Medium-term results of extracorporeal membrane oxygenation for severe acute lung injury after lung transplantation

The American Association for Thoracic Surgery (AATS) 2022 Expert Consensus Document: The use of mechanical circulatory support in lung transplantation

OBJECTIVE

The use of mechanical circulatory support (MCS) in lung transplantation has been steadily increasing over the prior decade, with evolving strategies for incorporating support in the preoperative, intraoperative, and postoperative settings. There is significant practice variability in the use of these techniques, however, and relatively limited data to help establish institutional protocols. The objective of the AATS Clinical Practice Standards Committee (CPSC) expert panel was to review the existing literature and establish recommendations about the use of MCS before, during, and after lung transplantation.

METHODS

The AATS CPSC assembled an expert panel of 16 lung transplantation physicians who developed a consensus document of recommendations. The panel was broken into subgroups focused on preoperative, intraoperative, and postoperative support, and each subgroup performed a focused literature review. These subgroups formulated recommendation statements for each subtopic, which were evaluated by the entire group. The statements were then developed via discussion among the panel and refined until consensus was achieved on each statement.

RESULTS

The expert panel achieved consensus on 36 recommendations for how and when to use MCS in lung transplantation. These recommendations included the use of veno-venous extracorporeal membrane oxygenation (ECMO) as a bridging strategy in the preoperative setting, a preference for central veno-arterial ECMO over traditional cardiopulmonary bypass during the transplantation procedure, and the benefit of supporting selected patients with MCS postoperatively.

CONCLUSIONS

Achieving optimal results in lung transplantation requires the use of a wide range of strategies. MCS provides an important mechanism for helping these critically ill patients through the peritransplantation period. Despite the complex nature of the decision making process in the treatment of these patients, the expert panel was able to achieve consensus on 36 recommendations. These recommendations should provide guidance for professionals involved in the care of end-stage lung disease patients considered for transplantation.

Extracorporeal Membrane Oxygenation for Primary Graft Dysfunction After Lung Transplantation

Extracorporeal membrane oxygenation (ECMO) is used as the last resort for primary graft dysfunction (PGD). The aim of this study is to explore the predictors and outcomes for early mortality in postlung transplant patients who required ECMO for PGD. Between January 2006 and December 2015, 1,049 cases of lung transplantation were performed at our center. Ninety-six patients required ECMO support after lung transplantation, 52 patients (54%) had PGD. Seven patients (13.5%) required venoarterial ECMO due to concomitant hemodynamical instability, and the others required venovenous ECMO. The patients were on ECMO for 5.00 ± 10.6 days. Forty-four patients (84.6%) were successfully decannulated. The 90 day, 1 year, and 5 year survival of patients who required ECMO for PGD after lung transplantation were 67.3%, 50.0%, and 31.5%, respectively. Cox regression indicated that when the patient was placed on ECMO later than 48 hours after transplantation, the patient could have higher in-house mortality (hazard ratio, 2.79; 95% CI, 1.21-6.43) and also higher 3 year mortality (hazard ratio, 2.30; 95% CI, 1.13-4.68) regardless of the patients' preoperative conditions or complexity of lung transplantation. Earlier recognition of PGD and initiation of ECMO may be beneficial in this population.

Extracorporeal support, during and after lung transplantation: the history of an idea

During recent years, continuous technological innovation has provoked an increase of extracorporeal life support (ECLS) use for perioperative cardiopulmonary support in lung transplantation. Initial results were disappointing, due to ECLS-specific complications and high surgical risk of the supported patients. However, the combination of improved patient management, multidisciplinary team work and standardization of ECLS protocols has recently yielded excellent results in several case series from high-volume transplant centres. Therein, it was demonstrated that, although the prevalence of complications remains higher in supported patients, there may be no difference in long-term graft function between supported and non-supported patients. These results are important, because most of the patients who require ECLS support in lung transplantation are young and have no other chance to survive, but to be transplanted. Moreover, there is no device for "bridging to destination" therapy in lung transplantation. Of note, the evidence in favour of ECLS support in lung transplantation was never validated by randomized controlled trials, but by everyday experience at the patient bed-side. Here, we review the state-of-the-art ECLS evidence for intraoperative and postoperative cardiopulmonary support in lung transplantation.

Prone positioning as a bridge to recovery from refractory hypoxaemia following lung transplantation

OBJECTIVES

Refractory hypoxaemia is the leading cause of mortality in the postoperative period after lung transplantation. The role of prone positioning as a rescue therapy in this setting has not been assessed. We evaluated its effects in lung transplant recipients presenting refractory hypoxaemia following the surgery.

METHODS

Prospectively collected data from 131 consecutive adult patients undergoing lung transplantation between January 2013 and December 2014 were evaluated. Twenty-two patients received prone position therapy. Indications, associated complications, time to initiation and duration of the manoeuvre were analysed and the effects of prone position on gas exchange were evaluated. Finally, outcomes in this cohort were compared against the rest of lung transplant recipients.

