Lung Function, Pulmonary Complications, and Mortality after Allogeneic Blood and Marrow Transplantation in Children

Detection of Bronchiolitis Obliterans Syndrome after Pediatric Hematopoietic Stem Cell Transplantation: An Official American Thoracic Society Clinical Practice Guideline

Background: Many children undergo allogeneic hematopoietic stem cell transplantation (HSCT) for the treatment of malignant and nonmalignant conditions. Unfortunately, pulmonary complications occur frequently post-HSCT, with bronchiolitis obliterans syndrome (BOS) being the most common noninfectious pulmonary complication. Current international guidelines contain conflicting recommendations regarding post-HSCT surveillance for BOS, and a recent NIH workshop highlighted the need for a standardized approach to post-HSCT monitoring. As such, this guideline provides an evidence-based approach to detection of post-HSCT BOS in children. Methods: A multinational, multidisciplinary panel of experts identified six questions regarding surveillance for, and evaluation of, post-HSCT BOS in children. A systematic review of the literature was undertaken to answer each question. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to rate the quality of evidence and the strength of recommendations. Results: The panel members considered the strength of each recommendation and evaluated the benefits and risks of applying the intervention. In formulating the recommendations, the panel considered patient and caregiver values, the cost of care, and feasibility. Recommendations addressing the role of screening pulmonary function testing and diagnostic tests in children with suspected post-HSCT BOS were made. Following a Delphi process, new diagnostic criteria for pediatric post-HSCT BOS were also proposed. Conclusions: This document provides an evidence-based approach to the detection of post-HSCT BOS in children while also highlighting considerations for the implementation of each recommendation. Further, the document describes important areas for future research.

Diagnosis of Post-Hematopoietic Stem Cell Transplantation Bronchiolitis Obliterans Syndrome in Children: Time for a Rethink?

Hematopoietic stem cell transplantation (HSCT) is undertaken in children with the aim of curing a range of malignant and nonmalignant conditions. Unfortunately, pulmonary complications, especially bronchiolitis obliterans syndrome (BOS), are significant sources of morbidity and mortality post-HSCT. Currently, criteria developed by a National Institutes of Health (NIH) working group are used to diagnose BOS in children post-HSCT. Unfortunately, during the development of a recent American Thoracic Society (ATS) Clinical Practice Guideline on this topic, it became apparent that the NIH criteria have significant limitations in the pediatric population, leading to late diagnosis of BOS. Specific limitations include use of an outdated pulmonary function testing reference equation, a reliance on spirometry, use of a fixed forced expiratory volume in 1 second (FEV1) threshold, focus on obstructive defects defined by FEV1/vital capacity, and failure to acknowledge that BOS and infection can coexist. In this review, we summarize the evidence regarding the limitations of the current criteria. We also suggest potential evidence-based ideas for improving these criteria. Finally, we highlight a new proposed criteria for post-HSCT BOS in children that were developed by the authors of the recently published ATS clinical practice guideline, along with a pathway forward for improving timely diagnosis of BOS in children post-HSCT.

Pathobiological signatures of dysbiotic lung injury in pediatric patients undergoing stem cell transplantation

Hematopoietic cell transplantation (HCT) uses cytotoxic chemotherapy and/or radiation followed by intravenous infusion of stem cells to cure malignancies, bone marrow failure and inborn errors of immunity, hemoglobin and metabolism. Lung injury is a known complication of the process, due in part to disruption in the pulmonary microenvironment by insults such as infection, alloreactive inflammation and cellular toxicity. How microorganisms, immunity and the respiratory epithelium interact to contribute to lung injury is uncertain, limiting the development of prevention and treatment strategies. Here we used 278 bronchoalveolar lavage (BAL) fluid samples to study the lung microenvironment in 229 pediatric patients who have undergone HCT treated at 32 children's hospitals between 2014 and 2022. By leveraging paired microbiome and human gene expression data, we identified high-risk BAL compositions associated with in-hospital mortality (P = 0.007). Disadvantageous profiles included bacterial overgrowth with neutrophilic inflammation, microbiome contraction with epithelial fibroproliferation and profound commensal depletion with viral and staphylococcal enrichment, lymphocytic activation and cellular injury, and were replicated in an independent cohort from the Netherlands (P = 0.022). In addition, a broad array of previously occult pathogens was identified, as well as a strong link between antibiotic exposure, commensal bacterial depletion and enrichment of viruses and fungi. Together these lung-immune system-microorganism interactions clarify the important drivers of fatal lung injury in pediatric patients who have undergone HCT. Further investigation is needed to determine how personalized interpretation of heterogeneous pulmonary microenvironments may be used to improve pediatric HCT outcomes.

Clinical analysis of air-leak syndrome following allogeneic hematopoietic stem cell transplantation in pediatric patients

BACKGROUND

Air-leak syndrome (ALS) is considered as an independent risk factor for poor prognosis in adult patients who had received hematopoietic stem cell transplantation (HSCT), and the 5-year overall survival (OS) of ALS is less than 30%. However, the clinical features of ALS among post-transplant pediatric patients have rarely been explored.

PROCEDURES

We retrospectively reviewed 2206 pediatric patients who had received an allo-HSCT between January 2013 and December 2019 at the Hebei Yanda Lu Daopei Hospital, and analyzed the role of ALS in prognosis following HSCT.

RESULTS

In our research, ALS was divided into two categories: 15 cases of bronchiolitis obliterans syndrome (BOS) and 13 cases of idiopathic pneumonia syndrome (IPS). Following treatment of the ALS, 18 patients survived (18/28, 64.3%), and 10 patients died of respiratory failure or infection (10/28, 35.7%).

CONCLUSIONS

The OS of ALS in Hebei Yanda Lu Daopei Hospital is significantly higher than others, and they were cited to be related to early diagnosis and timely FAM treatment in previous reports.

Intensive care risk and long-term outcomes in pediatric allogeneic hematopoietic cell transplant recipients

ABSTRACT

Allogeneic hematopoietic cell transplantation (HCT) can be complicated by life-threatening organ toxicity and infection necessitating intensive care. Epidemiologic data have been limited by single-center studies, poor database granularity, and a lack of long-term survivors. To identify contemporary trends in intensive care unit (ICU) use and long-term outcomes, we merged data from the Center for International Blood and Marrow Transplant Research and the Virtual Pediatric Systems databases. We identified 6995 pediatric patients with HCT aged ≤21 years who underwent first allogeneic HCT between 2008 and 2014 across 69 centers in the United States or Canada and followed patients until the year 2020. ICU admission was required for 1067 patients (8.3% by day +100, 12.8% by 1 year, and 15.3% by 5 years after HCT), and was linked to demographic background, pretransplant organ toxicity, allograft type and HLA-match, and the development of graft-versus-host disease or malignancy relapse. Survival to ICU discharge was 85.7%, but more than half of ICU survivors required ICU readmission, leading to 52.5% and 42.6% survival at 1- and 5-years post-ICU transfer, respectively. ICU survival was worse among patients with malignant disease, poor pretransplant organ function, and alloreactivity risk factors. Among 1-year HCT survivors, those who required ICU in the first year had 10% lower survival at 5 years and developed new dialysis-dependent renal failure at a greater rate (P<.001). Thus, although ICU management is common and survival to ICU discharge is high, ongoing complications necessitate recurrent ICU admission and lead to a poor 1-year outcome in select patients who are at high risk.

Pulmonary microbiome and transcriptome signatures reveal distinct pathobiologic states associated with mortality in two cohorts of pediatric stem cell transplant patients

Lung injury is a major determinant of survival after pediatric hematopoietic cell transplantation (HCT). A deeper understanding of the relationship between pulmonary microbes, immunity, and the lung epithelium is needed to improve outcomes. In this multicenter study, we collected 278 bronchoalveolar lavage (BAL) samples from 229 patients treated at 32 children's hospitals between 2014-2022. Using paired metatranscriptomes and human gene expression data, we identified 4 patient clusters with varying BAL composition. Among those requiring respiratory support prior to sampling, in-hospital mortality varied from 22-60% depending on the cluster (p=0.007). The most common patient subtype, Cluster 1, showed a moderate quantity and high diversity of commensal microbes with robust metabolic activity, low rates of infection, gene expression indicating alveolar macrophage predominance, and low mortality. The second most common cluster showed a very high burden of airway microbes, gene expression enriched for neutrophil signaling, frequent bacterial infections, and moderate mortality. Cluster 3 showed significant depletion of commensal microbes, a loss of biodiversity, gene expression indicative of fibroproliferative pathways, increased viral and fungal pathogens, and high mortality. Finally, Cluster 4 showed profound microbiome depletion with enrichment of Staphylococci and viruses, gene expression driven by lymphocyte activation and cellular injury, and the highest mortality. BAL clusters were modeled with a random forest classifier and reproduced in a geographically distinct validation cohort of 57 patients from The Netherlands, recapitulating similar cluster-based mortality differences (p=0.022). Degree of antibiotic exposure was strongly associated with depletion of BAL microbes and enrichment of fungi. Potential pathogens were parsed from all detected microbes by analyzing each BAL microbe relative to the overall microbiome composition, which yielded increased sensitivity for numerous previously occult pathogens. These findings support personalized interpretation of the pulmonary microenvironment in pediatric HCT, which may facilitate biology-targeted interventions to improve outcomes.

