Lung size mismatch in bilateral lung transplantation is associated with allograft function and bronchiolitis obliterans syndrome

Unveiling the potential of lung transplantation for situs inversus

INTRODUCTION

Situs inversus is a rare congenital condition where the organs in the chest and abdomen are reversed, thus complicating surgeries such as lung transplantation. Kartagener syndrome (KS), associated with situs inversus, includes chronic sinusitis and bronchiectasis, which can progress to end-stage lung disease requiring transplantation. This review discusses the unique surgical considerations, technical challenges, and outcomes of lung transplantation in patients with situs inversus, particularly KS.

AREAS COVERED

The review highlights anatomical and physiological challenges in lung transplantation due to reversed organ positioning, requiring customized surgical approaches and intraoperative modifications. Preoperative imaging, anesthesia adjustments, and tailored surgical techniques are crucial for successful transplantation. Postoperative care focuses on managing complications such as primary graft dysfunction, infections, and anastomotic issues. Literature on survival rates, chronic lung allograft dysfunction, and quality of life is analyzed, indicating outcomes comparable to other lung transplant recipients.

EXPERT OPINION

Despite significant challenges, lung transplantation in patients with situs inversus and KS is feasible with outcomes similar to traditional cases. Advances in imaging, surgical planning, and minimally invasive techniques offer promise for improved outcomes. Ongoing research, collaboration, and ethical considerations are essential to optimizing care and expand treatment possibilities for this high-risk patient population.

Oversizing lung allografts deteriorates outcomes in patients with pulmonary fibrosis

BACKGROUND

Lung transplantation is the only curative treatment for patients with end-stage pulmonary fibrosis. It is still under debate whether over- or undersizing of lung allografts is preferably performed regarding the postoperative outcome. We therefore analyzed our data using predicted total lung capacity to compare size mismatches.

METHODS

Patient records were retrospectively reviewed. Three groups were formed, 1 including patients with a donor-recipients pTLC ratio (DRPR) of <1.0 (undersized group), the second with a DRPR of ≥1.0 and <1.1 (size-matched group), and the third group with a DRPR of ≥1.1 (oversized group). Outcomes were evaluated using chi-square test and Kruskall-Wallis test as well as Kaplan-Meier analysis, competing risk analysis, and multivariable analysis, respectively.

RESULTS

Between January 2010 and May 2023, among the 1501 patients transplanted at our institution, 422 (28%) patients were included, 26 (2%) patients forming the oversized group (median DRPR: 1.14), 101 (7%) patients forming the size-matched group (median DRPR: 1.03), and 296 (20%) patients forming the undersized group (median DRPR: 0.92). Patients from the oversized group had a higher PGD grade 3 rate at 24 (p < 0.001), 48 (p < 0.001), and 72 (p = 0.039) hours after transplantation as well as a higher in-hospital mortality compared to the undersized group (p = 0.033). The long-term survival was also better in the undersized group compared to the oversized group (p = 0.011) and to the size-matched group (p = 0.01).

CONCLUSIONS

Oversizing lung allografts more than 10% deteriorated early postoperative outcomes and long-term survival in patients with pulmonary fibrosis.

Increased Donor Organ Size and Age is Associated with Reduced Survival in Female Lung Transplant Recipients

BACKGROUND

Organ selection in lung transplantation (LTx) is still controversial. We here analyze the impact of mismatches in size, age, and gender on early and long-term outcome after LTx.

METHODS

Retrospective analysis of donor and recipient characteristics of patients who underwent double LTx between March 2003 and December 2021. Statistical analysis was performed using SPSS and GraphPad software.

RESULTS

Two hundred three patients were included (94 women and 109 men). In the whole cohort, oversizing donor organs 10% to 20% compared to the recipients' predicted total lung capacity led to a decreased incidence of severe Primary Graft Dysfunction grades 2 and 3 (2/3; 15% vs 41%, P = .03), and further oversizing > 20% was associated with reduced long-term survival (hazard ratio, 2.33, P = .011). Analyzing donor and recipient age, we found that increased donor age correlated with reduced long-term survival (P = .013). In this cohort, female recipients received older organs (median 57 vs 46 years, P = .0003) and had a higher incidence of > 20% oversizing (13% vs 4%, P = .019) of donor lungs, which resulted in a significantly reduced long-term survival (P = .02) compared with male recipients. Median Lung Allocation Scores were similar in both groups.

CONCLUSION

Mismatch of donor age and size can be important for organ function and survival in LTx recipients. Particularly female recipients seem to have a higher risk for unfavorable long-term outcome when transplanting organs of increased size and age. Multicenter studies are warranted to further address this question.

TRIAL REGISTRATION NUMBER

(DKRS): 00033312.

Advances in lung transplantation: 60 years on

Lung transplantation is a well-established treatment for advanced lung disease, improving survival and quality of life. Over the last 60 years all aspects of lung transplantation have evolved significantly and exponential growth in transplant volume. This has been particularly evident over the last decade with a substantial increase in lung transplant numbers as a result of innovations in donor utilization procurement, including the use donation after circulatory death and ex-vivo lung perfusion organs. Donor lungs have proved to be surprisingly robust, and therefore the donor pool is actually larger than previously thought. Parallel to this, lung transplant outcomes have continued to improve with improved acute management as well as microbiological and immunological insights and innovations. The management of lung transplant recipients continues to be complex and heavily dependent on a tertiary care multidisciplinary paradigm. Whilst long term outcomes continue to be limited by chronic lung allograft dysfunction improvements in diagnostics, mechanistic understanding and evolutions in treatment paradigms have all contributed to a median survival that in some centres approaches 10 years. As ongoing studies build on developing novel approaches to diagnosis and treatment of transplant complications and improvements in donor utilization more individuals will have the opportunity to benefit from lung transplantation. As has always been the case, early referral for transplant consideration is important to achieve best results.

Impulse Oscillometry Versus Spirometry to Detect Bronchiolitis Obliterans Syndrome in Bilateral Lung Transplant Recipients: A Prospective Diagnostic Study

BACKGROUND

Chronic lung allograft dysfunction (CLAD), and especially bronchiolitis obliterans syndrome (BOS), remain dominant causes of morbidity and mortality after lung transplantation. Interest is growing in the forced oscillation technique, of which impulse oscillometry (IOS) is a form, as a tool to improve our understanding of these disorders. However, data remain limited and no longitudinal studies have been published, meaning there is no information regarding any capacity IOS may have for the early detection of CLAD.

METHODS

We conducted a prospective longitudinal study enrolling a consecutive sample of adult bilateral lung transplant recipients with healthy lung allografts or CLAD and performed ongoing paired IOS and spirometry tests on a clinically determined basis. We assessed for correlations between IOS and spirometry and examined any predictive value either modality may hold for the early detection of BOS.

RESULTS

We enrolled 91 patients and conducted testing for 43 mo, collecting 558 analyzable paired IOS and spirometry tests, with a median of 9 tests per subject (interquartile range, 5-12) and a median testing interval of 92 d (interquartile range, 62-161). Statistically significant moderate-to-strong correlations were demonstrated between all IOS parameters and spirometry, except resistance at 20 Hz, which is a proximal airway measure. No predictive value for the early detection of BOS was found for IOS or spirometry.