RESULTS

Prone positioning was more frequently implemented within the first 72 h (68.2%) and its main indication was primary graft dysfunction. The manoeuvre was maintained during a median of 21 h. After prone position, the pressure of arterial oxygen/fraction of inspired oxygen ratio significantly increased from 81.0 mmHg [interquartile range (IQR) 71.5-104.0] to 220.0 (IQR 160.0-288.0) (P < 0.001). No complications related with the technique were reported. Patients who underwent the manoeuvre had longer hospital stay [50.0 days (IQR 36.0-67.0) vs 30.0 (IQR 23.0-56.0), P = 0.006] than the rest of the population. No differences were found comparing either 1-year mortality (9.1% vs 15.6%; P = 0.740) or 1-year graft function [forced expiratory volume in 1 second of 70.0 (IQR 53.0-83.0) vs 68.0 (IQR 53.5-80.5), P = 0.469].

CONCLUSIONS

Prone positioning is safe and significantly improves gas exchange in patients with refractory hypoxaemia after lung transplantation. It should be considered as a possible treatment in these patients.

Principi e indicazioni dell’assistenza circolatoria e respiratoria extracorporea in chirurgia toracica

In origine, l’extracorporeal membrane oxygenation (ECMO) era una tecnica di assistenza respiratoria che utilizzava uno scambiatore gassoso a membrana. Per estensione, l’ECMO è diventata una tecnica respiratoria e cardiopolmonare utilizzata in caso di deficit respiratorio e/o cardiaco nell’attesa della restaurazione della funzione deficitaria o di un eventuale trapianto. Il supporto emodinamico può essere parziale o totale. Gli accessi vascolari possono essere periferici o centrali. Questo tipo di assistenza utilizza il concetto di circolazione extracorporea (CEC) sanguigna che in epoca moderna si è estesa con l’utilizzo di polmoni artificiali a membrana. Il circuito di base è semplice e comprende una pompa, un ossigenatore (che permette al sangue di caricarsi di O₂ e di eliminare CO₂) e delle vie d’accesso (una di drenaggio e una di reinfusione). La sua attuazione è facile, veloce e può essere avviata al letto del malato. Il miglioramento delle attrezzature, una migliore conoscenza delle tecniche e delle indicazioni, e le politiche di salute pubblica hanno reso popolare questa tecnica. Alcuni centri di chirurgia toracica la utilizzano di routine come assistenza alla realizzazione di un intervento terapeutico (soprattutto trapianto) assieme a team di rianimazione per il trattamento della sindrome da distress respiratorio acuto. Nel quadro della malattia polmonare dell’adulto, l’idea principale è quella di sviluppare il concetto di strategia minimalista con l’uso di una CEC adiuvante parziale – più che sostitutiva totale – che permetterebbe il recupero metabolico ad integrum del paziente. Nei prossimi anni, i progressi della tecnologia e dell’ingegneria così come le conoscenze approfondite permetteranno il miglioramento della prognosi dei pazienti colpiti da deficit respiratorio sotto assistenza meccanica.

[Extracorporeal life support in thoracic surgery: What are the indications and the pertinence?]

INTRODUCTION

In thoracic surgery, extracorporeal life support (ECLS) technologies are used in cases of severe and refractory respiratory failure or as intraoperative cardiorespiratory support. The objectives of this review are to describe the rationale of ECLS techniques, to review the pulmonary diseases potentially treated by ECLS, and finally to demonstrate the efficacy of ECLS, using recently published data from the literature, in order to practice evidence based medicine.

STATE OF THE ART

ECLS technologies should only be undertaken in expert centers. ECLS allows a protective ventilatory strategy in severe ARDS. In the field of lung transplantation, ECLS may be used successfully as a bridge to transplantation, as intraoperative cardiorespiratory support or as a bridge to recovery in cases of severe primary graft dysfunction. In general thoracic surgery, ECLS technology seems to be safe and efficient as intraoperative respiratory support for tracheobronchial surgery or for severe respiratory insufficiency, without significant increase in perioperative risk.

PERSPECTIVE

The indications for ECLS are going to increase. Future improvements both in scientific knowledge and bioengineering will improve the prognosis of patients treated with ECLS for respiratory failure. Multicenter randomized controlled trials will refine the indications for ECLS and improve the global care strategies for these patients.

CONCLUSION

ECLS is an efficient therapeutic strategy that will improve the prognosis of patients suffering from, or exposed to, the risks of severe respiratory failure.

