Lung clearance index (LCI2.5) changes after initiation of Elexacaftor/Tezacaftor/Ivacaftor in children with cystic fibrosis aged between 6 and 11 years: The "real-world" differs from trial data

BACKGROUND

Elexacaftor in combination with Tezacaftor and Ivacaftor (ETI) became licensed in the United Kingdom in early 2022 for children aged 6-11 years with cystic fibrosis (CF) and an eligible mutation. Many in this age group have excellent prior lung health making quantitative measurement of benefit challenging. Clinical trials purport that lung clearance index (LCI2.5) measurement is most suitable for this purpose.

OBJECTIVES

This study aimed to understand the clinical utility of LCI2.5 in detecting change after commencing ETI in the real world.

PATIENT SELECTION/METHODS

Baseline anthropometric data were collected along with spirometry (forced expiratory volume in 1 s [FEV1], forced vital capacityFV and LCI2.5 measures in children aged 6-11 years with CF before starting ETI. Measures were repeated after a mean (range) of 8.2 (7-14) months of ETI treatment. The primary endpoint was a change in LCI2.5, with secondary endpoints including change in FEV1 and change in body mass index (BMI) also reported.

RESULTS

Twelve children were studied (seven male, mean age 9.5 years at baseline). Our study population had a mean (SD) LCI2.5 of 7.01 (1.14) and FEV1 of 96 (13) %predicted at baseline. Mean (95% confidence interval) changes in LCI2.5 [-0.7 (-1.4, 0), p = .06] and BMI [+0.7 (+0.1, +1.3), p = .03] were observed, along with changes in FEV1 of +3.1 (-1.9, +8.1) %predicted.

CONCLUSIONS

Real-world changes in LCI2.5 (-0.7) are different to those reported in clinical trials (-2.29). Lower baseline LCI2.5 as a result of prior modulator exposure, high baseline lung health, and new LCI2.5 software analyses all contribute to lower LCI2.5 values being recorded in the real world of children with CF.

Intra-subject variability in oscillometry correlates with acute rejection and CLAD post-lung transplant

Background

Chronic lung allograft dysfunction (CLAD) is the major cause of death post-lung transplantation, with acute cellular rejection (ACR) being the biggest contributing risk factor. Although patients are routinely monitored with spirometry, FEV₁ is stable or improving in most ACR episodes. In contrast, oscillometry is highly sensitive to respiratory mechanics and shown to track graft injury associated with ACR and its improvement following treatment. We hypothesize that intra-subject variability in oscillometry measurements correlates with ACR and risk of CLAD.

Methods

Of 289 bilateral lung recipients enrolled for oscillometry prior to laboratory-based spirometry between December 2017 and March 2020, 230 had ≥ 3 months and 175 had ≥ 6 months of follow-up. While 37 patients developed CLAD, only 29 had oscillometry at time of CLAD onset and were included for analysis. These 29 CLAD patients were time-matched with 129 CLAD-free recipients. We performed multivariable regression to investigate the associations between variance in spirometry/oscillometry and the A-score, a cumulative index of ACR, as our predictor of primary interest. Conditional logistic regression models were built to investigate associations with CLAD.

Results

Multivariable regression showed that the A-score was positively associated with the variance in oscillometry measurements. Conditional logistic regression models revealed that higher variance in the oscillometry metrics of ventilatory inhomogeneity, X5, AX, and R5-19, was independently associated with increased risk of CLAD (p < 0.05); no association was found for variance in %predicted FEV₁.

Conclusion

Oscillometry tracks graft injury and recovery post-transplant. Monitoring with oscillometry could facilitate earlier identification of graft injury, prompting investigation to identify treatable causes and decrease the risk of CLAD.

Lung involvement in children with COVID-19 multisystem inflammatory syndrome

Since the beginning of the COVID-19 pandemic, multisystem inflammatory syndrome in children (MIS-C) has been reported in increasing numbers, mostly focusing on cardiac dysfunction. Very few studies have evaluated lung involvement in terms of imaging findings, while data regarding pulmonary function in children with MIS-C are not available. The purpose of our study was to evaluate lung involvement in MIS-C by imaging and lung function by structured light plethysmography (SLP) at hospital admission and 6 months afterwards. Spirometry is the gold standard technique to evaluate lung function in children. However, SLP has the advantage of not requiring contact with the patient, offering an effective solution for the evaluation of lung function during the pandemic. To our knowledge this is the first study that aims to investigate pulmonary function by SLP in children with MIS-C.

