Lung Clearance Index and Quantitative Computed Tomography of Post-Infectious Bronchiolitis Obliterans in Infants

Update in postinfectious bronchiolitis obliterans

Postinfectious bronchiolitis obliterans (PiBO) is a rare and severe form of chronic obstructive lung disease caused by an infectious injury to the lower respiratory tract. The most commonly recognized inciting stimuli leading to PiBO are airway pathogens, such as adenovirus and Mycoplasma. PiBO is characterized by persistent and nonreversible airway obstruction, with functional and radiological evidence of small airway involvement. The literature has limited information on the aetiology, clinical profile, treatment, and outcome of PiBO.

Low- and High-Attenuation Lung Volume in Quantitative Chest CT in Children without Lung Disease

In contrast to studies of adults with emphysema, application of fixed thresholds to determine low- and high-attenuation areas (air-trapping and parenchymal lung disease) in pediatric quantitative chest CT is problematic. We aimed to assess age effects on: (i) mean lung attenuation (full inspiration); and (ii) low and high attenuation thresholds (LAT and HAT) defined as mean attenuation and 1 SD below and above mean, respectively. Chest CTs from children aged 6-17 years without abnormalities were retrieved, and histograms of attenuation coefficients were analyzed. Eighty examinations were included. Inverse functions described relationships between age and mean lung attenuation, LAT or HAT (p < 0.0001). Predicted value for LAT decreased from -846 HU in 6-year-old to -950 HU in 13- to 17-year-old subjects (cut-off value for assessing emphysema in adults). %TLC_CT with low attenuation correlated with age (r_s = -0.31; p = 0.005) and was <5% for 9-17-year-old subjects. Inverse associations were demonstrated between: (i) %TLC_CT with high attenuation and age (r² = 0.49; p < 0.0001); (ii) %TLC_CT with low attenuation and TLC_CT (r² = 0.47; p < 0.0001); (iii) %TLC_CT with high attenuation and TLC_CT (r² = 0.76; p < 0.0001). In conclusion, quantitative analysis of chest CTs from children without lung disease can be used to define age-specific LAT and HAT for evaluation of pediatric lung disease severity.

Cord blood group 2 innate lymphoid cells are associated with lung function at 6 weeks of age

Objective

Offspring born to mothers with asthma in pregnancy are known to have lower lung function which tracks with age. Human group 2 innate lymphoid cells (ILC2) accumulate in foetal lungs, at 10‐fold higher levels compared to adult lungs. However, there are no data on foetal ILC2 numbers and the association with respiratory health outcomes such as lung function in early life. We aimed to investigate cord blood immune cell populations from babies born to mothers with asthma in pregnancy.

Methods

Cord blood from babies born to asthmatic mothers was collected, and cells were stained in whole cord blood. Analyses were done using traditional gating approaches and computational methodologies (t‐distributed stochastic neighbour embedding and PhenoGraph algorithms). At 6 weeks of age, the time to peak tidal expiratory flow as a percentage of total expiratory flow time (tPTEF/tE%) was determined as well as Lung Clearance Index (LCI), during quiet natural sleep.

Results

Of 110 eligible infants (March 2017 to November 2019), 91 were successfully immunophenotyped (82.7%). Lung function was attempted in 61 infants (67.0%), and 43 of those infants (70.5% of attempted) had technically acceptable tPTEF/tE% measurements. Thirty‐four infants (55.7% of attempted) had acceptable LCI measurements. Foetal ILC2 numbers with increased expression of chemoattractant receptor‐homologous molecule (CRTh2), characterised by two distinct analysis methodologies, were associated with poorer infant lung function at 6 weeks of age.”

Conclusion

Foetal immune responses may be a surrogate variable for or directly influence lung function outcomes in early life.

Prediction of postinfectious bronchiolitis obliterans prognosis in children

INTRODUCTION

The prognosis of postinfectious bronchiolitis obliterans (PIBO) has many implications, ranging between reduced quality of life and life-threatening complications. We evaluated the prognostic factors for PIBO using the baseline clinical characteristics of patients and built a prediction model for determining the prognoses of PIBO patients using the identified parameters.

METHODS

We included 47 PIBO patients who underwent spirometry and impulse oscillometry and followed them up for at least 1 year. A patient's prognosis was classified as poor if the patient experienced at least one of the following: persistent respiratory symptoms for more than 1 year, two or more instances of hospitalizations due to respiratory symptoms, or more than one intensive care unit admission.

RESULTS

The prognoses of 32/47 (68.1%) patients was good, while that of 15/47 (31.9%) was poor. Spirometry results showed significantly lower forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁ ), forced expiratory flow at 25%-75% of FVC, and post-bronchodilator (BD) FEV₁ values in the poor prognosis group; chest computed tomography (CT) demonstrated more inflammatory bronchiolitis findings. We created a nomogram for predicting prognoses using post-BD FEV₁ and inflammatory bronchiolitis on chest CT. The area under the curve for the nomogram was 84.6% (95% confidence interval: 72.8%-96.4%).

CONCLUSIONS

PIBO patients with lower pulmonary function values and more findings of inflammatory bronchiolitis on initial examination have poor prognoses. The nomogram for predicting PIBO prognosis is easy to use and can be applied at the time of diagnosis.

Lung hyperinflation quantitated by chest CT in children with bronchiolitis obliterans syndrome following allogeneic hematopoietic cell transplantation

OBJECTIVES

Bronchiolitis obliterans syndrome (BOS) diagnosis in children following allogeneic hematopoietic stem cell transplantation (post-HSCT) is based on detection of airway obstruction on spirometry and air-trapping, small airway thickening or bronchiectasis on chest CT. We assessed the relationship between spirometry indices and low-attenuation lung volume at total lung capacity (TLC) on CT.