Principi e indicazioni dell’assistenza circolatoria e respiratoria extracorporea in chirurgia toracica

In origine, l’extracorporeal membrane oxygenation (ECMO) era una tecnica di assistenza respiratoria che utilizzava uno scambiatore gassoso a membrana. Per estensione, l’ECMO è diventata una tecnica respiratoria e cardiopolmonare utilizzata in caso di deficit respiratorio e/o cardiaco nell’attesa della restaurazione della funzione deficitaria o di un eventuale trapianto. Il supporto emodinamico può essere parziale o totale. Gli accessi vascolari possono essere periferici o centrali. Questo tipo di assistenza utilizza il concetto di circolazione extracorporea (CEC) sanguigna che in epoca moderna si è estesa con l’utilizzo di polmoni artificiali a membrana. Il circuito di base è semplice e comprende una pompa, un ossigenatore (che permette al sangue di caricarsi di O₂ e di eliminare CO₂) e delle vie d’accesso (una di drenaggio e una di reinfusione). La sua attuazione è facile, veloce e può essere avviata al letto del malato. Il miglioramento delle attrezzature, una migliore conoscenza delle tecniche e delle indicazioni, e le politiche di salute pubblica hanno reso popolare questa tecnica. Alcuni centri di chirurgia toracica la utilizzano di routine come assistenza alla realizzazione di un intervento terapeutico (soprattutto trapianto) assieme a team di rianimazione per il trattamento della sindrome da distress respiratorio acuto. Nel quadro della malattia polmonare dell’adulto, l’idea principale è quella di sviluppare il concetto di strategia minimalista con l’uso di una CEC adiuvante parziale – più che sostitutiva totale – che permetterebbe il recupero metabolico ad integrum del paziente. Nei prossimi anni, i progressi della tecnologia e dell’ingegneria così come le conoscenze approfondite permetteranno il miglioramento della prognosi dei pazienti colpiti da deficit respiratorio sotto assistenza meccanica.

When the Battle is Lost and Won: Delayed Chest Closure After Bilateral Lung Transplantation

In this article we summarize benefits of delayed chest closure strategy in lung transplantation, addressing indications, different surgical techniques, and additional perioperative treatment. Delayed chest closure seems to be a valuable and safe strategy in managing patients with various conditions after lung transplantation, such as instable hemodynamics, need for high respiratory pressures, coagulopathy, and size mismatch. Therefore, this approach should be considered in lung transplant centers to give patients time to recover before the chest is closed.

Latent class analysis identifies distinct phenotypes of primary graft dysfunction after lung transplantation

BACKGROUND

There is significant heterogeneity within the primary graft dysfunction (PGD) syndrome. We aimed to identify distinct grade 3 PGD phenotypes based on severity of lung dysfunction and patterns of resolution.

METHODS

Subjects from the Lung Transplant Outcomes Group (LTOG) cohort study with grade 3 PGD within 72 h after transplantation were included. Latent class analysis (LCA) was used to statistically identify classes based on changes in PGD International Society for Heart & Lung Transplantation grade over time. Construct validity of the classes was assessed by testing for divergence of recipient, donor, and operative characteristics between classes. Predictive validity was assessed using time to death.

RESULTS

Of 1,255 subjects, 361 had grade 3 PGD within the first 72 h after transplantation. LCA identified three distinct phenotypes: (1) severe persistent dysfunction (class 1), (2) complete resolution of dysfunction within 72 h (class 2), and (3) attenuation, without complete resolution within 72 h (class 3). Increased use of cardiopulmonary bypass, greater RBC transfusion, and higher mean pulmonary artery pressure were associated with persistent PGD (class 1). Subjects in class 1 also had the greatest risk of death (hazard ratio, 2.39; 95% CI, 1.57-3.63; P &lt; .001).

CONCLUSIONS

There are distinct phenotypes of resolution of dysfunction within the severe PGD syndrome. Subjects with early resolution may represent a different mechanism of lung pathology, such as resolving pulmonary edema, whereas those with persistent PGD may represent a more severe phenotype. Future studies aimed at PGD mechanism or treatment may focus on phenotypes based on resolution of graft dysfunction.

[Extracorporeal membrane oxygenation in primary graft dysfunction in a paediatric double lung transplant: presentation of a case]

Primary graft dysfunction is a leading cause of morbimortality in the immediate postoperative period of patients undergoing lung transplantation. Among the treatment options are: lung protective ventilatory strategies, nitric oxide, lung surfactant therapy, and supportive treatment with extracorporeal membrane oxygenation (ECMO) as a bridge to recovery of lung function or re-transplant. We report the case of a 9-year-old girl affected by cystic fibrosis who underwent double-lung transplantation complicated with a severe primary graft dysfunction in the immediate postoperative period and refractory to standard therapies. Due to development of multiple organ failure, it was decided to insert arteriovenous ECMO catheters (pulmonary artery-right atrium). The postoperative course was satisfactory, allowing withdrawal of ECMO on the 5th post-surgical day. Currently the patient survives free of rejection and with an excellent quality of life after 600 days of follow up.

