Quality control for spirometry in preschool children with and without lung disease

Assessment of bronchodilator response in preschoolers: A systematic review

BACKGROUND

Several techniques can be used to assess bronchodilator response (BDR) in preschool-aged children, including spirometry, respiratory oscillometry, the interrupter technique, and specific airway resistance. However, there has not been a systematic comparison of BDR thresholds across studies yet.

METHODS

A systematic review was performed on all studies up to May 2023 measuring a bronchodilator effect in children 2-6 years old using one of these techniques (PROSPERO CRD42021264659). Studies were identified using MEDLINE, Cochrane, EMBASE, CINAHL via EBSCO, Web of Science databases, and reference lists of relevant manuscripts.

RESULTS

Of 1224 screened studies, 43 were included. Over 85% were from predominantly European ancestry populations, and only 22 studies (51.2%) calculated a BDR cutoff based on a healthy control group. Five studies included triplicate testing with a placebo to account for the within-subject intrasession repeatability. A relative BDR was most consistently reported by the included studies (95%) but varied widely across all techniques. Various statistical methods were used to define a BDR, with six studies using receiver operating characteristic analyses to measure the discriminative power to distinguish healthy from wheezy and asthmatic children.

CONCLUSION

A BDR in 2- to 6-year-olds cannot be universally defined based on the reviewed literature due to inconsistent methodology and cutoff calculations. Further studies incorporating robust methods using either distribution-based or clinical anchor-based approaches to define BDR are required.

Detection of Bronchiolitis Obliterans Syndrome Using Nitrogen Multiple Breath Washout in Children Posthemopoietic Stem Cell Transplant

Bronchiolitis obliterans syndrome (BOS) is a severe complication following hemopoietic stem cell transplantation (HSCT) and is often undetected until there is significant deterioration in pulmonary function. Lung clearance index (LCI2.5) derived from the nitrogen multiple breath washout (N2MBW) test may be more feasible and sensitive than spirometry, which is currently used for surveillance and detection of BOS. We aimed to examine the feasibility of performing surveillance N2MBW in children post-HSCT, and in an exploratory analysis, determine if LCI2.5 led to earlier detection of BOS when compared to spirometric indices. Participants aged 5 to 17 years were recruited prior to receiving HSCT into a prospective, single-center, feasibility study at the Royal Children's Hospital, Melbourne. N2MBW and spirometry were performed within the month prior to transplant and repeated at 3, 6, 9, and 12 months post-transplant. Data were also collected on the presence of graft-versus-host (GVHD) disease in any organ, including the lungs. Twenty-one (12 male) children with a mean age of 13.4 (range 9.2 to 17.1) years at recruitment participated in this study. Prior to HSCT, all participants had normal LCI2.5, while 16 (76%) demonstrated normal forced expiratory volume in 1 second (FEV1). Ninety-nine percent of N2MBW tests were technically acceptable, compared with 66% of spirometry tests. Three participants developed BOS, while 2 participants died of other respiratory complications. At 6 and 12 months post-transplant, the BOS group had increases in LCI2.5 ranging from 3 to 5 units and mean reductions in FEV1 % predicted of 40% to 53% relative to pre HSCT values, respectively. In those who developed BOS, post-HSCT LCI2.5 values were significantly worse when compared with the no BOS group (P < .001). Relative changes in LCI2.5 and FEV1 were both predictive of BOS at 6 months post HSCT. This study demonstrates that N2MBW is a more feasible test compared with spirometry in children post HSCT. However, in an exploratory analysis, LCI2.5 did not lead to earlier detection of BOS, when compared to spirometry.

Changes in urinary glutathione sulfonamide (GSA) levels between admission and discharge of patients with cystic fibrosis

There is an urgent need to develop sensitive, non-invasive biomarkers that can track airway inflammatory activity for patients with cystic fibrosis (CF). Urinary glutathione sulfonamide (GSA) levels correlate well with GSA levels in BAL samples and other markers of neutrophilic inflammation, suggesting that this biomarker may be suitable for tracking disease activity in this population. We recruited 102 children (median 11.5 years-old) and 64 adults (median 32.5 years-old) who were admitted to hospital for management of an acute pulmonary exacerbation and/or eradication of infectious agents such as Pseudomonas aeruginosa or Staphylococcus aureus. Our aim was to explore how urinary GSA levels changed across admission timepoints. Urine samples were collected at admission and discharge, and GSA measured by liquid chromatography with mass spectrometry. Paired admission-discharge results were compared using Wilcoxon signed-rank test. Paired admission-discharge samples were available for 53 children and 60 adults. A statistically significant difference was observed between admission-discharge for children and adults. Spearman's correlation analysis identified a correlation between urinary GSA levels and sex and S. aureus infection for children only. Our preliminary findings suggest that urinary GSA is responsive to the resolution of an acute pulmonary exacerbation and therefore warrants further studies in this population.

Multiple breath washout and oscillometry after allogenic HSCT: a scoping review

Pulmonary chronic graft-versus-host disease (cGVHD) is a substantial cause of pulmonary morbidity and mortality post-haematopoietic stem cell transplantation (HSCT). Current spirometry-based monitoring strategies have significant limitations. Understanding the utility of novel peripheral airway function tests - multiple breath washout (MBW) and oscillometry - is critical in efforts to improve detection, facilitate earlier intervention and improve outcomes. In this scoping review, we identified 17 studies investigating MBW or oscillometry, or both, after allogenic HSCT. Despite small study numbers limiting the ability to draw firm conclusions, several themes were evident. Detectable peripheral airway abnormality in MBW occurred in a substantial proportion prior to HSCT. MBW indices post-HSCT were more frequently abnormal than spirometry when reporting group data and among those with extrapulmonary cGVHD and pulmonary cGVHD. Changes in MBW indices over time may be more indicative of pulmonary complications than absolute values at any given time point. Oscillometry indices were often normal at baseline, but more frequently abnormal in those who developed pulmonary cGVHD. Pooling currently available individual participant data across these studies may improve our ability to formally compare their respective sensitivity and specificity at specific time points and assess the trajectory of MBW and oscillometry indices over time.

Lung Function Tests in Infants and Children

Lung function testing is an essential modality of investigation in children as it provides objective evidence of lung disease/health. With advances in technology, various tests are available that can aid in the diagnosis of lung disease, assess the progression and response to therapy and document the lung development and evolving lung diseases in infants. This narrative review discusses lung function tests in infants and children. Currently, lung function tests can be performed in every age group, from neonates to the elderly. Spirometry and peak expiratory flow rate (PEFR) are the most employed tests in children more than six years of age. Spirometry helps diagnose and monitoring of both obstructive and restrictive diseases. There is a need for expertise to perform and interpret spirometry correctly. The forced oscillation technique (FOT) or impulse oscillometry (IOS) is done with tidal volume breathing and is feasible even in preschool children. Their utility is mainly restricted to asthma in children at present. Lung function tests can be performed in neonates, infants and children using infant pulmonary function test (PFT) equipment, although their availability is limited. Diffusion capacity for carbon monoxide (DLCO) is a valuable tool in restrictive lung diseases. Lung volumes can be assessed by body plethysmography and multiple washout technique. The latter can also assess lung clearance index. It is essential to perform and interpret the lung function test results correctly and correlate them with the clinical condition for optimum treatment and outcome.

