Reference equations for pulmonary function tests in preschool children: a review

GEMA 5.3. Spanish Guideline on the Management of Asthma

The Spanish Guideline on the Management of Asthma, better known by its acronym in Spanish GEMA, has been available for more than 20 years. Twenty-one scientific societies or related groups both from Spain and internationally have participated in the preparation and development of the updated edition of GEMA, which in fact has been currently positioned as the reference guide on asthma in the Spanish language worldwide. Its objective is to prevent and improve the clinical situation of people with asthma by increasing the knowledge of healthcare professionals involved in their care. Its purpose is to convert scientific evidence into simple and easy-to-follow practical recommendations. Therefore, it is not a monograph that brings together all the scientific knowledge about the disease, but rather a brief document with the essentials, designed to be applied quickly in routine clinical practice. The guidelines are necessarily multidisciplinary, developed to be useful and an indispensable tool for physicians of different specialties, as well as nurses and pharmacists. Probably the most outstanding aspects of the guide are the recommendations to: establish the diagnosis of asthma using a sequential algorithm based on objective diagnostic tests; the follow-up of patients, preferably based on the strategy of achieving and maintaining control of the disease; treatment according to the level of severity of asthma, using six steps from least to greatest need of pharmaceutical drugs, and the treatment algorithm for the indication of biologics in patients with severe uncontrolled asthma based on phenotypes. And now, in addition to that, there is a novelty for easy use and follow-up through a computer application based on the chatbot-type conversational artificial intelligence (ia-GEMA).

Development and validation of predictive equations for spirometry in Portuguese children

Background

There are no data on lung function reference values for Portuguese children, and the contribution from the Portuguese data set in the Global Lung Function Initiative (GLI) is scant.

Objectives

We aimed to estimate new up-to-date reference values for Portuguese children by fitting a multivariable regression model to a general population sample. Further, we intended to assess the external validity of the obtained reference values and to compare them to the GLI reference values.

Methods

A random sample of 858 children from 20 primary schools were screened by health questionnaire, physical examination, and spirometry. Spirometric parameters recorded were FVC, FEV1, and FEF25-75. Multiple regression models were used to derive reference equations.

Results

Overall, 481 children, aged between 7 and 12 years, 267 boys (55.5%), were included. Boys had higher values for FVC and FEV1 than girls (P < .05). The strongest correlation was found for FVC with height (r = 0.71 for boys and 0.70 for girls), while the lowest correlation was observed in both sexes for FEF25-75 with age (r = 0.23). Height was the most significant predictor of FVC, FEV1, and FEF25-75 in our models. Weight and body mass index were not significant predictors for boys but had a significant effect on girls' equations for all spirometry parameters. Compared to obtained reference equations with GLI, they performed better for FVC in boys, FEV1 in girls, and FEF25-75 in both boys and girls.

Conclusion

We offer up-to-date reference values of spirometry for Portuguese children that can be used in clinical practice and research.

Reference equations for spirometry in healthy Asian children aged 5 to 18 years in Taiwan

Background and objective

This study aimed to establish reference equations for spirometry in healthy Taiwanese children and assess the applicability of the Global Lung Function Initiative (GLI)-2012 equations to Taiwanese children.

Methods

Spirometric data collected from 757 healthy Taiwanese children aged 5 to 18 years in a population-based cohort study. Prediction equations derived using linear regression and the generalized additive models for location, scale and shape (GAMLSS) method, respectively.

Results

The GLI-2012 South East Asian equations did not provide a close fit with mean ± standard error z-scores of −0.679 ± 0.030 (FVC), −0.186 ± 0.044 (FEV₁), −0.875 ± 0.049 (FEV₁/FVC ratio) and −2.189 ± 0.063 (FEF_25-75) for girls; and 0.238 ± 0.059, −0.061 ± 0.053, −0.513 ± 0.059 and −1.896 ± 0.077 for boys. The proposed GAMLSS models took age, height, and weight into account. GAMLSS models for boys and girls captured the characteristics of spirometric data in the study population closely in contrast to the linear regression models and the GLI-2012 equations.

