Reference values of Forced Expiratory Volumes and pulmonary flows in 3-6 year children: a cross-sectional study

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.

Standardization of Spirometry 2019 Update. An Official American Thoracic Society and European Respiratory Society Technical Statement

Background: Spirometry is the most common pulmonary function test. It is widely used in the assessment of lung function to provide objective information used in the diagnosis of lung diseases and monitoring lung health. In 2005, the American Thoracic Society and the European Respiratory Society jointly adopted technical standards for conducting spirometry. Improvements in instrumentation and computational capabilities, together with new research studies and enhanced quality assurance approaches, have led to the need to update the 2005 technical standards for spirometry to take full advantage of current technical capabilities.Methods: This spirometry technical standards document was developed by an international joint task force, appointed by the American Thoracic Society and the European Respiratory Society, with expertise in conducting and analyzing pulmonary function tests, laboratory quality assurance, and developing international standards. A comprehensive review of published evidence was performed. A patient survey was developed to capture patients' experiences.Results: Revisions to the 2005 technical standards for spirometry were made, including the addition of factors that were not previously considered. Evidence to support the revisions was cited when applicable. The experience and expertise of task force members were used to develop recommended best practices.Conclusions: Standards and consensus recommendations are presented for manufacturers, clinicians, operators, and researchers with the aims of increasing the accuracy, precision, and quality of spirometric measurements and improving the patient experience. A comprehensive guide to aid in the implementation of these standards was developed as an online supplement.

Evaluation of Food Insecurity in Adults and Children With Cystic Fibrosis: Community Case Study

Advances in the care and treatment of cystic fibrosis (CF) have led to improved mortality rates; therefore, considerably more individuals with CF are living into adulthood. With an increased number of CF patients advancing into adulthood, there is the need for more research that surrounds the aging adult CF patient. It is important to conduct research and collect results on the aging CF population to help better prepare the CF patient, who is dealing with the heavy treatment and financial burden of their disease, build autonomy and increase their quality of life. Of note, research has found that social, behavioral, and physical factors influence the ability of those with CF to follow dietary recommendations. A primary treatment goal in CF is a high calorie, high protein, and high fat diet. A socio-economic factor that has not been adequately investigated with regards to dietary compliance of individuals with CF is food insecurity. The aim of this community case study was to document the experiences and estimate the prevalence of food insecurity among CF patients residing in Idaho. The correlation between food insecurity and health outcomes (lung function and body mass index) was also examined. Participants included adult patients and parents of pediatric patients with CF. Food insecurity rates among CF patients of all ages were found to be significantly higher than that seen in the overall community; however, no specific correlation between food insecurity and body mass index (BMI) or lung function emerged. This case study highlights the need for continued research around food access issues in this patient population. The data resulting from this study shows the value of CF advocacy organizations promoting efforts to build resources and provide education around food insecurity issues.

Comparison of spirometric results obtained from the sitting and standing position in children participating in an epidemiological study

Introduction

It is recommended that spirometric testing in children be completed while sitting. Our experience indicates that children prefer standing during spirometry.

Aim

We sought to compare spirometric results obtained from the sitting (SIP) and standing (STP) positions.

Material and methods

Two testing sessions were performed in random order (SIP vs. STP: 30–45 min apart) in 118 children (7–13 years), attending one, randomly selected, primary school (response rate: 92%).

Results

Acceptable quality was found in 77.9% of STP and 77.1% of SIP maneuvers. Higher values of spirometric variables on STP, compared to SIP, were obtained for forced vital capacity (FVC) (2.12 ±0.41 l vs. 2.11 ±0.39 l) and forced expiratory volume in 1 s (FEV₁) (1.78 ±0.36 l vs. 1.77 ±0.35 l) but the differences were not statistically significant. Relative between-position differences (RBPD) ≤ 5% were found with the following frequencies: FVC: 56.4%, FEV₁: 69.2%, PEF: 21.7%, and FEF_25–75: 24.3%. Similar patterns were found for FEF₂₅, FEF₅₀, and FEF₇₅. Relative between-position differences were related to age in the case of FEV₁ (p = 0.005), FEF₂₅ (p = 0.02), and FEF_25–75 (p = 0.01) where older children had smaller RBPD. Forced vital capacity RBPD was lower (p = 0.01) in subjects with current wheeze; PEF RBPD were lower (p = 0.02) in children with asthma.