Oscillometry to support clinical assessment in asthmatic preschoolers: Real-life impact

In preschoolers, asthma control is assessed clinically using history and physical examination. In certain centres, oscillometry is used to support clinical assessment; yet its clinical utility for asthma management remains to be quantified. The objectives were to determine if oscillometry, as adjunct to clinical assessment, influences asthma assessment, management and control, compared to clinical assessment alone in preschoolers. We conducted a cross-sectional study in children aged 3-5 years with a confirmed asthma diagnosis. Oscillometry-tested preschoolers were matched by propensity score to untested children. The co-primary outcomes, the likelihood of a persistent asthma phenotype and a maintenance therapy prescription at the index visit, were examined by multivariable logistic regression. Asthma control over the next year was examined by cumulative logistic regression in the nested retrospective cohort with available drug claim data. The cohort comprised 726 (249 oscillometry-tested; 477 untested) children with 57.4% male (median age: 4.6 years). Propensity score matching resulted in comparable groups. Compared to controls, oscillometry-tested children were more frequently labelled with a persistent phenotype (67% vs. 50%; adjusted OR [95% CI]: 2.34 [1.66-3.34]) with no significant difference in maintenance therapy prescription (65% vs. 58%; 1.37 [0.98-1.92]); but experienced a lower likelihood of poor control over the next year (adjusted OR [95% CI]: 0.24 [0.08-0.74]). The association between the addition of oscillometry to clinical assessment with more persistent phenotype labelling and better asthma control supports its clinical utility; no significant impact on maintenance therapy prescription was observed at the index visit.

Assessing the effect of BTEX on blood and spirometry parameters staff in a petroleum refinery

This study aimed to investigate the impact of BTEX compound on blood and spirometry parameters of staff in the Abadan petroleum refinery (Iran). In 80 staff was examined in terms of BTEX exposure (40 exposed and 40 non-exposed). In this study, the air sampling was carried out according to the NIOSH 1,501 method and an automated hematology analyzer was used to analyze all blood samples to evaluate blood parameters and using a Micro Direct automated computerized spirometer. Spss20 software was used to interpret the performance. According to the obtained results, total BTEX concentrations with the recommended standard level showed that, toluene, ethylbenzene, and xylenes, concentrations in Abadan Oil Refining Company Workers' breathing zone were lower than the TLV-TWA recommended by ACGIH. However, the average concentration of benzene was higher than the allowable limit. Therefore, in this study the effect of benzene on the blood and respiratory parameters of the workers was evaluated, the comparison of the blood and respiratory parameters between the groups of exposed and unexposed workers did not reveal any statistical difference between the groups (p > 0.001). The results showed no statistically significant connection between mean blood and spirometry parameters and benzene exposure. Also, based on results the effect of benzene problems needs to be prevented in employees with adequate engineering and management controls and periodic inspection.

Influence of Age on Effort Required to Complete Spirometry in Children and Adolescents

Although effort required to complete spirometry is known to differ by age, no studies have addressed this issue. The present study aimed to identify the difference in the effort required to complete spirometry by age in children and adolescents. Data from 707 children (mean age, 10.2 years; range, 4-25 years) from 6 medical centers were analyzed. In addition to demographics, we obtained information on the time required for as well as the number of demonstrations and spirometry demonstrations and trials from the patients' electronic medical records. A total of 398 (56.3%) male participants were included, and 300 (42.4%) participants had no prior experience receiving spirometry. The mean time required for spirometry demonstration was 2.7 minutes (standard deviation [SD], 2.1 minutes), whereas that for spirometry trial was 5.9 minutes (SD, 5.1 minutes). The total mean time required for spirometry was 8.6 minutes (SD, 6.5 minutes). Significant negative associations were observed between age and effort required to complete spirometry with respect to the time and number of demonstrations and trials. The results of the present study suggest that age may affect the degree of effort required to complete spirometry, with a pattern of increasing effort with decreasing age. This finding provides important evidence for the establishment of health care policies especially regarding lung diseases that can benefit from spirometry.

Does the routine use of spirometry improve clinical outcomes in children?-A systematic review

Spirometry provides a quantitative measure of lung function and its use is recommended as an adjunct to enhance pediatric respiratory healthcare in many clinical practice guidelines. However, there is limited evidence confirming the benefits (or otherwise) of using spirometry from either clinician or patient perspectives. This systematic review aimed to determine the impact of spirometry on change in clinical decision making and patient-reported outcome measures. We searched PubMed, Embase, Cochrane Central Register of Controlled Trials, www.clinicaltrials.gov, and World Health Organization International Clinical Trials Registry Platform, from inception to July 2021. We included randomized controlled trials (RCTs) comparing the use versus non-use of spirometry during standard clinical review in children aged <18 years with respiratory problems in clinics. We used Cochrane methodology. The search identified 3475 articles; 8 full-text articles were reviewed but only 1 study fulfilled the inclusion criteria. The single study involved two cluster RCTs of spirometry for children with asthma in general practice. The included study did not find any significant intergroup difference at the 12-month follow-up for asthma-related quality-of-life and clinical endpoints. However, the findings were limited by methodological weaknesses and high risks of bias. With a paucity of data, the clinical benefits of spirometry remain unclear. Thus, there is a clear need for RCTs that provide high-quality evidence to support the routine use of spirometry in children with suspected or known lung disease. Pending the availability of better evidence, we recommend that clinicians adhere to the current clinical practice recommendations.

Going the Extra Mile: Why Clinical Research in Cystic Fibrosis Must Include Children

This is an exciting time for research and novel drug development in cystic fibrosis. However, rarely has the adage, “Children are not just little adults” been more relevant. This article is divided into two main sections. In the first, we explore why it is important to involve children in research. We discuss the potential benefits of understanding a disease and its treatment in children, and we highlight that children have the same legal and ethical right to evidence-based therapy as adults. Additionally, we discuss why extrapolation from adults may be inappropriate, for example, medication pharmacokinetics may be different in children, and there may be unpredictable adverse effects. In the second part, we discuss how to involve children and their families in research. We outline the importance and the complexities of selecting appropriate outcome measures, and we discuss the role co-design may have in improving the involvement of children. We highlight the importance of appropriate staffing and resourcing, and we outline some of the common challenges and possible solutions, including practical tips on obtaining consent/assent in children and adolescents. We conclude that it is unethical to simply rely on extrapolation from adult studies because research in young children is challenging and that research should be seen as a normal part of the paediatric therapeutic journey.

Lung clearance index predicts persistence of preschool wheeze

BACKGROUND

The lung clearance index (LCI) is a measure of pulmonary function. Variable feasibility (50->80%) in preschool children has been reported. There are limited studies exploring its relationship to respiratory symptoms and how it predicts persistent wheeze. We aimed to assess the association with respiratory symptoms in preschool-aged children with LCI and determine its utility in predicting persistent wheeze.

METHODS

LCI was measured in a subcohort of the CHILD Cohort Study at age 3 years using SF₆  multiple breath washout test mass spectrometry. Respiratory symptom phenotypes at age 3 were derived from children's respiratory symptoms reported by their parents. Responses were used to categorize children into 4 symptom groups: recurrent wheeze (3RW), recurrent cough (3RC), infrequent symptoms (IS), and no current symptoms (NCS). At age 5 years, these children were seen by a specialist clinician and assessed for persistent wheeze (PW).