Conclusion

This study provides up-to-date reference values for spirometry using GAMLSS modeling in healthy Taiwanese children aged 5 to 18 years. Our study provides evidence that the GLI-2012 reference equations are not properly matched to spirometric data in a contemporary Taiwanese child population, indicating the urgent need for an update of GLI reference values by inclusion of more data of non-Caucasian decent.

Prediction equations of forced oscillation technique: the insidious role of collinearity

Many studies have reported reference data for forced oscillation technique (FOT) in healthy children. The prediction equation of FOT parameters were derived from a multivariable regression model examining the effect of age, gender, weight and height on each parameter. As many of these variables are likely to be correlated, collinearity might have affected the accuracy of the model, potentially resulting in misleading, erroneous or difficult to interpret conclusions.

The aim of this work was: To review all FOT publications in children since 2005 to analyze whether collinearity was considered in the construction of the published prediction equations. Then to compare these prediction equations with our own study. And to analyse, in our study, how collinearity between the explanatory variables might affect the predicted equations if it was not considered in the model. The results showed that none of the ten reviewed studies had stated whether collinearity was checked for. Half of the reports had also included in their equations variables which are physiologically correlated, such as age, weight and height. The predicted resistance varied by up to 28% amongst these studies. And in our study, multicollinearity was identified between the explanatory variables initially considered for the regression model (age, weight and height). Ignoring it would have resulted in inaccuracies in the coefficients of the equation, their signs (positive or negative), their 95% confidence intervals, their significance level and the model goodness of fit. In Conclusion with inaccurately constructed and improperly reported models, understanding the results and reproducing the models for future research might be compromised.

Is forced oscillation technique the next respiratory function test of choice in childhood asthma

Respiratory diseases, especially asthma, are common in children. While spirometry contributes to asthma diagnosis and management in older children, it has a limited role in younger children whom are often unable to perform forced expiratory manoeuvre. The development of novel diagnostic methods which require minimal effort, such as forced oscillation technique (FOT) is, therefore, a welcome and promising addition. FOT involves applying external, small amplitude oscillations to the respiratory system during tidal breathing. Therefore, it requires minimal effort and cooperation. The FOT has the potential to facilitate asthma diagnosis and management in pre-school children by faciliting the objective measurement of baseline lung function and airway reactivity in children unable to successfully perform spirometry. Traditionally the use of FOT was limited to specialised centres. However, the availability of commercial equipment resulted in its use both in research and in clinical practice. In this article, we review the available literature on the use of FOT in childhood asthma. The technical aspects of FOT are described followed by a discussion of its practical aspects in the clinical field including the measurement of baseline lung function and associated reference ranges, bronchodilator responsiveness and bronchial hyper-responsiveness. We also highlight the difficulties and limitations that might be encountered and future research directions.

Defining 'healthy' in preschool-aged children for forced oscillation technique reference equations

BACKGROUND AND OBJECTIVE

Selecting 'healthy' preschool-aged children for reference ranges may not be straightforward. Relaxing inclusion criteria for normative data does not affect spirometry z-scores. We therefore investigated the effect of similarly relaxing inclusion criteria in preschoolers on reference ranges for respiratory impedance (Zrs) using a modified forced oscillation technique (FOT).

METHODS

The International Study of Asthma and Allergies in Childhood questionnaire classified 585 children into a healthy and five mutually exclusive groups. Zrs was measured between 4 and 26 Hz and resistance (R) and compliance (C) obtained by model fitting. Prediction models were determined using mixed effect models and z-scores compared between healthy children and the five groups.

RESULTS

Zrs data were obtained for 494 participants (4.30 ± 0.7 years) on 587 occasions. Comparison of the Zrs z-scores between the healthy children and the health groups found significant differences in children with asthma, current wheeze and respiratory symptoms, but not in children born preterm or with early-life wheeze. Adding these two groups to the healthy dataset had no significant effect on the distribution of z-scores and increased the size of the dataset by 22.3%.