Migration is not the perfect answer: How the cross-talk error correction for multiple breath nitrogen washout (MBWN2 ) parameters differs on directly collected vs. legacy data

Recently, a cross-talk error with commercial multiple breath nitrogen washout (MBWN₂ ) software was discovered, which produced an absolute over-reading of N₂ of approximately 1%, i.e., 2% N₂ read as 3%. This caused an extended tail to the washout, and over-estimated lung clearance index (LCI_2.5 ) values. Subsequently an updated and corrected software version has been released. Within the field there have been discussions on how to correct legacy data, whether to migrate or completely "rerun" raw data A-files from the old software into the new corrected software. To our knowledge, no research has been published assessing whether either method is equivalent to directly collecting data in the new corrected software. We prospectively recruited 19 participants, 10 adult healthy controls and 9 people with cystic fibrosis (CF). MBWN₂ was performed using the Exhalyzer® D first on the old 3.1.6 software and next, directly on corrected 3.3.1 software. Multiple breath washout (MBW) data directly collected in 3.3.1 was significantly different from both migrated and rerun data. A total of 7 of the 19 participants (37%; 4 CF) had a relative difference in LCI_2.5  > 10% for both migrated and rerun data compared to 3.3.1 collected data. Our findings have implications for the Global Lung Initiative MBW project, which is accepting a combination of directly collected, A-file reruns and migrated data to establish normative values. Further, caution must be used in clinical practice when comparing corrected legacy data versus 3.3.1 collected data for clinical interpretation. We recommend that a new baseline is collected directly on 3.3.1. before clinical interpretation and decisions are determined when comparing consecutive MBW tests.

Assessment of bronchodilator response by forced oscillation technique in a preterm infant with evolving bronchopulmonary dysplasia: A case report

Inhaled bronchodilators are often given in preterm infants with evolving or established bronchopulmonary dysplasia. However, it is unclear which patients may benefit from it and when it is the best time to start treatment. The forced oscillation technique (FOT) is a noninvasive method for assessing lung mechanics that proved sensitive to airway obstruction reversibility in children and adults. FOT does not need patient cooperation, which is ideal for infants. Bedside tools for applying FOT in infants during spontaneous breathing and different respiratory support modes are becoming available. This case report illustrates for the first time that FOT has potential value in assessing airway obstruction reversibility in preterm infants, informing which infants may manifest a clinical benefit from the treatment with bronchodilators.

Bronchodilator responsiveness in cystic fibrosis children treated for pulmonary exacerbations

BACKGROUND

Cystic fibrosis (CF) pulmonary exacerbations (PEx) are associated with a significant drop in pulmonary function. The clinical value of measuring bronchodilator (BD) responsiveness during treatment for PEx to monitor or predict recovery of lung function is unclear.

METHODS

A retrospective analysis of spirometry with BD response testing obtained during hospital admissions for PEx in pediatric CF patients. Repeated events were included for patients with BD testing during multiple admissions.

RESULTS

Two hundred forty-nine spirometries with BD testing in 102 patients were completed around Day 7 (Days 4-10) of hospital admission for treatment of CF PEx. Median (IQR) forced expiratory volume in 1 s (FEV₁ ) was 70.6% predicted (58.1, 84.6) before the PEx event (best FEV₁ in 6 months before admission), 54.4% (41.5, 66.9) at admission, 62.3% (48.4, 74.7) around Day 7 of admission and 67.1% predicted (53.8, 78.2) at the end of treatment. BD response around Day 7 correlated poorly with FEV₁ before PEx (r = -.16, p = .02) and did not correlate with recovery to baseline FEV₁ at end of treatment (r = .08, p = .22). Only 23/249 (9%) individual tests had a BD response in FEV₁ of ≥12% and 200 ml. BD response was not related to age or severity of lung disease and led to an immediate change in clinical management in only four cases.

CONCLUSIONS

Significant BD response in CF patients treated for PEx is rare, shows poor correlation with baseline pulmonary function and does not correlate with the recovery of FEV₁ with treatment. These data suggest that routine testing for BD response is not indicated during PEx.