RESULTS

At age 3 years, 69% (234/340) had feasible LCI. Excluding two children with missing data, 232 participants were categorized as follows: 33 (14%) 3RW; 28 (12%) 3RC; 17 (7%) IS; and 154 (66%) NCS. LCI z-score at age 3 years was highest in children with 3RW compared to 3RC (mean (SD): 1.14 (1.56) vs. 0.09 (0.95), p < .01), IS (mean (SD): -0.14 (0.59), p < .01), and NCS (mean (SD): -0.08 (1.06), p < .01). LCI z-score at age 3 was predictive of persistent wheeze at age 5 (PW) (AUROC: 0.87).

CONCLUSIONS

LCI at age 3 was strongly associated with recurrent wheeze at age 3, and predictive of its persistence to age 5.

Impact of using spirometry on clinical decision making and quality of life in children: protocol for a single centre randomised controlled trial

INTRODUCTION

Although spirometry has been available for decades, it is underused in paediatric practice, other than in specialist clinics. This is unsurprising as there is limited evidence on the benefit of routine spirometry in improving clinical decision making and/or outcomes for children. We hypothesised that using spirometry for children being evaluated for respiratory diseases impacts on clinical decision making and/or improves patient-related outcome measures (PROMs) and/or quality of life (QoL), compared with not using spirometry.

METHODS AND ANALYSIS

We are undertaking a randomised controlled trial (commenced in March 2020) that will include 106 children (aged 4-18 years) recruited from respiratory clinics at Queensland Children's Hospital, Australia. Inclusion criteria are able to perform reliable spirometry and a parent/guardian who can complete questionnaire(s). Children (1:1 allocation) are randomised to clinical medical review with spirometry (intervention group) or without spirometry (control group) within strata of consultation status (new/review), and cough condition (present/absent). The primary outcome is change in clinical decision making. The secondary outcomes are change in PROM scores, opinions regarding spirometry and degree of diagnosis certainty. Intergroup differences of these outcomes will be determined by χ2 test or unpaired t-test (or Mann-Whitney if not normally distributed). Change in outcomes within the control group after review of spirometry will also be assessed by McNemar's test or paired t-test/Wilcoxon signed-rank test.

ETHICS AND DISSEMINATION

The Human Research Ethics Committee of the Queensland Children's Hospital approved the study. The trial results will be disseminated through conference presentations, teaching avenues and publications.

TRIAL REGISTRATION NUMBER

ACTRN12619001686190; Pre-results.

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.

Epidemiology of wheeze among preschool children: a population-based cross-sectional study from rural Sri Lanka

OBJECTIVES

To assess the prevalence of wheeze and factors associated with its severity among 3-6 years old children.

METHODOLOGY

DESIGN: A population-based, cross-sectional study using the WHO 30 cluster methodology with probability proportionate to size sampling.

SETTING

36 preschools registered at the divisional secretariat offices of Anuradhapura district, Sri Lanka.

PARTICIPANTS

We recruited 1060 preschool children from 36 preschools aged 3-6 years.

MAIN OUTCOME MEASUREMENTS

We used the International Study of Asthma and Allergy in Childhood questionnaire to assess the prevalence, symptomatology and associated factors of wheeze.

RESULTS

The study sample consisted of 548 (51.70%) male and 512 (48.30%) female children with a mean age of 4.41 (±0.66) years. At least one wheezing episode ever was reported in 323 (30.47%; 95% CI 27.71% to 33.34%) children and 247 (23.30%; 95% CI 20.79% to 25.97%) children had a wheezing attack in the preceding year. Severe episodes of wheezing were reported in 76 (7.17%; 95% CI 5.69% to 8.89%) participants. However, only 27 (35.53%; 95% CI 24.88% to 47.34%) children with severe wheezing had been diagnosed as asthmatics by a clinician. The identified independent risk factors for severe wheeze were allergic rhinitis (OR 6.90; 95% CI 3.84 to 12.40), domestic dog(s) (OR 2.34; 95% CI 1.01 to 5.40), frequent consumption of skipjack tuna (OR 1.94; 95% CI 1.11 to 3.39) and passive smoking (OR 1.70; 95% CI 0.93 to 3.11) while living in a house with a cement floor is a protective factor (OR 0.41; 95% CI 0.21 to 0.80).

CONCLUSION

Wheezing commonly affects one-fourth of preschool children in rural Sri Lanka. Severe wheezing is often not diagnosed as asthma despite frequent symptoms, probably due to hesitancy in labelling preschool children as asthmatics. Allergic rhinitis, domestic dogs, frequent consumption of Skipjack tuna fish and exposure to passive smoking were independent risk factors for severe wheeze.

Which factors can influence the number of forced expiratory manoeuvres on spirometry in schoolchildren?

INTRODUCTION

Spirometry is of great value for understanding respiratory function and management of lung diseases. Adaptations in the exam were made to meet paediatric population since the forced expiratory manoeuvres (FEM) present in the exam require effort and cooperation; therefore, its use should be reconsidered.

OBJECTIVE

To analyse factors that may influence the number of FEM required for successful spirometry in schoolchildren.

METHOD

Healthy children aged between 6 and 12 years were tested. FEM were conducted according to the American Thoracic Society/European Respiratory Society guideline. The children were divided into three groups according to the number of attempts: G3M if child completed the test in three FEM; G4M if child completed in four attempts FEM; and G5/8M if child completed the test in five to eight FEM. Factors that potentially influenced the number of FEM included: age; impulse oscillometry parameters; slow vital capacity; respiratory muscle strength; orofacial motor function, school performance, physical activity level and quality of life. The Kolmogorov-Smirnov test was performed, followed by the Chi-Square, repeated measures ANOVA and Kruskal-Wallis tests; thereafter, a multinomial logistic regression was applied.

RESULTS

One hundred and forty-nine schoolchildren (80 girls) with mean age of 9.13 years (±1.98) were included, age was related to the required number of FEM (F = 3.38(2), P = .03) and children with poor school performance had a 2.84-fold greater chance of completing the exam in more than five attempts.

CONCLUSION

Age and school performance influenced the number of FEM required for a successful spirometry in schoolchildren.

Exploring pulmonary function and physical function in childhood cancer: A systematic review

BACKGROUND

Children with cancer experience pulmonary and physical function side effects from the cancer itself and the medical interventions. This systematic review examines the known relationship between pulmonary function and physical function in childhood cancer and identifies gaps in the literature.

METHODS

A search of Ovid Medline, CINAHL (EbscoHost) and Embase to identify literature from 2009 to March 2020.

RESULTS

Fifty-seven studies met inclusion criteria. Thirty-seven studies reported impaired pulmonary function. Incidence of pulmonary dysfunction ranged from 45.5 % to 84.1 %. Eighteen studies reported impaired physical function. Three studies investigated the relationship between pulmonary function and physical function. No studies explored inspiratory muscle strength.

CONCLUSION

Pulmonary function and physical function are related and frequently impaired in children during and after cancer treatment. A literature gap was found in diaphragm function and its relationship with physical function. Future studies should focus on interventions that target the pulmonary mechanisms impacting physical function.