CONCLUSIONS

This study presents the first longitudinal data from IOS after lung transplantation and adds considerably to the growing literature, showing unequivocal correlations with spirometry but failing to demonstrate a predictive value for BOS.

Donor and recipient risk factors for the development of primary graft dysfunction following lung transplantation

Primary Graft Dysfunction (PGD) is a major cause of both short-term and long-term morbidity and mortality following lung transplantation. Various donor, recipient, and technical risk factors have been previously identified as being associated with the development of PGD. Here, we present a comprehensive review of the current literature as it pertains to PGD following lung transplantation, as well as discussing current strategies to mitigate PGD and future directions. We will pay special attention to recent advances in lung transplantation such as ex-vivo lung perfusion, thoracoabdominal normothermic regional perfusion, and up-to-date literature published in the interim since the 2016 ISHLT consensus statement on PGD and the COVID-19 pandemic.

Computed Tomography Volumetrics for Size Matching in Lung Transplantation for Restrictive Disease

BACKGROUND

There is no consensus on the optimal allograft sizing strategy for lung transplantation in restrictive lung disease. Current methods that are based on predicted total lung capacity (pTLC) ratios do not account for the diminutive recipient chest size. The study investigators hypothesized that a new sizing ratio incorporating preoperative recipient computed tomographic lung volumes (CTVol) would be associated with postoperative outcomes.

METHODS

A retrospective single-institution study was conducted of adults undergoing primary bilateral lung transplantation between January 2016 and July 2020 for restrictive lung disease. CTVol was computed for recipients by using advanced segmentation software. Two sizing ratios were calculated: pTLC ratio (pTLCdonor/pTLCrecipient) and a new volumetric ratio (pTLCdonor/CTVolrecipient). Patients were divided into reference, oversized, and undersized groups on the basis of ratio quintiles, and multivariable models were used to assess the effect of the ratios on primary graft dysfunction and survival.

RESULTS

CTVol was successfully acquired in 218 of 220 (99.1%) patients. In adjusted analysis, undersizing on the basis of the volumetric ratio was independently associated with decreased primary graft dysfunction grade 2 or 3 within 72 hours (odds ratio, 0.42; 95% CI, 0.20-0.87; P =.02). The pTLC ratio was not significantly associated with primary graft dysfunction. Oversizing on the basis of the volumetric ratio was independently associated with an increased risk of death (hazard ratio, 2.27; 95% CI, 1.04-4.99; P =.04], whereas the pTLC ratio did not have a significant survival association.

CONCLUSIONS

Using computed tomography-acquired lung volumes for donor-recipient size matching in lung transplantation is feasible with advanced segmentation software. This method may be more predictive of outcome compared with current sizing methods, which use gender and height only.

Lung transplantation in children

Lung transplantation is a well-established treatment for children facing advanced lung disease and pulmonary vascular disorders. However, organ shortage remains highest in children. For fitting the small chest of children, transplantation of downsized adult lungs, lobes, or even segments were successfully established. The worldwide median survival after pediatric lung transplantation is currently 5.7 years, while under consideration of age, underlying disease, and peri- and posttransplant center experience, median survival of more than 10 years is reported. Timing of referral for transplantation, ischemia-reperfusion injury, primary graft dysfunction, and acute and chronic rejection after transplantation remain the main challenges.

A new method for evaluating lung volume: AI-3D reconstruction

Objective: This study aims to explore the clinical application of an AI-3D reconstruction system in measuring lung volume and analyze its practical value in donor-recipient size matching in lung transplantation. Methods: The study retrospectively collected data from 75 subjects who underwent a plethysmography examination and lung CT at the First Hospital of Jilin University. General data and information related to lung function, and imaging results were collected. The correlation between actual total lung volume (aTLV), predicted total lung volume (pTLV), and artificial intelligence three-dimensional reconstruction CT lung volume (AI-3DCTVol) was analyzed for the overall, male, and female groups. The correlation coefficient and the absolute error percentage with pTLV and AI-3DCTVol were obtained. Results: In the overall, male, and female groups, there were statistical differences (p <0.05) between the pTLV formula and AI-3D reconstruction compared to the plethysmography examination value. The ICC between pTLV and aTLV for all study participants was 0.788 (95% CI: 0.515-0.893), p <0.001. Additionally, the ICC value between AI-3D reconstruction and aTLV was 0.792 (95% CI: 0.681-0.866), p <0.001. For male study participants, the ICC between pTLV and aTLV was 0.330 (95% CI: 0.032-0.617), p = 0.006. Similarly, the ICC value between AI-3D reconstruction and aTLV was 0.413 (95% CI: 0.089-0.662), p = 0.007. In the case of female research subjects, the ICC between pTLV and aTLV was 0.279 (95% CI: 0.001-0.523), p = 0.012. Further, the ICC value between AI-3D reconstruction and aTLV was 0.615 (95% CI: 0.561-0.870), p <0.001. Conclusion: The AI-3D reconstruction, as a convenient method, has significant potential for application in lung transplantation.

Evaluating the Use of CT-Derived Lung Volumes in Donor-Recipient Lung Size Matching for Lung Transplantation in Patients With Interstitial Lung Disease and/or Idiopathic Pulmonary Fibrosis

PURPOSE

This study aims to assess the efficacy of current measurement strategies for lung sizing and the feasibility of future use of computed tomography (CT)-derived lung volumes to predict a donor-recipient lung size match during bilateral lung transplants.

METHODS

We reviewed the data of 62 patients who underwent bilateral lung transplantation for interstitial lung disease and/or idiopathic pulmonary fibrosis from 2018 to 2019. Data for recipients was retrieved from the department's transplant database and medical records, and the donor's data was retrieved from the DonorNet. The data included demographic data, lung heights, measured total lung capacity (TLC) from plethysmography for recipients and estimated TLC for donors, clinical data, and CT-derived lung volumes in both pre- and post-transplant recipients. The post-transplant CT-derived lung volume in recipients was used as a surrogate for donor lung CT volumes due to inadequate or poor donor CT data. Computed tomography-derived lung volumes were calculated using thresholding, region growing, and cutting techniques on Computer-Aided Design and Mimics (Materialise NV, Leuven, Belgium) programs. Preoperative CT-derived lung volumes in recipients were compared with the plethysmography TLC, Frustum Model, and donor-predicted TLC. The ratio of the recipient's pre-and postoperative CT-derived volumes, the ratio of preoperative CT-derived lung volume, and donor-estimated TLC were studied to detect a correlation with 1-year outcomes.

RESULTS

The recipient preoperative CT-derived volume correlated with the recipient preoperative plethysmography TLC (Pearson correlation coefficient [PCC] of 0.688) and with the recipient Frustum model volume (PCC of 0.593). The recipient postoperative CT-derived volume correlated with the recipient's postoperative plethysmography TLC (PCC of 0.651). There was no statistically significant correlation between recipients' CT-derived pre- or postoperative volume with donor-estimated TLC. The ratio of preoperative CT-derived volume to donor-estimated TLC correlated inversely with the length of ventilation (P value = .0031). The ratio of postoperative CT-derived volume to preoperative CT-derived volume correlated inversely with delayed sternal closure (P = .0039). No statistically significant correlations were found in evaluating outcomes related to lung oversizing in the recipient (defined as a postoperative to preoperative CT-derived lung volume ratio of >1.2).

