Pediatric lung transplantation

Flexible bronchoscopy in pediatric lung transplantation

Pediatric lung transplantation represents a treatment option for children with advanced lung disease or pulmonary vascular disorders who are deemed an appropriate candidate. Pediatric flexible bronchoscopy is an important and evolving field that is highly relevant in the pediatric lung transplant population. It is thus important to advance our knowledge to better understand how care for children after lung transplant can be maximally optimized using pediatric bronchoscopy. Our goals are to continually improve procedural skills when performing bronchoscopy and to decrease the complication rate while acquiring adequate samples for diagnostic evaluation. Attainment of these goals is critical since allograft assessment by bronchoscopic biopsy is required for histological diagnosis of acute cellular rejection and is an important contributor to establishing chronic lung allograft dysfunction, a common complication after lung transplant. Flexible bronchoscopy with bronchoalveolar lavage and transbronchial lung biopsy plays a key role in lung transplant graft assessment. In this article, we discuss the application of bronchoscopy in pediatric lung transplant evaluation including historical approaches, our experience, and future directions not only in bronchoscopy but also in the evolving pediatric lung transplantation field. Pediatric flexible bronchoscopy has become a vital modality for diagnosing lung transplant complications in children as well as assessing therapeutic responses. Herein, we review the value of flexible bronchoscopy in the management of children after lung transplant and discuss the application of novel techniques to improve care for this complex pediatric patient population and we provide a brief update about new diagnostic techniques applied in the growing lung transplantation field.

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.

Primary graft dysfunction grade 3 following pediatric lung transplantation is associated with chronic lung allograft dysfunction

BACKGROUND

Severe primary graft dysfunction (PGD) is associated with the development of bronchiolitis obliterans syndrome (BOS), the most common form of chronic lung allograft dysfunction (CLAD), in adults. However, PGD associations with long-term outcomes following pediatric lung transplantation are unknown. We hypothesized that PGD grade 3 (PGD 3) at 48- or 72-hours would be associated with shorter CLAD-free survival following pediatric lung transplantation.

METHODS

This was a single center retrospective cohort study of patients ≤ 21 years of age who underwent bilateral lung transplantation between 2005 and 2019 with ≥ 1 year of follow-up. PGD and CLAD were defined by published criteria. We evaluated the association of PGD 3 at 48- or 72-hours with CLAD-free survival by using time-to-event analyses.

RESULTS

Fifty-one patients were included (median age 12.7 years; 51% female). The most common transplant indications were cystic fibrosis (29%) and pulmonary hypertension (20%). Seventeen patients (33%) had PGD 3 at either 48- or 72-hours. In unadjusted analysis, PGD 3 was associated with an increased risk of CLAD or mortality (HR 2.10, 95% CI 1.01-4.37, p=0.047). This association remained when adjusting individually for multiple potential confounders. There was evidence of effect modification by sex (interaction p = 0.055) with the association of PGD 3 and shorter CLAD-free survival driven predominantly by males (HR 4.73, 95% CI 1.44-15.6) rather than females (HR 1.23, 95% CI 0.47-3.20).

CONCLUSIONS

PGD 3 at 48- or 72-hours following pediatric lung transplantation was associated with shorter CLAD-free survival. Sex may be a modifier of this association.

Extracorporeal membrane oxygenation and paracorporeal lung assist devices as a bridge to pediatric lung transplantation

BACKGROUND

"Bridging" is a term used to describe the implementation of various treatment modalities to improve waitlist survival while a patient awaits lung transplantation. ECMO and PLAD are technologies used to bridge patients to lung transplantation. ECMO and PLAD are cardiopulmonary support systems that help move blood forward while using an artificial membrane to remove CO₂ from and add O₂ to the blood. Recent studies showed that these technologies are increasingly effective in bridging patients to lung transplantation, especially with optimizing patient selection, implementing physical rehabilitation and ambulation goals, standardization of management decisions, and increasing staff experience, among other considerations. We review these technologies, their roles as bridges to pediatric lung transplantation, as well as indications, contraindications, complications, and mortality rates.

CONCLUSION

Finally, we discuss the existing knowledge gaps and areas for future research to improve patient outcomes and understanding of lung assist devices.

Optimization of initial dose regimen of tacrolimus in paediatric lung transplant recipients based on Monte Carlo simulation

WHAT IS KNOWN AND OBJECTIVES

The initial tacrolimus dose regimen in paediatric lung transplant recipients is unknown. The present study optimized the initial tacrolimus dose regimen for paediatric lung transplant recipients.

METHODS

This study was based on a published population pharmacokinetic model of tacrolimus in lung transplant recipients and used Monte Carlo simulations to recommend an initial dose regimen of tacrolimus in paediatric lung transplant recipients.

RESULTS

Without voriconazole, the tacrolimus doses recommended for paediatric lung transplant recipients who were not CYP3A5*1 carriers were 0.02, 0.03, and 0.04 mg/kg/day, split into two doses, for weights of 10-16, 16-30, and 30-40 kg, respectively. For paediatric lung transplant recipients who were CYP3A5*1 carriers, the tacrolimus doses of 0.03, 0.04, 0.05, and 0.06 mg/kg/day, split into two doses, were recommended for weights of 10-16, 16-25, 25-30, and 30-40 kg, respectively. With voriconazole, the tacrolimus dose recommended for paediatric lung transplant recipients who were not CYP3A5*1 carriers was 0.02 mg/kg/day, split into two doses, for weights of 10-40 kg. For paediatric lung transplant recipients who were CYP3A5*1 carriers, tacrolimus doses of 0.02 and 0.03 mg/kg/day, split and two doses, were recommended for weights of 10-24 and 24-40 kg, respectively.