Peripheral obstruction without airflow limitation is rare and not specific to asthma in children

Peripheral (or small) airway obstruction (PAO) is considered a marker of childhood asthma but the techniques able to directly measure it are rarely used in routine. Usual spirometry and plethysmography can detect a certain degree of PAO when reduced forced vital capacity (FVC) is associated to normal forced expiratory volume in 1 s (FEV₁ ) to FVC ratio, and normal total lung capacity (TLC). The frequency of this functional pattern has never been studied in different pediatric respiratory conditions. To assess the prevalence and outcome of PAO in children with different diseases or symptoms, we retrospectively extracted from our database all files of Caucasian subjects encompassing spirometry and plethysmography measurements. Spirometry patterns (normal, airflow limitation [AFL; low FEV₁ /FVC], low FVC [with normal FEV₁ /FVC]) and final functional patterns (normal, AFL, PAO, restrictive [low TLC], or mixed) were described. We included 4394 files recorded in 1794 children (median [IQR] age: 10.7 [9.2-12.9] years). At inclusion, 125 (7%) children had low FVC of which 56 (44.8%, and 3.1% [95% CI 2.3-3.9] of the whole population) had PAO. PAO prevalence increased with age (OR (95% CI) per 2-year-increase: 2.26 (1.59-3.23); p < .001), and was more frequent in chronic bronchial diseases other than asthma (1.6% vs. 8.0%). On repeated tests, PAO frequently normalized (26.1%) or persisted (43.5%), but it less often progressed into AFL (13%) or restrictive (13%) patterns. PAO is an infrequent nonspecific and persistent functional pattern. Its prevalence increases with age and in diagnosis of chronic respiratory diseases other than asthma.

Pulmonary function testing in patients with neuromuscular disease

Progressive neuromuscular disease leads to muscle weakness or failure that produces loss of pulmonary function and clinical respiratory morbidity. Tracking pulmonary function in a practical and effective way is very important because it can help identify a stage of disease when a morbidity, such as inadequate airway clearance or respiratory failure, may be present. There are four general categories of pulmonary function outcome measures such as volume, flow, pressure, and gas exchange. These outcome measures have variable precision and accuracy in predicting clinical change, and practicality in performing them relative to age and condition. It is widely recommended to follow multiple measurements longitudinally and create an accurate and timely clinical picture. This manuscript will review the most commonly used and most practical measures for use in clinical practice and how they can help to assess morbidity, disease state, and help optimize patient management.

Bronchiectasis associated with electronic cigarette use: A case series

Bronchiectasis (BE) is defined as a permanent, irreversible dilation of the bronchial tree. In the pediatric population, this disease process is most commonly associated with patients with cystic fibrosis (CF). However, BE unrelated to CF is increasingly noted as a cause of chronic respiratory related morbidity worldwide. Chronic inflammation and recurrent infection result in cellular cascades that lead to irreversible structural changes of the airways. When these architectural changes occur, they confer extensive risks to morbidity usually due to continued infections. In the adult population, BE has been associated with chronic obstructive pulmonary disease, which is mainly caused by cigarette smoking. In this report, the authors reviewed various cases of BE in the pediatric population at our institution. After a comprehensive case by case review, we compiled details of three cases of newly diagnosed BE where the most likely inciting factor was the electronic cigarette use. Common features of the three cases included at least a year of e-cigarette use with conjunction of tetrahydrocannabinol and radiologic findings of BE, ground glass opacities, and nodule formation.

Pediatric pulmonology year in review 2019: Physiology

Pulmonary physiologic assessments are critical for the care and study of pediatric respiratory disease. In 2019, there were numerous contributions to this topic in Pediatric Pulmonology.

Impact of scoliosis surgery on pulmonary function in patients with muscular dystrophies and spinal muscular atrophy

BACKGROUND

Scoliosis is a common complication of severe neuromuscular diseases. The aim of this study is to determine the impact of posterior spinal fusion on pulmonary function parameters in patients with severe neuromuscular disease at our medical center.

METHODS

Retrospective chart review of all patients with severe neuromuscular disease who had posterior spinal fusion between 2012 and 2017 at Texas Children's Hospital. Patients with growing rods, brain injury or malformation, and/or spina bifida were excluded. Pulmonary function measures before and after spinal surgery were determined.

RESULTS

A total of 20 eligible patients were identified, 7 with Duchenne muscular dystrophy, 6 with spinal muscular atrophy, 3 with merosin deficient muscular dystrophy, 2 with Charcot-Marie-Tooth, 1 with central core disease, and 1 with dystroglycanopathy. The mean change in vital capacity from pre- to postspine surgery was a loss of 0.63 L for the spinal muscular atrophy patients, a loss of 0.36 L for the Duchenne muscular dystrophy patients, and a gain of 0.23 L for the merosin deficient patients. The difference between spinal muscular atrophy and merosin deficient patients was statistically significant (P = .02) CONCLUSION: In this single-center retrospective study, we found that after spine surgery for scoliosis, all patients with spinal muscular atrophy and most patients with Duchenne muscular dystrophy lost vital capacity, while the patients with merosin deficient muscular dystrophy gained vital capacity. These differences were not associated with differences is respiratory strength, body mass index, or surgical outcomes.

