Predictors of lung transplant survival in eurotransplant

Knockdown of swine leukocyte antigen expression in porcine lung transplants enables graft survival without immunosuppression

Immune rejection remains the major obstacle to long-term survival of allogeneic lung transplants. The expression of major histocompatibility complex molecules and minor histocompatibility antigens triggers allogeneic immune responses that can lead to allograft rejection. Transplant outcomes therefore depend on long-term immunosuppression, which is associated with severe side effects. To address this problem, we investigated the effect of genetically engineered transplants with permanently down-regulated swine leukocyte antigen (SLA) expression to prevent rejection in a porcine allogeneic lung transplantation (LTx) model. Minipig donor lungs with unmodified SLA expression (control group, n = 7) or with modified SLA expression (treatment group, n = 7) were used to evaluate the effects of SLA knockdown on allograft survival and on the nature and strength of immune responses after terminating an initial 4-week period of immunosuppression after LTx. Genetic engineering to down-regulate SLA expression was achieved during ex vivo lung perfusion by lentiviral transduction of short hairpin RNAs targeting mRNAs encoding β2-microglobulin and class II transactivator. Whereas all grafts in the control group were rejected within 3 months, five of seven animals in the treatment group maintained graft survival without immunosuppression during the 2-year monitoring period. Compared with controls, SLA-silenced lung recipients had lower donor-specific antibodies and proinflammatory cytokine concentrations in the serum. Together, these data demonstrate a survival benefit of SLA-down-regulated lung transplants in the absence of immunosuppression.

Extracorporeal membrane oxygenation as a bridge to transplant in neonates with fatal pulmonary conditions: A review

Neonates with progressive respiratory failure should be referred early for subspecialty evaluation and lung transplantation consideration. ECMO should be considered for patients with severe cardiopulmonary dysfunction and a high likelihood of death while on maximal medical therapy, either in the setting of reversible medical conditions or while awaiting lung transplantation. While ECMO offers hope to neonates that experience clinical deterioration while awaiting transplant, the risks and benefits of this intervention should be considered on an individual basis. Owing to the small number of infant lung transplants performed yearly, large studies examining the outcomes of various bridging techniques in this age group do not exist. Multiple single-centre experiences of transplanted neonates have been described and currently serve as guidance for transplant teams. Future investigation of outcomes specific to neonatal transplant recipients bridged with advanced devices is needed.

A comparison of outcomes after lung transplantation between European and North American centers

BACKGROUND

With advancements in basic science and clinical medicine, lung transplantation (LT) has evolved rapidly over the last three decades. However, it is unclear if significant regional variations exist in long-term outcomes after LT.

METHODS

To investigate potential differences, we performed a retrospective, comparative cohort analysis of adult patients undergoing deceased donor single or double LT in North America (NA) or Europe between January 2006 and December 2016. Data up to April 2019 were abstracted from the International Society for Heart and Lung Transplantation (ISHLT) Thoracic Organ Registry. We compared overall survival (OS) between North American and European LT centers in a propensity score matched analysis.

RESULTS

In 3,115 well-matched pairs, though 30-day survival was similar between groups (NA 96.2% vs Europe 95.4%, p = 0.116), 5-year survival was significantly higher in European patients (NA 60.1% vs Europe 70.3%, p < 0.001).

CONCLUSIONS

This survival difference persisted in a sensitivity analysis excluding Canadian patients. Prior observations suggest that these disparities are at least partly related to better access to care via universal healthcare models prevalent in Europe. Future studies are warranted to confirm our findings and explore other causal mechanisms. It is likely that potential solutions will require concerted efforts from healthcare providers and policymakers.

Critical Care of the Lung Transplant Patient

Lung transplantation is a therapeutic option for end-stage lung disease that improves survival and quality of life. Prelung transplant admission to the intensive care unit (ICU) for bridge to transplant with mechanical ventilation and extracorporeal membrane oxygenation (ECMO) is common. Primary graft dysfunction is an important immediate complication of lung transplantation with short- and long-term morbidity and mortality. Later transplant-related causes of respiratory failure necessitating ICU admission include acute cellular rejection, atypical infections, and chronic lung allograft dysfunction. Lung transplantation for COVID-19-related ARDS is increasingly common..

The Assessment and Outcomes of Crossmatching in Lung Transplantation in Korean Patients

BACKGROUND

In lung transplantation, human leukocyte antigen (HLA) compatibility is not included in the lung allocation score system or considered when placing donor allografts. However, HLA matching may affect the outcomes of lung transplantation. This study evaluated the current assessment status, prevalence, and effects of HLA crossmatching in lung transplantation in Korean patients using nationwide multicenter registry data.