Hospital survival following pediatric HSCT: changes in complications, ICU therapies and outcomes over 10 years

Introduction

Hematopoietic stem cell transplantation (HSCT) is an increasingly utilized therapy for malignant and non-malignant pediatric diseases. HSCT complications, including infection, organ dysfunction, and graft-versus-host-disease (GVHD) often require intensive care unit (ICU) therapies and are associated with mortality. Our aims were to identify the HSCT characteristics, complications and ICU therapies associated with (1) survival, and (2) survival changes over a ten-year period in a national dataset.

Methods

A national sample from the Health Facts (Cerner Corporation, Kansas City, MO) database from 2009 to 2018 was utilized. Inclusion criteria were age 30 days to <22 years and HSCT procedure code. For patients with >1 HSCT, the first was analyzed. Data included demographics, hospital length of stay (LOS), hospital outcome, transplant type and indication. HSCT complications included GVHD and infections. ICU therapies were positive pressure ventilation (PPV), vasoactive infusion, and dialysis. Primary outcome was survival to discharge. Statistical methods included bivariate analyses and multivariate logistic regression.

Results

473 patients underwent HSCT with 93% survival. 62% were allogeneic (89% survival) and 38% were autologous (98% survival). GVHD occurred in 33% of allogeneic HSCT. Infections occurred in 26% of all HSCT. ICU therapies included PPV (11% of patients), vasoactive (25%), and dialysis (3%). Decreased survival was associated with allogeneic HSCT (p < 0.01), GVHD (p = 0.02), infection (p < 0.01), and ICU therapies (p < 0.01). Survival improved from 89% (2009-2013) to 96% (2014-2018) (p < 0.01). Allogeneic survival improved (82%-94%, p < 0.01) while autologous survival was unchanged. Survival improvement over time was associated with decreasing infections (33%-21%, p < 0.01) and increasing vasoactive infusions (20%-28%, p = 0.05). On multivariate analysis, later time period was associated with improved survival (p < 0.01, adjusted OR 4.28).

Discussion

Hospital survival for HSCT improved from 89% to 96% from 2009 to 2018. Factors associated with mortality included allogeneic HSCT, GVHD, infections and ICU therapies. Improving survival coincided with decreasing infections and increasing vasoactive use.

The Role of Pre-bone Marrow Transplantation Pulmonary Function Test in Predicting Post-transplant Noninfectious Pulmonary Complications

Background

Pulmonary function test (PFT) is used as a tool for pre-transplant risk assessment and as a predictor of post-transplant outcomes. As there are currently few studies that discuss the role of PFT in bone marrow transplantation (BMT) patients in Saudi settings, and as the number of transplant patients with benign and malignant conditions continues to increase, this study was conducted with the aim of assessing the local practice.

Methods

This retrospective cohort study included all adult patients who underwent BMT at Princess Noorah Oncology Center, King Abdulaziz Medical City, Jeddah, between 2014 and 2020. The association between established patient-related risk factors and the incidence of pulmonary complications among autologous and allogeneic groups was assessed.

Results

A total of 186 patients were included (autologous = 143; allogenic = 43), of which 115 (61.8%) were male. At the pre-BMT phase, about 30% of the patients had comorbidities and 51% had received two rounds of salvage chemotherapy, while 16.1% had received radiation therapy. In the autologous group, the only PFT parameter that was a significant predictor of post-BMT pulmonary complications was forced vital capacity <80% (P = 0.012), while in the allogenic group, no parameter was significantly associated with pulmonary complications. The patient-related factors that were associated with respiratory distress in the autologous group were lung involvement (P = 0.03) and pre-transplant radiation (P = 0.044).

Conclusion

The findings of this study indicated that forced vital capacity <80% was a significant factor in predicting non-infectious complications in the autologous group. Furthermore, lung involvement and pre-transplant radiation were the patient-related factors associated with pulmonary complications.

Critical Illness Risk and Long-Term Outcomes Following Intensive Care in Pediatric Hematopoietic Cell Transplant Recipients

Background

Allogeneic hematopoietic cell transplantation (HCT) can be complicated by the development of organ toxicity and infection necessitating intensive care. Risk factors for intensive care admission are unclear due to heterogeneity across centers, and long-term outcome data after intensive care are sparse due to a historical paucity of survivors.

Methods

The Center for International Blood and Marrow Transplant Research (CIBMTR) was queried to identify patients age ≤21 years who underwent a 1st allogeneic HCT between 2008-2014 in the United States or Canada. Records were cross-referenced with the Virtual Pediatric Systems pediatric ICU database to identify intensive care admissions. CIBMTR follow-up data were collected through the year 2020.

Result

We identified 6,995 pediatric HCT patients from 69 HCT centers, of whom 1,067 required post-HCT intensive care. The cumulative incidence of PICU admission was 8.3% at day +100, 12.8% at 1 year, and 15.3% at 5 years post HCT. PICU admission was linked to younger age, lower median zip code income, Black or multiracial background, pre-transplant organ toxicity, pre-transplant CMV seropositivity, use of umbilical cord blood and/or HLA-mismatched allografts, and the development of post-HCT graft-versus-host disease or malignancy relapse. Among PICU patients, survival to ICU discharge was 85.7% but more than half of ICU survivors were readmitted to a PICU during the study interval. Overall survival from the time of 1st PICU admission was 52.5% at 1 year and 42.6% at 5 years. Long-term post-ICU survival was worse among patients with malignant disease (particularly if relapsed), as well as those with poor pre-transplant organ function and alloreactivity risk-factors. In a landmark analysis of all 1-year HCT survivors, those who required intensive care in the first year had 10% lower survival at 5 years (77.1% vs. 87.0%, p<0.001) and developed new dialysis-dependent renal failure at a greater rate (p<0.001).

Conclusions

Intensive care management is common in pediatric HCT patients. Survival to ICU discharge is high, but ongoing complications necessitate recurrent ICU admission and lead to a poor 1-year outcome in many patients. Together, these data suggest an ongoing burden of toxicity in pediatric HCT patients that continues to limit long-term survival.

The Determining Factors for Outcome of Pediatric Intensive Care Admitted Children After Stem Cell Transplantation

INTRODUCTION

Requiring pediatric intensive care unit (PICU) admission relates to high mortality and morbidity in patients who received hematopoietic stem cell transplantation (HSCT). In this study, we aimed to evaluate the indications for PICU admission, treatments, and the determining risk factors for morbidity and mortality in patients who had allogeneic HSCT from various donors.

MATERIALS AND METHODS

In this retrospective study, we enrolled to patients who required the PICU after receiving allogeneic HSCT at our Pediatric Bone Marrow Transplantation Unit between 2005 and 2020. We evaluated to indication to PICU admission, applications, mortality rate, and the determining factors to outcomes.

RESULTS

Thirty-three (7%) patients had 47 PICU admissions and 471 patients underwent bone marrow transplantation during 16-year study period. Also, 14 repeated episodes were registered in 9 different patients. The median age of PICU admitted patients was 4 (0.3 to 18) years and 29 (62%) were male. The main reasons for PICU admission were a respiratory failure, sepsis, and neurological event in 20, 8, and 7 patients, respectively. The average length of PICU stay was 14.5 (1 to 80) days, 14 (43%) of patients survived and the mortality rate was 57%. Multiple organ failure ( P =0.001), need for respiratory support ( P =0.007), inotrope agents ( P =0.001), and renal replacement therapy ( P =0.013) were found as significant risk factors for mortality.

CONCLUSIONS

Allogeneic HSCT recipients need PICU admission because of its related different life-threatening complications. But there is a good chance of survival with quality PICU care and different advanced organ support methods.

Peri-Intubation Adverse Events in the Critically Ill Child After Hematopoietic Cell Transplant

OBJECTIVES

Mechanically ventilated children post-hematopoietic cell transplant (HCT) have increased morbidity and mortality compared with other mechanically ventilated critically ill children. Tracheal intubation-associated adverse events (TIAEs) and peri-intubation hypoxemia universally portend worse outcomes. We investigated whether adverse peri-intubation associated events occur at increased frequency in patients with HCT compared with non-HCT oncologic or other PICU patients and therefore might contribute to increased mortality.

DESIGN

Retrospective cohort between 2014 and 2019.

SETTING

Single-center academic noncardiac PICU.