The utility of moment ratios and abbreviated endpoints of the multiple breath washout test in preschool children with cystic fibrosis

BACKGROUND

The multiple breath washout (MBW) test may be most useful in tracking disease progression over time to inform treatment decisions. In the clinical setting, alternative outcomes, which can be obtained quickly and easily, may facilitate interpretation of clinically relevant changes in lung function.

METHODS

In this secondary analysis of data from 78 cystic fibrosis (CF) and 72 healthy control (HC) subjects between the ages of 2.6 and 5.9 years, MBW was performed at enrollment, 1, 3, 6, 9, and 12 months, as well as during symptomatic visits using the Exhalyzer D (EcoMedics AG, Duernten, Switzerland). The lung clearance index, LCI_2.5, was compared to moment ratios (M₁ /M₀ and M₂ /M₀ ) at the standard cutoff (1/40th of starting tracer gas concentration) as well as LCI₅ and moment ratios at 1/20th of the starting concentration (M₁ /M₀ at LCI₅ , and M₂ /M₀ at LCI₅ ).

RESULTS

All outcomes were able to distinguish between health and disease. LCI₅ reduced testing time by 40% and increased feasibility by more than 10%. The limits of biological reproducibility in healthy children were similar between LCI_2.5 (15%), LCI₅ (12%), M₁ /M₀ at LCI_2.5 (14%), and M₁ /M₀ at LCI₅ (12%), but markedly larger for M₂ /M₀ at LCI_2.5 (30%) and M₂ /M₀ at LCI₅ (25%). Each outcome deteriorated significantly with worsening pulmonary symptoms, the magnitude of deterioration was greatest for M₂ /M₀ .

CONCLUSIONS

In preschool children with CF, LCI₅ was more feasible to obtain and track disease progression. The second moment ratio was most sensitive to pulmonary symptoms, but had the greatest variability both within and between subjects.

Effects of age, sex, race/ethnicity, and allergy status in obesity-related pediatric asthma

RATIONALE

Obesity in children increases the risk for new asthma. How age, sex, race/ethnicity, and allergy status affect the relationship between obesity and asthma is unclear. This study describes the relationship between high body mass index (BMI) and incident asthma.

METHODS

We conducted a retrospective cohort study to compare asthma incidence among normal weight, overweight, and obese 2 to 6, 7 to 11, and 12 to 17 year olds to define the effects of sex, race/ethnicity, and allergy status. Weight status was determined at baseline and asthma incidence was defined as ≥2 asthma encounters and ≥1 asthma prescriptions. We used multivariable Poisson regression to estimate adjusted incident asthma rates and risk ratios.

RESULTS

Data from 192 843 2 to 6 year olds, 157 284 7 to 11 year olds, and 157 369 12 to 17 year olds were included. The relative risks (95% confidence interval [CI]) of new asthma among obese children in 2 to 6 year olds, 7 to 11 year olds, and 12 to 17 year olds were 1.25 (1.15, 1.37), 1.49 (1.32, 1.69) and 1.40 (1.21, 1.63), respectively. Among children with underlying allergic rhinitis, obesity did not increase the risk of new asthma. In children without allergic rhinitis, the risk for obesity-related asthma was highest in 7 to 11 year olds (risk ratio = 1.50 95% CI, 1.33, 1.60). Before age 12, females had a higher risk for obesity-related asthma; but after age 12, obese males had a higher asthma risk (interaction P-value < .05).

CONCLUSION

Obesity is a major preventable risk factor for pediatric asthma that appears to vary along the pediatric age continuum and depends on sex, race/ethnicity and atopy status.

Pediatric Pulmonology year in review 2018: Asthma, physiology/pulmonary function testing, and respiratory infections

Pediatric Pulmonology publishes original research, reviews, and case reports related to a wide range of children's respiratory disorders. In our "Year in Review" series, we summarize publications in our major topic areas from 2018, in the context of selected literature in these areas from other journals relevant to our discipline. This review covers selected articles on asthma, physiology/lung function testing, and respiratory infections.

Cystic fibrosis year in review 2018, part 1

Cystic fibrosis research and case reports were robust in the year 2018. This report summarizes research and cases related to Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) modulator therapies, inflammation and infection, epidemiology and the physiologic, and imaging assessment of disease.