Conclusions

In epidemiological studies, the position of spirometric testing does not affect the results of lung function assessment.

Global Lung Function Initiative 2012 reference values for spirometry in South Italian children

RATIONALE

Despite the widespread use of the Global Lung Function Initiative (GLI) 2012 reference values, there is still the need of testing their applicability in local areas.

OBJECTIVES

The aims of this study are to evaluate applicability of GLI reference equations in a large population-based sample of normal schoolchildren from Sicily, and to compare GLI and previous prediction equations in terms of spirometry test interpretation.

METHODS

GLI equations were evaluated in 1243 normal schoolchildren, 49% males, aged 7-16 years, height 116-187 cm. Normality assumptions for the GLI z-scores (FEV₁, FVC, FEV₁/FVC) were tested, and bootstrap confidence intervals for the mean (0 expected) and the variance (1 expected) were derived. GLI and other reference equations were compared in terms of probabilities to fall below the lower limit of normal (LLN).

RESULTS

The GLI z-score normality assumption held for males but not for females (p < 0.001). According to the mean z-score, predicted values were: slightly underestimated for FEV₁ (0.15 in males, 0.07 in females); overestimated for FVC (-0.27 in males, -0.32 in females); highly underestimated for FEV₁/FVC (0.75 in males, 0.81 in females). Variability was correctly estimated. The probability of FEV₁<LLN correctly approached 0.05 when using GLI, Hankinson and Quanjer equations. Wang equations yielded correct probabilities of abnormal FVC; Pistelli equations yielded correct probabilities of abnormal FEV₁/FVC for females.

CONCLUSIONS

GLI 2012 references underestimate FEV₁/FVC predicted values in a sample of normal South Italian children. Physicians interpreting spirometry should be aware to test reference values prior to their use in a local area.

Spirometry in Asthma Care: A Review of the Trends and Challenges in Pediatric Practice

BACKGROUND

Given the rising incidence of noncommunicable diseases (NCDs) globally, especially bronchial asthma, there is the need to reduce the associated morbidity and mortality by adopting an objective means of diagnosis and monitoring.

AIM

This article aims to review the trends and challenges in the use of spirometry for managing childhood bronchial asthma especially in developing countries.

METHODS

We conducted a literature search of published data on the use of spirometry for the diagnosis of childhood bronchial asthma with special emphasis resource-poor countries.

RESULTS

Guidelines for the diagnosis and treatment of childhood asthma recommend the use of spirometry, but this is currently underused in both tertiary and primary care settings especially in developing countries. Lack of spirometers and proper training in their use and interpretation of findings as well as a dearth of asthma guidelines remains core to the underuse of spirometry in managing children with asthma. Targeting education of health care staff was, however, observed to improve its utility, and practical implementable strategies are highlighted.

CONCLUSIONS

Spirometry is not frequently used for asthma diagnosis in pediatric practice especially in resource-poor countries where the NCD burden is higher. Strategies to overcome the obstacles are implementable and can make a difference in reducing the burden of NCD.

Lung function and functional capacity in school age children

Abstract Introduction: Six-minute walk test (TC6’) and peak expiratory flow (PEF) can be influenced by variables like gender, age and body mass index (BMI). In the school context, these tests can identify losses caused by sedentary habits and/or manifestation of overweight/obesity. Nevertheless, although widely studied in the adult context, they have not been properly clarified in the child public. Objective: To assess the PEF and TC6’ between students in the public and private network and to correlate them with factors like age, gender and BMI. Methods: 39 male and female children between eight and ten years of age were selected for the study. The TC6’ was held at a sports court. The child was instructed to walk at maximum speed for six minutes and the PEF test took place in accordance to the recommendations by Pereira et al (1). Results: No significant correlation was found between the BMI and the PEF and TC6’ scores. No significant correlation was found between sex and PEF, with measures within normal parameters for the entire sample. The EPF measures did not influence the distance walked in the TC6’. A significant correlation was found between sex and distance walked in the TC6’ only among male children attending public schools. Conclusion: Both sex and BMI did not influence the PEF measures which, in turn, does not seem to have influenced the distance the sample walked in the TC6’. Also concerning the TC6’, only the children from public school reached the normal scores proposed in the literature.