Assessment of bronchial obstruction and its reversibility by shape indexes of the flow-volume loop in asthmatic children

Asthma assessment by spirometry is challenging in children as forced expiratory volume in 1 s (FEV1) is frequently normal at baseline. Bronchodilator (BD) reversibility testing may reinforce asthma diagnosis but FEV1 sensitivity in children is controversial. Ventilation inhomogeneity, an early sign of airway obstruction, is described by the upward concavity of the descending limb of the forced expiratory flow-volume loop (FVL), not detected by FEV1. The aim was to test the sensitivity and specificity of FVL shape indexes as β-angle and forced expiratory flow at 50% of the forced vital capacity (FEF50)/peak expiratory flow (PEF) ratio, to identify asthmatics from healthy children in comparison to "usual" spirometric parameters. Seventy-two school-aged asthmatic children and 29 controls were prospectively included. Children performed forced spirometry at baseline and after BD inhalation. Parameters were expressed at baseline as z-scores and BD reversibility as percentage of change reported to baseline value (Δ%). Receiver operating characteristic curves were generated and sensitivity and specificity at respective thresholds reported. Asthmatics presented significantly smaller zβ-angle, zFEF50/PEF and zFEV1 (p ≤ .04) and higher BD reversibility, significant for Δ%FEF50/PEF (p = .02) with no difference for Δ%FEV1. zβ-angle and zFEF50/PEF exhibited better sensitivity (0.58, respectively 0.60) than zFEV1 (0.50), and similar specificity (0.72). Δ%β-angle showed higher sensitivity compared to Δ%FEV1 (0.72 vs. 0.42), but low specificity (0.52 vs. 0.86). Quantitative and qualitative assessment of FVL by adding shape indexes to spirometry interpretation may improve the ability to detect an airway obstruction, FEV1 reflecting more proximal while shape indexes peripheral bronchial obstruction.

The Need for Testing-The Exercise Challenge Test to Disentangle Causes of Childhood Exertional Dyspnea

Exertional dyspnea is a common symptom in childhood which can induce avoidance of physical activity, aggravating the original symptom. Common causes of exertional dyspnea are exercise induced bronchoconstriction (EIB), dysfunctional breathing, physical deconditioning and the sensation of dyspnea when reaching the physiological limit. These causes frequently coexist, trigger one another and have overlapping symptoms, which can impede diagnoses and treatment. In the majority of children with exertional dyspnea, EIB is not the cause of symptoms, and in asthmatic children it is often not the only cause. An exercise challenge test (ECT) is a highly specific tool to diagnose EIB and asthma in children. Sensitivity can be increased by simulating real-life environmental circumstances where symptoms occur, such as environmental factors and exercise modality. An ECT reflects daily life symptoms and impairment, and can in an enjoyable way disentangle common causes of exertional dyspnea.

Prenatal exposure to VOCs and NOx and lung function in preschoolers

BACKGROUND

Several studies have shown that exposure to air pollutants affects lung growth and development and can result in poor respiratory health in early life.

METHODS

We included a subsample of 772 Mexican preschoolers whose mothers participated in a Prenatal Omega-3 fatty acid Supplements, GRowth, And Development birth cohort study with the aim to evaluate the impact of prenatal exposure to volatile organic compounds and nitrogen oxides on lung function measured by oscillation tests. The preschoolers were followed until 5 years of age. Anthropometric measurements and forced oscillation tests were performed at 36, 48, and 60 months of age. Information on sociodemographic and health characteristics was obtained during follow up. Prenatal exposure to volatile organic compounds and nitrogen oxides was evaluated using a land use regression models and the association between them was tested using a lineal regression and longitudinal linear mixed effect models adjusting for potential confounders.

RESULTS

Overall, the mean (standard deviation) of the measurements of respiratory system resistance and respiratory system reactance at 6, 8, and 10 Hz during the follow-up period was 11.3 (2.4), 11.1 (2.4), 10.3 (2.2) and -5.2 (1.6), -4.8 (1.7), and -4.6 hPa s L^-1 (1.6), respectively. We found a significantly positive association between respiratory resistance (β_Rrs6  = 0.011; 95%CI: 0.001, 0.023) (P < .05) and prenatal exposure to nitrogen dioxide and a marginally negatively association between respiratory reactance (β_Xrs6  = -11.40 95%CI: -25.26, 1.17 and β_Xrs8  = -11.91 95%CI: -26.51, 1.43) (P = .07) and prenatal exposure to xylene.

CONCLUSION

Prenatal exposure to air pollutants was significantly associated with the alteration of lung function measured by oscillation tests in these preschool children.

Multiple Breath Washout for Diagnosing Asthma and Persistent Wheeze in Young Children

Rationale: There is an unmet need for sensitive lung function tests for young children to aid in the diagnosis of asthma and wheezy disorders. We hypothesized that multiple breath washout (MBW) could be a valuable tool for such a purpose. Objectives: To compare the ability of MBW lung clearance index with traditional lung function measurements to discriminate between preschool children with well-controlled asthma/persistent wheeze and healthy children. Methods: We investigated 646 children from the COPSAC₂₀₁₀ (Copenhagen Prospective Studies on Asthma in Childhood 2010) mother-child cohort, who completed MBW testing with nitrogen, spirometry, and plethysmography before age 6 years. Asthma/persistent wheeze was prospectively diagnosed according to a validated symptom-based algorithm at the COPSAC clinic. Student's t tests and receiver operating characteristic curves were applied to analyze the discriminative ability of the lung function indices. Results: A total of 144 (22.3%) children were diagnosed with asthma/persistent wheeze during their first 6 years of life. Lung clearance index from MBW was not significantly different in children with versus those without asthma/persistent wheeze (mean standard deviation [SD] = 6.96 [1.14] vs. 6.95 [0.93], mean difference [95% confidence interval] = 0.02 [-0.18 to 0.22], P = 0.86, area under the curve [AUC] = 0.48), whereas significant differences were observed for specific airway resistance from plethysmography (1.21 kPa/s [0.31] vs. 1.14 kPa/s [0.25]; +0.07 kPa/s [0.02-0.13]; P < 0.01; AUC = 0.56) and spirometry forced expiratory volume in 1 second (FEV₁) % predicted (99.4% [12.0] vs. 102.6% [12.5]; -3.2% [-5.6 to -0.9]; P < 0.01; AUC = 0.56) and forced expiratory flow at 25-75% (1.55 L/s [0.44] vs. 1.68 L/s [0.46]; -0.14 L/s [-0.22 to -0.05]; P < 0.01; AUC = 0.58). FEV₁ (L/s) and FEV₁/forced vital capacity ratio were not significantly different (P > 0.4). Conclusions: MBW, spirometry, and plethysmography are not sensitive tools for diagnosing mild asthmatic disease in young children.

Methacholine bronchial provocation test for assessment of bronchial hyperresponsiveness in preschool children

Background

Bronchial hyperresponsiveness (BHR) has not been extensively performed in preschool children, possibly because of the difficulty in cooperating with the tests. We sought to determine the usefulness and safety of methacholine bronchial provocation test (MCh-BPT) for BHR assessment in preschool children.