Identifying pediatric lung disease: A comparison of forced oscillation technique outcomes

RATIONALE

Increasing evidence suggests the forced oscillation technique (FOT) has the capacity to provide non-invasive monitoring and diagnosis of respiratory disease in young children. However, which FOT outcomes provide the most pertinent clinical information is currently unknown. The aim of this study was to determine which FOT outcomes were most sensitive for differentiating between health and specific childhood respiratory disease.

METHODS

Respiratory impedance was measured using a commercial device (i2M, Chess Medical, Belgium) in children aged between 3 and 7 years, who had been diagnosed with either cystic fibrosis (N = 84), asthma (N = 99) or were born very preterm (N = 114). Z-scores were calculated for respiratory system resistance (Rrs) and reactance (Xrs) at 6, 8, and 10 Hz, the resonance frequency (Fres), frequency dependence (Fdep_4-24 ), and area under the reactance curve (AX). Pairwise comparisons of the area under the receiver operating characteristic (ROC) curve were used to determine the most relevant FOT variables.

RESULTS AND CONCLUSIONS

The FOT outcomes best able to discern between health and disease were Fres (P < 0.0001) in cystic fibrosis, Fres (P < 0.0001) in asthma and Xrs₈ (P < 0.0001) in children born preterm. These findings suggest the utility of specific FOT outcomes is dependent on the respiratory disease being assessed. It is hoped that a disease-specific approach to interpreting FOT data can help further refine the FOT technique to aid in the diagnosis of children with pediatric respiratory disease.

Pediatric Pulmonology year in review 2017: Part 3

Pediatric Pulmonology publishes original research, reviews, and case reports related to a wide range of children's respiratory disorders. We here summarize the past year's publications in our major topic areas, in the context of selected literature in these areas from other journals relevant to our discipline. This review (Part 3 of a 5-part series) covers selected articles on asthma, physiology/lung function testing, and respiratory infections.

In-vitro oxidation model for UHMWPE incorporating synovial fluid lipids

Post-irradiation melting of ultra-high molecular weight polyethylene (UHMWPE) reduced the oxidation potential of UHMWPE in vivo. After mid-term (5-10 years) use in vivo, there is detectable oxidation in irradiated and melted joint implant retrievals. The absorption of the synovial fluid lipid squalene was identified as a possible factor initiating oxidation. We investigated the role of lipids in UHMWPE oxidation by asking: (1) Do other synovial fluid lipids initiate oxidation in irradiated and melted UHMWPE?; (2) What is the effect of the absorption of multiple lipids on UHMWPE oxidation?; (3) How does lipid-initiated oxidation in vitro compare to what is observed in long-term retrievals? We diffused emulsified single and mixed lipids into irradiated and melted UHMWPE and accelerated aged them. We analyzed the oxidation in these samples and in four long-term highly crosslinked, irradiated, and melted Longevity™ UHMWPE liner retrievals (in vivo for up to 190 months) using Fourier Transform Infrared Spectroscopy (FTIR). We showed that lipids other than squalene could initiate oxidation in UHMWPE and that the types of absorbed lipids determined the amount of resultant oxidation. Although mixed lipids doping and accelerated aging reproduced the average and maximum oxidation values and oxidation products observed in vivo, the oxidation depth profile and its effect on cross-link density was different. One reason for this was the variability of oxidation in retrievals, suggesting additional factors contributing to oxidation. The understanding of oxidative processes in vivo and the development of clinically relevant in vitro protocols to evaluate implant materials is crucial for their long-term performance. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1833-1839, 2018.

Tidal breath eNO measurements in a cohort of unsedated hospitalized neonates-A method validation

AIM

Exhaled Nitric oxide (eNO) is an inflammatory marker. In 2002 Hall et al. [J Appl Physiol. 92:59-66] established an infant eNO measurement method, fulfilling four criteria of feasibility: simple, non-invasive, without impact on the natural breathing pattern, and accounting for flow by NO output (V'NO). Although tidal breathing is accepted as an eNO measurement method in uncooperative patients, it is seldom used outside research labs. The variability and lack of validated methods have restrained from exploring the area in preterm and term neonates the last years. This study aimed to validate clinically feasible longitudinal online tidal eNO and V'NO in a real-life birth cohort of un-sedated, hospitalized preterm, and term neonates.

METHOD

We included 149 newborns, GA 28-42 weeks. Each scheduled for six repeated, non-invasive, on-line eNO measurements with Ecomedics CLD 88sp and NO-free air. We used three 60-second-eNO measurements. The method was adapted to fit preterm and term neonates with unstable respiration, without excluding sighs and surrounding breaths.