CONCLUSIONS

Generating CT-derived lung volumes is a valid and convenient method for evaluating lung volumes for transplantation in patients with ILD and/or IPF. Donor-estimated TLC should be interpreted carefully. Further studies should derive donor lung volumes from CT scans for a more accurate evaluation of lung size matching.

Potential Role of Computed Tomography Volumetry in Size Matching in Lung Transplantation

BACKGROUND

Accumulated knowledge on the outcomes related to size mismatch in lung transplantation derives from predicted total lung capacity equations rather than individualized measurements of donors and recipients. The increasing availability of computed tomography (CT) makes it possible to measure the lung volumes of donors and recipients before transplantation. We hypothesize that CT-derived lung volumes predict a need for surgical graft reduction and primary graft dysfunction.

METHODS

Donors from the local organ procurement organization and recipients from our hospital from 2012 to 2018 were included if their CT exams were available. The CT lung volumes and plethysmography total lung capacity were measured and compared with predicted total lung capacity using Bland Altman methods. We used logistic regression to predict the need for surgical graft reduction and ordinal logistic regression to stratify the risk for primary graft dysfunction.

RESULTS

A total of 315 transplant candidates with 575 CT scans and 379 donors with 379 CT scans were included. The CT lung volumes closely approximated plethysmography lung volumes and differed from the predicted total lung capacity in transplant candidates. In donors, CT lung volumes systematically underestimated predicted total lung capacity. Ninety-four donors and recipients were matched and transplanted locally. Larger donor and smaller recipient lung volumes estimated by CT predicted a need for surgical graft reduction and were associated with higher primary graft dysfunction grade.

CONCLUSION

The CT lung volumes predicted the need for surgical graft reduction and primary graft dysfunction grade. Adding CT-derived lung volumes to the donor-recipient matching process may improve recipients' outcomes.

Airway oscillometry parameters in baseline lung allograft dysfunction: Associations from a multicenter study

BACKGROUND

Baseline lung allograft dysfunction (BLAD), the failure to achieve ≥80%-predicted spirometry after lung transplant (LTx), is associated with impaired survival. Physiologic abnormalities in BLAD are poorly understood. Airway oscillometry measures respiratory system mechanics and may provide insight into understanding the mechanisms of BLAD.

OBJECTIVES

This study aims to describe and measure the association between airway oscillometry parameters [Reactance (X_rs5, Ax), Resistance (R_rs5, R_rs5-19)] (1) stable LTx recipients, comparing those with normal spirometry and those with BLAD; and (2) in recipients with chronic lung allograft dysfunction (CLAD), comparing those with normal baseline spirometry and those with BLAD.

METHODS

A multi-center cross-sectional study was performed including bilateral LTx between January 2020 and June 2021. Participants performed concurrent airway oscillometry and spirometry. Multivariable logistic regression was performed to measure the association between oscillometry parameters and BLAD.

RESULTS

A total of 404 LTx recipients performed oscillometry and 253 were included for analysis. Stable allograft function was confirmed in 149 (50.2%) recipients (92 (61.7%) achieving normal spirometry and 57 (38.3%) with BLAD). Among stable LTx recipients, lower X_rs5 Z-Score (aOR 0.50 95% CI 0.37-0.76, p = 0.001) was independently associated with BLAD. CLAD was present in 104 (35.0%) recipients. Among recipients with CLAD, lower X_rs5 Z-Score (aOR 0.73 95% CI 0.56-0.95, p = 0.02) was associated with BLAD.

CONCLUSIONS

Oscillometry provides novel physiologic insights into mechanisms of BLAD. The independent association between X_rs5 and BLAD, in both stable recipients and those with CLAD suggests that respiratory mechanics, in particular abnormal elastance, is an important physiologic feature. Further longitudinal studies are needed to understand the trajectory of oscillometry parameters in relation to allograft outcomes.

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 role of donor-recipient gender matching in lung transplantation: a systematic review

INTRODUCTION

Donor to recipient (D-R) matching in lung transplantation (LTx) is firstly directed by blood group (identity or compatibility), immunological status and morphological criteria. Sex matching is ignored and impact on outcome less investigated.

EVIDENCE ACQUISITION

Systematic review of English literature using PubMed (1990-2019) was performed to evaluate the potential role of D-R matching in determining long-term outcome in patients after LTx. Search terms included (LTx) AND (sex) OR (gender) OR (matching) OR (mismatch) OR (donor characteristics) and were restricted to articles' title. Only articles directly reporting LTx survival outcome according to gender match/mismatch and D-R gender combination in LTx were included. Two authors independently extracted articles using predefined data fields, including study quality indicators. MOOSE Guidelines for Meta-Analyses and Systematic Reviews of Observational Studies applied.

EVIDENCE SYNTHESIS

Nine articles were analyzed and included into this study. All studies analyzed the effect of the different D-R gender combinations on survival while seven of them investigated exclusively the role of sex matching on LTx outcome. In this latter group two out of seven showed a trend towards an overall survival advantage for sex matching LTx combination. The worst survival results were reported for F to M gender combination in 3 studies and for M to F gender combination by 1 study. No differences were reported in remaining 4 studies.

CONCLUSIONS

This systematic review suggests that sex matching and several gender combinations could play a role in determining overall survival rate after LTx. Data deriving from unbiased studies supported that matching female-female (F-F) and male-male (M-M) could improve LTx outcome while FD-MR combination should be avoided. Unfortunately, a good part of the analyzed data are affected by bias due to confounding factors. Up-to-date immunological, hormonal and morphological factors could explain the gender-based difference in LTx outcome. Further investigations should clarify their role and importance to define the effects of gender combinations on survival.

Changes in Thoracic Cavity Volume After Bilateral Lung Transplantation

Purpose

End-stage lung diseases result in anatomical changes of the thoracic cavity. However, very few studies have assessed changes in the thoracic cavity after lung transplantation (LTx). This study aimed to evaluate the relationships between thoracic cavity volume (TCV) changes after LTx and underlying lung disease.

Methods

We reviewed 89 patients who underwent a pre-LTx pulmonary function test (PFT), chest computed tomography (CT) scan, and 1-year follow-up CT after LTx. These patients were classified into two groups according to pre-LTx PFT as follows: obstructive group [forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio < 70%] and restrictive group (FEV1/FVC ratio > 70%). We measured TCV using CT scan before and at 1 year after LTx and compared the TCV change in the two groups.

Results

In the restrictive group, TCV increased after LTx (preop: 2,347.8 ± 709.5 mL, 1-year postop: 3,224.4 ± 919.0 mL, p < 0.001). In contrast, in the obstructive group, it decreased after LTx (preop: 4,662.9 ± 1,296.3 mL, 1-year postop: 3,711.1 ± 891.7 mL, p < 0.001). We observed that restrictive lung disease, taller stature, lower body mass index, and larger donor lung were independently associated with increased TCV after LTx.

Conclusion

The disease-specific chest remodeling caused by restriction and hyperinflation is at least, in part, reversible. After LTx, the chest remodeling appears to occur in the opposite direction to the disease-specific remodeling caused by the underlying lung disease in recipients.

Diaphragmatic plication among lung transplant patients: A single-center experience

BACKGROUND

There is lack of data reporting outcomes among patients needing diaphragmatic plication (DP) during or after lung transplantation (LT). We sought to assess the association of DP with post-transplant spirometry among other outcomes.