PATIENTS

Critically ill children who underwent tracheal intubation (TI).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data from the local airway management quality improvement databases and Virtual Pediatric Systems were merged. These data were supplemented with a retrospective chart review for HCT-related data, including HCT indication, transplant-related comorbidity status, and patient condition at the time of TI procedure. The primary outcome was defined as the composite of hemodynamic TIAE (hypo/hypertension, arrhythmia, cardiac arrest) and/or peri-intubation hypoxemia (oxygen saturation < 80%) events. One thousand nine hundred thirty-one encounters underwent TI, of which 92 (4.8%) were post-HCT, while 319 (16.5%) had history of malignancy without HCT, and 1,520 (78.7%) had neither HCT nor malignancy. Children post-HCT were older more often had respiratory failure as an indication for intubation, use of catecholamine infusions peri-intubation, and use of noninvasive ventilation prior to intubation. Hemodynamic TIAE or peri-intubation hypoxemia were not different across three groups (HCT 16%, non-HCT with malignancy 10%, other 15). After adjusting for age, difficult airway feature, provider type, device, apneic oxygenation use, and indication for intubation, we did not identify an association between HCT status and the adverse TI outcome (odds ratio, 1.32 for HCT status vs other; 95% CI, 0.72-2.41; p = 0.37).

CONCLUSIONS

In this single-center study, we did not identify an association between HCT status and hemodynamic TIAE or peri-intubation hypoxemia during TI.

Evaluation of Children with Malignancies for Blood and Marrow Transplantation: A Report from the ASTCT Committee on Practice Guidelines

Evaluation of a candidate for hematopoietic cell transplantation (HCT) is a complex process with substantial intercenter variability. Although literature providing guidance for evaluating the eligibility of adults is well established, similar guidance for children is lacking. To address gaps between adult recommendations and the specific needs of children, we convened a panel of pediatric HCT experts from a wide geographic range of American Society of Transplantation and Cellular Therapy (ASTCT) member institutions to offer recommendations for pediatric-focused pre-HCT evaluation. In this report from the ASTCT Committee on Practice Guidelines, we present a practical framework for evaluating children with malignancies who are candidates for HCT. We also highlight key differences from adults and emphasize areas of unmet need that require additional research to delineate best practices.

Expanded HCT-CI Definitions Capture Comorbidity Better for Younger Patients of Allogeneic HCT for Nonmalignant Diseases

Allogeneic hematopoietic cell transplantation (HCT) can cure many nonmalignant conditions, but concern for morbidity and mortality remains. To help physicians estimate patient-specific transplant mortality risk, the HCT comorbidity index (HCT-CI) is used. However, pediatric physicians use the HCT-CI less frequently than adult counterparts. We used the Center for International Blood and Marrow Transplant Research database to expand the HCT-CI comorbidity definitions to be more inclusive of children and adolescent and young adult (AYA) patients, adding history of mechanical ventilation, history of invasive fungal infection, assessment of chronic kidney disease (CKD) by estimated glomerular filtration rate, expanding the definition of obesity, and adding an underweight category. A total of 2815 children and AYAs (<40 years old) who received first allogeneic HCT for nonmalignant diseases from 2008 to 2017 were included to create an expanded youth nonmalignant HCT-CI (expanded ynHCT-CI) and a simplified non-malignant (simplified ynHCT-CI) HCT-CI. The expanded comorbidities occurred frequently-history of mechanical ventilation (9.6%), history of invasive fungal infection (5.9%), mild CKD (12.2%), moderate/severe CKD (2.1%), obesity (10.9%), and underweight (14.5%). Thirty-nine percent of patients had an increase in their comorbidity score using the expanded ynHCT-CI, leading to a redistribution of scores: ynHCT-CI score 0 (35%), 1-2 (36.4%), and ≥3 (28.6%). Patients with an increase in their comorbidity score had an increased hazard of mortality compared to those whose score remained the same (hazard ratio = 1.41; 95% confidence interval, 1.01-1.98). Modifications to the HCT-CI can benefit children and AYA patients with nonmalignant diseases, creating a risk assessment tool that is clinically relevant and better captures comorbidity in this younger population.

Serial Transthoracic Ultrasonography Studies in Hematopoietic Cell Transplant Patients: A Tool for Early Lung Pathology Detection

Early detection of pulmonary complications can improve outcomes for patients with hematological malignancy (HM). For detecting lung injuries, lung ultrasound (LUS) images have been found to be of greater sensitivity than radiographic images. Our group performed a pilot study of LUS imaging to enhance early detection of pulmonary complications in HM patients. This prospective single-center feasibility study evaluated LUS for detecting pulmonary complications in 18 HM patients enrolled while hospitalized for a hematopoietic cell transplant (HCT) (concurrent-HCT group) or re-hospitalized for complications (post-HCT group). Serial LUS exams were performed and assigned a score from 0 to 5 based on pleural line, B-line, consolidation and pleural effusion features. Correlations between patients' clinical characteristics and LUS features were analyzed. Comparisons between the LUS and radiographic images were evaluated. In the concurrent-HCT patients (79 LUS exams), non-significant fluctuating findings were commonly identified, but one-third of the patients presented pathologic findings (LUS scores ≥ 3). In the post-HCT patients (29 LUS exams), LUS images revealed severe pathologic findings (LUS score = 5) in every patient and, compared with radiographic images, were more sensitive for detecting pleural effusions (p < 0.05). LUS can be routinely performed on hospitalized HM patients, allowing point-of-care early detection of pulmonary complications.

Sleep-related breathing disorder in non-infectious pulmonary complications after pediatric allogeneic stem cell transplantation

BACKGROUND

Chronic lung problems are a rare but serious complication of allogeneic hematopoietic stem cell transplantation (HSCT). We studied clinical phenotypes and polysomnography appearance of breathing abnormality in late onset non-infectious pulmonary complications (NIPS).

METHODS

We reviewed Finnish national reference database between the years 1999 and 2016. We identified 12 children with most severely decreased pulmonary function and performed polysomnography and 24 aged-matched controls out of 325 performed pediatric allogeneic HSCTs.

RESULTS

All patients with NIPS had severely decreased pulmonary function already at 6 months post HSCT with median FEV₁ value 42% (interquartile range (IQR) 30-52%) of predicted normal values. Seven children had obstructive and five children more restrictive lung function. Children with obstructive lung function showed laborious breathing (7/7), decreased oxygenation and ventilation-to-perfusion mismatch (6/7), or REM-sleep-related hypoventilation (4/7) on polysomnography. Children with restrictive lung function (5/12) did not show sleep-related breathing disorder.

CONCLUSIONS

Children going through allogeneic HSCT who develop severe chronic obstructive lung function are more likely to present with sleep-related hypoxia and hypoventilation than children with restrictive lung function.

IMPACT

Children with severe obstructive lung function and chronic lung graft-versus-host disease following hematopoietic stem cell transplantation are more likely to present with sleep-related mild hypoxia and hypoventilation than children with restrictive lung disease. To our knowledge there are no reports on sleep-related breathing disorders and ventilatory function measured by polysomnography in children with pulmonary complications after allogeneic HSCT. Polysomnography may add to the differential diagnostics between patients with BOS and other non-infectious pulmonary complications.

Early pulmonary complications related to cancer treatment in children

In this review, we summarize early pulmonary complications related to cancer therapy in children and highlight characteristic findings on imaging that should be familiar to a radiologist reviewing imaging from pediatric cancer patients.

Comparison of Pulmonary Toxicity after Total Body Irradiation- and Busulfan-Based Myeloablative Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Patients

Pulmonary toxicity after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for childhood leukemia and myelodysplastic syndrome (MDS), along with the impact of different myeloablative conditioning regimens, remain incompletely described. Here we compared the acute and long-term incidence of pulmonary toxicity (PT) after total body irradiation (TBI)- and busulfan-based myeloablative conditioning. We conducted this retrospective cohort study of 311 consecutive pediatric patients with leukemia or MDS who underwent allo-HSCT at Dana-Farber Cancer Institute/Boston Children's Hospital between 2008 and 2018. PT was graded using Common Terminology Criteria for Adverse Events version 5.0. The primary objective was to compare the cumulative incidence of grade ≥3 and grade 5 PT after TBI-based and busulfan-based myeloablative conditioning using Gray's test. Secondary objectives were to determine factors associated with PT and overall survival (OS) using competing risk analysis and Cox regression analyses, respectively. There was no significant difference between the TBI-conditioned group (n = 227) and the busulfan-conditioned group (n = 84) in the incidence of grade ≥3 PT (29.2% versus 34.7% at 2 years; P = .26) or grade 5 pulmonary toxicity (6.2% versus 6.1% at 2 years; P = .47). Age (hazard ratio [HR], 1.70, 95% confidence interval [CI], 1.11 to 2.59; P = .01), grade ≥2 PT prior to allo-HSCT or preexisting pulmonary conditions (HR, 1.84, 95% CI, 1.24 to 2.72; P < .01), acute graft-versus-host disease (GVHD) (HR, 2.50; 95% CI, 1.51 to 4.14; P < .01), and chronic GVHD (HR, 2.61; 95% CI, 1.26 to 5.42; P = .01) were associated with grade ≥3 PT on multivariable analysis. Grade ≥3 PT was associated with worse OS (81.1% versus 61.5% at 2 years; P < .01). In pediatric allo-HSCT recipients, rates of PT were similar in recipients of TBI-based and recipients of busulfan-based myeloablative conditioning regimens. Age, the presence of PT or preexisting pulmonary conditions prior to transplantation, and the development of either acute or chronic GVHD were associated with grade ≥3 PT post-transplantation. Furthermore, the occurrence of grade 3-4 PT post-transplantation was associated with inferior OS.