RESULT

Protocol measurements with a maximum mutual difference of 1 ppb succeeded in 85-99%, increasing with postnatal age. We performed mixed model analyses in three hierarchical measurement levels. Despite the irregular breathing of newborns, the predictions of individual eNO levels in the average infant was a 0.05 SD. Exhaled NO was flow-dependent (P = 0.028); V'NO but not eNO was associated with preterm birth (P < 0.001) and >24 h CPAP treatment (P = 0.0316).

CONCLUSION

We validated clinically, non-invasive, online eNO measurements in neonates. The method was well tolerated and exhibited low subject-specific-prediction-variance and high success rates.

Pulmonary function disparities exist and persist in Hispanic patients with cystic fibrosis: A longitudinal analysis

BACKGROUND

Hispanic patients with cystic fibrosis (CF) have decreased life expectancy compared to non-Hispanic white patients. Pulmonary function is a main predictor of life expectancy in CF. Ethnic differences in pulmonary function in CF have been understudied. The objective was to compare longitudinal pulmonary function between Hispanic and non-Hispanic white patients with CF.

METHODS

This cohort study of 15 018 6-25 years old patients in the CF Foundation Patient Registry from 2008 to 2013 compared FEV₁ percent predicted and longitudinal change in FEV₁ percent predicted in Hispanic to non-Hispanic white patients. We used linear mixed effects models with patient-specific slopes and intercepts, adjusting for 14 demographic and clinical variables. We did sub-analyses by CFTR class, F508del copies, and PERT use.

RESULTS

Hispanic patients had lower FEV₁ percent predicted (79.9%) compared with non-Hispanic white patients (85.6%); (-5.8%, 95%CI -6.7% to -4.8%, P < 0.001), however, there was no difference in FEV₁ decline over time. Patients on PERT had a larger difference between Hispanic and non-Hispanic white patients in FEV₁ percent predicted than patients not on PERT (-6.0% vs -4.1%, P = 0.02). The ethnic difference in FEV₁ percent predicted was not statistically significant between CFTR classes (Class I-III: -6.1%, Class IV-V: -5.9%, Unclassified: -5.7%, P > 0.05) or between F508del copies (None: -7.6%, Heterozygotes: -5.6%, Homozygotes: -5.3%, P > 0.05).

CONCLUSIONS

Disparities in pulmonary function exist in Hispanic patients with CF early in life and then persist without improving or worsening over time. It is valuable to investigate the factors contributing to pulmonary function in Hispanic patients with CF.

Exercise capacity is not decreased in children who have undergone lung resection early in life for congenital thoracic malformations compared to healthy age-matched children

PURPOSE

The purpose of this study was to compare (i) the exercise capacity and (ii) lung function prior to and immediately post cardiopulmonary exercise tests (CPET) of children who underwent early life lung resection for Congenital Pulmonary Airway Malformations (CPAM) to healthy control children.

METHOD

Eight children with CPAM (four males, age 9.6 ± 1.8 years) and eight control children without respiratory disease (three males, age 9.4 ± 1.4 years) performed a CPET on a cycle ergometer, during which maximal oxygen consumption (V̇O_2max ) and heart rate were measured. Prior to and immediately post CPET, lung function measures including Nitrogen Multiple Breath Washout (MBW) and spirometry were performed.

RESULTS

There were no significant between group differences in pre CPET lung function (P > 0.05) or maximal exercise capacity (V̇O_2max CPAM: 39.4 mL^. kg^-1. min^-1 , Control: 40.5 mL^. kg^-1. min^-1 ). Post CPET, FEV₁ was significantly lower in the CPAM group, with two participants diagnosed subsequently with exercise induced bronchospasm based on post-CPET spirometry and follow-up clinical investigations.

CONCLUSION

Early life lung resection for CPAM does not appear to have negative implications for exercise capacity later in childhood. Clinicians should be aware that dyspnoea following exercise may be due to asthma rather than residual effects of CPAM in these children.

Small airway oscillometry indices: Repeatability and bronchodilator responsiveness in young children

INTRODUCTION

The impulse oscillometry (IOS) indices absolute and relative difference between respiratory resistance at 5 and 20 Hz (R5-20 and R5-20%, respectively) and the area under the reactance curve (AX) are postulated to reflect small airway function. Data on their cutoff values to evaluate bronchodilator responsiveness (BDR) or between-visit changes after interventions are limited in young children.

METHODS

We evaluated the BDR of 103 healthy children aged 2-7 years, who received either salbutamol (n = 84) or placebo (n = 19) in order to determine cutoff values for BDR of R5-20, R5-20%, and AX. We then determined the repeatability within and between two IOS measurements 7-14 days apart in young children aged 4-8 years with asthmatic symptoms (n = 43), including cutoff values for significant between-visit changes.