METHODS

Data of children post-HSCT with and without BOS were analyzed. An age-specific, low-attenuation threshold (LAT) was defined as average of (mean-1SD) lung parenchyma attenuation of 5 control subjects without lung disease matched to each age subgroup of post-HSCT patients. % CT lung volume at TLC with attenuation values <LAT was calculated. Association between % lung volume with low attenuation and FEV₁/FVC was assessed.

RESULTS

Twenty-nine children post-HSCT were referred to exclude BOS and 12 of them had spirometry and an analyzable chest CT. We studied: (i) 6 children post-HSCT/BOS (median age: 8.5 years [IQR 7, 15]; median FEV₁/FVC z-score: -2.60 [IQR -2.93, -2.14]); (ii) 6 children post-HSCT/no BOS (age: 13.5 years [9.8, 16.3]; FEV₁/FVC z-score: 0.44 [-0.30, 2.10]); and (iii) 40 controls without lung disease (age:11 years [8.3, 15.8]). Patients post-HSCT/BOS had significantly higher % lung volume with low attenuation than patients post-HSCT/no BOS: median % volume 16.4% (7.1%, 37.2%) vs. 0.61% (0.34%, 2.79%), respectively; P = .004. An exponential model described the association between % CT lung volume below LAT and FEV₁/FVC z-score (r² = 0.76; P < .001).

CONCLUSION

In children post-HSCT with BOS, low-attenuation lung volume on chest CT is associated with airway obstruction severity as expressed by FEV₁/FVC z-score.

Lung clearance index: A new measure of late lung complications of cancer therapy in children

INTRODUCTION

Childhood cancer survivors (CSs) might face an increased lifelong risk of lung function impairment. The lung clearance index (LCI) has been described as being more sensitive than spirometry in the early stages of some lung diseases. The aim of this study was to evaluate this index in a cohort of patients with a history of childhood cancer for the first time.

MATERIALS AND METHODS

We evaluated 57 off-treatment CSs aged 0-18 years old and 50 healthy controls (HCs). We used the multiple-breath washout method to study LCI and spirometry.

RESULTS

CSs did not show any differences from the controls in ventilation homogeneity (LCI 6.78 ± 1.35 vs. 6.32 ± 0.44; p: not significant [ns]) or lung function (FEV1 99.9 ± 11.3% vs. 103.0 ± 5.9% of predicted; p: ns; FVC 98.2 ± 10.3% vs. 101.1 ± 3.3% of predicted). LCI significantly correlated with the number of years since the last chemotherapy (r = .35, p < .05).

CONCLUSIONS

Our study describes the trend of LCI in a cohort of CSs and compares it with the results obtained from HCs. The results show that patients maintain both good values of respiratory function and good homogeneity of ventilation during childhood. Moreover, as LCI increases and worsens as the years pass after the end of the treatment could identify the tendency toward pulmonary fibrosis, which is typical of adult CSs, at an earlier time than spirometry.

Postinfectious Bronchiolitis Obliterans in Children: Diagnostic Workup and Therapeutic Options: A Workshop Report

Bronchiolitis obliterans (BO) is a rare, chronic form of obstructive lung disease, often initiated with injury of the bronchiolar epithelium followed by an inflammatory response and progressive fibrosis of small airways resulting in nonuniform luminal obliteration or narrowing. The term BO comprises a group of diseases with different underlying etiologies, courses, and characteristics. Among the better recognized inciting stimuli leading to BO are airway pathogens such as adenovirus and mycoplasma, which, in a small percentage of infected children, will result in progressive fixed airflow obstruction, an entity referred to as postinfectious bronchiolitis obliterans (PIBO). The present knowledge on BO in general is reasonably well developed, in part because of the relatively high incidence in patients who have undergone lung transplantation or bone marrow transplant recipients who have had graft-versus-host disease in the posttransplant period. The cellular and molecular pathways involved in PIBO, while assumed to be similar, have not been adequately elucidated. Since 2016, an international consortium of experts with an interest in PIBO assembles on a regular basis in Geisenheim, Germany, to discuss key areas in PIBO which include diagnostic workup, treatment strategies, and research fields.

Imaging of Acute Pulmonary and Airway Diseases in Children

소아의 다양한 응급질환 중 급성 폐질환 또는 급성 기도질환은 영상의학과 의사가 자주 대하게 되는 임상 상황이며, 일차적으로 시행되는 영상검사는 흉부 방사선사진이다. 따라서 다양한 임상 상황에서의 감별진단과 영상 소견을 숙지하는 것이 중요하다. 본 종설에서는 급성 폐질환의 다양한 원인과 폐렴을 알아보고, 폐렴과 감별해야 하는 급성 폐질환을 생각해보았다. 급성 기도질환으로는 크룹, 급성 후두염, 기관연화증, 천식, 감염 후 폐쇄세기관지염, 그리고 이물 흡인을 검토하였다. 이렇게 소아에서 고려해야 할 질환들의 영상 소견을 검토하여 진단과 치료에 도움을 줄 수 있길 바란다.

Post-infectious bronchiolitis obliterans

Bronchiolitis obliterans is a rare and severe chronic lung disease resulting from a lower respiratory tract lesion. It may occur after a bone marrow or lung transplantation, infectious diseases, or less frequently after inhaling toxic substances or after connective tissue diseases. Pathology, pathogenesis, and molecular biology, as well as the best treatment of bronchiolitis obliterans, remain the subject of ongoing research. This review discusses our current knowledge of different areas of bronchiolitis obliterans associated with infectious lesions.