Assessing bronchodilator response in preschool children using spirometry

BACKGROUND

Measuring lung function, including bronchodilator response (BDR), is an integral part of asthma management in older children. While spirometry is possible in preschool-aged children, the question remains whether measuring BDR aids in asthma diagnosis in this age group.

METHODS

431 healthy children and 289 children with asthma, aged 3-5 years, were recruited from kindergartens and the pulmonology clinic in Trelew, Argentina. Spirometry was performed at visit 1 and repeated after 15 min, with children randomised to placebo or salbutamol (400 µg). Spirometry was again performed within 8 weeks at visit 2. Within-session repeatability from visit 1 and between-session reproducibility were calculated using baseline spirometry. The within-session repeatability and receiver operating characteristic curve analyses were used to determine the optimal threshold values for BDR for spirometry outcome variables measured at the first visit, and sensitivity, specificity and diagnostic accuracy were determined.

RESULTS

As a group, children with asthma had lower lung function (FVC 1.11±0.12 L vs 1.01±0.15 L; FEV_0.75 1.01±0.10 L vs 0.91±0.15 L) and a greater BDR (FEV_0.75 group difference 8.6 (95% CI -5.0 to 14.3)%) than healthy children. BDR was best defined by change in FEV_0.75; an increase of 11% showed the best balance between sensitivity (51%), specificity (88%), positive predictive value (47%) and negative predictive value (89%) for discriminating healthy from preschool-aged children with asthma.

CONCLUSIONS

A negative BDR in a child suspected of having asthma makes a diagnosis of asthma less likely.

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.

Prediction equations for spirometry in four- to six-year-old children

OBJECTIVE

To generate prediction equations for spirometry in 4- to 6-year-old children.

METHODS

Forced vital capacity, forced expiratory volume in 0.5s, forced expiratory volume in one second, peak expiratory flow, and forced expiratory flow at 25-75% of the forced vital capacity were assessed in 195 healthy children residing in the town of Sete Lagoas, state of Minas Gerais, Southeastern Brazil. The least mean squares method was used to derive the prediction equations. The level of significance was established as p<0.05.

RESULTS

Overall, 85% of the children succeeded in performing the spirometric maneuvers. In the prediction equation, height was the single predictor of the spirometric variables as follows: forced vital capacity=exponential [(-2.255)+(0.022×height)], forced expiratory volume in 0.5s=exponential [(-2.288)+(0.019×height)], forced expiratory volume in one second=exponential [(-2.767)+(0.026×height)], peak expiratory flow=exponential [(-2.908)+(0.019×height)], and forced expiratory flow at 25-75% of the forced vital capacity=exponential [(-1.404)+(0.016×height)]. Neither age nor weight influenced the regression equations. No significant differences in the predicted values for boys and girls were observed.

CONCLUSION

The predicted values obtained in the present study are comparable to those reported for preschoolers from both Brazil and other countries.

Feasibility of spirometry testing in preschool children

RATIONALE

The primary purpose of this study was to evaluate the feasibility of obtaining acceptable and reproducible spirometry data in preschool aged children (3-5 years) by technicians without prior experience with spirometry.

METHODS

Two technicians were trained to perform spirometry testing (ndd Easy on-PC) and to administer standardized questionnaires. Preschool aged children were enrolled from two Head Start centers and a local primary care clinic. Subjects were trained in proper spirometry technique and tested until at least two acceptable efforts were obtained or the subject no longer produced acceptable efforts.