RESULTS

The investigated IOS parameters showed marked BDR (fifth percentile cutoff of 75-110% of the baseline value) in healthy children, whereas no significant changes were seen after inhalation of placebo. The agreement within the triplicate IOS measurement was excellent (ICC > 0.80), and the agreement of results between visits was good (ICC > 0.60). A change in R5-20, R5-20%, and AX of 0.65, 1.08, and 0.84 z-scores, respectively, would exceed 95% confidence intervals for between-visit variability.

CONCLUSION

We introduce cutoff values for BDR of R5-20, R5-20%, and AX, and their repeatability indices and cutoff limits for significant between-visit changes. These IOS parameters may show greater variability than the conventional IOS indices during follow-up, but the between-visit agreement remains good, providing potentially useful endpoints for monitoring lung function in young children.

Pediatric pulmonology year in review 2016: Part 2

Pediatric Pulmonology continues to publish research and clinical topics related to the entire range of children's respiratory disorders. As we have done annually in recent years, we here summarize some of the past year's publications in our major topic areas, as well as selected literature in these areas from other core journals relevant to our discipline. This review (Part 2) covers selected articles on neonatology, asthma, physiology and lung function testing, and infectious diseases.

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.

Spirometer guided chest imaging in children: It is worth the effort!

PURPOSE

Computed tomography (CT) and magnetic resonance imaging (MRI) scans are used to assess and monitor several pediatric lung diseases. It is well recognized that lung volume at the moment of acquisition has a major impact on the appearance of lung parenchyma and airways. Importantly, the sensitivity of chest CT and MRI to detect bronchiectasis and gas trapping is highly dependent on adequate volume control during the image acquisition. This paper describes a feasible method to obtain accurate control of lung volume during chest imaging in pediatric patients with lung disease.

PROCEDURE

A procedure to obtain maximal respiratory manoeuvres with spirometry guidance during image acquisition for CT and MRI is described. This procedure requires training of the subject, an MRI compatible spirometer and close collaboration between a lung function scientist and the radiographer. A good to excellent target volume level for the inspiratory or expiratory scan can be achieved in around 90% of children. An important condition for this success rate is the training of the subject, executed prior to each chest CT or MRI, and instructions by the lung function scientist during the chest CT.

CONCLUSION

Implementing lung volume guidance with a spirometer is an important and feasible step to standardize chest imaging and to optimize the diagnostic yield of chest CT and MRI in children with lung disease. Training and the collaborative effort by a lung function scientist and radiographer is the key factor for success of this procedure. Pediatr Pulmonol. 2017;52:48-56. © 2016 Wiley Periodicals, Inc.

The bronchodilator response in preschool children: A systematic review

BACKGROUND

The bronchodilator response (BDR) is frequently used to support diagnostic and therapeutic decision-making for children who wheeze. However, there is little evidence-based guidance describing the role of BDR testing in preschool children and it is unclear whether published cut-off values, which are derived from adult data, can be applied to this population.

METHODS

We searched MEDLINE, EMBASE, Web of Science, and Cochrane databases (inception-September 2015) for studies reporting response to a bronchodilator in healthy preschool children, response following placebo inhalation, and the diagnostic efficacy of BDR compared with a clinical diagnosis of asthma/recurrent wheezing.

FINDINGS

We included 14 studies. Thirteen studies provided BDR data from healthy preschool children. Two studies reported response to placebo in preschool children with asthma/recurrent wheezing. Twelve studies compared BDR measurements from preschool children with asthma/recurrent wheeze to those from healthy children and seven of these studies reported diagnostic efficacy. Significant differences between the BDR measured in healthy preschool children compared with that in children with asthma/recurrent wheeze were demonstrated in some, but not all studies. Techniques such as interrupter resistance, oscillometry, and plethysmography were more consistently successfully completed than spirometry. Between study heterogeneity precluded determination of an optimum technique.

INTERPRETATION

There is little evidence to suggest spirometry-based BDR can be used in the clinical assessment of preschool children who wheeze. Further evaluation of simple alternative techniques is required. Future studies should recruit children in whom airways disease is suspected and should evaluate the ability of BDR testing to predict treatment response. Pediatr Pulmonol. 2016;51:1242-1250. © 2016 Wiley Periodicals, Inc.