WHAT IS NEW AND CONCLUSIONS

This study developed tacrolimus dose regimens for the first time for paediatric lung transplant recipients using Monte Carlo simulation and optimized initial dosage in paediatric lung transplant recipients.

Postoperative management of children after lung transplantation

Pediatric lung transplantation is a highly specialized treatment option at a select few hospitals caring for children. Advancements in surgical and medical approaches in the care of these children have improved their care with only minimal improvement in outcomes which remain the lowest of all solid organ transplants. A crucial time period in the management of these children is in the perioperative period after performance of the lung transplant. Supporting allograft function, preventing infection, maintaining fluid balance, achieving pain control, and providing optimal respiratory support are all key factors required for this highly complex pediatric patient population. We review commonly encountered complications that these patients often experience and provide strategies for management.

Pulmonary Manifestations of Immunodeficiency and Immunosuppressive Diseases Other than Human Immunodeficiency Virus

Immune deficiencies may alter normal lung function and protective mechanisms, resulting in a myriad of pulmonary manifestations. Primary immunodeficiencies involve multiple branches of the immune system, and defects may predispose to recurrent upper and lower respiratory infections by common pathogens; opportunistic infections; and autoimmune, inflammatory, and malignant processes that may result in interstitial pneumonias. Secondary immunodeficiencies may result from neoplasms or their treatment, organ transplant and immunosuppression, and from autoimmune diseases and their treatments. Primary and secondary immunodeficiencies and their pulmonary manifestations may be difficult to diagnose and treat. A multidisciplinary approach to evaluation is essential.

Surgical considerations in infant lung transplantation: Challenges and opportunities

Lung transplantation is a crucial component in the treatment of end-stage lung disease in infants. Traditionally, most lung transplants have been performed in older children and adults, resulting in a scarcity of data for infant patients. To address the challenges unique to this age group, novel strategies to provide the best preoperative, intraoperative, and postoperative care for these youngest patients are paramount. We review recent advances in bridge-to-transplantation therapy, including the use of a paracorporeal lung assist device, and differences in surgical technique, including bronchial artery revascularization, for incorporation into the overarching treatment strategy for infants undergoing lung transplantation.

Organ donation from brain-dead pediatric donors in Korea: A 5-year data analysis (2013-2017)

In Korea, 2-4% of brain-dead organ donations are from donors <16 years of age. We aimed to identify the current status of and challenges in pediatric organ donation from brain-dead donors in Korea. We performed a retrospective analysis using data from KONOS between January 1, 2013, and December 31, 2017. Our research identified 107 pediatric donors aged <16 years, representing 4.4% of all donors in Korea between 2013 and 2017. The consent rate was higher in PDs than in adult donors (47.0% vs 44.9%). The most common cause of brain death in PDs was hypoxia (28.0%), followed by brain tumor and trauma, whereas that in ADs was brain hemorrhage/stroke (42.4%), followed by trauma and hypoxia (P < .001). In both groups, the kidney (PDs vs ADs: 75.7% vs 88.5%), liver (58.9% vs 46.2%), and heart (32.7% vs 29.7%) were the organs most commonly transplanted. However, pancreatic (PDs vs ADs: 30.0% vs 11.7%, P < .001) and small bowel transplantations (4.7% vs 0.2%, P < .001) were more common in PDs, whereas lung (7.5% vs 14.5%, P = .046) and corneal transplantations (14.0% vs 36.2%) were more common in ADs. Only a small proportion of organ donations in Korea are from PDs, but this rate has been maintained. Given the current status of brain-dead pediatric organ donation, a more active approach is required to bring about improvement.

Solid organ transplantation after hematopoietic stem cell transplantation in childhood: A multicentric retrospective survey

We report data obtained from a retrospective multicenter pediatric survey on behalf of the European Society for Blood and Marrow Transplantation (EBMT). Information on solid organ transplantation (SOT) performed in pediatric recipients of either autologous or allogeneic hematopoietic stem cell transplantation (HSCT) between 1984 and 2016 was collected in 20 pediatric EBMT Centers (25.6%). Overall, we evaluated data on 44 SOTs following HSCT including 20 liver (LTx), 12 lung (LuTx), 6 heart (HTx), and 6 kidney (KTx) transplantations. The indication for SOT was organ failure related to intractable graft-vs-host disease in 16 children (36.3%), acute or chronic HSCT-related toxicity in 18 (40.9%), and organ dysfunction related to the underlying disease in 10 (22.8%). The median follow-up was 10.9 years (95% confidence interval: 1.7-29.5). The overall survival rate at 1 and 5 years after SOT was 85.7% and 80.4%, respectively: it was 74% and 63.2% after LTx, 83.2% after HTx, and 100% equally after LuTx and KTx. This multicenter survey confirms that SOT represents a promising option in children with severe organ failure occurring after HSCT. Additional studies are needed to further establish the effectiveness of SOT after HSCT and to better understand the mechanism underlying this encouraging success.