Methods

We recruited 252 preschool children (190 healthy and 62 with wheezing) who underwent MCh-BPT at baseline. MCh-BPT was re-scheduled in case initial attempts failed. Forced expiratory volumes in 0.5 (FEV_0.5), 0.75 (FEV_0.75) and one second (FEV₁) were measured. We recorded the provocative dose causing 15% (PD₁₅) or 20% reduction (PD₂₀) in FEV_0.5, FEV_0.75 and FEV₁, thus allowing for comparison of the diagnostic value of PD₁₅ and PD₂₀.

Results

A total of 209 children [156 (82.1%) healthy, 53 (85.5%) with wheezing] successfully completed MCh-BPT. Compared with healthy children, a significantly greater proportion of children with wheezing had measurable PD₁₅FEV_0.5, PD₁₅FEV_0.75 and PD₁₅FEV₁ (P<0.01), and PD₂₀FEV_0.5, PD₂₀FEV_0.75 and PD₂₀FEV₁ (P<0.05). The sensitivity was 92.5% and 94.3% for PD₂₀FEV₁, and PD₁₅FEV₁ and the specificity was 93.6% and 93.6% respectively, for discriminating asthmatic from healthy children.

Conclusions

Most preschool children successfully and safely complete MCh-BPT, with higher success rate in larger age group. PD₂₀FEV_0.5 and PD₂₀FEV_0.75 can be surrogates of PD₂₀FEV₁ among children whose expiration lasted for less than one second. PD₁₅ has a good diagnostic value as PD₂₀ for diagnosing of BHR in preschool children, which are also more suitable for children five years old or elder.

The Practical Significance of Measurement Error in Pulmonary Function Testing Conducted in Research Settings

Conventional spirometry produces measurement error by using repeatability criteria (RC) to discard acceptable data and terminating tests early when RC are met. These practices also implicitly assume that there is no variation across maneuvers within each test. This has implications for air pollution regulations that rely on pulmonary function tests to determine adverse effects or set standards. We perform a Monte Carlo simulation of 20,902 tests of forced expiratory volume in 1 second (FEV₁ ), each with eight maneuvers, for an individual with empirically obtained, plausibly normal pulmonary function. Default coefficients of variation for inter- and intratest variability (3% and 6%, respectively) are employed. Measurement error is defined as the difference between results from the conventional protocol and an unconstrained, eight-maneuver alternative. In the default model, average measurement error is shown to be ∼5%. The minimum difference necessary for statistical significance at p < 0.05 for a before/after comparison is shown to be 16%. Meanwhile, the U.S. Environmental Protection Agency has deemed single-digit percentage decrements in FEV₁ sufficient to justify more stringent national ambient air quality standards. Sensitivity analysis reveals that results are insensitive to intertest variability but highly sensitive to intratest variability. Halving the latter to 3% reduces measurement error by 55%. Increasing it to 9% or 12% increases measurement error by 65% or 125%, respectively. Within-day FEV₁ differences ≤5% among normal subjects are believed to be clinically insignificant. Therefore, many differences reported as statistically significant are likely to be artifactual. Reliable data are needed to estimate intratest variability for the general population, subpopulations of interest, and research samples. Sensitive subpopulations (e.g., chronic obstructive pulmonary disease or COPD patients, asthmatics, children) are likely to have higher intratest variability, making it more difficult to derive valid statistical inferences about differences observed after treatment or exposure.

Linking COPD epidemiology with pediatric asthma care: Implications for the patient and the physician

What are the implications of a lower than expected forced expiratory volume in one second (FEV1) in childhood on respiratory health later in adulthood? Lung function is known to track with age, and there is evidence from recent epidemiologic studies that impaired lung function early in life is associated with later chronic airflow limitation, or even chronic obstructive pulmonary disease, COPD. This risk seems particularly strong in subjects with persistent and severe forms of childhood asthma. Can we translate findings from longitudinal cohort studies to individual risk predictions and preventive guidelines in our pediatric care? In this review, we discuss the clinical implementations of recent epidemiological respiratory studies and the importance of preserved lung health across the life course. Also, we evaluate available clinical tools, primarily lung function measures, and profiles of risk factors, including biomarkers, that may help identifying children at risk of chronic airway disease in adulthood. We conclude that translating population level results to the individual patient in the pediatric care setting is not straight forward, and that there is a need for studies specifically designed to evaluate performance of prediction of risk profiles for long-term sequelae of childhood asthma and lung function impairment.

Why Is It Difficult to Diagnose My Child's Asthma? A Patient Physician Perspective of Asthma Management

This article is co-authored by the mother of a patient living with asthma, and two consultants in respiratory medicine from Birmingham Women’s and Children’s Hospital. The commentary article describes the mother’s experience of the diagnosis and treatment process of her son’s asthma. The consultants then discuss paediatric asthma diagnosis and management in the context of the patient’s experiences.

[Lung clearance index in cystic fibrosis]

INTRODUCTION

Small airways' involvement in cystic fibrosis (CF) pulmonary disease is a very early event, which can progress sub-clinically and insidiously since it is poorly reflected by commonly used lung function tests.

STATE OF ART

Sensitive and discriminative tools are available to investigate small airways function. However their complexity and/or invasiveness has confined their use to research purposes and to some specialized research teams. By contrast, the multiple breath washout (MBW) test is more affordable and non-invasive. Lung clearance index (LCI), which is the most used derived parameter, is reproducible and much more sensitive than spirometry in detecting small airways disease. However, MBW is operator dependent.

PERSPECTIVES

The recent commercialization of devices assessing LCI launches MBW as a potential tool in routine clinical care, although its use currently remains mostly dedicated to research purposes. However, important differences in LCI between various equipment settings raise a number of theoretical questions. Specific algorithms should be refined and more transparent. Standardization of MBW is still an ongoing process. Whether other MBW derived indices can prove superior over LCI deserves further study.

CONCLUSIONS

In CF, LCI is now a well-established outcome in research settings to detect early lung function abnormalities and new treatment effects, especially in patients with mild lung disease. In these patients, LCI seems an attractive tool for clinicians too. Yet, further investigation is needed to define clinically significant changes in LCI and to which extent this index can be useful in guiding clinical decisions remains to be studied.

Pathophysiological Mechanisms of Asthma

The recent Lancet commission has highlighted that "asthma" should be used to describe a clinical syndrome of wheeze, breathlessness, chest tightness, and sometimes cough. The next step is to deconstruct the airway into components of fixed and variable airflow obstruction, inflammation, infection and altered cough reflex, setting the airway disease in the context of extra-pulmonary co-morbidities and social and environmental factors. The emphasis is always on delineating treatable traits, including variable airflow obstruction caused by airway smooth muscle constriction (treated with short- and long-acting β-2 agonists), eosinophilic airway inflammation (treated with inhaled corticosteroids) and chronic bacterial infection (treated with antibiotics with benefit if it is driving the disease). It is also important not to over-treat the untreatable, such as fixed airflow obstruction. These can all be determined using simple, non-invasive tests such as spirometry before and after acute administration of a bronchodilator (reversible airflow obstruction); peripheral blood eosinophil count, induced sputum, exhaled nitric oxide (airway eosinophilia); and sputum or cough swab culture (bacterial infection). Additionally, the pathophysiology of risk domains must be considered: these are risk of an asthma attack, risk of poor airway growth, and in pre-school children, risk of progression to eosinophilic school age asthma. Phenotyping the airway will allow more precise diagnosis and targeted treatment, but it is important to move to endotypes, especially in the era of increasing numbers of biologicals. Advances in -omics technology allow delineation of pathways, which will be particularly important in TH2 low eosinophilic asthma, and also pauci-inflammatory disease. It is very important to appreciate the difficulties of cluster analysis; a patient may have eosinophilic airway disease because of a steroid resistant endotype, because of non-adherence to basic treatment, and a surge in environmental allergen burden. Sophisticated -omics approaches will be reviewed in this manuscript, but currently they are not being used in clinical practice. However, even while they are being evaluated, management of the asthmas can and should be improved by considering the pathophysiologies of the different airway diseases lumped under that umbrella term, using simple, non-invasive tests which are readily available, and treating accordingly.

