion-induced lung injury after lung transplantation. The challenge remains to improve the number of donor lungs available for transplantation. While the number of patients on the waiting list is constantly increasing, only 10% to 30% of donor lungs are currently being used for transplantation. Hence, the development of new strategies to assess, repair, and improve the quality of the lungs could have a tremendous impact on the number of transplants performed. In addition, an improved understanding of the mechanisms involved in lung preservation might help elucidate the potential link between acute lung injury and chronic graft dysfunction. In the future, genetic analysis using novel technologies such as microarray analysis will help researchers determine which genes control the injury seen in the transplantation process. Hopefully, this information will provide new insights into the mechanisms of injury and reveal potential new strategies and targets for therapies to improve lung preservation.

Survival benefit of lung transplantation for patients with idiopathic pulmonary fibrosis

OBJECTIVE

Although lung transplantation is viewed as an acceptable option for patients with end-stage idiopathic pulmonary fibrosis, the survival benefit of this approach is still debated. This study examined whether there was a survival benefit of lung transplantation in a cohort of patients referred to our transplant center with a diagnosis of idiopathic pulmonary fibrosis according to American Thoracic Society criteria.

METHODS

Forty-six patients accepted for lung transplantation during a 12-year period with a diagnosis of idiopathic pulmonary fibrosis form the basis of this study. Survival benefit offered by lung transplantation was assessed using Cox proportional-hazards modeling, with patients on a waiting list as the control group.

RESULTS

Twenty-eight patients underwent lung transplantation (27 single and 1 double), 16 patients died while waiting, and 2 patients remained on the active waiting list. Diagnosis of idiopathic pulmonary fibrosis was made on histologic examination of the explanted lung or lung biopsy before lung transplantation. There was a pattern of usual interstitial pneumonia in 31 cases (67%). The 15 remaining patients fulfilled all American Thoracic Society criteria for idiopathic pulmonary fibrosis. The median waiting time for organs was 51 days. Survival after lung transplantation was 79.4% at 1 year, 63.5% at 2 years, and 39% at 5 years. The multivariable analysis showed that lung transplantation reduced the risk of death by 75% (95% confidence interval, 8%-86%; P =.03) after adjustment on potential confounding variables.

CONCLUSIONS

Lung transplantation is effective in improving the survival of selected patients affected by idiopathic pulmonary fibrosis.

A randomized trial of inhaled nitric oxide to prevent ischemia-reperfusion injury after lung transplantation

Inhalation of nitric oxide (NO) has been advocated as a method to prevent ischemia-reperfusion injury after lung transplantation. We enrolled 84 patients into a concealed, randomized, placebo-controlled trial to evaluate the effect of inhaled NO (20 ppm NO or nitrogen) initiated 10 minutes after reperfusion on outcomes after lung transplantation. The groups (n = 42) were balanced with respect to age, sex, lung disease, procedure, and total ischemic times. PaO2/FIO2 ratios were similar on admission to the intensive care unit (ICU) (NO 361 +/- 134; control patients 357 +/- 132), and over the duration of the study. There were no differences in hemodynamics between the two groups. Severe reperfusion injury (PaO2/FIO2 < 150) was present at the time of admission to the ICU in 14.6% NO patients versus 9.5% of control patients (p = 0.48). The groups had similar median times to first successful trial of unassisted breathing (25 vs. 27 hours; p = 0.76), successful extubation (32 vs. 34 hours; p = 0.65), ICU discharge (3.0 days for both groups), and hospital discharge (27 vs. 29 days; p = 0.563). Five NO versus six control patients died during their hospital stay. Adjusting for age, sex, lung disease etiology, presence of pulmonary hypertension, and total ischemic time did not alter these results. In conclusion, we did not detect a significant effect of inhaled NO administered 10 minutes after reperfusion on physiologic variables or outcomes in lung transplant patients.