Extracorporeal membrane oxygenation for primary graft dysfunction after lung transplantation: long-term survival

BACKGROUND

Primary graft dysfunction (PGD) after lung transplantation is a major cause of morbidity and mortality. Venovenous or venoarterial extracorporeal membrane oxygenation (ECMO) allows lung recovery; however, the optimal approach and impact on long-term survival are unknown. We analyzed outcomes after ECMO use for PGD after lung transplantation at a single center over a 15-year period and assessed long-term survival.

METHODS

From March 1991 to March 2006, 763 lung or heart-lung transplants were performed at our center. Fifty-eight patients (7.6%) required early (0 to 7 days after transplant) ECMO support for PGD. Venovenous or venoarterial ECMO was implemented (32 and 26 cases) depending on the patient's hemodynamic stability, surgeon's preference, and the era of transplantation. Mean duration of support was 5.5 days (range, 1 to 20). Mean follow-up was 4.5 years.

RESULTS

Thirty-day and 1- and 5-year survivals were 56%, 40%, and 25%, respectively, for the entire group. Thirty-nine patients were weaned from ECMO, 21 venovenous and 18 venoarterial (53.8% and 46.2%), with 1- and 5-year survivals of 59% and 33%, inferior to recipients not requiring ECMO (p = 0.05). Survival at 30 days and at 1 and 5 years was similar for the patients supported with venoarterial or venovenous ECMO (58% versus 55%, p = 0.7; 42% versus 39%, p = 0.8; 29% versus 22%, p = 0.6).

CONCLUSIONS

Extracorporeal membrane oxygenation can provide acceptable support for PGD irrespective of the method used. Long-term survival of patients with primary graft dysfunction requiring ECMO (overall and weaned) was inferior to that of patients who did not require ECMO.

Early Trends in PaO 2 /Fraction of Inspired Oxygen Ratio Predict Outcome in Lung Transplant Recipients With Severe Primary Graft Dysfunction

BACKGROUND

The development of severe primary graft dysfunction (PGD) is a risk factor for perioperative death following lung transplantation. Our goal is to improve the predictive value of the earliest Pao(2)/fraction of inspired oxygen (P/F) measurements that gauge PGD severity.

METHODS

We identified 96 patients with severe PGD (P/F < 200) at ICU arrival through a retrospective review of 431 lung transplants performed at our institution from 1992 to 2005. The P/F trend, represented as quartiles of the 12-h percentage change in P/F, was analyzed using multivariate logistic regression. Study outcomes were 90-day death and long-term survival.

RESULTS

The median percentage change in P/F over 12 h was + 52% (interquartile range, +20 to 90%). We observed the highest early mortality among those in the lowest quartile of the P/F trend (an increase in P/F <or= 20%). Ninety-day death rates decreased across the quartiles (low quartile, 32%; low-mid quartile, 9%; high-mid quartile, 5%; high quartile, 5%; test for trend, p = 0.007). After adjustment for the use of cardiopulmonary bypass, those in the lowest quartile of P/F trend had 6.8 times the odds of early death vs patients with a more favorable trend (odds ratio, 6.80; 95% confidence interval, 1.73 to 0.51; p = 0.007). In the first 5 years after transplant, there were significantly more deaths within the low quartile group vs those with a more rapidly increasing P/F trend (log-rank test, p = 0.01).

CONCLUSIONS

Among lung recipients with severe PGD at ICU arrival, an improvement in P/F <or= 20% in the first 12 h portends a poor outcome.

Resolution of Severe Ischemia–Reperfusion Injury Post–Lung Transplantation After Administration of Endobronchial Surfactant

BACKGROUND

Ischemia-reperfusion injury (IRI) is a prominent cause of primary graft failure after lung transplantation and is associated with an altered surfactant profile. Experimental animal studies have found that replacement with exogenous surfactant administered via fiber-optic bronchoscopy (FOB) enhanced recovery from IRI with improved pulmonary compliance and gas exchange after lung transplantation. We report our clinical experience with FOB instillation of surfactant in severe IRI after human lung transplantation.

METHODS

This study is a retrospective review of 106 consecutive lung or heart-lung transplants performed at a single institution. Severe IRI was defined as diffuse roentgenographic alveolar infiltrates, worsening hypoxemia and decreased lung compliance within 72 hours of lung transplantation. One vial of surfactant (20 mg/ml phospholipid) was instilled into each segmental bronchus upon diagnosis of IRI.

RESULTS

Six patients (5 bilateral sequential and 1 re-do heart-lung transplant), mean age 46 years, were diagnosed with IRI and surfactant was administered at a mean of 37 hours (range 2.3 to 98) post-transplant. Mean graft ischemia time was 376 minutes (range 187 to 625) and cardiopulmonary bypass time 174 minutes (range 0 to 210). Mean Pao(2) [mm Hg]/Fio(2) ratio before and 48 hours after surfactant instillation was 70 and 223, respectively. Significant resolution of radiologic infiltrates was evident in all cases within 24 hours. Successful extubation occurred at a mean of 13.5 days and survival is presently 100% at 19 months (range 3 to 54).