Pulmonary microbiome and gene expression signatures differentiate lung function in pediatric hematopoietic cell transplant candidates

Impaired baseline lung function is associated with mortality after pediatric allogeneic hematopoietic cell transplantation (HCT), yet limited knowledge of the molecular pathways that characterize pretransplant lung function has hindered the development of lung-targeted interventions. In this study, we quantified the association between bronchoalveolar lavage (BAL) metatranscriptomes and paired pulmonary function tests performed a median of 1 to 2 weeks before allogeneic HCT in 104 children in The Netherlands. Abnormal pulmonary function was recorded in more than half the cohort, consisted most commonly of restriction and impaired diffusion, and was associated with both all-cause and lung injury-related mortality after HCT. Depletion of commensal supraglottic taxa, such as Haemophilus, and enrichment of nasal and skin taxa, such as Staphylococcus, in the BAL microbiome were associated with worse measures of lung capacity and gas diffusion. In addition, BAL gene expression signatures of alveolar epithelial activation, epithelial-mesenchymal transition, and down-regulated immunity were associated with impaired lung capacity and diffusion, suggesting a postinjury profibrotic response. Detection of microbial depletion and abnormal epithelial gene expression in BAL enhanced the prognostic utility of pre-HCT pulmonary function tests for the outcome of post-HCT mortality. These findings suggest a potentially actionable connection between microbiome depletion, alveolar injury, and pulmonary fibrosis in the pathogenesis of pre-HCT lung dysfunction.

Survival of pediatric patients requiring admission in the intensive care unit post hematopoietic stem cell transplantation: Prognostic factors associated with mortality

BACKGROUND

Although hematopoietic stem cell transplantation (HSCT) is the only curative option for some children with malignant and nonmalignant disorders, the procedure itself carries a high risk of complications. A proportion of children undergoing HSCT develop severe transplant-related complications requiring hospitalization in the pediatric intensive care unit (PICU).

METHODS

A retrospective cohort study included 793 children with malignant and nonmalignant diseases that underwent 963 HSCTs in two large pediatric hospitals over 15 years. Ninety-one patients needed 105 (11%) PICU admissions. The objective of the study was to analyze the risk factors associated with morbidity and mortality in children post HSCT who were admitted to the PICU.

RESULTS

Survival rate of a single PICU hospitalization was 43%. Long-term survival rate (classified as 1 year and 3 years) was 29.1% and 14.9% among PICU hospitalized patients compared with 74.6% and 53.3% among patients who had undergone HSCT and did not require PICU hospitalization. Factors found to have a significant negative association with PICU survival were respiratory failure as indication for PICU admission, neutropenia, graft-versus-host disease, mechanical ventilation, inotropic support, need for dialysis, and multiple-organ failure (MOF) with more than one systemic intensive intervention. The strongest prognostic factors associated with mortality were MOF (p < .001) and the need for inotropic support (p = .004).

CONCLUSIONS

Neutropenia was found to be negatively associated with survival, suggesting non-engraftment and late engraftment are important risk factors for HSCT patients hospitalized in PICU. MOF and inotropic support were found to be the main negatively associated predictive factors with survival.

Pulmonary Complications After Pediatric Stem Cell Transplant

The number of disorders that benefit from hematopoietic stem cell transplantation (HSCT) has increased, causing the overall number of HSCT to increase accordingly. Disorders treated by HSCT include malignancy, benign hematologic disorders, bone marrow failure syndromes, and certain genetic diagnoses. Thus, understanding the complications, diagnostic workup of complications, and subsequent treatments has become increasingly important. One such category of complications includes the pulmonary system. While the overall incidence of pulmonary complications has decreased, the morbidity and mortality of these complications remain high. Therefore, having a clear differential diagnosis and diagnostic workup is imperative. Pulmonary complications can be subdivided by time of onset and whether the complication is infectious or non-infectious. While most infectious complications have clear diagnostic criteria and treatment courses, the non-infectious complications are more varied and not always well understood. This review article discusses pulmonary complications of HSCT recipients and outlines current knowledge, gaps in knowledge, and current treatment of each complication. This article includes some adult studies, as there is a significant paucity of pediatric data.

Cardiorespiratory fitness and physical performance after childhood hematopoietic stem cell transplantation: a systematic review and meta-analysis

The effects of childhood hematopoietic stem cell transplantation (HSCT) on key organs can impair cardiorespiratory fitness, muscle strength, and physical performance. We aimed to provide an overview of childhood HSCT survivors' status on these parameters compared with healthy controls and discuss current insights into clinical risk factors. We performed a systematic search in six scientific databases, including studies published before April 2019 and performed a meta-analysis on cardiorespiratory fitness. Muscle strength and physical performance status were presented narratively. We included ten studies embodying 517 childhood HSCT survivors (mean 17.8 years at follow-up). The meta-analysis (n = 4 studies) showed that childhood HSCT survivors have lower cardiorespiratory fitness compared with healthy controls (Standard mean difference (SMD) -1.32 [95% CI -1-58 to -1.07]; I² 2%, p < 0.00001). Collectively, the studies indicated that childhood HSCT survivors have lower muscle strength (n = 4 studies) and physical performance (n = 3 studies) compared with healthy controls. Childhood HSCT survivors have impaired cardiorespiratory fitness years after ended treatment. Muscle strength and physical performance seem to be impaired, although these measures are insufficiently investigated. Associations between HSCT-specific clinical risk factors and cardiorespiratory fitness, muscle strength, and physical performance are required.

Pulmonary Complications of Pediatric Hematopoietic Cell Transplantation. A National Institutes of Health Workshop Summary

Approximately 2,500 pediatric hematopoietic cell transplants (HCTs), most of which are allogeneic, are performed annually in the United States for life-threatening malignant and nonmalignant conditions. Although HCT is undertaken with curative intent, post-HCT complications limit successful outcomes, with pulmonary dysfunction representing the leading cause of nonrelapse mortality. To better understand, predict, prevent, and/or treat pulmonary complications after HCT, a multidisciplinary group of 33 experts met in a 2-day National Institutes of Health Workshop to identify knowledge gaps and research strategies most likely to improve outcomes. This summary of Workshop deliberations outlines the consensus focus areas for future research.

The pulmonary metatranscriptome prior to pediatric HCT identifies post-HCT lung injury

Lung injury after pediatric allogeneic hematopoietic cell transplantation (HCT) is a common and disastrous complication that threatens long-term survival. To develop strategies to prevent lung injury, novel tools are needed to comprehensively assess lung health in HCT candidates. Therefore, this study analyzed biospecimens from 181 pediatric HCT candidates who underwent routine pre-HCT bronchoalveolar lavage (BAL) at the University Medical Center Utrecht between 2005 and 2016. BAL fluid underwent metatranscriptomic sequencing of microbial and human RNA, and unsupervised clustering and generalized linear models were used to associate microbiome gene expression data with the development of post-HCT lung injury. Microbe-gene correlations were validated using a geographically distinct cohort of 18 pediatric HCT candidates. The cumulative incidence of post-HCT lung injury varied significantly according to 4 pre-HCT pulmonary metatranscriptome clusters, with the highest incidence observed in children with pre-HCT viral enrichment and innate immune activation, as well as in children with profound microbial depletion and concomitant natural killer/T-cell activation (P < .001). In contrast, children with pre-HCT pulmonary metatranscriptomes containing diverse oropharyngeal taxa and lacking inflammation rarely developed post-HCT lung injury. In addition, activation of epithelial-epidermal differentiation, mucus production, and cellular adhesion were associated with fatal post-HCT lung injury. In a separate validation cohort, associations among pulmonary respiratory viral load, oropharyngeal taxa, and pulmonary gene expression were recapitulated; the association with post-HCT lung injury needs to be validated in an independent cohort. This analysis suggests that assessment of the pre-HCT BAL fluid may identify high-risk pediatric HCT candidates who may benefit from pathobiology-targeted interventions.