METHODS

Two hundred and twenty patients who received lung transplantation at six tertiary hospitals in South Korea between March 2015 and December 2019 were retrospectively reviewed. Clinical data, including general demographic characteristics, primary diagnosis, and pretransplant status of the recipients and donors registered by the Korean Organ Transplant Registry, were retrospectively analyzed. Survival analysis was performed using the Kaplan-Meier method with log-rank tests.

RESULTS

Complement-dependent cytotoxic crossmatch (CDC-XM) was performed in 208 patients (94.5%) and flow cytometric crossmatch (flow-XM) was performed in 125 patients (56.8%). Among them, nine patients (4.1%) showed T cell- and/or B cell-positive crossmatches. The incidences of postoperative complications, including primary graft dysfunction, acute rejection, and chronic allograft dysfunction in positively crossmatched patients, were not significant compared with those in patients without mismatches. Moreover, Kaplan-Meier analyses showed poorer 1-year survival in patients with positive crossmatch according to CDC-XM (P < 0.001) and T lymphocyte XM (P = 0.002) than in patients without mismatches.

CONCLUSION

Positive CDC and T lymphocyte crossmatching results should be considered in the allocation of donor lungs. If unavailable, the result should be considered for postoperative management in lung transplantation.

Factors associated with short- versus long-term survival after lung transplant

OBJECTIVE

A small but growing proportion of lung transplant recipients survive longer than a decade post-transplant. The aim of this study was to identify factors associated with survival beyond a decade after lung transplant.

METHODS

We queried the United Network for Organ Sharing registry for adult (age ≥18 years) recipients undergoing first-time isolated lung transplantation between the introduction of the Lung Allocation Score in 2005 and 2009. Recipients were stratified into 3 cohorts: those who survived less than 1 year, 1 to 10 years, and greater than 10 years. Multivariable logistic regression was used to identify factors independently associated with early mortality (<1 year) and long-term (>10 years) survival.

RESULTS

A total of 5171 lung transplant recipients and their associated donors met inclusion criteria, including 964 (18.6%) with early mortality, 2843 (55.0%) with intermediate survival, and 1364 (26.3%) long-term survivors. Factors independently associated with early mortality included donor Black race, cigarette use, arterial oxygen partial pressure/fractional inspired oxygen ratio, diabetes, recipient Lung Allocation Score, total bilirubin, extracorporeal membrane oxygenation bridge requirement, single lung transplantation, and annual lung transplant center volume. The only factors independently associated with long-term survival among those who survived at least 1 year was donor age and single lung transplantation.

CONCLUSIONS

Of patients undergoing lung transplantation after the implementation of the Lung Allocation Score, approximately one-quarter survived 10 years post-transplant. There was minimal overlap between the factors associated with 1-year and 10-year survival. Of note, the Lung Allocation Score was not associated with long-term survival. Further research is needed to better refine patient selection and optimize management strategies to increase the number of long-term survivors.

Risk Factors for Acute Rejection in the First Year after Lung Transplant. A Multicenter Study

Rationale: Acute rejection, manifesting as lymphocytic inflammation in a perivascular (acute perivascular rejection [AR]) or peribronchiolar (lymphocytic bronchiolitis [LB]) distribution, is common in lung transplant recipients and increases the risk for chronic graft dysfunction.Objectives: To evaluate clinical factors associated with biopsy-proven acute rejection during the first post-transplant year in a present-day, five-center lung transplant cohort.Methods: We analyzed prospective diagnoses of AR and LB from over 2,000 lung biopsies in 400 newly transplanted adult lung recipients. Because LB without simultaneous AR was rare, our analyses focused on risk factors for AR. Multivariable Cox proportional hazards models were used to assess donor and recipient factors associated with the time to the first AR occurrence.Measurements and Main Results: During the first post-transplant year, 53.3% of patients experienced at least one AR episode. Multivariable proportional hazards analyses accounting for enrolling center effects identified four or more HLA mismatches (hazard ratio [HR], 2.06; P ≤ 0.01) as associated with increased AR hazards, whereas bilateral transplantation (HR, 0.57; P ≤ 0.01) was associated with protection from AR. In addition, Wilcoxon rank-sum analyses demonstrated bilateral (vs. single) lung recipients, and those with fewer than four (vs. more than four) HLA mismatches demonstrated reduced AR frequency and/or severity during the first post-transplant year.Conclusions: We found a high incidence of AR in a contemporary multicenter lung transplant cohort undergoing consistent biopsy sampling. Although not previously recognized, the finding of reduced AR in bilateral lung recipients is intriguing, warranting replication and mechanistic exploration.