METHODS

We included all patients who underwent LT between 2012&2016 (n = 324, mean age 56.3±13.4 years; M:F 198:126). We compared early and late outcomes based on the need for DP.

RESULTS

The frequency of diaphragm dysfunction (DD)on pre-transplant fluoroscopy was 52.2%. A total of 38 DP procedures were performed among 37 patients (11.4% of LT patients). DP was done for anatomic (sizing or spacing issues) or functional indications (symptomatic DD). While patients with DP had significantly lower spirometry throughout the 3-year follow-up period, their slope of decline, functional assessments at the first annual visit, the risk of CLAD, and mortality were similar to patients without DP. A sub-group analysis limited to patients with restrictive lung diseases as the transplant indication had similar findings.

CONCLUSIONS

Pre-transplant DD is common among LT candidates although it did not predict the need for DP. DP may be performed for functional or anatomic indications especially for addressing the donor-recipient size mismatch. Despite the lack of favorable effect on post-transplant spirometry, patients undergoing DP have acceptable and comparable early and late outcomes. This article is protected by copyright. All rights reserved.

The role of mechanical ventilation in primary graft dysfunction in the postoperative lung transplant recipient: A single center study and literature review

Background

Primary graft dysfunction (PGD) is still a major complication in patients undergoing lung transplantation (LTx). Much is unknown about the effect of postoperative mechanical ventilation on outcomes, with debate on the best approach to ventilation.

Aim/Purpose

The goal of this study was to generate hypotheses on the association between postoperative mechanical ventilation settings and allograft size matching in PGD development.

Method

This is a retrospective study of LTx patients between September 2011 and September 2018 (n = 116). PGD was assessed according to the International Society of Heart and Lung Transplantation (ISHLT) criteria. Data were collected from medical records, including chest x‐ray assessments, blood gas analysis, mechanical ventilator parameters and spirometry.

Results

Positive end‐expiratory pressures (PEEP) of 5 cm H₂O were correlated with lower rates of grade 3 PGD. Graft size was important as tidal volumes calculated according to the recipient yielded greater rates of PGD when low volumes were used, a correlation that was lost when donor metrics were used.

Conclusion

Our results highlight a need for greater investigation of the role donor characteristics play in determining post‐operative ventilation of a lung transplant recipient. The mechanical ventilation settings on postoperative LTx recipients may have an implication for the development of acute graft dysfunction. Severe PGD was associated with the use of a PEEP higher than 5 and lower tidal volumes and oversized lungs were associated with lower long‐term mortality. Lack of association between ventilatory settings and survival may point to the importance of other variables than ventilation in the development of PGD.

Advanced considerations in organ donors

The rising need for lung transplantation over recent years has not paralleled the availability of suitable lung allografts. The number of lung transplantations performed each year in the United States remains limited by an inadequate supply of suitable donors as well as low donor utilization rates. While several methods have been proposed for increasing the donor pool, there is considerable disparity between acceptance and utilization of these practices among transplant centers. In this review article, we explore various approaches for enhancing donor selection and expanding the donor pool. We discuss the use of “extended criteria” donors including high risk groups such as drug overdose donors, and we examine the role of techniques in donor assessment and selection such as the use of computed tomography for accurate size matching. We review topics in donor management such as the establishment of specialized donor care facilities and the implementation of lung-focused resuscitation protocols, and we discuss advancements in donor procurement such as the utilization of local procurement teams. We also review barriers to donation, such as variability in organ procurement organization (OPO) consent practices, as well as patient-specific factors such as religious or cultural beliefs. Addressing these aspects of donor evaluation, management, and accessibility is essential in maximizing the number of lungs available for transplantation within the existing donor pool.

Complications of Lung Transplantation: Update on Imaging Manifestations and Management

As lung transplantation has become the most effective definitive treatment option for end-stage chronic respiratory diseases, yearly rates of this surgery have been steadily increasing. Despite improvement in surgical techniques and medical management of transplant recipients, complications from lung transplantation are a major cause of morbidity and mortality. Some of these complications can be classified on the basis of the time they typically occur after lung transplantation, while others may occur at any time. Imaging studies, in conjunction with clinical and laboratory evaluation, are key components in diagnosing and monitoring these conditions. Therefore, radiologists play a critical role in recognizing and communicating findings suggestive of lung transplantation complications. A description of imaging features of the most common lung transplantation complications, including surgical, medical, immunologic, and infectious complications, as well as an update on their management, will be reviewed here. Keywords: Pulmonary, Thorax, Surgery, Transplantation Supplemental material is available for this article. © RSNA, 2021.

Donor quality assessment and size match in lung transplantation

Careful donor quality assessment and size match can impact long-term survival in lung transplantation. With this article, we review the conceptual and practical aspects of the preoperative donor lung quality assessment and size matching.

Emphysematous changes and lower levels of plasma irisin are associated with bronchiolitis obliterans syndrome after bilateral living-donor lobar lung transplantation

PURPOSE

Decreased irisin levels may be associated with the development of emphysema. Similarly, emphysematous changes may develop in patients with chronic lung allograft dysfunction (CLAD) after living-donor lobar lung transplantation (LDLLT). We investigated the severity of emphysematous changes and the relationship between irisin levels and CLAD after bilateral LDLLT and cadaveric lung transplantation (CLT).

METHODS

The subjects of this retrospective study were 59 recipients of bilateral LDLLT (n = 31) or CLT (n = 28), divided into a non-CLAD group (n = 41), a LDLLT-CLAD group (n = 11), and a CLT-CLAD group (n = 7). We compared the severity of emphysematous changes, the skeletal muscle mass, and the plasma irisin levels among the groups.

RESULTS

The emphysematous changes were significantly more severe in the LDLLT-CLAD and CLT-CLAD groups (p = 0.046 and 0.036), especially in patients with bronchiolitis obliterans syndrome (BOS), than in the non-CLAD group. Although the skeletal muscle mass was similar in all the groups, the plasma irisin levels were significantly lower in the LDLLT-CLAD group (p = 0.022), especially in the patients with BOS after LDLLT, than in the non-CLAD group.

CONCLUSION

Emphysematous changes and lower levels of plasma irisin were associated with CLAD, especially in patients with BOS, after bilateral LDLLT.

Lung protective ventilation based on donor size is associated with a lower risk of severe primary graft dysfunction after lung transplantation

BACKGROUND

Mechanical ventilation immediately after lung transplantation may impact the development of primary graft dysfunction (PGD), particularly in cases of donor-recipient size mismatch as ventilation is typically based on recipient rather than donor size.

METHODS

We conducted a retrospective cohort study of adult bilateral lung transplant recipients at our center between January 2010 and January 2017. We defined donor-based lung protective ventilation (dLPV) as 6 to 8 ml/kg of donor ideal body weight and plateau pressure <30 cm H₂O. We calculated the donor-recipient predicted total lung capacity (pTLC) ratio and used logistic regression to examine relationships between pTLC ratio, dLPV and PGD grade 3 at 48 to 72 hours. We used Cox proportional hazards modelling to examine the relationship between pTLC ratio, dLPV and 1-year survival.