Late Effects After Haematopoietic Stem Cell Transplantation in ALL, Long-Term Follow-Up and Transition: A Step Into Adult Life

Haematopoietic stem cell transplant (HSCT) can be a curative treatment for children and adolescents with very-high-risk acute lymphoblastic leukaemia (ALL). Improvements in supportive care and transplant techniques have led to increasing numbers of long-term survivors worldwide. However, conditioning regimens as well as transplant-related complications are associated with severe sequelae, impacting patients' quality of life. It is widely recognised that paediatric HSCT survivors must have timely access to life-long care and surveillance in order to prevent, ameliorate and manage all possible adverse late effects of HSCT. This is fundamentally important because it can both prevent ill health and optimise the quality and experience of survival following HSCT. Furthermore, it reduces the impact of preventable chronic illness on already under-resourced health services. In addition to late effects, survivors of paediatric ALL also have to deal with unique challenges associated with transition to adult services. In this review, we: (1) provide an overview of the potential late effects following HSCT for ALL in childhood and adolescence; (2) focus on the unique challenges of transition from paediatric care to adult services; and (3) provide a framework for long-term surveillance and medical care for survivors of paediatric ALL who have undergone HSCT.

Transplant characteristics and self-reported pulmonary outcomes in Swiss childhood cancer survivors after hematopoietic stem cell transplantation-a cohort study

Childhood cancer survivors treated with hematopoietic stem cell transplantation are at high risk for pulmonary morbidity and mortality. In this retrospective study we described transplant characteristics of pediatric patients who underwent hematopoietic stem cell transplantation in Switzerland and how these characteristics changed over time, compared self-reported pulmonary outcomes between transplanted and non-transplanted survivors, and investigated risk factors for the reported pulmonary outcomes. As part of the population-based Swiss Childhood Cancer Survivor Study, we sent questionnaires to all ≥5-year childhood cancer survivors diagnosed 1976–2010 at age ≤20 years. We included 132 transplanted survivors and 368 matched non-transplanted survivors. During the study period transplant characteristics changed, with decreasing use of total body irradiation and increased use of peripheral blood stem cells and mismatched and unrelated donors as transplant source. One-fifth of transplanted survivors (20%, 95%CI 13–27%) and 18% of non-transplanted survivors (95%CI 13–21%) reported at least one pulmonary outcome. None of the analyzed factors was significantly associated with an increased risk of pulmonary outcomes in multivariable analysis. We found that pulmonary outcomes were frequently reported in transplanted and non-transplanted childhood cancer survivors, indicating a strong need for long-term pulmonary follow-up care.

Limitations of Applying the Hematopoietic Cell Transplantation Comorbidity Index in Pediatric Patients Receiving Allogeneic Hematopoietic Cell Transplantation

Identifying which patients are at high risk for transplant-related mortality, prior to allogeneic hematopoietic cell transplantation (alloHCT), is crucial both to guide decision making with patients and families and to inform the alloHCT approach. There is a paucity of data evaluating the utility of the HCT comorbidity index (HCT-CI) in pediatric patients. We performed a retrospective cohort study of 188 patients who underwent alloHCT between January 2008 and October 2016 and assessed pretransplant comorbidities defined and weighted by the HCT-CI. The primary endpoint of our study was overall survival (OS). Kaplan-Meier method was used to assess survival estimates at 1-year post-transplant and did not differ based on HCT-CI scores: 78.7% (SE 6.69%) for HCT-CI = 0, 74.7% (SE 6.33%) for HCT-CI = 1 to 2, and 77.3% (SE 4.17%) for HCT-CI ≥3. Multivariable Cox proportional hazards analysis did not show HCT-CI having an effect on OS: hazard ratio (HR) of 0.633 (95% confidence interval [CI], 0.297 to 1.347) for HCT-CI scores 1 to 2 and HR of 0.935 (95% CI, 0.456 to 1.918) for HCT-CI scores ≥3 compared to scores of 0. The most frequent comorbidities observed were hepatic disease (mild in 29%, severe in 23%) and pulmonary disease (moderate in 15% and severe in 29%). However, only 55% were able to complete pulmonary function testing. Hepatic disease was based on transaminitis in 48% and by bilirubin alone in 26% of patients; 46% of patients with hepatic dysfunction had an underlying hemoglobinopathy and hyperbilirubinemia related to ongoing hemolysis. This study evaluates HCT-CI comorbidities in greater detail than has been performed previously in children undergoing alloHCT. We identify challenges with the HCT-CI in the pediatric population and highlight the comorbidities that may benefit from adjustments to their definition to create an improved risk assessment tool for children.

Pulmonary Metagenomic Sequencing Suggests Missed Infections in Immunocompromised Children

BACKGROUND

Despite improved diagnostics, pulmonary pathogens in immunocompromised children frequently evade detection, leading to significant mortality. Therefore, we aimed to develop a highly sensitive metagenomic next-generation sequencing (mNGS) assay capable of evaluating the pulmonary microbiome and identifying diverse pathogens in the lungs of immunocompromised children.

METHODS

We collected 41 lower respiratory specimens from 34 immunocompromised children undergoing evaluation for pulmonary disease at 3 children's hospitals from 2014-2016. Samples underwent mechanical homogenization, parallel RNA/DNA extraction, and metagenomic sequencing. Sequencing reads were aligned to the National Center for Biotechnology Information nucleotide reference database to determine taxonomic identities. Statistical outliers were determined based on abundance within each sample and relative to other samples in the cohort.

RESULTS

We identified a rich cross-domain pulmonary microbiome that contained bacteria, fungi, RNA viruses, and DNA viruses in each patient. Potentially pathogenic bacteria were ubiquitous among samples but could be distinguished as possible causes of disease by parsing for outlier organisms. Samples with bacterial outliers had significantly depressed alpha-diversity (median, 0.61; interquartile range [IQR], 0.33-0.72 vs median, 0.96; IQR, 0.94-0.96; P < .001). Potential pathogens were detected in half of samples previously negative by clinical diagnostics, demonstrating increased sensitivity for missed pulmonary pathogens (P < .001).

CONCLUSIONS

An optimized mNGS assay for pulmonary microbes demonstrates significant inoculation of the lower airways of immunocompromised children with diverse bacteria, fungi, and viruses. Potential pathogens can be identified based on absolute and relative abundance. Ongoing investigation is needed to determine the pathogenic significance of outlier microbes in the lungs of immunocompromised children with pulmonary disease.

Respiratory pathogens associated with intubated pediatric patients following hematopoietic cell transplant

BACKGROUND

We describe organisms found in the respiratory tracts of a multicenter cohort of pediatric hematopoietic cell transplant (HCT) recipients with respiratory failure.

METHODS

Twelve centers contributed up to 25 pediatric allogeneic HCT recipients requiring mechanical ventilation for respiratory failure to a retrospective database. Positive respiratory pathogens and method of obtaining sample were recorded. Outcomes were assessed using Mann-Whitney U test or chi-squared analysis.

RESULTS

Of the 222 patients in the database, ages 1 month through 21 years, 34.6% had a positive respiratory culture. 105 pathogens were identified in 77 patients; of those, 48.6% were viral, 34.3% bacterial, 16.2% fungal, and 1% parasitic. PICU mortality with a respiratory pathogen was 68.8% compared to 54.9% for those without a respiratory pathogen (P = .045). Those with a positive respiratory pathogen had longer PICU length of stay, 20 days (IQR 14.0, 36.8) vs 15 (IQR 6.5, 32.0), P = .002, and a longer course of mechanical ventilation, 17 days (IQR 10, 29.5) vs 8 (3, 17), P < .0001. Method of pathogen identification, type of pathogen, and the presence of multiple pathogens were not associated with changes in PICU outcomes.

CONCLUSIONS

In this multicenter retrospective cohort of intubated pediatric post-HCT patients, there was high variability in the respiratory pathogens identified. Type of pathogen and method of detection did not affect PICU mortality. The presence of any organism leads to increased PICU mortality, longer PICU stay, and increased duration of mechanical ventilation suggesting that early detection and treatment of pathogens may be beneficial in this population.

American Thoracic Society 2019 Pediatric Core Curriculum

The American Thoracic Society Pediatric Core Curriculum updates clinicians annually in pediatric pulmonary disease in a 3 to 4 year recurring cycle of topics. The 2019 course was presented in May during the Annual International Conference. An American Board of Pediatrics Maintenance of Certification module and a continuing medical education exercise covering the contents of the Core Curriculum can be accessed online at www.thoracic.org.

Assessment of pulmonary outcomes, exercise capacity, and longitudinal changes in lung function in pediatric survivors of high-risk neuroblastoma

BACKGROUND/OBJECTIVES

Survivors of high-risk neuroblastoma (NB) are exposed to multimodality therapies early in life and confront late therapy-related toxicities. This study assessed respiratory symptoms, exercise capacity, and longitudinal changes in pulmonary function tests (PFTs) among survivors.