Contemporary approaches in the use of extracorporeal membrane oxygenation to support patients waiting for lung transplantation

The introduction of the lung allocation score in 2005 prioritized patients with decreased transplant-free survival as the recipients of donor organs and effectively increased the number of critically-ill patients with end-stage lung disease waiting for transplantation. This change presented transplant programs with the challenge of how to both extend the lives of critically-ill, end-stage lung disease patients waiting for donor organs and maintain patient vitality to survival through the rigors of surgery and post-transplant recovery. Motivated by the dismal outcomes of patients maintained on mechanical ventilation pre-transplant, transplant centers increasingly deploy extracorporeal membrane oxygenation (ECMO) as a means of supporting patients with advanced disease as a bridge to successful lung transplantation. ECMO is an extracorporeal gas exchange device providing delivery of oxygen and removal of carbon dioxide from blood passed through the circuit. The specific cannulation strategy determines whether ECMO provides primarily respiratory or circulatory support. The cannulation approach is tailored to the specific physiological manifestations of the pre-lung transplant candidate's disease process. For patients with profound hypoxic respiratory failure, a cannulation strategy that captures a large fraction of the venous return is required to maintain adequate support whereas lower circuit flows are sufficient for patients with predominantly hypercapnic respiratory failure. Improving outcomes and increasing experience with ECMO is motivating transplant centers to initiate support before patients require mechanical ventilation. Awake cannulation is increasingly common and is used to avoid the complications associated with intubation in advanced lung failure. Determining criteria for initiation of support and identifying the optimal approach to support patients with right heart failure in need of circulatory support are avenues of active investigation. Use of ECMO and other forms of extracorporeal support are rapidly becoming a mainstay in the care of the pre-lung transplant patient with advanced disease.

Sequence of refusals for donor quality, organ utilization, and survival after lung transplantation

BACKGROUND

Lung donor utilization rates remain low, with many organs refused for donor quality. However, some centers have successfully transplanted these organs despite multiple refusals for donor quality (RDQs) by other centers. We hypothesized that the number of refusals due to donor quality does not impact post-transplant outcomes.

METHODS

Lung transplants (LTxs) from 2006 to 2015, identified using the United Network for Organ Sharing (UNOS) database, were matched against the potential transplant recipient (PTR) data set by donor identification. Transplants were categorized into 2 groups: low RDQ (0 to 3 RDQs) and high RDQ (>3 RDQs). Post-transplant survival and predictors for high RDQ were observed using Kaplan‒Meier and logistic regression analyses, respectively.

RESULTS

Of 10,126 adult (>18 years) LTxs, 77% had at least 1 RDQ, with a median of 4 RDQs. Post-transplant 1-year survival was similar for both the low and high RDQ groups (p = 0.49). Furthermore, groups of recipients who received donors with an increasing number of RDQs (>3, >6, or >10) also had similar post-transplant 1-year survival (p = 0.77). Treatment for rejection within 1 year and intubation at 72 hours post-transplant were higher in the high RDQ group (p < 0.01). An inverse relationship was identified between the number of RDQs and likelihood of utilization. After 10 RDQs, the likelihood of utilization varied significantly by donor characteristics.

CONCLUSIONS

Lung transplant survival is not associated with number of refusals due to donor quality. When determining whether an organ is suitable for transplant, the number of refusals due to donor quality should not influence one's decision, especially in this era of limited donor supply.

Extracorporeal Life Support as a Bridge to Lung Transplantation in Patients With Acute Respiratory Failure

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is being used more often as a bridge to transplantation (BTT) in patients with acutely decompensated end-stage lung disease in Korea. ECMO as a BTT may be the only rescue strategy for severe acute respiratory failure, but many centers still consider it to be a relative contraindication to lung transplantation because of its poor outcome. Because there are not enough lung donors, it is important to determine their optimal use. We reviewed and analyzed our experiences with the use of ECMO as a BTT in patients with acute respiratory failure.

METHODS

This was a retrospective analysis of all patients with acutely decompensated end-stage lung disease treated with ECMO as a bridge to lung transplantation between March 2012 and February 2016.

RESULTS

Of the 194 patients who underwent respiratory ECMO over a 4-year period, a BTT strategy was used for 19 patients (median age, 58 years) on our institution's lung transplantation waiting list (15 veno-venous, 3 veno-veno-arterial, 1 veno-arterial). Fourteen patients (73.7%) were successfully bridged to transplantation; however, 3 died while on the waiting list and 2 returned to their baseline functions without transplantation. The overall in-hospital survival rate was 57.9% (11 of 19), including the 9 (64.3%) patients who underwent transplantation.