Human Early Life Exposome (HELIX) study: a European population-based exposome cohort

PURPOSE

Essential to exposome research is the collection of data on many environmental exposures from different domains in the same subjects. The aim of the Human Early Life Exposome (HELIX) study was to measure and describe multiple environmental exposures during early life (pregnancy and childhood) in a prospective cohort and associate these exposures with molecular omics signatures and child health outcomes. Here, we describe recruitment, measurements available and baseline data of the HELIX study populations.

PARTICIPANTS

The HELIX study represents a collaborative project across six established and ongoing longitudinal population-based birth cohort studies in six European countries (France, Greece, Lithuania, Norway, Spain and the UK). HELIX used a multilevel study design with the entire study population totalling 31 472 mother-child pairs, recruited during pregnancy, in the six existing cohorts (first level); a subcohort of 1301 mother-child pairs where biomarkers, omics signatures and child health outcomes were measured at age 6-11 years (second level) and repeat-sampling panel studies with around 150 children and 150 pregnant women aimed at collecting personal exposure data (third level).

FINDINGS TO DATE

Cohort data include urban environment, hazardous substances and lifestyle-related exposures for women during pregnancy and their offspring from birth until 6-11 years. Common, standardised protocols were used to collect biological samples, measure exposure biomarkers and omics signatures and assess child health across the six cohorts. Baseline data of the cohort show substantial variation in health outcomes and determinants between the six countries, for example, in family affluence levels, tobacco smoking, physical activity, dietary habits and prevalence of childhood obesity, asthma, allergies and attention deficit hyperactivity disorder.

FUTURE PLANS

HELIX study results will inform on the early life exposome and its association with molecular omics signatures and child health outcomes. Cohort data are accessible for future research involving researchers external to the project.

Interrupter resistance to measure dose-response to salbutamol in wheezy preschool children

AIM

Using a non-invasive lung function technique (interrupter resistance, Rint), we aimed to determine whether a dose-response to salbutamol could be detected in wheezy preschool children and if so, which dose of salbutamol should be administered to routinely evaluate bronchial reversibility.

METHOD

Wheezy children (3 to <7 years) were enrolled in a prospective multicenter study. Rint was measured at baseline, and after random assignment to a first dose (100 or 200 μg) and a second dose (cumulative dose: 400, 600, or 800 μg) of salbutamol. Data were analyzed using mixed modeling approach with an inhibitory maximal effect (I_max ) model, to account for a sparse sampling design. Simulations were performed to predict the percentage of children with significant Rint reversibility at several doses.

RESULTS

Final results were available in 99 children out of 106 children included. The model adequately fitted the data, showing satisfactory goodness-of-fit plots and a low residual error of 8%. Children with uncontrolled symptoms had lower I_max (ie, showed less reversibility) compared to children with totally/partly controlled symptoms (0.23 vs. 0.31, P < 0.001). Dose to reach 50% of I_max (D₅₀ ) was 51 μg. According to simulations, 88.1% of children with significant reversibility at dose 800 μg would already show significant reversibility at 400 μg.

CONCLUSION

Interrupter resistance was able to measure a dose-response curve to salbutamol in wheezy preschool children, which was similar to that of older patients. Young children require a high dose of salbutamol to correctly assess airway bronchodilator response, especially these with poor symptom control.

Spirometry and Impulse Oscillometry in Preschool Children: Acceptability and Relationship to Maternal Smoking in Pregnancy

BACKGROUND

Comparisons of the technical acceptability of spirometry and impulse oscillometry (IOS) and clinical correlations of the measurements have not been well studied in young children. There are no large studies focused on African American and Hispanic children.

OBJECTIVES

We sought to (1) compare the acceptability of spirometry and IOS in 3- to 5-year-old children and (2) examine the relationship of maternal smoking during pregnancy to later lung function.

METHODS

Spirometry and IOS were attempted at 4 sites from the Urban Environmental and Childhood Asthma Study birth cohort at ages 3, 4, and 5 years (472, 471, and 479 children, respectively). We measured forced expiratory flow in 0.5 s (forced expiratory volume in 0.5 seconds [FEV0.5]) with spirometry and area of reactance (AX), resistance and reactance at 5 Hz (R5 and X5, respectively) using IOS.

RESULTS

Children were more likely to achieve acceptable maneuvers with spirometry than with IOS at age 3 (60% vs 46%, P < .001) and 5 years (89% vs 84%, P = .02). Performance was consistent among the 4 study sites. In children without recurrent wheeze, there were strong trends for higher FEV0.5 and lower R5 and AX over time. Maternal smoking during pregnancy was associated with higher AX at ages 4 and 5 years (P < .01 for both years). There was no significant difference in FEV0.5 between children with and without in utero exposure to smoking.

CONCLUSION

There is a higher rate of acceptable maneuvers with spirometry compared with IOS, but IOS may be a better indicator of peripheral airway function in preschool children.

Lung function tests to monitor respiratory disease in preschool children

Pulmonary function tests are routinely used in the diagnosis and follow-up of respiratory diseases. In preschool children assessment and evaluation of lung function has always been challenging but improved techniques that require only minimal collaboration allowed obtaining reliable and useful results even in this group of patients. In this review we will describe the different techniques used in clinical practice to measure lung function in preschool children.(www.actabiomedica.it)

Impulse oscillometry at preschool age is a strong predictor of lung function by flow-volume spirometry in adolescence

BACKGROUND

The transition from early childhood wheezing to persistent asthma is linked to lung function impairment over time. Little is known how the methods used to study lung function at different ages correlate longitudinally.

METHODS

Sixty-four children with a history of hospitalization for bronchiolitis before 6 months of age were prospectively studied with impulse oscillometry (IOS) at the mean age of 6.3 years and these preschool IOS results were compared with flow-volume spirometry (FVS) measurements at mean age of 11.4 years.

RESULTS

The baseline respiratory system resistance at 5 Hz (Rrs5) showed a modest statistically significant correlation with all baseline FVS parameters except FVC. The post-bronchodilator (post-BD) Rrs5 showed a modest statistically significant correlation with post-BD FEV₁ and FEV₁ /FVC. The bronchodilator-induced decrease in Rrs5 showed a modest statistically significant correlation with the percent increase in FEV₁ . Baseline and post-BD respiratory reactance at 5 Hz (Xrs5) showed a modest statistically significant correlation with baseline and post-BD FVS parameters except post-BD FEV₁ /FVC, respectively, and post-BD Xrs5 showed a strong correlation with post-BD FVC (ρ = 0.61) and post-BD FEV₁ (ρ = 0.59). In adjusted linear regression, preschool Xrs5 remained as a statistically significant independent predictor of FVS parameters in adolescence; the one-unit decrease in the Z-score of preschool post-BD Xrs5 predicted 9.6% lower post-BD FEV₁ , 9.3% lower post-BD FVC, and 9.7% lower post-BD MEF₅₀ when expressed as %-predicted parameters.