RESULTS

The cohort included 373 recipients; 24 (6.4%) developed PGD grade 3 at 48 to 72 hours, and 213 (57.3%) received dLPV. Mean pTLC ratio was 1.04 ± 0.18. dLPV was associated with significantly lower risks of PGD grade 3 (OR = 0.44; 95% CI: 0.29-0.68, p < 0.001) and 1-year mortality (HR = 0.49; 95% CI: 0.29-0.8, p = 0.018). There was a significant association between pTLC ratio and the risk of PGD grade 3, but this was attenuated by the use of dLPV.

CONCLUSIONS

dLPV is associated with decreased risk of PGD grade 3 at 48 to 72 hours and decreased 1-year mortality. Additionally, dLPV attenuates the association between pTLC and both PGD grade 3 and 1-year mortality. Donor-based ventilation strategies may help to mitigate the risk of PGD and other adverse outcomes associated with size mismatch after lung transplantation.

A simplified strategy for donor-recipient size-matching in lung transplant for interstitial lung disease

BACKGROUND

Donor-recipient size-matching has been repeatedly reported to improve outcomes following lung transplantation (LTx). However, there is significant variability in practice and the optimal strategy for size-matching is yet to be defined. For recipients with ILD, size-matching decisions are complicated by concerns regarding the potential impact of pre-LTx pulmonary restriction. We evaluate whether a specific donor-to-recipient size-matching strategy, based on predicted total lung capacity, benefits this patient group.

METHODS

This retrospective, single-centre, cohort study describes the post-LTx outcomes of adults who underwent LTx for ILD between 1983 and 2020. Only patients with restrictive physiology, based on pre-LTx pulmonary function testing were included. Post-LTx outcomes were compared based on donor-recipient predicted TLC (D-R pTLC) ratio. A D-R pTLC ratio of ≥0.8 or <1.2 for DLTx, and a D-R pTLC ratio of ≥0.8 or <1.0 for SLTx were classified as 'size-matched'.

RESULTS

Five-hundred and fifty LTx recipients met inclusion criteria. Of these, 404 underwent DLTx and 146 underwent SLTx. Size-matching was achieved in 78% of DLTx and 47% of SLTx. Overall survival (p = 0.007) and CLAD-free survival (p < 0.001) was significantly improved following a size-matched DLTx, compared to those with D-R pTLC ratios <0.8 or ≥1.2. Size-matching based on a D-R pTLC ratio 0.8≥ <1.0 for SLTX did not significantly improve survival.

CONCLUSIONS

D-R pTLC size-matching, based on a ratio of 0.8≥ <1.2 improved post-DLTx outcomes for patients with restrictive lung disease. This is simple to do, and if applied clinically, could improve overall outcomes in lung transplantation.

Graft reduction surgery is associated with poorer outcome after lung transplantation: a single-centre propensity score-matched analysis

OBJECTIVES

Implanted lung volume-reduction surgery due to donor/recipient size mismatch could affect both lung function and survival. We examined the outcomes of lung volume-reduction procedures post-lung transplant.

METHODS

We retrospectively reviewed 366 consecutive adult lung transplants carried out between January 2014 and December 2018 at one single centre. Patients were divided into either a non-reduced-size lung transplant or a reduced-size lung transplant (RT) group. To adjust for covariates, a propensity score analysis was performed. Survival was estimated using the Kaplan-Meier method. Differences were considered significant with P-values <0.05.

RESULTS

In the RT group, 45 patients (12.3%) had some type of graft reduction surgery: 31 (68.9%) patients had pulmonary lobectomies and 14 (31.1%) wedge resections. Of the total cohort, 30 patients (8.2%) were prioritized, 23% of whom required graft reduction surgery. The propensity score analysis matched 41 patients in each group. In the RT group, there was an increased need for cardiopulmonary bypass (P = 0.017) during surgery and extracorporeal membrane oxygenation (P = 0.025) after lung transplant. Furthermore, the median length of mechanical ventilation was higher (P = 0.008), and lung function at discharge, 3 and 6 months post-lung transplant was significantly lower in the RT group (P < 0.05). Survival analysis demonstrated a significantly poorer overall outcome at 1, 3 and 5 years post-lung transplantation in patients with a reduced graft (P = 0.007), while the 1-year conditional survival was also worse in this group (P = 0.025).

CONCLUSIONS

Graft reduction surgery in lung transplant recipients is associated with lower pulmonary function and poorer overall survival. However, it does allow transplantation in prioritized recipients for whom it might otherwise be impossible to find an organ of suitable size.

Chest X-ray Sizing for Lung Transplants Reflects Pulmonary Diagnosis and Body Composition and Is Associated With Primary Graft Dysfunction Risk

BACKGROUND

Donor-recipient oversizing based on predicted total lung capacity (pTLC) is associated with a reduced risk of primary graft dysfunction (PGD) following lung transplant but the effect varies with the recipient's diagnosis. Chest x-ray (CXR) measurements to estimate actual total lung capacity (TLC) could account for disease-related lung volume changes, but their role in size matching is unknown.

METHODS

We reviewed adult double lung transplant recipients 2007-2016 and measured apex-to-costophrenic-angle distance (=lung height) on pretransplant donor and recipient CXRs (oversized donor-recipient ratio >1; undersized ≤1]. We tested the relationship between recipient lung height to actual TLC; between lung height ratio and donor/recipient characteristics; and between both lung height ratio or pTLC ratio and grade 3 PGD with logistic regression.

RESULTS

Two hundred six patients were included and 32 (16%) developed grade 3 PGD at 48 or 72 hours. Recipient lung height was related to TLC (r2=0.7297). Pulmonary diagnosis, donor BMI, and recipient BMI were the major determinants of lung height ratio (AUC 0.9036). Lung height ratio oversizing was associated with increased risk of grade 3 PGD (odds ratio, 2.51; 95% confidence interval, 1.17-5.47; P = 0.0182) in this cohort, while pTLC ratio oversizing was not.

CONCLUSIONS

CXR lung height estimates actual TLC and reflects pulmonary diagnosis and body composition. Oversizing via CXR lung height ratio increased PGD risk moreso than pTLC-based oversizing in our cohort.

Pediatric lung transplantation as standard of care

For infants, children, and adolescents with progressive advanced lung disease, lung transplantation represents the ultimate therapy option. Fortunately, outcomes after pediatric lung transplantation have improved in recent years now producing good long-term outcomes, no less than comparable to adult lung transplantation. The field of pediatric lung transplantation has rapidly advanced; thus, this review aims to update on important issues such as transplant referral and assessment, and extra-corporal life support as "bridge to transplantation". In view of the ongoing lack of donor organs limiting the success of pediatric lung transplantation, donor acceptability criteria and surgical options of lung allograft size reduction are discussed. Post-transplant, immunosuppression is vital for prevention of allograft rejection; however, evidence-based data on immunosuppression are scarce. Drug-related side effects are frequent, close therapeutic drug monitoring is highly advised with an individually tailored patient approach. Chronic lung allograft dysfunction (CLAD) remains the Achilles' heel of pediatric lung transplant limiting its long-term success. Unfortunately, therapy options for CLAD are still restricted. The last option for progressive CLAD would be consideration for lung re-transplant; however, numbers of pediatric patients undergoing lung re-transplantation are very small and its success depends highly on the optimal selection of the most suitable candidate.