CONCLUSIONS

Our findings support the view that well-selected candidates with acutely decompensated end-stage lung disease may be safely bridged until a suitable donor is identified. ECMO is not able to reverse the course of patients; however, it could be a life-saving option for patients with acute respiratory failure requiring lung transplantation.

Is SAPS 3 better than APACHE II at predicting mortality in critically ill transplant patients?

OBJECTIVES

This study compared the accuracy of the Simplified Acute Physiology Score 3 with that of Acute Physiology and Chronic Health Evaluation II at predicting hospital mortality in patients from a transplant intensive care unit.

METHOD

A total of 501 patients were enrolled in the study (152 liver transplants, 271 kidney transplants, 54 lung transplants, 24 kidney-pancreas transplants) between May 2006 and January 2007. The Simplified Acute Physiology Score 3 was calculated using the global equation (customized for South America) and the Acute Physiology and Chronic Health Evaluation II score; the scores were calculated within 24 hours of admission. A receiver-operating characteristic curve was generated, and the area under the receiver-operating characteristic curve was calculated to identify the patients at the greatest risk of death according to Simplified Acute Physiology Score 3 and Acute Physiology and Chronic Health Evaluation II scores. The Hosmer-Lemeshow goodness-of-fit test was used for statistically significant results and indicated a difference in performance over deciles. The standardized mortality ratio was used to estimate the overall model performance.

RESULTS

The ability of both scores to predict hospital mortality was poor in the liver and renal transplant groups and average in the lung transplant group (area under the receiver-operating characteristic curve = 0.696 for Simplified Acute Physiology Score 3 and 0.670 for Acute Physiology and Chronic Health Evaluation II). The calibration of both scores was poor, even after customizing the Simplified Acute Physiology Score 3 score for South America.

CONCLUSIONS

The low predictive accuracy of the Simplified Acute Physiology Score 3 and Acute Physiology and Chronic Health Evaluation II scores does not warrant the use of these scores in critically ill transplant patients.

The impact of pretransplant mechanical ventilation on short- and long-term survival after lung transplantation

Lung transplantation in mechanically ventilated (MV) patients has been associated with decreased posttransplant survival. Under the Lung Allocation Score (LAS) system, patients at greatest risk of death on the waiting list, particularly those requiring MV, are prioritized for lung allocation. We evaluated whether pretransplant MV is associated with poorer posttransplant survival in the LAS era. Using a national registry, we analyzed all adults undergoing lung transplantation in the United States from 2005 to 2010. Propensity scoring identified nonventilated matched referents for 419 subjects requiring MV at the time of transplantation. Survival was evaluated using Kaplan-Meier methods. Risk of death was estimated by hazard ratios employing time-dependent covariates. We found that pretransplant MV was associated with decreased overall survival after lung transplantation. In the first 6 months posttransplant, ventilated subjects had a twofold higher risk of death compared to nonventilated subjects. However, after 6 months posttransplant, survival did not differ by MV status. We also found that pretransplant MV was not associated with decreased survival in noncystic fibrosis obstructive lung diseases. These results suggest that under the LAS, pretransplant MV is associated with poorer short-term survival posttransplant. Notably, the increased risk of death appears to be strongest the early posttransplant period and limited to certain pretransplant diagnoses.

Successful treatment of ventilator dependent emphysema with Chartis treatment planning and endobronchial valves

INTRODUCTION

Emphysema is a leading cause of disability and death. Patients who require ventilator support as a result of respiratory failure have limited treatment options. We report a successful outcome for a ventilator dependent patient in whom endobronchial valves were inserted into lobes assessed as being without collateral ventilation.

PRESENTATION OF CASE

A 54 year old male patient had been ventilator dependent for two months due to respiratory insufficiency from emphysema. Prior to admission, FEV(1) was 0.89L (25% predicted) and RV was 4.5L (205% predicted). CT scan showed destruction of right lower and middle lobes and left lower lobe. Chartis assessment showed the absence of collateral ventilation. Zephyr endobronchial valves were placed in left and right lower lobes. Lung volume reduction bilaterally was confirmed on chest X-ray and CT scan the following day. On day three, ventilator support was discontinued and there was no requirement for supplementary oxygen. At 30 days post procedure, the RV reduced to 3.2L (142% predicted) and the FEV(1) increased to 1.32L (38% predicted).

DISCUSSION

Hyperinflation in emphysema compromises lung function. For this ventilator dependent patient, there were no other treatment options. Endoscopic lung volume reduction was successfully achieved by bilateral lower lobe placement of Zephyr endobronchial valves with a prior assessment using Chartis to determine the absence of collateral flow in the targeted lobes. The patient achieved an impressive 48% improvement in FEV(1) and a 29% reduction in RV.