RESULTS

200 subjects were enrolled: mean age 4.0 years (± 0.7 SD); age distribution: 51 (25.5%) 3 years old, 103 (51.5%) 4 years old, and 46 (23%) 5 years old. Fifty-six percent male and 75% Hispanic. One hundred thirty (65%) subjects produced at least one acceptable effort on their first visit: 23 (45%) for 3 years old, 67 (65%) for 4 years old, and 40 (87%) for 5 years old. The number of acceptable efforts correlated with age (r = 0.29, P < 0.001) but not gender. The mean number of acceptable efforts on the first visit was 2.66 (± 2.54 SD; range 0-10). One hundred twenty subjects (60%) had two acceptable efforts; 102 had FEV0.5 within 10% or 0.1 L and 104 had FVC within 10% or 0.1 L of best effort. The Asthma Health Screening Survey (AHSS) was 78% sensitive when compared to a specialist exam and 86% compared to a self-reported prior diagnosis of asthma.

CONCLUSIONS

Technicians without prior experience were able to obtain acceptable and reproducible spirometry results from the preschool aged children; the number of acceptable efforts correlated significantly with age.

Lung function changes from childhood to adolescence: a seven-year follow-up study

BACKGROUND

As part of an investigation into the respiratory health in children conducted in Torino, northwestern Italy, our aim was to assess development in lung function from childhood to adolescence, and to assess changes or persistence of asthma symptoms on the change of lung function parameters. Furthermore, the observed lung function data were compared with the Global Lung Function Initiative (GLI) reference values.

METHODS

We conducted a longitudinal study, which lasted 7 years, composed by first survey of 4-5 year-old children in 2003 and a follow-up in 2010. Both surveys consisted in collecting information on health by standardized SIDRIA questionnaire and spirometry testing with FVC, FEV1, FEV1/FVC% and FEF25-75 measurements.

RESULTS

242 subjects successfully completed both surveys. In terms of asthma symptoms (AS = asthma attacks or wheezing in the previous 12 months), 191/242 were asymptomatic, 13 reported AS only in the first survey (early transient), 23 had AS only in the second survey (late onset), and 15 had AS in both surveys (persistent). Comparing the lung function parameters observed with the predicted by GLI only small differences were detected, except for FVC and FEF25-75, for which more than 5% of subjects had Z-score values beyond the Z-score normal limits. Furthermore, as well as did not significantly affect developmental changes in FVC and FEV1, the decrease in FEV1/FVC ratio was significantly higher in subjects with AS at the time of follow-up (late onset and persistent phenotypes) while the increase in FEF25-75 was significantly smaller in subjects with persistent AS (p < 0.05).

CONCLUSIONS

The GLI equations are valid in evaluating lung function during development, at least in terms of lung volume measurements. Findings also suggest that the FEF25-75 may be a useful tool for clinical and epidemiological studies of childhood asthma.

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.

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.

Measurement of Interrupter Respiratory Resistance and Spirometry in Preschool Children: Influence of Respiratory Symptoms

Pulmonary function tests play an important role in the diagnosis and management of respiratory diseases in children. The purpose of the study was to evaluate lung function using the interrupter resistance technique (Rint) and spirometry (flow-volume and volume-time) in preschool children and to correlate the findings with respiratory symptoms. We studied 103 children (65 males, 38 females; mean age 5.2±0.7 years; range 3.6–5.8). For each child we collected family history concerning: respiratory diseases, skin prick tests, smoking during maternal pregnancy, history of gestational and neonatal period. All children performed lung function tests (Rint and spirometry) and skin prick test for inhalant and food allergens. Twenty-eight subjects (27.2%) had respiratory symptoms (RS). Expiratory Rint were performed in all subjects and spirometry was carried out on 76 children (73.8%). Spirometric indices were not statistically different between subjects without respiratory symptoms (controls) and RS children except for FEF25–75 expressed as a percentage of the predicted value (RS: 81.5±13.7% vs controls: 94.5±15.8%; p <0.001). Rint mean values were significantly higher in RS children than in controls (RS: 135.6 ±24.8% vs controls: 102.4 ±21.7%; p< 0.0001). We found a statistically negative correlation between Rint and the following Spirometric indices: FEV0.5 (R= −0.696; p < 0.0001), FEV, (R= − 0.728; p < 0.0001) and FEF25–75 (R= −0.681; p < 0.0001). In preschool children with respiratory disease we found significantly higher mean values of Rint and lower FEF25-75 than in the control group and a significant negative relationship between Rint and Spirometric indices.