CONCLUSION

Persistent post-BD small airway impairment in children with a history of bronchiolitis detected with IOS at preschool age predicted FVS results measured in early adolescence.

Lung Development and Aging

The onset of chronic obstructive pulmonary disease (COPD) can arise either from failure to attain the normal spirometric plateau or from an accelerated decline in lung function. Despite reports from numerous big cohorts, no single adult life factor, including smoking, accounts for this accelerated decline. By contrast, five childhood risk factors (maternal and paternal asthma, maternal smoking, childhood asthma and respiratory infections) are strongly associated with an accelerated rate of lung function decline and COPD. Among adverse effects on lung development are transgenerational (grandmaternal smoking), antenatal (exposure to tobacco and pollution), and early childhood (exposure to tobacco and pollution including pesticides) factors. Antenatal adverse events can operate by causing structural changes in the developing lung, causing low birth weight and prematurity and altered immunological responses. Also important are mode of delivery, early microbiological exposures, and multiple early atopic sensitizations. Early bronchial hyperresponsiveness, before any evidence of airway inflammation, is associated with adverse respiratory outcomes. Overlapping cohort studies established that spirometry tracks from the preschool years to late middle age, and those with COPD in the sixth decade already had the worst spirometry at age 10 years. Alveolar development is now believed to continue throughout somatic growth and is adversely impacted by early tobacco smoke exposure. Genetic factors are also important, with genes important in lung development and early wheezing also being implicated in COPD. The inescapable conclusion is that the roots of COPD are in early life, and COPD is a disease of childhood adverse factors interacting with genetic factors.

SPIROMETRY IN SCHOOLCHILDREN FOR FIELD STUDIES: DOES TESTING ON DIFFERENT DAYS CHANGE THE RESULT OF THE EXAM?

OBJECTIVE

To analyze if there is variation in the results of spirometry performed by healthy schoolchildren on different days.

METHODS

Cross-sectional study with healthy schoolchildren aged 7 to 12 years old, in Florianópolis, Santa Catarina, Southern Brazil. Prepubescent children, non-athletes, born at full term, without cardiorespiratory, rheumatic, musculoskeletal, neurological and visual or hearing deficit were included. The child's health was assessed by a health questionnaire and by the survey International Study of Asthma and Allergies in Childhood. The spirometric test was performed on 3 different days, not exceeding the interval of 15 days between the first and last exams, following the guidelines of the American Thoracic Society. The absolute values and percentages of predicted values of forced vital capacity, forced volume in the first second and peak expiratory flow were analyzed. Statistical analysis was performed using the Shapiro-Wilk normality test followed by one-way analysis of variance or Friedman test and by Bonferroni's post-hoc test for multiple parametric comparisons. Also, the intraclass correlation coefficient was applied to compare results on the same patients on the different tested days.

RESULTS

Twenty-two children were analyzed, with a mean age of 9.3±1.1 years. All the spirometric parameters showed a reduction in absolute value after the first exam, but without significant difference. Regarding reproducibility of spirometry results, the tests presented intraclass correlation coefficient >0.70.

CONCLUSIONS

There was no change in the results of spirometry performed by healthy schoolchildren on three different days.

Respiratory functional and motor control deficits in children with spinal cord injury

Children with spinal cord injury (SCI) are at high risk for developing complications due to respiratory motor control deficits. However, underlying mechanisms of these abnormalities with respect to age, development, and injury characteristics are unclear. To evaluate the effect of SCI and age on respiratory motor control in children with SCI, we compared pulmonary function and respiratory motor control outcome measures in healthy typically developing (TD) children to age-matched children with chronic SCI. We hypothesized that the deficits in respiratory functional performance in children with SCI are due to the abnormal and age-dependent respiratory muscle activation patterns. Fourteen TD (age 7±2 yrs., Mean±SD) and twelve children with SCI (age 6±1 yrs.) were evaluated by assessing Forced Vital Capacity (FVC); Forced Expiratory Volume in 1sec (FEV₁); and respiratory electromyographic activity during maximum inspiratory and maximum expiratory airway pressure measurements (PI_max and PE_max). The results indicate a significant reduction (p<.01) of FVC, FEV₁ and PE_max values in children with SCI compared to TD controls. During PE_max assessment, children with SCI produced significantly decreased (p<.01) activation of respiratory muscles below the neurological level of injury (rectus abdominous and external oblique muscles). In addition, children with SCI had significantly increased (p<.05) compensatory muscle activation above the level of injury (upper trapezius muscle). In the TD group, age, height, and weight significantly (p<.05) contributed towards increase in FVC and FEV₁. In children with SCI, only age was significantly (p<.05) correlated with FVC and FEV₁ values. These findings indicate the degree of SCI-induced respiratory functional and motor control deficits in children are age-dependent.

Raised-Volume Forced Expiratory Flow-Volume Curve in Healthy Taiwanese Infants

The raised-volume rapid thoracoabdominal compression (RVRTC) manoeuvre has been applied to obtain full forced expiratory flow-volume curves in infants. No reference data are available for Asian populations. This study was conducted to establish predictive reference equations for Taiwanese infants. Full-term infants without any chronic disease or major anomaly were enrolled from this cohort study. Full forced expiratory flow-volume curves were acquired using RVRTC manoeuvres through Jaeger's system. Tidal breath analysis, passive respiratory mechanics, and tidal forced expiratory flow-volume curves were performed and collected at the same measurement. Multiple linear analyses were used to model the variables. We performed 117 tests of RVRTC flow-volume curves in 97 infants. The results revealed that all parameters, except for FEV_0.5 /FVC, correlated highly and positively with body length. These parameters correlated significantly with other parameters of passive respiratory mechanics and tidal forced expiratory flow-volume curves. This is the first study to establish equipment-specific reference data of full forced expiration using RVRTC manoeuvres in Asian infants. The results revealed that parameters of RVRTC manoeuvres are moderately related to other parameters of infant lung function. These race-specific reference data can be used to more precisely and efficiently diagnose respiratory diseases in infants of Chinese ethnicity.

Infantile wheeze: rethinking dogma

Wheeze is a common symptom in young children and is usually associated with viral illnesses. It is a major source of morbidity and is responsible for a high consumption of healthcare and economic resources worldwide. A few children have a condition resembling classical asthma. Rarer specific conditions may have a wheezy component and should be considered in the differential diagnosis. Over the last half century, there have been many circular discussions about the best way of managing preschool wheeze. In general, intermittent wheezing should be treated with intermittent bronchodilator therapy, and a controller therapy should be prescribed for a young child with recurrent wheezing only if positively indicated, and only then if carefully monitored for efficacy. Good multidisciplinary support, attention to environmental exposition and education are essential in managing this common condition. This article analyses the pathophysiological basis of wheezing in infancy and critically discusses the evolution of the scientific progress over time in this unique field of respiratory medicine.