CONCLUSION

Endoscopic lung volume reduction assisted by Chartis to plan treatment resulted in a clinical and a health-economic benefit.

Endoscopic lung volume reduction effectively treats acute respiratory failure secondary to bullous emphysema

Emphysema often affects the lungs in a heterogeneous fashion, and collapse or removal of severely hyperinflated portions of lung can improve overall lung function and symptoms. The role of lung volume reduction (LVR) surgery in selected patients is well established, but that of non-surgical LVR is still being defined. In particular, use of endobronchial LVR is still under development. This case report describes a 48-year-old non-smoker with severe bullous emphysema complicated by acute hypercapnic respiratory failure, who was successfully treated by endobronchial valve placement while intubated in an intensive care unit.

Should lung transplantation be performed for patients on mechanical respiratory support? The US experience

OBJECTIVE

The study objectives were to (1) compare survival after lung transplantation in patients requiring pretransplant mechanical ventilation or extracorporeal membrane oxygenation with that of patients not requiring mechanical support and (2) identify risk factors for mortality.

METHODS

Data were obtained from the United Network for Organ Sharing for lung transplantation from October 1987 to January 2008. A total of 15,934 primary transplants were performed: 586 in patients on mechanical ventilation and 51 in patients on extracorporeal membrane oxygenation. Differences between nonsupport patients and those on mechanical ventilation or extracorporeal membrane oxygenation support were expressed as 2 propensity scores for use in comparing risk-adjusted survival.

RESULTS

Unadjusted survival at 1, 6, 12, and 24 months was 83%, 67%, 62%, and 57% for mechanical ventilation, respectively; 72%, 53%, 50%, and 45% for extracorporeal membrane oxygenation, respectively; and 93%, 85%, 79%, and 70% for unsupported patients, respectively (P < .0001). Recipients on mechanical ventilation were younger, had lower forced vital capacity, and had diagnoses other than emphysema. Recipients on extracorporeal membrane oxygenation were also younger, had higher body mass index, and had diagnoses other than cystic fibrosis/bronchiectasis. Once these variables, transplant year, and propensity for mechanical support were accounted for, survival remained worse after lung transplantation for patients on mechanical ventilation and extracorporeal membrane oxygenation.

CONCLUSION

Although survival after lung transplantation is markedly worse when preoperative mechanical support is necessary, it is not dismal. Thus, additional risk factors for mortality should be considered when selecting patients for lung transplantation to maximize survival. Reduced survival for this high-risk population raises the important issue of balancing maximal individual patient survival against benefit to the maximum number of patients.

Factors indicative of long-term survival after lung transplantation: a review of 836 10-year survivors

INTRODUCTION

Despite 20 years of lung transplantation (LTx), factors influencing long-term survival remain largely unknown. The United Network for Organ Sharing (UNOS) data set provides an opportunity to examine long-term LTx survivors.

METHODS

We conducted a case-control study embedded within the prospectively collected UNOS LTx cohort to identify 836 adults from 1987 to 1997 who survived >or=10 years after first LTx. LTx patients within the same era and surviving 1 to 5 years served as controls. Multivariable logistic regression with incorporation of spline terms evaluated the odds of being a 10-year survivor. Two separate models were constructed. Model A incorporated pre-operative, operative, and donor-specific factors. Model B incorporated the factors used in Model A with post-operative covariates. Additional outcomes evaluated included hospitalizations for infection, rejection, and bronchiolitis obliterans.

RESULTS

Of 4,818 LTx patients from 1987 to 1997, 836 (17.3%) survived >or=10 years with a mean follow-up of 148.8 +/- 21.6 months. Mean follow-up for 1,657 controls was 34.0 +/- 13.9 months. The distribution of 10-year survivors by disease was cystic fibrosis, 170 (20%); chronic obstructive pulmonary disease, 254 (30%); and idiopathic pulmonary fibrosis, 92 (11%). On multivariable logistic regression, significant factors influencing 10-year survival included age <or=35 years (odds ratio [OR] 1.07, 95% confidence interval [CI], 1.03-1.11; p = 0.01), bilateral LTx (OR. 1.71; 95% CI, 1.25-2.34; p = 0.001), and hospitalizations for infections (OR, 1.40; 95% CI, 1.27-1.54; p < 0.001) and for rejection (OR, 0.55; 95% CI, 0.48-0.65; p < 0.001).

CONCLUSIONS

Examination of a cohort of long-term LTx survivors in the UNOS data set indicates that bilateral LTx and fewer hospitalizations for rejection may portend improved long-term survival after LTx.

Lung transplantation for ventilator-dependent respiratory failure

INTRODUCTION

Lung transplantation of patients on mechanical ventilation is controversial, but successful transplantation of these patients has been reported. This report describes our institutional experience with lung transplantation of mechanically ventilated patients since 2003.