Feasibility and reproducibility of spirometry and inductance plethysmography in healthy Brazilian preschoolers

RATIONALE

Preschoolers show peculiarities that reinforce the importance of assessing their pulmonary function. However, there are few data on the success rate and between-occasions reproducibility of pulmonary function tests in preschoolers, particularly in the Brazilian population.

OBJECTIVE

To assess the success rate and between-occasions reproducibility of the variables obtained by spirometry and respiratory inductive plethysmography in healthy children aged 4-6 years.

METHODS

Breathing pattern was assessed by plethysmography (tidal volume-V(T), respiratory rate-f, inspiratory duty cycle-Ti/Ttot, mean respiratory flow-V(T)/Ti, displacement of the rib cage-RC and phase relation during the total breath-PhRTB) and spirometry (forced vital capacity-FVC, forced expiratory volume in 0.5 sec-FEV0.5 and forced expiratory volume in first second-FEV1) in 47 healthy children, aged 4-6 years. To evaluate between-occasions reproducibility, 10 children (according to the sample size calculation) were reassessed after 3 weeks. Between-occasions reproducibility was evaluated by paired t-test, considering significant P < 0.05, Intraclass Correlation Coefficient (ICC) and coefficient of variation of method error (CV(ME)).

RESULTS

The results showed an 83% success rate for spirometry and a 98% success rate for plethysmography. Regarding reproducibility, there were no significant differences between the variables of any test. Spirometry ICC was above 0.80 and the CV(ME) was lower than 10%. The plethysmography ICC was between 0.61 and 0.95, and the CV(ME) was between 2% and 31%.

CONCLUSIONS

These results suggest a high success rate in performing the pulmonary function tests and good between-occasions reproducibility for spirometry and plethysmography in healthy preschoolers.

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.

Forced expiratory decay in asthmatic preschool children--is it adult type?

BACKGROUND

The forced expiratory decay in healthy preschool children portrays a convex shape that differs from the linear decay in the older healthy population. The "adult-type" expiratory decay during airway obstruction is concave. The study objective was to determine if the expiratory decay in young asthmatic children is "adult-type".

METHODS

Among 245 children (age 3-7 yrs), 178 had asthma (asthmatics) and 67 were non-asthmatic (controls). The expiratory flow decay was inspected by FEF25-75/FVC ratio (=1.0 when linear). Values were compared to those of our formerly studied (n = 108) healthy children. A meaningful obstruction in FEF25-75/FVC ratio was defined as 2-zScores from healthy. A meaningful response to bronchodilators was related to non-asthmatics.

RESULTS

In healthy subjects FEF25-75/FVC ratio declined with age from 1.73 ± 0.17 to 1.28 ± 0.11. Non-asthmatics portrayed ratio values similar to those of healthy subjects. In asthmatics, 118/178 displayed a convex to linear expiratory decay (FEF25-75/FVC = 1.33 ± 0.22). Sixty/178 asthmatics portrayed concavity (FEF25-75/FVC-0.79 ± 0.16) that appeared when FEF50 was 43.4 ± 12%healthy. Concavity appearance was also age-dependent (30.4% of 3-4 y old and 59.1% of 6-7 y). Vital-Capacity decreased in either decays, forming a visually petit curve. Most asthmatic children respond to bronchodilators by a meaningful elevation in FEF25-75/FVC values and by a visual change in the shape of the curve. Other common spirometry indices also increased meaningfully.

CONCLUSION

Most asthmatic preschool children portray convex to linear expiratory decay with diminished vital-capacity, resulting in a visually smaller than healthy curve, with seemingly normal expiratory decay. These curves may be misinterpreted as "normal" or as "no-cooperation" and may lead to misinterpretation. In response to bronchodilators, FEF25-75/FVC value increases in asthmatics and the curve changes from concave to linear or from linear to convex contour.