Significance of Best Spirometry in the First Year After Bilateral Lung Transplantation: Association With 3-Year Outcomes

BACKGROUND

Spirometry is the cornerstone of monitoring allograft function after lung transplantation (LT). We sought to determine the association of variables on best spirometry during the first year after bilateral LT with 3-year posttransplant survival.

METHODS

We reviewed charts of patients who survived at least 3 months after bilateral LT (n = 157; age ± SD: 54 ± 13 y, male:female = 91:66). Best spirometry was calculated as the average of 2 highest measurements at least 3 weeks apart during the first year. Airway obstruction was defined as forced expiratory volume in 1-second (FEV1)/forced vital capacity (FVC) ratio <0.7. Survival was compared based on the ventilatory defect and among groups based on the best FEV1 and FVC measurements (>80%, 60%-80%, and <60% predicted). Primary outcome was 3-year survival.

RESULTS

Overall, 3-year survival was 67% (n = 106). Obstructive defect was uncommon (7%) and did not have an association with 3-year survival (72% versus 67%, P = 0.7). Although one-half patients achieved an FVC>80% predicted (49%), 1 in 5 (19%) remained below 60% predicted. Irrespective of the type of ventilatory defect, survival worsened as the best FVC (% predicted) got lower (>80: 80.8%; 60-80: 63.3%; <60: 40%; P < 0.001). On multivariate logistic regression analysis, after adjusting for age, gender, transplant indication, and annual bronchoscopy findings, best FVC (% predicted) during the first year after LT was independently associated with 3-year survival.

CONCLUSIONS

A significant proportion of bilateral LT patients do not achieve FVC>80% predicted. Although the type of ventilatory defect on best spirometry does not predict survival, failure to achieve FVC>80% predicted during the first year was independently associated with 3-year mortality.

Size Mismatching Increases Mortality After Lung Transplantation in Preadolescent Patients

BACKGROUND

The effect of size mismatch between donor and recipient in pediatric lung transplantation (PLTx) is currently unknown. Previous studies in adults have suggested that oversized allografts are associated with improved outcomes after lung transplantation. We investigated this relationship to quantify its effect on posttransplant outcomes in children.

METHODS

The United Network of Organ Sharing database was queried for preadolescent (age <13 years) patients undergoing PLTx. Donor-to-recipient height, weight, and predictive total lung capacity (pTLC; ages 4 to 13; pTLC = 0.160 x exp[0.021 x height]) ratios were calculated. Exploratory analysis was performed to identify disjoint intervals at which survival was statistically different. Patients were categorized as well-matched, undersized, or oversized. Multivariate Cox proportional hazard regression modeling assessed the adjusted effect of mismatching on mortality. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

The analysis included 540 children. One-year mortality was higher with a height mismatch of 5% or less (hazard ratio [HR], 2.97; p = 0.001) and above 5% (HR, 2.22; p = 0.009). Similarly, 1-year mortality was worse with weight mismatch of 10% or less (HR, 1.99; p = 0.035) and above 10% (HR, 2.04; p = 0.028). On unadjusted analysis, a pTLC ratio of less than 0.9 was associated with worse survival (p = 0.017). This finding persisted after multivariate risk adjustment (HR, 2.93; p = 0.02). Contrary to findings in adults, an oversized allograft (pTLC ratio > 1.1) was not associated with improved survival (HR, 1.95; p = 0.147).

CONCLUSIONS

In preadolescent children undergoing PLTx, size mismatching is associated with increased death. Our findings differ from studies in adults, which demonstrated improved survival associated with oversized allografts. Accordingly, well-matched allografts should be prioritized when assessing donor-recipient pairs for transplantation.

Chest computed tomography imaging improves potential lung donor assessment

OBJECTIVE

Chest computed tomography (CT) imaging is being increasingly used for potential lung donor assessment. However, the efficacy of CT imaging in this setting remains unknown. We hypothesize that chest CT imaging independently affects the decision-making process in donor lung utilization.

METHODS

We conducted a retrospective cohort study of all adult donation after brain death donors managed through our local organ procurement organization from June 2011 to November 2016. An experienced thoracic radiologist independently reviewed donor chest CT and chest x-ray images in a blinded, standardized manner to determine the presence of structural lung disease (eg, emphysema, interstitial lung disease [ILD]) and acute abnormalities (eg, traumatic lung injury [TLI]). Distinct models of lung utilization were fit to groups with initial partial pressure of oxygen (iPaO₂) ≤300 mm Hg (suboptimal) and iPaO₂ >300 mm Hg (optimal).

RESULTS

The organ procurement organization managed 753 donors during the study period, with a lung utilization rate ([lung donors/all organ donors] × 100) of 36.5% (275 of 753). Four hundred forty-five (59.1%) donors received chest CT imaging, revealing emphysema (13.7%), ILD (2.5%), and TLI (7.2%). In univariate analysis, findings of TLI (odds ratio [OR], 2.23; 95% confidence interval [CI], 1.08-4.61) were positively associated with lung utilization, whereas findings of emphysema (OR, 0.18; CI, 0.08-0.40) were negatively associated with utilization. In multivariate analysis, CT findings of emphysema (OR, 0.21; CI 0.08-0.54) remained negatively associated with utilization. No potential donors with CT findings of ILD became lung donors. After controlling for chest x-ray findings, chest CT imaging findings of structural lung disease remained negatively associated with utilization (P = .0001). Lung utilization rate in the suboptimal and optimal iPaO₂ populations was 35.1% and 41.4%, respectively, and CT findings of emphysema had a significant association with nonutilization in both groups.

CONCLUSIONS

In the evaluation of potential lung donors, chest CT imaging findings of structural lung disease, such as emphysema and ILD, have a significant negative association with lung utilization. Our findings suggest that chest CT imaging might be an important adjunct to conventional lung donor assessment criteria.

Transplant options for end stage chronic obstructive pulmonary disease in the context of multidisciplinary treatments

Lung transplantation (LTx) in advanced stage chronic obstructive pulmonary disease (COPD) patients is associated with significant improvement in lung function and exercise capacity. However, demonstration that the procedure also provides a survival benefit has been more elusive compared to other respiratory conditions. Identification of patients with increased risk of mortality is crucial: a low forced expiratory volume in 1 second (FEV₁) is perhaps the most common reason for referral to a lung transplant center, but in itself is insufficient to identify which COPD patients will benefit from LTx. Many variables have to be considered in the selection of candidates, time for listing, and choice of procedure: age, patient comorbidities, secondary pulmonary hypertension, the balance between individual and community benefit. This review will discuss patient selection, transplant listing, potential benefits and critical issues of bilateral (BLTx) and single lung (SLTx) procedure, donor-to-recipient organ size-matching; furthermore, it will describe LTx outcomes and its effects on recipient survival and quality of life.

Native upper lobe-sparing living-donor lobar lung transplantation maximizes respiratory function of the donor graft

BACKGROUND

We have developed a novel method for native upper lobe-sparing living-donor lobar lung transplantation (LDLLT) to overcome a small-for-size graft in standard LDLLT with acceptable results. We hypothesized that grafts implanted with this procedure might work more efficiently than those in standard lobe transplantation.