CONCLUSIONS

Bronchoscopic instillation of surfactant improves oxygenation and prognosis after severe IRI in lung transplant recipients. It represents a cost-effective, relatively non-invasive therapeutic alternative to extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation for primary graft dysfunction after lung transplantation: analysis of the Extracorporeal Life Support Organization (ELSO) registry

BACKGROUND

Some patients with severe primary graft dysfunction (PGD) after lung transplantation (LTx) require gas exchange support using an extracorporeal membrane oxygenator (ECMO) as a life-saving therapy. A few single-center experiences have been reported with relatively few cases of ECMO after LTx.

METHODS

We reviewed outcomes of ECMO in lung transplant recipients included in the Extracorporeal Life Support Organization (ELSO) registry, which was established with the intention to improve quality and outcome of extracorporeal life support (ECLS) in patients treated with ECMO applied for all indications.

RESULTS

The ELSO registry currently includes 31,340 ECMO cases, of which 151 were post-LTx patients with primary graft dysfunction (PGD). The mean age was 35 +/- 18 years. Indications for LTx were acute respiratory distress syndrome, (15%), cystic fibrosis (15%), idiopathic pulmonary fibrosis (8%), primary pulmonary hypertension, (10%), emphysema (15%), acute lung failure (11%), other (23%), and unknown (3%). ECMO run time was 140 +/- 212 hours. Venovenous ECMO was used in 25, venoarterial in 89, and other modes in 15 patients (unknown in 22). ECMO was discontinued in 93 patients owing to lung recovery. It was also discontinued in 29 patients with multiorgan failure, in 22 patients that died with no further specification, and in 7 patients for other reasons. In total, 63 (42%) patients survived the hospital stay. Major complications during ECMO included hemorrhage (52%), hemodialysis (42%), neurologic (12%), and cardiac (28%) complications, inotropic support (77%), and sepsis (15%).

CONCLUSIONS

Although the ELSO registry was not primarily established to study ECMO in LTx, it provides valuable insights and evidence that there is indeed an appreciable salvage rate with the use of ECMO for PGD after LTx. Clearly, this is a very high-risk patient population, and no single center can accumulate a large experience of ECMO for this specific indication. These data, however, underscore the importance of developing a specific registry for patients put on ECLS devices so that we can better study the outcomes, determine optimum treatment strategies, and optimize patient and device selection, and thus improve the outcomes of patients requiring this unique therapy.

Potential Refinements of The International Society for Heart And Lung Transplantation Primary Graft Dysfunction Grading System

Primary graft dysfunction (PGD) is responsible for significant morbidity and mortality after lung transplantation and The International Society for Heart and Lung Transplantation (ISHLT) Working Group on PGD has recently reported standardized consensus criteria, based on the recipient arterial blood-gas analysis and chest X-ray findings, to define PGD and determine its severity (grade range, 0-3). The grading system has been shown to predict post-transplant outcomes; however, further evaluation and refinement of the validity of the grading system is an important next step to enhance its utility. In this review, we describe advantage and disadvantages of the current PGD grading system based on series of analyses we have conducted and possible options for its potential refinement. The suggested revisions are (1) additional assessment time points at 6 and 12 hours should be included, (2) only bilateral infiltrates on chest X-ray (not unilateral infiltrates) should be considered as an infiltrate in bilateral lung transplants, (3) information from the chest X-ray is useful within 6 hours of final lung reperfusion (T0) but is not necessary to classify grade 3 at 12 to 72 hours, (4) apply PGD grade to single and bilateral lung transplant separately, (5) all extubated patients should be considered as grade 0 to 1, (6) note if PGD grade is being defined by specific inclusion and exclusion criteria, including extubation, with clear chest X-ray, on nitric oxide or extracorporeal membrane oxygenation. Although, further evaluations of the PGD definition and grading system are needed, the suggested refinements in this review may further enhance the reliability and validity of the PGD grading system as an important new lung transplant study instrument.

Early institution of extracorporeal membrane oxygenation for primary graft dysfunction after lung transplantation improves outcome

BACKGROUND

Primary graft dysfunction (PGD) after lung transplantation (LTx) carries a significant mortality and clinical management is controversial. Extracorporeal membrane oxygenation (ECMO) has been used infrequently for recovery from acute lung injury (ALI) in this setting. We reviewed our experience with ECMO after primary LTx.

METHODS

The present study is a retrospective analysis of all LTx patients between 1991 and 2004. Twenty-two patients sustained severe PGD with subsequent placement on ECMO. We analyzed indications and 30-day, 1-year and 3-year mortality. Complications and incidence of multiple-organ failure (MOF) were determined. Critical appraisal of the evidence available to date was performed.