CONCLUSION

Our data suggest that preschool-aged children born preterm or with early-life wheeze can be included in FOT reference equations, while those with asthma, current wheeze and respiratory symptoms within 4 weeks of testing should be excluded. This more inclusive approach results in more robust FOT reference ranges.

The Global Lung Function Initiative (GLI) Network: bringing the world's respiratory reference values together

The Global Lung Function Initiative (GLI) Network has become the largest resource for reference values for routine lung function testing ever assembled. This article addresses how the GLI Network came about, why it is important, and its current challenges and future directions. It is an extension of an article published in Breathe in 2013 [1], and summarises recent developments and the future of the GLI Network.

Learn about the GLI Network, the largest resource reference for routine lung function testinghttp://ow.ly/ZZor30epWgi

Challenges in Collating Spirometry Reference Data for South-Asian Children: An Observational Study

Availability of sophisticated statistical modelling for developing robust reference equations has improved interpretation of lung function results. In 2012, the Global Lung function Initiative(GLI) published the first global all-age, multi-ethnic reference equations for spirometry but these lacked equations for those originating from the Indian subcontinent (South-Asians). The aims of this study were to assess the extent to which existing GLI-ethnic adjustments might fit South-Asian paediatric spirometry data, assess any similarities and discrepancies between South-Asian datasets and explore the feasibility of deriving a suitable South-Asian GLI-adjustment.

Spirometric reference values for healthy Han children aged 5-15 years in Guangzhou, southern China

BACKGROUND

Reliable interpretation of spirometry rests on appropriate reference values, but there are few published reference values for healthy children in China.

OBJECTIVE

To develop the updated spirometric normative values for healthy children aged 5-15 years in Guangzhou, southern China, and to explore the differences by comparison with published reference values.

METHODS

In this cross-sectional study, health questionnaire and physical examination conducted for screening healthy Han children. Spirometry was performed by well-trained technicians according to American Thoracic Society guidelines. Using Lambda-Mu-Sigma (LMS) algorithm, predicted equations for the median and lower limits of normal were derived for forced vital capacity (FVC), forced expiratory volume in one second (FEV1 ), peak expiratory flow (PEF), and maximal mid-expiratory flow (FEF25-75% ). Predicted values were compared with other published spirometric reference equations.

RESULTS

Data were obtained from 422 healthy children (226 boys and 196 girls) aged 5-15 years. Spirometric parameters showed moderate-to-strong positive correlations with age, height, and weight in both genders, with height being the most crucial predictor. There were significant differences between spirometric values and other published reference values. Spirometric values were comparable with the data derived from the same area population in 2002, with exception of increased height and weight in the equivalent age groups.

CONCLUSIONS

The present spirometric reference equations are feasible for assessment of lung function among children in southern China. Further studies for establishment of reference values for Chinese children in other regions are needed.

Reference value of impulse oscillometry in taiwanese preschool children

BACKGROUND

Impulse oscillometry is a potential technique for assessing the respiratory mechanism-which includes airway resistance and reactance during tidal breathing-in minimally cooperative young children. The reference values available in Asian preschool children are limited, especially in children of Chinese ethnicity. This study aimed to develop reference equations for lung function measurements using impulse oscillometry in Taiwanese children for future clinical application and research exploitation.

METHODS

Impulse oscillometry was performed in 150 healthy Taiwanese children (aged 2-6 years) to measure airway resistance and reactance at various frequencies. We used regression analysis to generate predictive equations separately by age, body height, body weight, and gender. The stepwise regression model revealed that body height was the most significant determinant of airway resistance and reactance in preschool young children.

RESULTS

With the growth in height, a decrease in airway resistance and a paradoxical increase in reactance occurred at different frequencies. The regression curve of resistance at 5 Hz was comparable to previous reference values.