METHODS

Bilateral LDLLT was performed in 31 patients with a functional graft matching of less than 60% at our institution between August 2008 and December 2015. Of these, 22 patients were available for evaluation of pulmonary function more than 1 year later: 15 undergoing standard LDLLT with less than 60% functional matching and 7 undergoing native upper lobe-sparing LDLLT.

RESULTS

Overall survival at 2 years was 87.5% in the lobe-sparing LDLLT patients and 79.0% in the standard LDLLT patients (p = 0.401). The median forced vital capacity size-matching levels were 50.7% ± 1.6% in the standard LDLLT and 45.2% ± 2.3% in the sparing LDLLT group (p = 0.074). The 1-year and 2-year post-operative volume ratios of inspiration to expiration were significantly different between the 2 groups, at 1.76 and 1.45 after standard LDLLT (p = 0.019) vs 2.41 and 2.23 after lobe-sparing LDLLT (p = 0.015).

CONCLUSIONS

The grafts in lobe-sparing LDLLT functioned more effectively than those in standard LDLLT. This advantage was associated with the improvement of pulmonary functions.

Chest wall strapping increases expiratory airflow and detectable airway segments in computer tomographic scans of normal and obstructed lungs

Chest wall strapping (CWS) induces breathing at low lung volumes but also increases parenchymal elastic recoil. In this study, we tested the hypothesis that CWS dilates airways via airway-parenchymal interdependence. In 11 subjects (6 healthy and 5 with mild to moderate COPD), pulmonary function tests and lung volumes were obtained in control (baseline) and the CWS state. Control and CWS-CT scans were obtained at 50% of control (baseline) total lung-capacity (TLC). CT lung volumes were analyzed by CT volumetry. If control and CWS-CT volumetry did not differ by more than 25%, airway dimensions were analyzed via automated airway segmentation. CWS-TLC was reduced on average to 71% of control-TLC in normal subjects and 79% of control-TLC in subjects with COPD. CWS increased expiratory airflow at 50% of control-TLC by 41% (3.50 ± 1.6 vs. 4.93 ± 1.9 l/s, P = 0.04) in normals and 316% in COPD(0.25 ± 0.05 vs 0.79 ± 0.39 l/s, P = 0.04). In 10 subjects (5 normals and 5 COPD), control and CWS-CT scans at 50% control-TLC did not differ more than 25% on CT volumetry and were included in the airway structure analysis. CWS increased the mean number of detectable airways with a diameter of ≤2 mm by 32.5% (65 ± 10 vs. 86 ± 124, P = 0.01) in normal subjects and by 79% (59 ± 19 vs. 104 ± 16, P = 0.01) in subjects with COPD. There was no difference in the number of detectable airways with diameters 2-4 mm and >4 mm in normal or in COPD subjects. In conclusion, CWS enhances the detection of small airways via automated CT airway segmentation and increases expiratory airflow in normal subjects as well as in subjects with mild to moderate COPD. NEW & NOTEWORTHY In normal and COPD subjects, chest wall strapping(CWS) increased the number of detectable small airways using automated CT airway segmentation. The concept of dysanapsis expresses the physiological variation in the geometry of the tracheobronchial tree and lung parenchyma based on development. We propose a dynamic concept to dysanapsis in which CWS leads to breathing at lower lung volumes with a corresponding increase in the size of small airways, a potentially novel, nonpharmacological treatment for COPD.

Imaging features of intrathoracic complications of lung transplantation: What the radiologists need to know

Lung transplantation has been a method for treating end stage lung disease for decades. Despite improvements in the preoperative assessment of recipients and donors as well as improved surgical techniques, lung transplant recipients are still at a high risk of developing post-operative complications which tend to impact negatively the patients’ outcome if not recognised early. The recognised complications post lung transplantation can be broadly categorised into acute and chronic complications. Recognising the radiological features of these complications has a significant positive impact on patients’ survival post transplantation. This manuscript provides a comprehensive review of the radiological features of post lung transplantations complications over a time continuum.

Higher BMI is associated with higher expiratory airflow normalised for lung volume (FEF25-75/FVC) in COPD

INTRODUCTION

The obesity paradox in chronic obstructive pulmonary disease (COPD), whereby patients with higher body mass index (BMI) fare better, is poorly understood. Higher BMIs are associated with lower lung volumes and greater lung elastic recoil, a key determinant of expiratory airflow. The forced expiratory flow (25-75) (FEF25-75)/forced vital capacity (FVC) ratio reflects effort-independent expiratory airflow in the context of lung volume and could be modulated by BMI.

METHODS

We analysed data from the COPDGene study, an observational study of 10 192 subjects, with at least a 10 pack-year smoking history. Data were limited to subjects with BMI 20-40 kg/m2 (n=9222). Subjects were stratified according to forced expiratory volume in 1 s (FEV1) (%predicted)-quintiles. In regression analyses and Cox proportional hazard models, we analysed the association between BMI, the FEF25-75/FVC ratio, the imaging phenotype, COPD exacerbations, hospitalisations and death.

RESULTS

There was no correlation between BMI and FEV1(%predicted). However, a higher BMI is correlated with a higher FEF25-75/FVC ratio. In CT scans, a higher BMI was associated with less emphysema and less air trapping. In risk-adjusted models, the quintile with the highest FEF25-75/FVC ratio was associated with a 46% lower risk of COPD exacerbations (OR 0.54, p<0.001) and a 40% lower risk of death (HR 0.60, p=0.02), compared with the lowest quintile. BMI was not independently associated with these outcomes.

CONCLUSIONS

A higher BMI is associated with lower lung volumes and higher expiratory airflows when normalised for lung volume, as quantified by the FEF25-75/FVC ratio. A higher FEF25-75/FVC ratio is associated with a lower risk of COPD exacerbations and death and might quantify functional aspects of the paradoxical effect of higher BMIs on COPD.

Transplant size mismatch in restrictive lung disease

To maximize the benefit of lung transplantation, the effect of size mismatch on survival in lung transplant recipients with restrictive lung disease (RLD) was examined. All single and bilateral RLD lung transplants from 1987 to 2011 in the United Network for Organ Sharing (UNOS) Database were identified. Donor predicted total lung capacity (pTLC):Recipient pTLC ratio (pTLCr) quantified mismatch. pTLCr was segregated into five strata. A Cox proportional hazards model evaluated the association of pTLCr with mortality hazard. To identify a critical pTLCr, a Cox model using a restricted cubic spline for pTLCr was used. A total of 6656 transplants for RLD were identified. Median pTLCr for single orthotopic lung transplant (SOLT) and bilateral orthotopic lung transplant (BOLT) was 1.0 (0.69-1.47) and 0.98 (0.66-1.45). Examination of pTLCr as a categorical variable revealed that undersizing (pTLCr <0.8) for SOLT and moderate oversizing (pTLCr = 1.1-1.2) for SOLT and BOLT had a harmful survival effect [for SOLT pTLC <0.8: HR 1.711 (95% CI 1.146-2.557), P = 0.01 and for BOLT pTLC 1.1-1.2: HR 1.717 (95% CI 1.112-2.651), P = 0.02]. Spline analysis revealed significant changes in SOLT mortality by variation of pTLCr between 0.8-0.9 and 1.1-1.2. RLD patients undergoing SOLT are susceptible to detriments of an undersized lung. RLD patients undergoing BOLT have higher risk of mortality when pTLCr falls between 1.1 and 1.2.