DESIGN/METHODS

Survivors of high-risk NB followed in the long-term follow-up clinic at Memorial Sloan Kettering Cancer Center were enrolled. Symptom and physical activity questionnaires were completed. Medical records were reviewed for treatments and comorbidities. Participants completed spirometry, plethysmography, diffusion capacity of the lung for carbon monoxide, 6-minute walk tests (6MWTs), and cardiopulmonary exercise testing. Questionnaires and PFTs were repeated at least one year after enrollment.

RESULTS

Sixty-two survivors participated (median age at study: 10.92 years; median age at diagnosis: 2.75 years; median time since completion of therapy: 5.29 years). Thirty-two percent had chronic respiratory symptoms. Seventy-seven percent had PFT abnormalities, mostly mild to moderate severity. Thirty-three completed 6MWTs (median, 634.3 meters); eight completed cardiopulmonary exercise tests (mean VO₂ max: 63% predicted); 23 completed a second PFT revealing declines over a median 2.97 years (mean percent predicted forced vital capacity: 79.9 to 70.0; mean forced expiratory volume in 1 second: 81.6 to 69.9). Risks for abnormalities included thoracic surgery, chest radiation therapy (RT), thoracic surgery plus chest RT, and hematopoietic stem cell transplant.

CONCLUSIONS

In this cohort of survivors of high-risk NB, PFT abnormalities were common but mostly mild or moderate. Maximal exercise capacity may be affected by respiratory limitations and declines in lung function may occur over time. Continued pulmonary surveillance of this at-risk population is warranted.

Impact of the Conditioning Regimen Dose Intensity Before Autologous Stem Cell Transplantation on the Pulmonary Function Test Abnormalities in Patients With Lymphoma and Multiple Myeloma: Single Center Experience

BACKGROUND

Most studies addressing the impact of hematopoietic stem cell transplantation (SCT) on pulmonary function test (PFT), and the various factors affecting that impact have been performed on the allogenic type. Few have addressed PFT changes in autologous SCT. This study describes PFT changes seen in autologous SCT recipients and addresses the various factors impacting these changes.

PATIENTS AND METHODS

We reviewed the medical records of 223 consecutive adult autologous SCT recipients. We collected pre-transplant and post-transplant data, as well as PFT data and long-term mortality.

RESULTS

A total of 123 patients with lymphoma receiving the BEAM (carmustine, etoposide, aracytin, and melphalan) conditioning regimen had a significant 5% drop in mean forced vital capacity and total lung capacity but no significant change in forced expiratory volume in one second/forced vital capacity ratio nor in diffusion lung capacity of carbon monoxide adjusted to volume. Fifteen percent of the patients with lymphoma had a clinically significant drop of 15% in their lung volume parameters. The patients with multiple myeloma receiving the melphalan conditioning regimen had no significant change in any of the PFT parameters. Smoking, baseline PFT parameters, and radiation did not affect lung function or mortality.

CONCLUSIONS

Autologous SCT impact on lung function depends on the disease and conditioning regimen. It leads to a drop in lung volumes but no obstruction or decrease in diffusion in patients with lymphoma receiving the BEAM regimen. Autologous SCT did not affect lung functions in patients with multiple myeloma, and these patients may not need screening PFTs.

Acute Respiratory Failure in Pediatric Hematopoietic Cell Transplantation: A Multicenter Study

OBJECTIVES

Acute respiratory failure is common in pediatric hematopoietic cell transplant recipients and has a high mortality. However, respiratory prognostic markers have not been adequately evaluated for this population. Our objectives are to assess respiratory support strategies and indices of oxygenation and ventilation in pediatric allogeneic hematopoietic cell transplant patients receiving invasive mechanical ventilation and investigate how these strategies are associated with mortality.

DESIGN

Retrospective, multicenter investigation.

SETTING

Twelve U.S. pediatric centers.

PATIENTS

Pediatric allogeneic hematopoietic cell transplant recipients with respiratory failure.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Two-hundred twenty-two subjects were identified. PICU mortality was 60.4%. Nonsurvivors had higher peak oxygenation index (38.3 [21.3-57.6] vs 15.0 [7.0-30.7]; p < 0.0001) and oxygen saturation index (24.7 [13.8-38.7] vs 10.3 [4.6-21.6]; p < 0.0001), greater days with FIO2 greater than or equal to 0.6 (2.4 [1.0-8.5] vs 0.8 [0.3-1.6]; p < 0.0001), and more days with oxygenation index greater than 18 (1.4 [0-6.0] vs 0 [0-0.3]; p < 0.0001) and oxygen saturation index greater than 11 (2.0 [0.5-8.8] vs 0 [0-1.0]; p < 0.0001). Nonsurvivors had higher maximum peak inspiratory pressures (36.0 cm H2O [32.0-41.0 cm H2O] vs 30.0 cm H2O [27.0-35.0 cm H2O]; p < 0.0001) and more days with peak inspiratory pressure greater than 31 cm H2O (1.0 d [0-4.0 d] vs 0 d [0-1.0 d]; p < 0.0001). Tidal volume per kilogram was not different between survivors and nonsurvivors.

CONCLUSIONS

In this cohort of pediatric hematopoietic cell transplant recipients with respiratory failure in the PICU, impaired oxygenation and use of elevated ventilator pressures were common and associated with increased mortality.

CALIPSO: A Randomized Controlled Trial of Calfactant for Acute Lung Injury in Pediatric Stem Cell and Oncology Patients

To assess if calfactant reduces mortality among children with leukemia/lymphoma or after hematopoietic cell transplantation (HCT) with pediatric acute respiratory distress syndrome (PARDS), we conducted a multicenter, randomized, placebo-controlled, double-blinded trial in 17 pediatric intensive care units (PICUs) of tertiary care children's hospitals. Patients ages 18 months to 25 years with leukemia/lymphoma or having undergone HCT who required invasive mechanical ventilation for bilateral lung disease with an oxygenation index (OI) > 10 and <37 were studied. Interventions used were intratracheal instillation of either calfactant or air placebo (1 or 2 doses). Forty-three subjects were enrolled between November 2010 and June 2015: 26 assigned to calfactant and 17 to placebo. There were no significant differences in the primary outcome, which was survival to PICU discharge (adjusted hazard ratio of mortality for calfactant versus placebo, 1.78; 95% confidence interval, .53 to 6.05; P = .35), OI, functional outcomes, or ventilator-free days, adjusting for risk strata and Pediatric Risk of Mortality (PRISM) score. Despite the risk-stratified randomization, more allogeneic HCT patients received calfactant (76% and 39%, respectively) due to low recruitment at various sites. This imbalance is important because independent of treatment arm and while adjusting for PRISM score, those with allogeneic HCT had a nonsignificant higher likelihood of death at PICU discharge (adjusted odds ratio, 3.02; 95% confidence interval, .76 to 12.06; P = .12). Overall, 86% of the patients who survived to PICU discharge also were successfully discharged from the hospital. These data do not support the use of calfactant among this high mortality group of pediatric leukemia/lymphoma and/or HCT patients with PARDS to increase survival. In spite of poor enrollment, allogeneic HCT patients with PARDS appeared to be characterized by higher mortality than even other high-risk immunosuppressed groups. Conducting research among these children is challenging but necessary, because survival to PICU discharge usually results in successful discharge to home.

High-Frequency Oscillatory Ventilation Use and Severe Pediatric ARDS in the Pediatric Hematopoietic Cell Transplant Recipient

INTRODUCTION

The effectiveness of high-frequency oscillatory ventilation (HFOV) in the pediatric hematopoietic cell transplant patient has not been established. We sought to identify current practice patterns of HFOV, investigate parameters during HFOV and their association with mortality, and compare the use of HFOV to conventional mechanical ventilation in severe pediatric ARDS.

METHODS

This is a retrospective analysis of a multi-center database of pediatric and young adult allogeneic hematopoietic cell transplant subjects requiring invasive mechanical ventilation for critical illness from 2009 through 2014. Twelve United States pediatric centers contributed data. Continuous variables were compared using a Wilcoxon rank-sum test or a Kruskal-Wallis analysis. For categorical variables, univariate analysis with logistic regression was performed.

RESULTS

The database contains 222 patients, of which 85 subjects were managed with HFOV. Of this HFOV cohort, the overall pediatric ICU survival was 23.5% (n = 20). HFOV survivors were transitioned to HFOV at a lower oxygenation index than nonsurvivors (25.6, interquartile range 21.1-36.8, vs 37.2, interquartile range 26.5-52.2, P = .046). Survivors were transitioned to HFOV earlier in the course of mechanical ventilation, (day 0 vs day 2, P = .002). No subject survived who was transitioned to HFOV after 1 week of invasive mechanical ventilation. We compared subjects with severe pediatric ARDS treated only with conventional mechanical ventilation versus early HFOV (within 2 d of invasive mechanical ventilation) versus late HFOV. There was a trend toward difference in survival (conventional mechanical ventilation 24%, early HFOV 30%, and late HFOV 9%, P = .08).