CONCLUSION

This study provided reference values for several variables of the impulse oscillometry measurements in healthy Taiwanese children aged 2-6 years. With these reference data, clinical application of impulse oscillometry would be expedient in diagnosing respiratory diseases in preschool children.

Improvement of pulmonary function in children with early-onset scoliosis using magnetic growth rods

STUDY DESIGN

Case series.

OBJECTIVE

To determine whether there is improvement in pulmonary function in children with early-onset scoliosis (EOS) using magnetic growth rods (MGRs).

SUMMARY OF BACKGROUND DATA

EOS deformities have large impacts on lung function and volumes. Deterioration of pulmonary function in scoliosis is multifactorial, including severity, location of apex vertebra, and medical comorbidities. MGR insertion has benefits including reduction in operative procedures with repeated anesthetics, cost-effectiveness, and minimizing surgical and psychological distress. Pulmonary function tests provide objective and quantitative information about functional impairment caused by scoliosis. This is the first study that observes the MGR lengthening and changes in pulmonary function during a minimum period of 2.2 years.

METHODS

Six cases of EOS secondary to neuromuscular disease were identified. Mean age at diagnosis was 2.8 year (2.1-4.9 yr), mean age at surgery was 7.5 year (5-10 yr), and mean follow-up was 2.5 year (2.2-2.8 yr). Pulmonary function test (forced vital capacity [FVC] + forced expired volume in 1 second [FEV1] both % predicted) was measured before and after insertion of MGR and at every lengthening clinic subsequently for a minimum 2 years. Coronal and sagittal Cobb angles were measured pre- and postoperatively as were length extension of growth rods. All except 1 patient had dual MGRs inserted (the other had a single rod). Lengthening was commenced and data was collected at 6-month intervals.

RESULTS

Average correction was 34° ± 18° and 36° ± 15° for coronal and sagittal Cobb angles, respectively. Mean lengthening achieved was 24.9 mm. Mean improvement in postoperative FVC and FEV1 was 14.1% and 17.2%, respectively. There was significant difference between the median preoperative and postoperative Cobb angle, P = 0.028.

CONCLUSION

This study demonstrates early intervention using MGR in patients with EOS is associated with significant improvement in postoperative pulmonary function tests; and significant improvement in deformity correction with use of MGR with added benefits of reduction in repeat anesthesia, reduction in surgical and psychological distress, and cost-effectiveness.

LEVEL OF EVIDENCE

4.

The effects of low-level environmental tobacco smoke exposure on pulmonary function tests in preschool children with asthma

OBJECTIVES

Though parents of children with asthma smoke, they often avoid smoking in their homes or near their children, thus limiting exposure. It is not known if such low-level environmental tobacco smoke (ETS) results in measurable exposure or affects lung function. The objectives of this study were to measure urinary cotinine in preschool children with asthma, and to examine the relationship between low-level ETS exposure and pulmonary function tests (PFTs).

METHODS

Preschool children with asthma were enrolled. Parents completed questionnaires on ETS exposure and asthma control, urinary cotinine concentrations were measured and PFTs were compared between subjects with and without recent ETS exposure.

RESULTS

Forty one subjects were enrolled. All parents denied smoking in their home within the last 2 weeks, but 14 (34%) parents admitted to smoking outside their homes or away from their children. Fifteen (37%; 95%CI: 23-53) of the children had urinary cotinine levels ≥1 ng/ml, of which seven (17%; 95%CI: 8-32) had levels ≥5 ng/ml. FEV1 and FEV0.5 were lower in subjects with a urinary cotinine level ≥5 ng/ml as compared to those with levels <1 ng/ml or between 1 and 5 ng/ml; both at baseline and after inhalation of albuterol. Five of seven subjects with urinary cotinine levels ≥5 ng/ml had FEV0.5 less than 65% of predicted values. There were no significant differences in IOS measures.

CONCLUSIONS

Despite parental denial of smoking near their children, preschool children may be exposed to ETS. Such low-level ETS exposure may affect lung function, possibly in a dose-dependent manner.