Pediatric lung transplantation

Pediatric lung transplantation has been undertaken since the 1980s, and it is today considered an accepted therapy option in carefully selected children with end-stage pulmonary diseases, providing carefully selected children a net survival benefit and improved health-related quality of life. Nowadays, >100 pediatric lung transplants are done worldwide every year. Here, specific pediatric aspects of lung transplantation are reviewed such as the surgical challenge, effects of immunosuppression on the developing pediatric immune system, and typical infections of childhood, as it is vital to comprehend that children undergoing lung transplants present a real challenge as children are not 'just small adults'. Further, an update on the management of the pediatric lung transplant patient is provided in this review, and future challenges outlined. Indications for lung transplantation in children are different compared to adults, the most common being cystic fibrosis (CF). However, the primary diagnoses leading to pediatric lung transplantation vary considerably by age group. Furthermore, there are regional differences regarding the primary indication for lung transplantation in children. Overall, early referral, careful patient selection and appropriate timing of listing are crucial to achieve real survival benefit. Although allograft function is to be preserved, immunosuppressant-related side effects are common in children post-transplantation. Strategies need to be put into practice to reduce drug-related side effects through careful therapeutic drug monitoring and lowering of target levels of immunosuppression, to avoid acute-reversible and chronic-irreversible renal damage. Instead of a "one fits all approach", tailored immunosuppression and a personalized therapy is to be advocated, particularly in children. Further, infectious complications are a common in children of all ages, accounting for almost 50% of death in the first year post-transplantation. However, chronic lung allograft dysfunction (CLAD) remains the major obstacle for improved long-term survival.

Contemporary Issues in Lung Transplant Allocation Practices

PURPOSE OF REVIEW

To discuss the current state of donor lung allocation in the United States, and future opportunities to increase the efficiency of donor lung allocation.

RECENT FINDINGS

The current donor lung allocation system prioritizes clinical acuity by use of the Lung Allocation Score (LAS) which has reduced waitlist mortality since its implementation in 2005. Access to donor lungs can be further improved through policy changes using broader geographic sharing, and developing new technology such as ex vivo lung perfusion to recover marginal donor lungs.

SUMMARY

The number of lung transplants in the U.S. continues to increase annually. However, the demand for donor lungs continues to be outpaced by an ever growing waitlist. Efficient allocation can be achieved through improved allocation policies and new technology.

Surgical Strategy for Lung Transplantation in Adults With Small Chests: Lobar Transplant Versus a Pediatric Donor

BACKGROUND

Adult lung transplant recipients with small chests have traditionally received lungs from pediatric donors, placing an additional strain on the already restricted pediatric donor pool. Performing lobar lung transplantation (LLT) can circumvent issues with donor-recipient size mismatch; however, LLT imparts additional risks. Here, we review our experience using LLT and standard lung transplantation using a pediatric donor (PDLT) for adults with small chests.

METHODS

We retrospectively reviewed consecutive patients with end-stage lung disease and a height of 65 inches or less who underwent LLT (n = 15) or PDLT (n = 15) between 2006 and 2012 at our institution, a high-volume lung transplant center.

RESULTS

Lobar lung transplantation recipients were older (54 ± 10 vs 48 ± 8 years) and had higher pulmonary pressure (57 ± 11 vs 52 ± 27 mmHg) and higher lung allocation scores (70 ± 9 vs 51 ± 8) than PDLT recipients (all P < 0.05). Mean waiting time was 62 days for PDLT and 9 days for LLT. Postoperatively, the incidence of severe primary graft dysfunction and the incidence of acute renal insufficiency were higher, and the mean intensive care unit stay was longer in the LLT group, but the incidence of bronchial anastomotic complications was higher in the PDLT group because of significant size discrepancy in the main bronchus (P < 0.05). Interestingly, long-term functional outcomes and survival rates were similar between the groups.

CONCLUSIONS

Both LLT and PDLT are viable surgical options for adult patients with small chests. Because of the potential impact on posttransplant outcomes, the technical complexity of transplantation, decisions regarding the best surgical approach should be made by experienced surgeons.

Lobar lung transplantation from deceased donors: A systematic review

AIM

To systematically review reports on deceased-donor-lobar lung transplantation (ddLLTx) and uniformly describe size matching using the donor-to-recipient predicted-total lung-capacity (pTLC) ratio.

METHODS

We set out to systematically review reports on ddLLTx and uniformly describe size matching using the donor-to-recipient pTLC ratio and to summarize reported one-year survival data of ddLLTx and conventional-LTx. We searched in PubMed, CINAHL via EBSCO, Cochrane Database of Systematic Reviews via Wiley (CDSR), Database of Abstracts of Reviews of Effects via Wiley (DARE), Cochrane Central Register of Controlled Trials via Wiley (CENTRAL), Scopus (which includes EMBASE abstracts), and Web of Science for original reports on ddLLTx.

RESULTS

Nine observational cohort studies reporting on 301 ddLLTx met our inclusion criteria for systematic review of size matching, and eight for describing one-year-survival. The ddLLTx-group was often characterized by high acuity; however there was heterogeneity in transplant indications and pre-operative characteristics between studies. Data to calculate the pTLC ratio was available for 242 ddLLTx (80%). The mean pTLCratio before lobar resection was 1.25 ± 0.3 and the transplanted pTLCratio after lobar resection was 0.76 ± 0.2. One-year survival in the ddLLTx-group ranged from 50%-100%, compared to 72%-88% in the conventional-LTx group. In the largest study ddLLTx (n = 138) was associated with a lower one-year-survival compared to conventional-LTx (n = 539) (65.1% vs 84.1%, P < 0.001).

CONCLUSION

Further investigations of optimal donor-to-recipient size matching parameters for ddLLTx could improve outcomes of this important surgical option.

Prediction of anatomical lung volume using planimetric measurements on chest radiographs

BACKGROUND

The anatomical lung volume is conventionally measured by computed tomography (CT). However, chest radiographs could be considered as an alternative method with low cost and low radiation.

PURPOSE

To predict the anatomical lung volume using planimetric measurements of chest radiographs.

MATERIAL AND METHODS

In total, 119 participants (M:F ratio = 66:53; age, 53.7 ± 9.6 years) who underwent chest CT for lung cancer screening were enrolled. The lung volume on CT was measured as a reference for the anatomical lung volume. To eliminate the bias from the degree of inspiration, virtual chest radiographs (posterior-anterior view and lateral view) were generated from the CT images using the thick multiplanar technique, and the lung area (cm(2)) was measured in the right (P), left (Q), and lateral (R) lungs according to the planimetric method. A regression equation predicting the anatomical lung volume from the planimetric measurements was generated. The correlation between the measured and estimated lung volumes was evaluated. The percentage error rate (%) was calculated and the equation was validated internally and externally.

RESULTS

The equation predicting the anatomical lung volume (mL) was 9.6*S-1367, where the summed lung area (S) was defined as (P + Q + R). The measured and estimated lung volumes were highly correlated (R = 0.941, P < 0.001). The absolute error rate was 5.7 ± 4.9%. The root mean square error of the equation was 290.2. The root mean square errors on internal and external validation were 300.4 and 267.0.

CONCLUSION

The anatomical lung volume may be feasibly and accurately predicted from planimetric measurements of chest radiographs.