Frequency and costs of pulmonary exacerbations in patients with cystic fibrosis in the United States

BACKGROUND

Information is limited regarding the cost of pulmonary exacerbations (PEx) among patients with cystic fibrosis in the United States.

METHODS

To examine PEx costs, medical chart data were linked to insurance claims for patients aged ≥6 years who had commercial coverage from a large US health insurer affiliated with Optum during 2008-2013. A PEx was categorized as an episode requiring newly started (1) oral antibiotics (PEx-O) or (2) intravenous (IV) antibiotics and/or inpatient stay (PEx-IV).

RESULTS

Among 241 patients, 88.0% had ≥1 PEx (2.9/year) of any type, and 48.1% had ≥1 PEx-IV. Prior PEx-IV was the strongest risk factor for subsequent PEx-IV. The mean cost per episode was $12,784 for PEx of any type and $36,319 for PEx-IV. Patients with worse lung function were more likely to experience a PEx and incurred higher annual PEx-related costs.

LIMITATIONS

This was an observational study using a convenience sample of patients with commercial coverage from a large US health insurer whose medical charts were available for abstraction. Results of the study may not be generalizable to individuals with Medicaid coverage and other types of insurance, or to the uninsured.

CONCLUSIONS

Most patients experience ≥1 PEx annually, and nearly half require IV antibiotics and/or inpatient stay at considerable cost.

[Quality scale for preschool spirometry interpretation]

Since 2007, there are international guidelines for implementation and interpretation of spirometry in preschool children. A percentage of these patients cannot obtain maneuvers that meet all eligibility criteria. The objective of this study was to develop a quality scale for interpreting these partially acceptable spirometry.

MATERIAL AND METHOD

Delphi methodology was used, which allows to reach consensus among experts analyzing a defined problem. We invited to participate pediatric pneumologists dedicated to lung function and who participated actively in scientific specialty societies in Chile. Successive rounds were conducted with questionnaires about criteria used to assess spirometry in preschool children. These criteria define the acceptability of spirometric maneuvers according to international guidelines. Proposed quality grades were “very good”, “good”, “fair” and “bad”.

RESULTS

Thirteen of the 15 invited experts accepted our invitation. In the first round 9 disagreed with the degree of “regular” quality. In the second round this was removed and 11 experts answered, 9 of them agreed with the use of this new version. The most contentious criterion was the end of expiration.

CONCLUSION

Most experts agreed with the final scale, using “very good”, “good” and “bad” judgments. This would help to improve the performance of spirometry in children between 2 and 5 years.

Respiratory function and symptoms in young preterm children in the contemporary era

OBJECTIVE

To determine the relationships between respiratory symptoms, lung function, and neonatal events in young preterm children.

METHODS

Preterm children (<32 w gestation), classified as bronchopulmonary dysplasia (BPD) or non-BPD, and healthy term controls were studied. Lung function was measured by forced oscillation technique (respiratory resistance [Rrs] and reactance [Xrs]) and spirometry. Respiratory symptom questionnaires were administered.

RESULTS

One hundred and fifty children (74 BPD, 44 non-BPD, 32 controls) 4-8 years were studied. Lung function (median Z-score [10,90th centile]) was significantly impaired in preterm children compared to controls for FVC (0.00 [-1.18, 1.76], 0.69 [-0.17,1.86]), FEV₁ (-0.44 [-1.94, 1.11], 0.49 [-0.83, 2.51]), Xrs (-1.26 [-3.31, 0.11], -0.11 [-0.97, 0.73]), and Rrs (0.55 [-0.48, 1.82], 0.28 [-0.99, 0.96]). Only Xrs differed between the BPD and non-BPD (-1.51 [-3.59, -0.41], -0.89 [-2.64, 0.52]). The prevalence of recent respiratory symptoms (range: 32-36%) did not differ between BPD and non-BPD children. Supplemental O₂ in hospital was positively associated with worsening Xrs and FEV₁ .

CONCLUSION

Preterm children have worse lung function than healthy controls. Only respiratory reactance differentiated between preterm children with and without BPD and was influenced by days of O₂ in hospital. Pediatr Pulmonol. 2016;51:1347-1355. © 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.

Bronchodilator response cut-off points and FEV 0.75 reference values for spirometry in preschoolers

OBJECTIVE:

To determine the cut-off points for FEV1, FEV0.75, FEV0.5, and FEF25-75% bronchodilator responses in healthy preschool children and to generate reference values for FEV0.75.

METHODS:

This was a cross-sectional community-based study involving children 3-5 years of age. Healthy preschool children were selected by a standardized questionnaire. Spirometry was performed before and after bronchodilator use. The cut-off point of the response was defined as the 95th percentile of the change in each parameter.

RESULTS:

We recruited 266 children, 160 (60%) of whom were able to perform acceptable, reproducible expiratory maneuvers before and after bronchodilator use. The mean age and height were 57.78 ± 7.86 months and 106.56 ± 6.43 cm, respectively. The success rate for FEV0.5 was 35%, 68%, and 70% in the 3-, 4-, and 5-year-olds, respectively. The 95th percentile of the change in the percentage of the predicted value in response to bronchodilator use was 11.6%, 16.0%, 8.5%, and 35.5% for FEV1, FEV0.75, FEV0.5, and FEF25-75%, respectively.

CONCLUSIONS:

Our results provide cut-off points for bronchodilator responsiveness for FEV1, FEV0.75, FEV0.5, and FEF25-75% in healthy preschool children. In addition, we proposed gender-specific reference equations for FEV0.75. Our findings could improve the physiological assessment of respiratory function in preschool children.

OBJETIVO:

Determinar os pontos de corte de resposta ao broncodilatador do VEF1, VEF0,75, VEF0,5 e FEF25-75% em crianças pré-escolares saudáveis e gerar valores de referência para o VEF0,75.

MÉTODOS:

Foi realizado um estudo transversal de base comunitária em crianças de 3-5 anos de idade. Pré-escolares saudáveis foram selecionados por um questionário padronizado. Foi realizada espirometria antes e depois do uso de broncodilatador. Foram definidos os pontos de corte dessa resposta como o percentil 95 de variação em cada parâmetro.

RESULTADOS:

Foram recrutadas 266 crianças, e 160 (60,0%) foram capazes de gerar manobras expiratórias aceitáveis e reprodutíveis antes e depois do uso de broncodilatador. As médias de idade e estatura dos participantes foram 57,78 ± 7,86 meses e 106,56 ± 6,43 cm, respectivamente. A taxa de sucesso para o VEF0,5 foi de 35%, 68% e 70%, respectivamente, nos participantes com 3, 4 e 5 anos de idade. O percentil 95 de variação percentual do valor previsto na resposta ao broncodilatador foram, respectivamente, de 11,6%, 16,0%, 8,5% e 35,5%, para VEF1, VEF0,75, VEF0,5 e FEF25-75%.

CONCLUSÕES:

Nossos resultados definiram pontos de corte de resposta ao broncodilatador para o VEF1, VEF0,75, VEF0,5 e FEF25-75 em crianças pré-escolares saudáveis. Adicionalmente, foram propostas equações de referência para o VEF0,75, separadas por sexo. Os achados deste estudo podem melhorar a avaliação fisiológica da função respiratória em pré-escolares.