Pediatric Pulmonology year in review 2015: Part 1

Our journal covers a broad range of research and scholarly topics related to children's respiratory disorders. For updated perspectives on the rapidly expanding knowledge in our field, we will summarize the past year's publications in our major topic areas, as well as selected publications in these areas from the core clinical journal literature outside our own pages. The current review covers articles on neonatal lung disease, pulmonary physiology, and respiratory infection. Pediatr Pulmonol. 2016;51:733-739. © 2016 Wiley Periodicals, Inc.

Diffuse panbronchiolitis in a 10-year-old boy

Diffuse panbronchiolitis is a progressive fatal respiratory disease of unknown cause seen predominantly in Southeast Asian adults. We report this condition in a 10-year-old child of Korean birth because of the uncommon presentation at this age and the favorable outcome associated with early diagnosis. Our objective was also to demonstrate the gradual but complete resolution of the disease and sustained remission from early institution of azithromycin.

Assessment of respiratory mechanics with forced oscillations in healthy newborns

BACKGROUND

Lung function data in healthy newborn infants are scarce largely due to lack of suitable techniques, although data for developmental and prenatal exposure studies are much needed. We have modified the forced oscillation technique (FOT) for the measurement of respiratory mechanical impedance (Zrs) in unsedated sleeping infants in the first 3 days of life.

METHODS

Zrs was measured during 30-s epochs of quiet sleep in term neonates born via spontaneous vaginal delivery with a non-invasive FOT between 8 and 48 Hz. Total respiratory resistance (R), compliance (C) and inertance (I) were obtained by fitting Zrs spectra. Cluster analysis was used to determine a set of minimal Zrs spectra representing optimal respiratory mechanics for each infant.

RESULTS

Successful measurements were obtained in each of the first 3 days in 30/38 (78.9%) neonates. Group mean (± SD) values of R, C, I, and resonant frequency pooled for the 3 days were 45.9 ± 16.6 hPa s L(-1), 0.97 ± 0.21 ml hPa(-1), 0.082 ± 0.031 hPa s(2)  L(-1) and 19.2 ± 3.2 Hz, respectively. Within-session variability represented by coefficient of variation was 5.34 ± 3.18% for R and 13.80 ± 8.57% for C. Greater between-session variability was observed for the individual infants; however, the only statistically significant change over time was a 13% increase in R from day 1 to day 2. Parameter interdependence was significant (r(2)  = 0.63) between R and I reflecting the large contribution of the upper airways to the total Zrs.

CONCLUSIONS

Noninvasive measurement of Zrs can be made in neonates during natural sleep with a high success rate, even in the first hours of life.

Dexmedetomidine for infant pulmonary function testing

For the last thirty years, oral chloral hydrate has been used for sedation of infants for lung function testing. Recently, however, availability of chloral hydrate became severely limited in the United States after two manufacturers discontinued manufacturing in 2012. Due to these limitations and the recent and ongoing shortage of chloral hydrate, other medications have been proposed for lung function testing, including midazolam and propofol. Herein, we describe our limited experience using intravenous dexmedetomedine (DMED), a medication thus far described as having minimal effect on pulmonary function or respiratory drive.

Exercise capacity in adolescent and adult patients with post infectious bronchiolitis obliterans

BACKGROUND

Post-infectious bronchiolitis obliterans (PBO) is a chronic lung disease characterized by the persistence of continuous obstructive respiratory symptoms following an acute and severe respiratory infection in children under 3 years old. The purpose of the present study was to investigate if adolescents and adults with diagnosis of PBO have reduced aerobic capacity and identify factors related with exercise performance.

METHODS

A convenience sample of 16 patients (10-23 years) that have consulted with established diagnosis of PBO in a tertiary care clinic were studied. Fourteen healthy matched subjects were selected from the community to serve as controls. They performed resting lung function tests and cycle incremental cardiopulmonary exercise tests.

RESULTS

Peak aerobic capacity (peak V˙O(2)) was significantly lower in patients compared to controls (84 ± 15 vs. 101 ± 17% pred; P < 0.01). Peak V˙O(2) was correlated with rest inspiratory capacity (IC) (r = 0.60; P = 0.02) and marginally with forced expiratory volume in the first second (FEV(1)) (r = 0.45; P = 0.09). Additionally, FEV(1) was correlated with IC (r = 0.83; P < 0.01) and residual volume/total lung capacity (r = -0.91, P < 0.01).

CONCLUSIONS

Adolescent and adult patients with PBO had reduced peak V˙O(2) compared to healthy controls. Peak V˙O(2) was correlated with parameters of airflow limitation and rest hyperinflation. The greater the air flow limitation (lower FEV(1)) the greater the hyperinflation, air trapping, and aerobic capacity reduction.