RESULTS

A total of 297 LTxs were performed during the study period, with 97.5%, 88.6% and 73.8% survival at 30 days, 1 year and 3 years, respectively. Twenty-two patients (7.9%) had severe allograft dysfunction leading to ECMO support. Twelve patients received single-lung (SLTx), 8 double-lung (BLTx), 1 single-lung/kidney (SLKTx) and 1 heart/lung (HLTx) transplantation. Thirty-day, 1-year and 3-year survival of LTx recipients with ECMO support post-operatively were 74.6%, 54% and 36%, respectively. MOF was the predominant cause of death (58.3%) in patients on ECMO support for PGD.

CONCLUSIONS

Our data suggest that, in addition to prolonged ventilation and pharmacologic support, ECMO should be considered as a bridge to recovery from PGD in lung transplantation. Early institution of ECMO may lead to diminished mortality in the setting of ALI despite the high incidence of MOF. Late institution of ECMO was associated with 100% mortality in this investigation.

Recipient vascular endothelial growth factor serum levels predict primary lung graft dysfunction

Primary graft dysfunction (PGD) is a severe complication in lung transplantation. Therapeutic strategies are limited and there exist no predictive markers for PGD. To investigate whether vascular endothelial growth factor (VEGF) that regulates vascular permeability could predict PGD, pretransplant VEGF serum concentrations were measured in 150 lung transplant patients and 12 controls by ELISA. PGD was scored from 0 to 3 using chest radiographs and PaO(2)/FiO(2) ratios according to the International Society for Heart and Lung Transplantation guidelines. The mean graft ischemia time was 5 h 47 min and the donors' PaO(2)/FiO(2) ratios were >300. PGD grades 0-3 occurred in 23%, 44%, 21%, and 11% of patients, respectively. Pre-operative VEGF serum concentrations were significantly higher in PGD grade 3 (p < 0.0001) versus grade 0-2 and controls. VEGF concentrations significantly predicted PGD grade 3 versus 0-2 in logistic regression analysis (p < 0.0001) and receiver operating analysis (AUC = 0.778). At a cut-off level of > or =650 pg/mL VEGF had 86% sensitivity and 62% specificity to identify PGD grade 3 versus 0-2. Pre-operative VEGF serum concentrations could identify lung transplant recipients with high PGD risk.

Marginal Lung Donors: A Diminishing Margin of Safety?

Lung donor shortages have resulted in the critical appraisal of cadaveric donor acceptability criteria and the gradual relaxation of once strict guidelines. Many centers have reported their results with these "extended criteria" donors and an increasing number of multicenter registry studies have also been published. The results have been contradictory and leave many questions unanswered. Important new data has however come to light since the last review of the subject by the International Society for Heart and Lung Transplantation Pulmonary Council. We review the current literature focusing on recent developments in the pursuit of an expanded lung donor pool with acceptable outcomes.

Extended use of extracorporeal membrane oxygenation after lung transplantation

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) for severe graft failure after lung transplantation is accepted immediately postoperatively; extending its use is controversial. We evaluated our post-lung transplant ECMO experience, which included extended indication, to (1) determine its prevalence, risk factors, indications, and timing, (2) compare complications and outcomes of these patients with those not requiring it, and (3) identify risk factors, including indications, for mortality.

METHODS

From February 1990 to October 2005, 474 patients underwent lung transplantation; postoperative ECMO support was instituted for severe graft failure 23 times in 22 patients (4.0%). Indications for ECMO and its timing were obtained by reviewing medical records and survival by systematic follow-up.

RESULTS

No factor evaluated predicted severe graft failure leading to ECMO. The most common indication for ECMO was early graft failure (13 patients); however, it was also used for pneumonia or sepsis (6) and acute rejection (4). ECMO was initiated at a median arterial oxygen tension/inspired oxygen fraction of 59 at a median of 2 days postoperatively and was maintained for a median of 4 days. The most common complications were renal failure (57%) and bleeding (43%). ECMO was effective in salvaging patients with rejection and early graft failure (survival at 1, 3, 6, and 12 months: 62%, 54%, 49%, and 41%), but ineffective for pneumonia or sepsis (survival at these intervals: 9%, 4%, 4%, and 3%).

CONCLUSIONS

ECMO can be extended beyond early severe graft failure to acute rejection and can be considered after the immediate postoperative period. Survival after ECMO in patients with pneumonia or sepsis is poor.

Update of early respiratory failure in the lung transplant recipient

PURPOSE OF REVIEW

Respiratory failure remains the most common complication in the perioperative period after lung transplantation. Consequently it is important to develop an approach to diagnosis and the treatment of respiratory failure in this population. This review highlights the advances made in the understanding and treatment of lung transplant patients in the early postoperative phase. Owing to its relative importance, advances in the understanding and treatment of ischaemia-reperfusion injury are highlighted.