Reference standards for forced expiratory indices in Chinese preschool children

Spirometric testing is traditionally achievable in children of school-age and beyond. Incorporation of interactive incentives motivates preschool children to facilitate measurement of forced expiratory indices. Validated spirometric reference standards are available for Caucasian preschoolers but lacking in Asians. We established spirometric references in Chinese children aged 2-7 years, who were recruited from 19 randomly selected nurseries and kindergartens in Hong Kong. Parents completed International Study of Asthma and Allergies in Childhood questionnaire, and children concurrently performed incentive spirometry on-site according to international guideline. Prediction equations for spirometric indices were formulated by linear regression. One thousand four hundred two (72.9%) of 1,922 consented children, with mean (SD) age 4.4 (1.0) years, successfully performed spirometry. Following exclusions due to medical and technical reasons, 895 (63.8%) children contributed spirometric data to our references. Girls had lower FEV0.5 , FEV0.75 , FEV1 , FVC, and PEF but similar FEF25-75 than boys, adjusted for age, weight, and standing height as covariates. Standing height was the most important predictor for FEV0.5 , FEV0.75 , FEV1 , FVC, and PEF in both boys (adjusted R(2) 0.525-0.734) and girls (adjusted R(2) 0.583-0.721), whereas the best prediction model for both gender is formed by standing height, weight, and age. At various standing heights, our preschoolers had FEV1 Z-scores 0.13-1.00 higher than those of collaborative Caucasian reference. This study justifies the need for ethnic-specific reference equations and presents spirometry references in young Chinese children. Their forced expiratory indices are determined by gender, age, weight and standing height, and standing height is the best anthropometric index to predict all spirometric indices.

Reference values for spirometry in preschool children

OBJECTIVES

Reference values for lung function tests differ in samples from different countries, including values for preschoolers. The main objective of this study was to derive reference values in this population.

METHODS

A prospective study was conducted through a questionnaire applied to 425 preschool children aged 3 to 6 years, from schools and day-care centers in a metropolitan city in Brazil. Children were selected by simple random sampling from the aforementioned schools. Peak expiratory flow (PEF), forced vital capacity (FVC), forced expiratory volumes (FEV1, FEV0.50), forced expiratory flow (FEF25-75) and FEV1/FVC, FEV0.5/FVC and FEF25-75/FVC ratios were evaluated.

RESULTS

Of the 425 children enrolled, 321 (75.6%) underwent the tests. Of these, 135 (42.0%) showed acceptable results with full expiratory curves and thus were included in the regression analysis to define the reference values. Height and gender significantly influenced FVC values through linear and logarithmic regression analysis. In males, R(2) increased with the logarithmic model for FVC and FEV1, but the linear model was retained for its simplicity. The lower limits were calculated by measuring the fifth percentile residues.

CONCLUSION

Full expiratory curves are more difficult to obtain in preschoolers. In addition to height, gender also influences the measures of FVC and FEV1. Reference values were defined for spirometry in preschool children in this population, which are applicable to similar populations.

Comparison of Reference Values and Short-Term Variability for Oscillatory and Spirometric Lung Function in Healthy Korean Preschool Children