METHODS

A retrospective cohort study was performed of all adult patients who underwent transplantation between October 2003 and October 2007. The patients on mechanical ventilation before transplantation were compared with patients without mechanical ventilation before transplantation. Survival, intensive care unit and hospital length of stay, post-transplant mechanical ventilation days, and primary graft function were analyzed.

RESULTS

Before transplantation, 15 patients received mechanical ventilation for a median of 20 days (range, 5-90 days); of these, 13 underwent transplantation, and 2 died waiting for transplantation. The control group comprised 70 patients. Time on the transplantation waiting list was significantly shorter for the study group vs the control group. The 2 groups did not differ in survival, post-transplantation hospital time, and primary graft dysfunction scores at 0, 24, 48 and 72 hours after transplantation. Median time of mechanical ventilation after transplantation and median length of stay in the intensive care unit stay were longer in the study group.

CONCLUSION

The survival rate and post-operative clinical course of patients undergoing transplantation while receiving mechanical ventilation for respiratory failure suggest that these patients can be considered for lung transplantation. Despite a longer time on post-operative mechanical ventilation and length of ICU stay, outcome is similar to that of other lung transplant candidates.

Prognosis Factors in Lung Transplant Recipients Readmitted to the Intensive Care Unit

OBJECTIVE

To identify outcome predictors and prognostic factors for survival among lung transplant recipients on readmission to the intensive care unit (ICU).

METHODS

This was a retrospective study of all lung transplant recipients during a 10-year period from 1997 to 2006. Data collection included age, gender, reason, and type of lung transplantation. Variables specific to individual ICU admissions included admission diagnosis, length of stay, duration of mechanical ventilation, interval from transplantation, Acute Physiology and Chronic Health Evaluation (APACHE) II score on ICU admission, and the identification of systemic organ dysfunction. We used Student t test (or where appropriate, its nonparametric equivalent) or the chi(2) test for comparisons among the patients who died and those who survived their ICU readmissions.

RESULTS

Among 144 lung transplant patients 28 were later readmitted to the ICU after at least 1 week. The admission diagnosis was sepsis in 20 cases (71.4%). Seventeen patients died during their ICU stay (60.7%). A higher APACHE II score (P = .008), the presence of three or more dysfunctional organs upon readmission (P = .016), and the need for mechanical ventilation (P = .022) were risk factors for mortality. The mortality risk was also higher among the group with a longer delay to ICU readmission (P = .003).

DISCUSSION

Readmission to the ICU, which is common among lung transplant recipients, was associated with a high mortality. Sepsis was the main cause of ICU readmission and the most frequent cause of death. APACHE II score, need for mechanical ventilation, number of dysfunctional organs, and delay in ICU readmission were important prognostic factors.

Lung Transplantation: Current Status and Challenges

The lung is an anatomically complex vital organ whose normal physiology depends on actively regulated ventilation and perfusion, and maintenance of a delicate blood-air barrier over a huge surface area in direct contact with a potentially hostile environment. Despite significant progress over the past 25 years, both short- and long-term outcomes remain significantly inferior for lung recipients relative to other "solid" organs. This review summarizes the current status of lung transplantation so as to frame the principle challenges currently facing end-stage lung-failure patients and the practitioners who care for them.

Bridge to lung transplantation with the novel pumpless interventional lung assist device NovaLung

BACKGROUND

Worsening of lung failure in patients awaiting a lung transplantation might lead to ventilation-refractory hypercapnia and respiratory acidosis. Most transplant centers consider pretransplantation extracorporeal membrane oxygenation as a contraindication for lung transplantation because of the poor outcome. We have, for the first time, applied the novel pumpless interventional lung assist NovaLung for bridge to lung transplantation in patients with severe ventilation-refractory hypercapnia. We report on our initial experience.

METHODS

Between March 2003 and March 2005, 176 lung transplantations were performed, of which 60% were high-urgency lung transplantations. Twelve of the high-urgency recipients had severe ventilation-refractory hypercapnia and respiratory acidosis. These patients were connected to the novel pumpless interventional lung assist NovaLung for bridge to lung transplantation.

RESULTS

The length of interventional lung assist NovaLung support was 15 +/- 8 days (4-32 days). PaO2, pH, and PaCO2 levels in arterial blood prior to interventional lung assist NovaLung implantation were 71 +/- 27 mm Hg, 7.121 +/- 0.1, and 128 +/- 42 mm Hg, respectively. Six hours after interventional lung assist NovaLung implantation, PaO2, pH, and PaCO2 levels had changed to 83 +/- 17 mm Hg (ns), 7.344 +/- 0.1 (P < .05), and 52 +/- 5 mm Hg (P < .05), respectively. Four patients died of multiorgan failure, 2 patients before and 2 after lung transplantation. Thus, 10 out of 12 patients were successfully bridged to lung transplantation, and 8 are still alive (1-year survival, 80%).