RECENT FINDINGS

The causes of respiratory failure and the complications seen after transplantation are time dependent, with ischaemia-reperfusion, infection, technical problems and acute rejection being the most common in the early perioperative phase, and obliterative bronchiolitis, rejection, and infections secondary to bacteria, fungi, and viruses becoming more prevalent after 3 months. The advances in lung preservation and postoperative care may be overshadowed by an increase in the complexity of the recipients and the use of more marginal organs. An improved mechanistic understanding of ischaemia-reperfusion injury has translated into potential therapeutic targets. The development of prospective clinical trials, however, is hampered by a relatively small sample of patients and a significant degree of heterogeneity in the lung transplant population.

SUMMARY

Many advances have been made in the understanding of ischaemia-reperfusion injury. Owing to the acute and long-term implications of this complication, interventions that reduce the risk of developing ischaemia-reperfusion need to be evaluated in prospective clinical trials.

Early changes in basement membrane thickness in airway walls post-lung transplantation

BACKGROUND

Identification of early histopathologic markers of future bronchiolitis obliterans syndrome (BOS) may enable preemptive targeted intervention, delaying and perhaps preventing the onset of BOS. This study aimed to determine if early changes in airway epithelial basement membrane thickness predisposes transplant recipients to the subsequent development of BOS.

METHODS

Basement membrane thickness was measured in serial endobronchial biopsies taken from 29 initially stable lung transplant recipients (sLTR) recruited 148 +/- 80 days post-transplant and followed for 3 years. A further 2 years of clinical follow-up was undertaken without biopsies to follow lung function and define ultimate BOS status. Nine healthy subjects (non-atopic, non-asthmatic) were recruited as controls. Sections of paraffinized endobronchial biopsies were stained for collagen type I immunohistochemically, and basement membrane thickness was assessed by computer image analysis.

RESULTS

BOS developed in 21 of 29 patients in the 5 years of follow-up, 16 of which had endobronchial biopsies available for analysis before BOS developed (ever-BOS). The first endobronchial biopsies showed increased BMT in the combined sLTR and ever-BOS patients compared with the controls. This initial increase in basement membrane thickness resolved to normal levels within 300 days post-transplant, with a strong negative correlation (r2 = 0.424, p < 0.0001) of basement membrane thickness vs time. Paradoxically, the sLTR tended to have the greatest basement membrane thickness at baseline.

CONCLUSION

An initial increase in basement membrane thickness is seen in the airway walls of all lung transplant recipients. This is transient and does not appear to be a risk factor for the subsequent development of BOS in lung allograft recipients.

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.

Outcomes of Delayed Chest Closure After Bilateral Lung Transplantation

BACKGROUND

Delayed chest closure (DCC) may be used after bilateral lung transplantation when significant bleeding/coagulopathy or severe pulmonary edema exists. Primary chest closure (PCC) in these patients can lead to heart and lung compression causing cardiopulmonary instability. The purpose of this study is to describe factors associated with DCC and evaluate outcomes after DCC.

METHODS

We performed a retrospective review of all patients undergoing bilateral lung transplantation between September 2003 and March 2005. Statistical significance was determined by two-tailed t test or Fisher's exact test.

RESULTS

Twenty-eight bilateral lung transplantations were performed. Indication for transplant was chronic obstructive pulmonary disease (13), pulmonary fibrosis (5), cystic fibrosis (5), sarcoidosis (3), and pulmonary hypertension (1). Seven patients (25%) required DCC. Mean time to DCC was 5.3 days. Six patients (86%) with DCC required tracheostomy versus 4 patients (20%) with PCC (p = 0.003). Mean days to discharge was 44 in the DCC group and 21 in the PCC group (p = 0.03). Thirty-day survival was 100% in the DCC group and 95% in the PCC group (p = 1.0). There were no wound infections in either group, and 1 patient in the PCC group had sternal nonunion. Delayed chest closure was associated with cardiopulmonary bypass use (p = 0.006), cardiopulmonary bypass time longer than mean cardiopulmonary bypass time (mean, 224 minutes; p = 0.04), PaO2/FiO2 less than mean + 1 SD (value = 4.63, p = 0.0002), evidence of moderate/severe reperfusion injury on chest radiograph (p = 0.0002), and PaO2/FiO2 less than mean plus moderate/severe reperfusion injury on chest radiograph (p = 0.002).

CONCLUSIONS

Cardiopulmonary bypass use, prolonged cardiopulmonary bypass time, and significant reperfusion injury, as determined by chest radiograph and a low PaO2/FiO2 ratio were all associated with an increased incidence of DCC in our bilateral lung transplantation patients. These patients had no wound infections or sternal complications, and although they had longer hospital stays than PCC patients, DCC did not affect operative survival. Delayed chest closure can be employed safely, when necessary, after bilateral lung transplantation with outcomes similar to patients with PCC.