Respiratory function measurements are important in the diagnosis and follow-up assessment of respiratory diseases. The aims of this study were to establish reference values for spirometry, to compare them with respiratory resistance and impedance by an impulse oscillometry system (IOS), and to analyze 3-month follow-up studies in healthy Korean preschool children. Six hundred seven questionnaires were distributed and 497 (82%) were returned. Lung function tests were performed in 183 healthy children of the age of 3-6 years. The 3-month follow-up studies were conducted from 19 children who visited our clinic twice. Of the 183 children who underwent both IOS and spirometry, 164 (90%) and 150 (82%) met the quality-control criteria for IOS and spirometry, respectively. The regression equations of each spirometric parameter were obtained. Height was the most consistently correlated measurement in both boys and girls. All spirometry parameters, except for FEF_25-75/FVC, were significantly correlated with IOS parameters. There were no significant differences in respiratory resistance at 5 Hz measured by IOS (Rrs_IOS5), forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV₁) between the first and second sets. The intraclass correlation coefficients and relative coefficients of repeatability for FEV₁, Rrs_IOS5, and respiratory system reactance (Xrs)_IOS5 were 0.90 (95% CI 0.73-0.96), 0.82 (95% CI 0.53-0.93), and 0.55 (95% CI -0.17-0.83) and 22.6%, 35.5%, and 91.8%, respectively. The obtained values and regression equations provide a reference for Korean preschool children and may be of importance in evaluating lung function of preschool children with pulmonary problems. Respiratory resistance and FEV₁ for healthy young Korean children are lower than literature reported reference values for Caucasian children. Rrs_IOS5 appears to be more stable on repeat testing than Xrs_IOS5.

Characterization of maximal respiratory pressures in healthy children

BACKGROUND

Measurements of maximal voluntary inspiratory (PI(max)) and expiratory (PE(max)) pressures are used in the management of respiratory muscle disease. There is little data on the appropriate reference range, success rates, or repeatability of PI(max) and PE(max) in children or on methodological factors affecting test outcomes.

OBJECTIVES

To determine PI(max) and PE(max) in healthy children and examine which published reference equations are best suited to a contemporary population. Secondary objectives were to assess within-test repeatability and the influence of lung volumes on PI(max) and PE(max).

METHODS

Healthy children were prospectively recruited from the community on a volunteer basis and underwent spirometry, static lung volumes, and PI(max) and PE(max) testing.

RESULTS

Acceptable and repeatable (to within 20%) PI(max) and PE(max) were obtained in 156 children, with 105 (67%) children performing both PI(max) and PE(max) measurements to within 10% repeatability. The reference equations of Wilson et al. [Thorax 1984;39:535-538] best matched our healthy Caucasian children. There was an inverse relationship between PI(max) and the percent of total lung capacity (TLC) at which the measurement was obtained (beta coefficient -0.96; 95% CI -1.52 to -0.39; p = 0.001), whereas at lung volumes of >80% TLC PE(max) was independent of lung volume (p = 0.26).

CONCLUSION

We demonstrated that the Wilson et al. [Thorax 1984;39:535-538] reference ranges are most suited for contemporary Caucasian Australasian children. However, robust multiethnic reference equations for maximal respiratory pressures are required. This study suggests that 10% within-test repeatability criteria are feasible in clinical practice, and that the use of lung volume measurements will improve the quality of maximal respiratory pressure measurements.

Discrepancies between pediatric laboratories in pulmonary function results from healthy children

BACKGROUND

Multi-center research studies that include pulmonary function as an objective outcome are increasingly important in pediatric respiratory medicine. The need for local controls rather than depending on published normative data for lung function remains debatable.

AIM

To compare pulmonary function in childhood controls with no respiratory symptoms from three centers in the United Kingdom and ascertain the extent to which current reference equations are appropriate for this population.

METHODS

Spirometry, plethysmographic lung volumes, and specific airways resistance (sRaw) were measured within specialized pediatric laboratories in children from three geographical locations throughout the UK (London, Leicester, and Glasgow), using identical equipment, software and standard operating procedures. Results were compared between centers and in relation to recent or commonly used UK pediatric reference values.

RESULTS

Pulmonary function was assessed in 94 healthy children (mean (SD) age: 7.7 (0.6) years; 88% white Caucasians; ∼30 from each center). There were no significant differences in background demographics or spirometric outcomes when compared between centers. By contrast, statistically significant differences in plethysmographic lung volumes and sRaw were observed between-centers. Significant differences in relation to published reference data for white subjects were noted for FEV(1) in all three centers and occasionally for other lung function measures but the differences from predicted values were small (within ± 0.5 z-score) and not clinically significant.