CONCLUSIONS

This report suggests that interventional lung assist NovaLung implantation is an effective bridge to lung transplantation strategy in patients with ventilation-refractory hypercapnia.

Pre-implantation multiple cytokine mRNA expression analysis of donor lung grafts predicts survival after lung transplantation in humans

While current donor selection with clinical findings is generally effective, the imprecise nature of the assessment forces clinicians to remain on the conservative side. A reliable biological marker would assist donor selection and would improve donor organ utilization. We collected biopsies from 169 donor lungs before implantation. Expression levels of IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma and IL-1beta were measured by quantitative real-time RT-PCR (qRT-PCR). Seventeen cases died within 30 days after transplantation. No donor factor was significantly associated with 30-day mortality. Univariate analysis of the 84 cases for development of the prediction model showed that IL-6, IL-8, TNF-alpha and IL-1beta were risk factors for mortality and IL-10 and IFN-gamma were protective factors. We analyzed the cytokine expression ratios of risk to protective cytokines. A stepwise logistic regression for 30-day mortality demonstrated that a model containing the ratio of IL-6/IL-10 was the most predictive (p = 0.0013). When applied to the remaining 85 cases for validation, the test of model fit was significant (p = 0.039). Using the cytokine ratio, we were able to define three risk groups with striking differences in survival (p = 0.0003). Multi-cytokine analysis of the donor lung graft with qRT-PCR shows significant promise as a strategy to biologically evaluate the donor lung prior to implantation.

Waiting for a thoracic transplant in Eurotransplant*

The prospects of patients on the thoracic waiting list are governed by the chance of receiving an organ in time and by the outcome of the transplantation. The former probability is determined by a triad of disease severity, resource size and allocation rules. The aim of this study was to provide an objective description of the distributional effects of the thoracic allocation system in Eurotransplant. It appears that the interpretation of waiting-list outflow indicators is not straightforward and that it is difficult to assess the fairness of an organ allocation system in the framework of changing donor-organ availability. The timing of listing for heart transplantation can substantially be improved; whether this is also true for lung transplantation cannot be determined from the available data. Allocation schemes cannot solve the problem of organ shortage; a shift of attention toward collaboration with procurement professionals is needed.

Thoracic organ transplantation in the United States, 1994-2003

Using OPTN/SRTR data, this article reviews the state of thoracic organ transplantation in 2003 and the previous decade. Time spent on the heart waiting list has increased significantly over the last decade. The percentage of patients awaiting heart transplantation for >2 years increased from 23% in 1994 to 49% by 2003. However, there has been a general decline in heart waiting list death rates over the decade. In 2003, the lung transplant waiting list reached a record high of 3,836 registrants, up slightly from 2002 and more than threefold since 1994. One-year patient survival for those receiving lungs in 2002 was 82%, a statistically significant improvement from 2001 (78%). The number of patients awaiting a heart-lung transplant, declining since 1998, reached 189 in 2003. Adjusted patient survival for heart-lung recipients is consistently worse than the corresponding rate for isolated lung recipients, primarily due to worse outcomes for heart-lung recipients with congenital heart disease. A new lung allocation system, approved in June 2004, derives from the survival benefit of transplantation with consideration of urgency based on waiting list survival, instead of being based solely on waiting time. A goal of the policy is to minimize deaths on the waiting list.

Lung transplantation with lungs from donors fifty years of age and older

BACKGROUND

A shortage of donors has led to the progressive expansion of criteria for donor selection in lung transplantation. The outcome of recipients of lungs from donors aged 50 years or older is analyzed systematically.

METHODS

From March 1998 to June 2003, 49 recipients received lungs from donors aged 50 years or older (range 50-64 years, mean 54 +/- 3 years). This group of recipients was compared with 244 patients receiving lungs from donors aged less than 50 years (range 7-49 years, mean 32 +/- 11 years). This study was undertaken on all 293 patients at our institution who received Perfadex-preserved lungs (Vitrolife, Goteborg, Sweden).