Quantification of shape of flow-volume loop of healthy preschool children and preschool children with wheezing disorders

BACKGROUND

The earliest change associated with airflow obstruction in small airways is reflected in a concave shape on the maximum expiratory flow-volume loop (MEFVL). The shape of the MEFL changes with age but reference values for curvilinearity indices (CI) for preschool children have not been published. We aimed to describe the normal curvilinearity of healthy preschool MEFVL by CI (the β angle and the ratio of maximum expiratory flow when 50% of forced vital capacity remains to be expired/peak expiratory flow (MEF(50%) /PEF)) and to test their capacity in detecting concavity in preschool children with wheezing disorders.

METHODS

Spirometric data were obtained from 132 healthy preschool children and 171 3-to-5-year-old preschool children with wheezing disorders and reference values for CI calculated.

RESULTS

Mean (SD) β angle of healthy children was 203° (16°) and mean MEF(50%) /PEF of healthy children was 0.71 (0.12) indicating convexity of MEFVL, both decreased with increasing age (P = 10(-4) ). Children with wheezing disorders had lower z-score values of CI (P ≤ 10(-6) ) indicating more concave MEFVL. Among the two CI, MEF(50%) /PEF allowed for the best discrimination between healthy children and children with wheezing disorders (Wilks' lambda = 0.898, P = 10(-7) ).

CONCLUSION

These CI can detect and quantify the concavity of the descending limb of the MEFVL in preschool children with wheezing disorders, MEF(50%) /PEF having the highest sensitivity in detecting the concavity.

Impulse oscillometry in the evaluation of diseases of the airways in children

OBJECTIVE

To provide an overview of impulse oscillometry and its application to the evaluation of children with diseases of the airways.

DATA SOURCES

Medline and PubMed search, limited to English language and human disease, with keywords forced oscillation, impulse oscillometry, and asthma.

STUDY SELECTIONS

The opinions of the authors were used to select studies for inclusion in this review.

RESULTS

Impulse oscillometry is a noninvasive and rapid technique requiring only passive cooperation by the patient. Pressure oscillations are applied at the mouth to measure pulmonary resistance and reactance. It is employed by health care professionals to help diagnose pediatric pulmonary diseases such asthma and cystic fibrosis; assess therapeutic responses; and measure airway resistance during provocation testing.

CONCLUSIONS

Impulse oscillometry provides a rapid, noninvasive measure of airway impedance. It may be easily employed in the diagnosis and management of diseases of the airways in children.

Viabilidade da realização de espirometria em pré-escolares

OBJETIVO: Determinar a taxa de sucesso na obtenção de resultados adequados de espirometria em pacientes pré-escolares. MÉTODOS: Foram analisados os resultados de espirometrias de crianças menores que 6 anos. Todos os testes foram realizados no Laboratório de Função Pulmonar do Hospital Infantil Jeser Amarante Faria, em Joinville (SC) entre junho de 2009 e fevereiro de 2010. O programa utilizado continha um incentivo de animação (bolhas de sabão).Os procedimentos foram realizados por um pneumologista infantil e obedeceram aos critérios de reprodutibilidade e aceitabilidade preconizados pela American Thoracic Society. Buscou-se atingir um tempo expiratório de pelo menos 1 s. Os seguintes parâmetros foram registrados: CVF, VEF0,5, VEF1 e relação VEF1/CVF. RESULTADOS: Nossa amostra consistiu de 74 crianças. A taxa de sucesso foi de 82%, com melhora no desempenho do teste em idades mais avançadas, mas sem significado estatístico (p > 0,05). Em média, foram necessárias 6,6 tentativas durante o exame para a obtenção de curvas aceitáveis e reprodutíveis. Todos os 61 testes bem sucedidos tiveram resultados de VEF0,5 e VEF1 satisfatórios. Através de escore Z, constatou-se que 21,6 % das crianças apresentavam com padrão obstrutivo. CONCLUSÕES: A taxa de sucesso da espirometria foi alta em nossa amostra, mostrando que esse é um método válido de avaliação da função pulmonar em pré-escolares. O uso de métodos de incentivo e a realização do teste por profissionais treinados no trabalho com crianças podem estar associados à elevada taxa de sucesso em nossa amostra

Clinically useful spirometry in preschool-aged children: evaluation of the 2007 American Thoracic Society Guidelines

RATIONALE

In 2007 the American Thoracic Society (ATS) recommended guidelines for acceptability and repeatability for assessing spirometry in preschool children. The authors aim to determine the feasibility of spirometry among children in this age group performing spirometry for the first time in a busy clinical practice.