CONCLUSION

After appropriate inter-laboratory standardization, spirometric measurements in children can be measured in different centers without evidence of systematic differences. However, even after extensive standardization procedures, plethysmographic measures appear more prone to inter-center differences and cannot, at present, be reliably compared across centers without incorporating controls at each location.

Equações preditivas e valores de normalidade para pressões respiratórias máximas na infância e adolescência

OBJETIVO: Pesquisar equações preditivas e valores de normalidade para pressões respiratórias máximas disponíveis na literatura para a faixa etária compreendida entre a infância e a adolescência. FONTES DE DADOS: Estudos publicados em inglês e em português no período entre 1980 e 2009. As bases de dados eletrônicas Lilacs e Medline foram consultadas utilizando-se as palavras-chave "capacidade respiratória máxima", "músculos respiratórios", "valores de referência", "adolescente" e "criança". SÍNTESE DOS DADOS: Foram incluídos oito artigos na revisão, totalizando 1.463 crianças e adolescentes avaliados. A faixa etária da população estudada variou de sete a 18 anos. Geralmente o indivíduo é avaliado na posição sentada e com um clipe nasal. Os esforços máximos são realizados a partir do volume residual e da capacidade pulmonar total e sustentados por um a três segundos. Valores de normalidade e equações de predição foram propostos em oito e dois estudos, respectivamente. Nestes, demonstra-se incremento nas pressões respiratórias máximas desde a infância à adolescência e a ocorrência de maiores valores de pressão expiratória máxima quando comparados à pressão inspiratória máxima em crianças e adolescentes de ambos os sexos. CONCLUSÕES: As pressões respiratórias máximas constituem um meio efetivo para avaliar a força muscular respiratória e diversos fatores contribuem para a grande variedade de equações preditivas e de valores de normalidade disponíveis. É preciso buscar um consenso para normatizar os métodos requeridos ao avaliar a força muscular respiratória em crianças e adolescentes.

Potential misinterpretation of infant lung function unless prospective healthy controls are studied

SUMMARY RATIONALE: Reliable interpretation of pulmonary function tests relies on appropriate reference data, which remain very limited for infants.

OBJECTIVES

This study aimed to assess the validity of published reference equations for forced expiratory flow-volume (FEFV) data in infants when using current, commercially available equipment, and how this could impact on interpretation of results from infants with lung disease.

METHODS

The Jaeger Masterscreen BabyBody (v4.67) equipment was used to perform partial and raised volume FEFV maneuvers in healthy infants and those with cystic fibrosis (CF). Results were initially expressed as Z-scores using published reference equations. Multilevel modeling was used to calculate differences, if any, from predicted scores in healthy infants.

RESULTS

Data were available from 66 healthy full term infants on 89 test occasions; [median (range) postnatal age 49.4 (12-101) weeks. All FEFV outcomes were significantly lower than predicted, with mean (SD) Z-score differences of -0.4 (1.1) for FVC; -0.6 (1.0) for FEV(0.5); -1.0 (1.0) for FEF(25-75) and -1.4 (1.1) for V'(maxFRC). After adjustments using multilevel modeling, mean Z-scores were within 0.1 (SD approximately 1.0) predicted for all outcomes in healthy infants. Among 50 infants with CF, studied on 85 test occasions, results were "abnormal" (<-1.96 Z-scores) on 35 (41%) and 37 (45%) test occasions for FEV(0.5) and FEF(25-75), respectively, when using published equations. This fell to 24 (28%) and 20 (24%), respectively, after adjustment.

CONCLUSIONS

Dependence on published equations for interpreting FEFV data in infants may lead to misinterpretation of lung function status, which could impact adversely both in the research setting and on clinical management. Use of a contemporary control group or establishment of equipment-specific reference data is essential for meaningful interpretation of infant lung function data.

A prospective comparative evaluation of persistent respiratory morbidity in esophageal atresia and congenital diaphragmatic hernia survivors

PURPOSE

The aim of the study was to compare long-term respiratory morbidity in children after repair of esophageal atresia (EA) or congenital diaphragmatic hernia (CDH).