Ischemia-reperfusion-induced lung injury

Ischemia-reperfusion-induced lung injury is characterized by nonspecific alveolar damage, lung edema, and hypoxemia occurring within 72 hours after lung transplantation. The most severe form may lead to primary graft failure and remains a significant cause of morbidity and mortality after lung transplantation. Over the past decade, better understanding of the mechanisms of ischemia-reperfusion injury, improvements in the technique of lung preservation, and the development of a new preservation solution specifically for the lung have been associated with a reduction in the incidence of primary graft failure from approximately 30 to 15% or less. Several strategies have also been introduced into clinical practice for the prevention and treatment of ischemia-reperfusion-induced lung injury with various degrees of success. However, only three randomized, double-blinded, placebo-controlled trials on ischemia-reperfusion-induced lung injury have been reported in the literature. In the future, the development of new agents and their application in prospective clinical trials are to be expected to prevent the occurrence of this potentially devastating complication and to further improve the success of lung transplantation.

Inhaled nitric oxide: more than a selective pulmonary vasodilator

Because of its high diffusing capacity through the alveolar-blood barrier and its high selectivity for the pulmonary vasculature, inhaled nitric oxide (NO) has been recently shown to be a viable and efficient approach to restore pulmonary NO deficiency. The most relevant applications of inhaled NO are in infants with primary pulmonary hypertension or hypoxia. In these patients, inhaled NO improves gas exchange and ventilation-perfusion matching, reduces the length of hospitalization and is without severe detrimental effects. The use of inhaled NO has also been extended to adults with pulmonary hypertension and the acute respiratory distress syndrome. In addition, recent clinical evidence supported by data from animal models, shows beneficial extra-pulmonary effects of inhaled NO, including protection against myocardial ischaemia-reperfusion injury.

VEGF-A and -C but not -B mediate increased vascular permeability in preserved lung grafts

BACKGROUND

Vascular endothelial growth factor (VEGF) is a potent endothelial cell growth and permeability factor, expressed in the lung. Overexpression of VEGF is associated with increased vascular permeability in the early stage of acute lung injury in mice. The role of various forms of VEGF in transplantation-induced lung injury is not well understood.

METHODS

VEGF mRNA and protein expression was measured in biopsies of preserved donor lung grafts as well as in control lung biopsies, using real-time reverse transcriptase-polymerase chain reaction and Western blot analysis. VEGF tissue expression was also evaluated by immunocytochemistry. Serum VEGF was measured in recipients after transplantation and in controls using ELISA.

RESULTS

Although VEGF-A and VEGF-C protein expression was up-regulated, their mRNA levels were decreased in donor versus control lung biopsies (P<0.05). VEGF-B mRNA was decreased, but its protein level was unchanged in donors. Flt-1 was unchanged, KDR gene expression was down-regulated in donors (P<0.05), and both receptors' protein expression was under the detection level in donor and control lungs. VEGF-A was detected in pulmonary vessels and bronchi, whereas VEGF-C was only detectable in vessels of both donor and control lungs. After transplantation, serum VEGF increased (P<0.05) and returned to control baseline levels 12 weeks after surgery. Wet-to-dry lung weight was increased in donor versus control lungs.

CONCLUSIONS

These results indicate that unventilated hypoxia increases vascular permeability in lung grafts and that this process is mainly regulated at VEGF-A and VEGF-C translational but not transcriptional level. Selective VEGF antagonism during graft preservation might be of benefit to counteract edema formation.

Intra-operative use of inhaled vasodilators: are there indications?

The US Food and Drug Administration and European authorities have recently approved inhaled nitric oxide for the treatment of neonates with hypoxic respiratory failure associated with pulmonary hypertension. In addition to this highly specific condition, there is an increasing 'off-label' use of inhaled nitric oxide and other inhaled vasodilators in the perioperative setting. Potential indications include right heart failure as a result of acute pulmonary hypertension in cardiac and non-cardiac surgery, the prevention of reperfusion injury in lung transplantation, the treatment of hypoxaemia during single-lung ventilation, and more recently, the treatment of sickle cell crisis.