CONCLUSIONS

In this large database of pediatric allogeneic hematopoietic cell transplant subjects who had acute respiratory failure requiring invasive mechanical ventilation for critical illness with severe pediatric ARDS, early use of HFOV was associated with improved survival compared to late implementation of HFOV, and the subjects had outcomes similar to those treated only with conventional mechanical ventilation.

Pediatric Hematopoietic Cell Transplant Patients Who Survive Critical Illness Frequently Have Significant but Recoverable Decline in Functional Status

The number of pediatric hematopoietic cell transplant (HCT) patients who survive pediatric intensive care unit (PICU) admission is increasing, yet little is known about their functional morbidity after PICU discharge. We hypothesized that relative to control subjects, pediatric HCT patients who survive PICU admission would have greater rates of new functional morbidity at the time of PICU discharge and only some of these patients would return to their functional baseline by the end of the hospitalization. We performed a retrospective cohort study with secondary data analysis of the Trichotomous Outcomes in Pediatric Critical Care dataset. The pediatric HCT cohort was identified by querying International Classification of Diseases, 9th edition, diagnostic codes. A control group consisted of previously healthy patients matched 4:1 on age, sex, and illness severity, as estimated by the Pediatric Risk of Mortality (PRISM) score. We benchmarked our findings by comparing with a previously healthy group of children with lower respiratory tract infections. Functional impairment was measured by the Functional Status Scale, wherein new morbidity was defined as an increase of ≥3 points relative to the prehospital baseline. Relative to matched control subjects, HCT patients had similar admission PRISM scores (P = .516) but greater PICU mortality (12.9% [11/85] versus 6.2% [21/340], P = .035). However, among those who survived to PICU discharge, HCT patients had similar rates of new morbidity at PICU discharge (14.9% [11/74] versus 17.2% [55/319], P = .622) and similar rates of resolution of new morbidity by hospital discharge (54.5% [6/11] versus 60.0% [33/55], P = .737). Relative to the comparison group with lower respiratory tract infections, HCT patients had both greater admission PRISM scores (P < .001) and greater PICU mortality (12.9% [11/85] versus 1.6% [5/308], P < .001). However, among those who survived to PICU discharge, HCT patients again displayed similar rates of new morbidity at PICU discharge (14.9% [11/74] versus 22.1% [67/303], P = .168) as well as resolution of new morbidity by hospital discharge (54.5% [6/11] versus 71.6% [48/67], P = .299). For pediatric HCT patients PICU survival with new functional morbidity is as prevalent an outcome as PICU mortality. Although pediatric HCT patients have greater PICU mortality than age-, sex-, and PRISM-matched control subjects, they have similar rates of new functional morbidity at PICU discharge and similar resolution of new functional morbidity at hospital discharge. Future interventions focused on improving functional status in pediatric HCT survivors of critical illness are warranted.

Long-term Pulmonary Outcomes in Pediatric Survivors of High-risk Neuroblastoma

BACKGROUND

Children with high-risk neuroblastoma are exposed to multimodality therapies early in life and survivors confront late therapy-related toxicities. This study assessed respiratory symptoms, pulmonary function tests (PFTs), and risk factors for abnormalities among survivors.

MATERIALS AND METHODS

High-risk neuroblastoma survivors followed in the long-term follow-up clinic at Memorial Sloan Kettering Cancer Center were enrolled. Self-administered symptom questionnaires were completed. Medical records were reviewed for treatment information and comorbidities. PFTs included spirometry, plethysmography, and diffusion capacity of the lung for carbon monoxide (DLCO).

RESULTS

Thirty-nine survivors participated (median age at study: 11.4 y; median age at diagnosis: 2.3 y; median time since completion of therapy: 5.5 y). Chronic respiratory symptoms were reported for 33%. PFT abnormalities were identified in 79% and included low forced expiratory volume in 1 second (38%), decreased total lung capacity (44%), and abnormal DLCO (67%). PFT abnormalities were mostly mild to moderate. Mean forced vital capacity, forced expiratory volume in 1 second, and total lung capacity were normal and mean DLCO was mildly abnormal. Risks included thoracic surgery, chest radiation therapy, thoracic surgery plus chest radiation therapy, and shorter time since completion of therapy (P<0.05).

CONCLUSIONS

Although respiratory abnormalities were common, they were mostly mild or moderate. Continued pulmonary surveillance of this at-risk population is warranted.

Recovery of Pulmonary Function after Allogeneic Hematopoietic Cell Transplantation in Children is Associated with Improved Survival

Abnormal pulmonary function is prevalent in survivors of allogeneic hematopoietic cell transplantation (HCT). Post-transplantation recovery of pulmonary function, and its effect on survival, in children are not known. This retrospective cohort study of 308 children followed for 10 years after HCT at a single institution included 2 groups of patients. Group 1 comprised 188 patients with 3 or more pulmonary function test (PFT) results, of which at least 1 was abnormal, and group 2 comprised 120 patients with 3 or more PFTs, all of which were normal. Pulmonary function normalized post-transplantation in 51 patients (27%) in group 1. Obstructive lung disease, restrictive lung disease, mixed lung disease, and normal pattern were seen in 43%, 25%, 5%, and 27% of patients, respectively, at a median of 5 years (range, 0.5 to 11.9 years) post-transplantation. Lung volumes recovered better than spirometric indices. Pulmonary complications were seen in 80 patients (43%) in group 1. Patients who recovered pulmonary function had better overall survival (P = .006), which did not differ significantly from that in patients in group 2 with normal lung function post-transplantation (P = .80). After adjusting for duration of follow-up, pulmonary complications (P = .01), and lower pretransplantation forced vital capacity z-scores (P = .01) were associated with poor recovery. T cell depletion (P < .001), lower pretransplantation forced expired volume in 1 second z-scores (P = .006), and chronic graft-versus-host disease (P < .001) increased the risk for pulmonary complications. Nonrecovery of lung function with pulmonary complications (P = .03), acute graft-versus-host disease (P = .004), and mechanical ventilation (P < .001) were risk factors for nonrelapse mortality. Normalization of pulmonary function is possible in long-term survivors of allogeneic HCT. Strategies to decrease the risk of pulmonary complications may improve outcomes.

Glutathione-S-transferase P1 may predispose children to a decline in pulmonary function after stem cell transplant

RATIONALE

Pulmonary complications after hematopoietic stem cell transplant (SCT) are associated with increased mortality. Genetic markers for those at risk for pulmonary impairment post-SCT have not been widely investigated.

METHODS

Forty-nine patients were retrospectively selected from a single institution's biorepository with linked clinical data. All subjects performed pre-SCT PFTs. Genotyping was conducted using the Infinium Exome-24 BeadChip. Four single nucleotide polymorphisms (SNPs) were selected (rs1800871, rs1695, rs1800629, rs12477314) and evaluated for association with PFT parameters as change over time from baseline. Associations between SNPs and PFT parameters were assessed and adjusted for the following confounding variables: age, gender, and race.

RESULTS

Using the recessive genetic model, patients with one or two minor alleles for the glutathione S-transferase P1 (GSTP1) SNP rs1695 had a lower decline in FEV₁ and FEF_25-75 at 1-year post-SCT compared to patients who were homozygous for the ancestral allele (adjusted P-values <0.01 and 0.02, respectively). No other SNPs were significantly associated with other PFT parameters.

CONCLUSIONS

Our findings suggest that GSTP1 genotype may be associated with lung function during the first year post-SCT. Identifying and investigating genes that predispose patients to pulmonary complications after SCT may allow for more personalized patient management based on pre-emptive genetic testing. The glutathione S-transferase gene merits further investigation.

Forced deflation pulmonary function test: a novel method to evaluate lung function in infants and young children

We describe the safety and feasibility of a forced deflation pulmonary function test (dPFT) in infants and young children. Fifty-two dPFT studies were performed in 26 patients (median age, 1.4 years). Forced vital capacity (FVC) and forced expiratory flow (FEF₇₅ ) were normal in all except one case, but respiratory system compliance (Crs) was reduced in 24% patients. There were no significant differences in pre-blood and marrow transplantation FVC, FEF₇₅ , and Crs between those patients who did and those who did not have posttransplant pulmonary complications. A larger study is needed to determine the prevalence and significance of PFT abnormalities in this age group.

Pulmonary Function and Pretransplant Evaluation of the Hematopoietic Cell Transplant Candidate

Pretransplant pulmonary function tests provide baseline data by which to reference subsequent respiratory impairment, as well as important prognostic information, for the hematopoietic cell transplant (HCT) recipient. Abnormalities in forced expiratory volume in 1 second and diffusing capacity of carbon monoxide are associated with early respiratory failure and increased all-cause mortality after allogeneic HCT. These parameters have been incorporated into risk assessment calculators that may aid in clinical decision making. This article discusses the clinical implications of pulmonary function parameters and other risk factors for pulmonary complications in the context of evolving allogeneic HCT practice.