Validation of the Proposed International Society for Heart and Lung Transplantation Grading System for Primary Graft Dysfunction After Lung Transplantation

BACKGROUND

A scoring system was recently proposed to grade the severity of primary graft dysfunction (PGD), a frequent early complication of lung transplantation. The purposes of this study are to: (1) validate the PGD grading system with respect to patient outcomes; and (2) compare the performance of criteria employing the arterial oxygenation to fraction of inspired oxygen (P/F) ratio to an alternative grading system employing the oxygenation index (OI).

METHODS

We retrospectively reviewed the medical records of 402 patients having undergone lung transplantation at our institution from 1992 through 2004. The ISHLT PGD grading system was modified and grades were assigned up to 48 hours post-transplantation as follows: Grade 1 PGD, P/F > 300; Grade 2, P/F 200 to 300; and Grade 3, P/F < 200. A worst score T(0-48) was also assigned, which reflects the highest grade recorded between T0 and T48.

RESULTS

The prevalence of severe PGD (P/F Grade 3) declined after transplant, from 25% at T0 to 15% at T48. Grouping patients by P/F grade at T48 demonstrated the clearest differentiation of 90-day death rates (Grade 1, 7%; Grade 2, 12%; Grade 3, 33%) (p = 0.0001). T48 OI grade also differentiates 90-day death rates. There was no difference in longer-term survival between patients with PGD Grades 1 and 2. OI grade at T0 qualitatively improved differential mortality between Grades 1 and 2; however, the differences did not reach statistical significance. Patients with a worst score T(0-48) of Grade 3 PGD did have significantly decreased long-term survival, as well as longer ICU and hospital stay, when compared with Grades 1 and 2 PGD. Significant risk factors for short- and long-term mortality in our multivariate model were P/F Grade 3 [worst score T(0-48) as well as T0 grade], single-lung transplant, use of cardiopulmonary bypass and high pre-operative mean pulmonary artery pressure.

CONCLUSIONS

There is an increased risk of short- and long-term mortality and length of hospital stay associated with severe (Grade 3) PGD. The proposed ISHLT grading system can rapidly identify patients with poor outcomes who may benefit from early, aggressive treatment. Refinement of the scoring system may further improve patient risk stratification.

Risk factors for primary graft dysfunction after lung transplantation

OBJECTIVE

The International Society for Heart and Lung Transplantation has proposed a new grading system for primary graft dysfunction based on the ratio of arterial oxygen to fraction of inspired oxygen measured within 48 hours after lung transplantation. Worsening primary graft dysfunction grade is associated with increased operative mortality rates and decreased long-term survival. This study evaluated donor and recipient risk factors for postoperative International Society for Heart and Lung Transplantation grade 3 primary graft dysfunction.

METHODS

We reviewed donor and recipient medical records of 402 consecutive lung transplantations performed between 1992 and 2004. We calculated a worst International Society for Heart and Lung Transplantation primary graft dysfunction grade in the first 48 hours postoperatively. Severe primary graft dysfunction (International Society for Heart and Lung Transplantation grade 3) was defined by a ratio of arterial oxygen to fraction of inspired oxygen of less than 200. Associations of potential risk factors with grade 3 primary graft dysfunction in the first 48 hours postoperatively were examined through bivariate and multivariate analysis.

RESULTS

The 90-day mortality rate associated with the development of International Society for Heart and Lung Transplantation grade 3 primary graft dysfunction in the first 48 hours postoperatively was 17% versus 9% in the group without grade 3 primary graft dysfunction. Significant bivariate risk factors associated with this end point were increasing donor age, donor smoking history of more than 10 pack-years, early transplantation era (1992-1998), increasing preoperative recipient pulmonary artery pressure, and recipient diagnosis. In the multivariate analysis only recipient pulmonary artery pressure, donor age, and transplantation era were associated with grade 3 primary graft dysfunction in the first 48 hours postoperatively at a P value of less than .05.

CONCLUSIONS

Our analysis of donor and recipient risk factors for severe primary graft dysfunction identified patient groups at high risk for poor outcomes after lung transplantation that might benefit from treatments aimed at reducing reperfusion injury.

Lung transplantation: donor and recipient critical care aspects

PURPOSE OF REVIEW

The purpose of this paper is to highlight new developments in donor and recipient lung transplant issues for the critical care physician.

RECENT FINDINGS

A shortage of suitable lung donors has led to the use of extended donors and the development of novel techniques such as live-donor lung transplantation and the use of non-heart-beating donors. The increased experience and success with lung transplantation has also resulted in the extension of this therapy to patients previously considered unsuitable for transplantation. Postoperative outcomes can be affected by many of these recent donor and recipient changes. Improved preservation solutions and techniques to reduce reperfusion injury may be able to ameliorate some of the new perioperative graft dysfunction, but morbidity is still potentially significant, and extraordinary interventions such as extracorporeal membrane oxygenation may be required in selected cases.

SUMMARY

Patients undergoing lung transplantation continue to be very challenging in the intensive care unit. A multidisciplinary approach to care, and early recognition of serious problems, will help improve outcomes.