PATIENTS AND METHODS

Children were seen at 6, 12, and 24 months and 5 years within a prospective longitudinal follow-up program in a tertiary children's hospital. Respiratory morbidity and physical condition were evaluated at all moments. At age 5 years, pulmonary function and maximal exercise performance were tested.

RESULTS

In 3 of 23 atresia patients and 10 of 20 hernia patients, bronchopulmonary dysplasia was developed. Seventeen atresia and 11 hernia patients had recurrent respiratory tract infections mainly in the first years of life. At age 5, 25% of EA and CDH patients measured showed reduced forced expiratory volume in 1 second (z-score < -2). Both atresia and hernia patients showed impaired growth, with catch-up growth at 5 years in patients with EA but not in those with hernia. Maximal exercise performance was significantly below normal for both groups.

CONCLUSIONS

Esophageal atresia and CDH are associated with equal risk of long-term respiratory morbidity, growth impairment, and disturbed maximal exercise performance. Prospective follow-up of EA patients aimed at identifying respiratory problems other than tracheomalacia should be an integral part of interdisciplinary follow-up programs.

Asthma in preschool children: the next challenge

PURPOSE OF REVIEW

To describe a prospective classification for preschool wheezers according to temporal symptom pattern, and summarize findings relating to the management of viral wheeze and the use of short-term therapy for intermittent severe wheeze.

RECENT FINDINGS

Phenotypes defined from cohort studies should only be applied retrospectively at school age. A new classification that can be applied prospectively is discussed. The importance of early rhinovirus-induced wheezing as a risk factor for asthma has become apparent. However, there is no benefit from short-course oral steroids for acute viral wheeze in the majority of cases. There is conflicting evidence for the role of intermittent montelukast or inhaled steroids in the treatment of acute, intermittent wheeze. A link between reduced vitamin D intake during pregnancy and increased preschool wheeze in offspring has emerged, suggesting a potential role for vitamin D supplementation in primary prevention.

SUMMARY

On the basis of current evidence, a trial of bronchodilators is first-line therapy for viral wheeze, and maintenance montelukast or inhaled steroids may be considered in preschool wheezers with persistent symptoms and risk factors for future asthma. No disease-modifying therapies are available. New therapeutic options for preschool wheezing disorders are desperately needed.

Lung function from infancy to the preschool years after clinical diagnosis of cystic fibrosis

RATIONALE

After recent standardization of forced expiratory maneuvers for both infants and preschool children, longitudinal measurements are now possible from birth.

OBJECTIVES

The aim of this study was to investigate the evolution of lung function during the first 6 years of life after a clinical diagnosis of cystic fibrosis (CF) in infancy in children with CF and in healthy control subjects.

METHODS

The raised volume technique was used during infancy and incentive spirometry during the preschool years.

MEASUREMENTS AND MAIN RESULTS

Forty-eight children with CF and 33 healthy control subjects had up to seven (median, 3) measurements. Over these early years, the diagnosis of CF itself accounted for a significant mean reduction of 7.5% (95% confidence interval, 0.9 - 13.6%) in FEV(0.75) and 15.1% (95% confidence interval, 3.6 - 25.3%) in FEF(25-75). Wheeze on auscultation, recent cough, and Pseudomonas aeruginosa (PsA) infection (even if apparently effectively treated) were all independently associated with further reductions in lung function. Premorbid lung function did not predict infection with PsA.

CONCLUSIONS

This is the first study to describe physiologic measurements from infancy through the preschool years in subjects with CF and healthy control subjects, the understanding of which is critical for future intervention trials. Airflow obstruction in uncomplicated CF persists through the preschool years despite treatment, with PsA acquisition being associated with further deterioration in lung function, even when apparently eradicated. This suggests that new therapies are needed to treat the airflow obstruction of uncomplicated CF, and rigorous strategies to prevent PsA acquisition.