The lung function score and its components as predictors of overall survival and chronic graft-vs-host disease after allogeneic stem cell transplantation

Aim

To retrospectively assess if the modified lung function score (LFS) and/or its components, forced expiratory volume within the first second (FEV₁) and diffusion capacity for carbon monoxide corrected for hemoglobin level (cDLCO), predict overall survival (OS) and chronic graft-vs-host-disease (cGvHD).

Methods

We evaluated 241 patients receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT) at the University of Regensburg Transplant Center between June 1998 and July 2005 in relation to their LFS, FEV₁ and cDLCO, before and after HSCT.

Results

Decreased OS after allo-HSCT was related to decreased pre-transplantation values of FEV₁<60% (P = 0.040), cDLCO<50% of predicted value (P = 0.025), and LFS≥III (P = 0.037). It was also related to decreased FEV₁ at 3 and 12 months after HSCT (P < 0.001 and P = 0.001, respectively) and increased LFS at 3 and 12 months after HSCT (P = 0.028 and P = 0.002, respectively), but not to changes of cDLCO. A higher incidence of cGvHD was related to decreased FEV₁ at 6, 12, and 18 months (P = 0.069, P = 0.054, and P = 0.009, respectively) and increased LFS at 12 months (P = 0.002), but not to changes in cDLCO.

Conclusions

OS was related to both LFS and FEV₁, but cGvHD had a stronger relation to FEV₁ than to cDLCO or LFS. FEV₁ alone offered more information on the outcome after allo-HSCT than LFS or cDLCO, suggesting limited value of LFS for the patients’ assessment after allo-HSCT.

Proteome Profiling in Lung Injury after Hematopoietic Stem Cell Transplantation

Pulmonary complications due to infection and idiopathic pneumonia syndrome (IPS), a noninfectious lung injury in hematopoietic stem cell transplant (HSCT) recipients, are frequent causes of transplantation-related mortality and morbidity. Our objective was to characterize the global bronchoalveolar lavage fluid (BALF) protein expression of IPS to identify proteins and pathways that differentiate IPS from infectious lung injury after HSCT. We studied 30 BALF samples from patients who developed lung injury within 180 days of HSCT or cellular therapy transfusion (natural killer cell transfusion). Adult subjects were classified as having IPS or infectious lung injury by the criteria outlined in the 2011 American Thoracic Society statement. BALF was depleted of hemoglobin and 14 high-abundance proteins, treated with trypsin, and labeled with isobaric tagging for relative and absolute quantification (iTRAQ) 8-plex reagent for two-dimensional capillary liquid chromatography (LC) and data dependent peptide tandem mass spectrometry (MS) on an Orbitrap Velos system in higher-energy collision-induced dissociation activation mode. Protein identification employed a target-decoy strategy using ProteinPilot within Galaxy P. The relative protein abundance was determined with reference to a global internal standard consisting of pooled BALF from patients with respiratory failure and no history of HSCT. A variance weighted t-test controlling for a false discovery rate of ≤5% was used to identify proteins that showed differential expression between IPS and infectious lung injury. The biological relevance of these proteins was determined by using gene ontology enrichment analysis and Ingenuity Pathway Analysis. We characterized 12 IPS and 18 infectious lung injury BALF samples. In the 5 iTRAQ LC-MS/MS experiments 845, 735, 532, 615, and 594 proteins were identified for a total of 1125 unique proteins and 368 common proteins across all 5 LC-MS/MS experiments. When comparing IPS to infectious lung injury, 96 proteins were differentially expressed. Gene ontology enrichment analysis showed that these proteins participate in biological processes involved in the development of lung injury after HSCT. These include acute phase response signaling, complement system, coagulation system, liver X receptor (LXR)/retinoid X receptor (RXR), and farsenoid X receptor (FXR)/RXR modulation. We identified 2 canonical pathways modulated by TNF-α, FXR/RXR activation, and IL2 signaling in macrophages. The proteins also mapped to blood coagulation, fibrinolysis, and wound healing-processes that participate in organ repair. Cell movement was identified as significantly over-represented by proteins with differential expression between IPS and infection. In conclusion, the BALF protein expression in IPS differed significantly from infectious lung injury in HSCT recipients. These differences provide insights into mechanisms that are activated in lung injury in HSCT recipients and suggest potential therapeutic targets to augment lung repair.

Invasive Mechanical Ventilation and Mortality in Pediatric Hematopoietic Stem Cell Transplantation: A Multicenter Study

OBJECTIVE

To establish the current respiratory practice patterns in pediatric hematopoietic stem cell transplant patients and investigate their associations with mortality across multiple centers.

DESIGN

Retrospective cohort between 2009 and 2014.

SETTING

Twelve children's hospitals in the United States.

PATIENTS

Two hundred twenty-two pediatric allogeneic hematopoietic stem cell transplant recipients with acute respiratory failure using invasive mechanical ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

PICU mortality of our cohort was 60.4%. Mortality at 180 days post PICU discharge was 74%. Length of PICU stay prior to initiation of invasive mechanical ventilation was significantly lower in survivors, and the odds of mortality increased for longer length of PICU stay prior to intubation. A total of 91 patients (41%) received noninvasive ventilation at some point during their PICU stay prior to intubation. Noninvasive ventilation use preintubation was associated with increased mortality (odds ratio, 2.1; 95% CI, 1.2-3.6; p = 0.010). Patients ventilated longer than 15 days had higher odds of death (odds ratio, 2.4; 95% CI, 1.3-4.2; p = 0.004). Almost 40% of patients (n = 85) were placed on high-frequency oscillatory ventilation with a mortality of 76.5% (odds ratio, 3.3; 95% CI, 1.7-6.5; p = 0.0004). Of the 20 patients who survived high-frequency oscillatory ventilation, 18 were placed on high-frequency oscillatory ventilation no later than the third day of invasive mechanical ventilation. In this subset of 85 patients, transition to high-frequency oscillatory ventilation within 2 days of the start of invasive mechanical ventilation resulted in a 76% decrease in the odds of death compared with those who transitioned to high-frequency oscillatory ventilation later in the invasive mechanical ventilation course.

CONCLUSIONS

This study suggests that perhaps earlier more aggressive critical care interventions in the pediatric hematopoietic stem cell transplant patient with respiratory failure requiring invasive mechanical ventilation may offer an opportunity to improve outcomes.

Blood transfusions and pulmonary complications after hematopoietic cell transplantation

BACKGROUND

Transfusion of blood products is an essential component of the hematopoietic cell transplantation (HCT) process. Blood transfusion carries several risks including, but not limited to, lung injury. The effect of transfusions on lung complications after HCT has not been previously investigated.

STUDY DESIGN AND METHODS

We retrospectively studied 215 adult allogeneic HCT recipients at the University of Minnesota and examined the association between transfusion of blood components and development of lung complications after HCT. Patients without lung complications were used as the control group.

RESULTS

A total of 113 (58%) of the patients developed lung injury events before Day 180 after HCT. Six-month survival was significantly lower in the lung event group (52%) versus the controls (78%; p = 0.01). Patients who eventually developed lung events received more transfusion episodes per week in the first month after HCT (median, 4.3 vs. 2.7 for controls), platelet units per week (3.5 vs. 2.0), and RBC units per week (1.8 vs. 1.4; p < 0.01) for all. In a multivariable analysis, each additional transfusion before Day +30 was associated with a 2.7% higher risk of lung complication (95% confidence interval, 0.8-4.8; p = 0.01), adjusting for time to engraftment, conditioning intensity, and donor type. Blood utilization increased after the lung event and remained high for several months relative to controls.

CONCLUSION

Our data suggest that transfusion of blood products is associated with and may further complicate lung complications after HCT. Cautious use of blood components in the post HCT period is recommended.

A Critical Care and Transplantation-Based Approach to Acute Respiratory Failure after Hematopoietic Stem Cell Transplantation in Children

Acute respiratory failure contributes significantly to nonrelapse mortality after allogeneic hematopoietic stem cell transplantation. Although there is a trend of improved survival over time, mortality remains unacceptably high. An understanding of the pathophysiology of early respiratory failure, opportunities for targeted therapy, assessment of the patient at risk, optimal use of noninvasive positive pressure ventilation, strategies to improve alveolar recruitment, appropriate fluid management, care of the patient with chronic lung disease, and importantly, a team approach between critical care and transplantation services may improve outcomes.

•

Outcomes from acute respiratory failure after hematopoietic stem cell transplantation remain unacceptably high.

•

The review focuses on strategies to improve these outcomes.