RESULTS

Recipient age, sex, and indications for transplant did not differ significantly between groups. Also, the percentage of the different types of transplants (bilateral or single lung transplantation) performed was equal in both cohorts. Donor Pa(O2) /F(IO2) ratios before lung retrieval (415 +/- 91 vs 439 +/- 113, respectively) and length of ischemic time (347 +/- 67 minutes vs 351 +/- 84 minutes, respectively) did not differ significantly between the older and younger donor groups. The following posttransplant parameters were also not statistically different: first Pa(O2)/F(IO2) at intensive care unit arrival (274 +/- 125 in the older donor group vs 253 +/- 119 in the younger donor group, respectively), mechanical ventilation time (328 +/- 427 hours vs 269 +/- 425 hours, respectively), and length of stay in the intensive care unit (16 +/- 18 days vs 14 +/- 18 days, respectively). Recipient survival in the older and younger donor groups at 30 days, 3, 6, 12, 24, and 60 months was 77% +/- 6%, 75% +/- 6%, 73% +/- 7%, 73% +/- 7%, 68% +/- 5%, and 68% +/- 4% versus 86% +/- 2%, 83% +/- 3%, 80% +/- 3%, 78% +/- 3%, 71% +/- 4%, and 66% +/- 4%, respectively.

CONCLUSIONS

Lung grafts from elderly donors have been considered as marginal organs for transplantation. However, this study indicates that transplantation of lungs from carefully selected donors aged 50 years or more may lead to similar short- and long-term outcomes compared with lungs from younger donors. The use of lungs from elderly donors may help to increase the number of donor organs in lung transplantation.

HLA-specific antibodies are risk factors for lymphocytic bronchiolitis and chronic lung allograft dysfunction

Bronchiolitis obliterans syndrome (BOS) represents a major limitation in lung transplantation. While acute rejection is widely considered the most important risk factor for BOS, the impact of HLA-specific antibodies is less understood. Of 51 lung recipients who were prospectively tested during a 4.2 +/- 1.6-year period, 14 patients developed HLA-specific antibodies. A multi-factorial analysis was performed to correlate the prevalence of BOS with HLA antibodies, persistent-recurrent acute rejection (ACR-PR), lymphocytic bronchiolitis, and HLA-A, -B, and -DR mismatches. HLA-specific antibodies were associated with ACR-PR (10/14 vs. 11/37 with no antibodies, p < 0.05), lymphocytic bronchiolitis (8/14 vs. 10/37, p < 0.05), and BOS (10/14, vs. 9/37, p < 0.005). Other risk factors for BOS were: lymphocytic bronchiolitis (13/18 vs. 6/33 with no lymphocytic bronchiolitis, p < 0.0001), ACR-PR (12/21 vs. 7/30 with no ACR-PR, p < 0.05), and the number of HLA-DR mismatches (1.7 +/- 0.48 in BOS vs. 1.2 +/- 0.63 without BOS, p < 0.05). The presence of antibodies exhibited a cumulative effect on BOS when it was associated with either lymphocytic bronchiolitis or ACR-PR. The complex relationship between the development of HLA antibodies and acute and chronic lung allograft rejection determines the importance of post-transplant screening for HLA-specific antibodies as a prognostic element for lung allograft outcome.

HLA-Specific antibodies are associated with high-grade and persistent-recurrent lung allograft acute rejection

BACKGROUND

The impact of HLA-specific antibodies is not well established in the acute rejection of lung allografts. Acute rejection represents the most important risk factor for the development of chronic lung allograft dysfunction.

METHODS

We analyzed the pattern of HLA antibodies before and after transplantation in 54 patients, and correlated our data with the presence and frequency of high-grade and persistent-recurrent acute rejection, during the first 18 post-operative months. The diagnosis of acute rejection was based on histologic International Society for Heart and Lung Transplantation (ISHLT)-published criteria.

RESULTS

Ten of 54 patients had a positive enzyme-linked immunoassay (ELISA) post-transplantation. In 90% of ELISA-positive patients, the presence of HLA antibodies was associated with persistent-recurrent acute rejections, compared with 34% in the ELISA-negative group (p < 0.005). There were 28 high-grade acute rejection episodes in the ELISA-positive group, compared with 36 in the ELISA-negative group (p < 0.0001). The ELISA-positive patients required a greater intensity of immunosuppressive therapy. The patients with ELISA-detected anti-HLA antibodies were at least 3-fold more likely to develop high-grade acute rejection and persistent-recurrent acute rejection, and 7-fold more likely to develop multiple episodes of persistent-recurrent acute rejection, compared with ELISA-negative patients.

CONCLUSIONS

ELISA-based screening for the development of HLA antibodies is a reliable method that can identify lung transplant recipients at increased risk for high-grade and persistent-recurrent acute rejection. Although bronchiolitis obliterans appears as a point of no return in the evolution of lung-transplanted patients, early detection of risk factors for acute rejection could indirectly decrease the incidence of bronchiolitis obliterans. These lung-transplanted patients may benefit from an altered strategy of immunosuppression.