METHODS

First-time spirometry for children age 4 to 5 years old was selected from the Children's Hospital Boston Pulmonary Function Test (PFT) database. Maneuvers were deemed acceptable if ( 1 ) the flow-volume loop showed rapid rise and smooth descent; ( 2 ) the back extrapolated volume (V(be)), the volume leaked by a subject prior to the forced maneuver, was ≤ 80 ml and 12.5% of forced vital capacity (FVC); and ( 3 ) cessation of expiratory flow was at a point ≤ 10% of peak expiratory flow rate (PEFR). Repeatability was determined by another acceptable maneuver with forced expiratory volume in t seconds (FEV(t)) and FVC within 10% or 0.1 L of the best acceptable maneuver. Post hoc analysis compared spirometry values for those with asthma and cystic fibrosis to normative values.

RESULTS

Two hundred and forty-eight preschool children performed spirometry for the first time between August 26, 2006, and August 25, 2008. At least one technically acceptable maneuver was found in 82.3% (n = 204) of the tests performed. Overall, 54% of children were able to perform acceptable and repeatable spirometry based on the ATS criteria. Children with asthma or cystic fibrosis did not have spirometry values that differed significantly from healthy controls. However, up to 29% of the overall cohort displayed at least one abnormal spirometry value.

CONCLUSIONS

Many preschool-aged children are able to perform technically acceptable and repeatable spirometry under normal conditions in a busy clinical setting. Spirometry may be a useful screen for abnormal lung function in this age group.

Lung function testing in preschool-aged children with cystic fibrosis in the clinical setting

In cystic fibrosis (CF) lung function testing is a means of monitoring progression of lung disease. The preschool years have often been referred to as the "silent years" due to the previous lack suitable measures of lung function testing in this age group. This review outlines the various techniques of lung function testing in preschool children with CF in the clinical setting. This includes measures requiring tidal breathing including the forced oscillation technique, the interrupter technique, plethysmography, and multiple breath washout, as well as spirometry that requires respiratory maneuvers. We describe the feasibility and variability of different lung function methods used in preschoolers and report measurements made during tidal breathing have greater feasibility, although greater variability compared to spirometry. We also report associations with lung function and markers of CF lung disease. In the preschool age group measurements made during tidal breathing may be more appropriate in the clinic setting than those that require a higher degree of cooperation and specific respiratory maneuvers.maneuvers.

Spirometric pulmonary function parameters of healthy Chinese children aged 3-6 years in Taiwan

Spirometry is a well-known technique for evaluating pulmonary function, but few studies have focused on preschool children. The aim of this study was to determine reference values of forced spirometric parameters in young Chinese children, aged 3-6 years, in Taiwan. Spirometric measurements were performed at day care centers by experienced pediatricians. Of 248 children without a history of chronic respiratory illness, at least two valid spirometric attempts were obtained from 214 children (109 boys and 105 girls; age: 36-83 [mean = 61] months; height: 90-131 [mean = 111] cm). Values of forced expiratory volume in 1 sec (FEV1) and 0.5 sec (FEV(0.5)), forced vital capacity (FVC), peak expiratory flow rate (PEF), forced expiratory between 25% and 75% FVC (FEF(25-75)), and forced expiratory flow rate at 25%, 50%, and 75% of FVC (FEF(25), FEF(50), and FEF(75)) were derived and analyzed. There were significant positive correlations between study parameters and body height, body weight, and age. Height was the most consistently correlated measurement in both boys and girls. Although boys tended to have higher spirometric values than girls, we found significant differences only in FVC and FEV1 between boys and girls aged 6 years. The regression equations of each parameter were obtained. In conclusion, spirometric pulmonary function tests are feasible in 3- to 6-year-old children. The obtained values and regression equations provide a reference for Chinese preschool children and may be of value in evaluating pulmonary function of children with respiratory problems in this age group.

Spirometry

Pulmonary function testing is useful for the diagnosis and management of a variety of pulmonary conditions, and the most commonly obtained component is spirometry. Spirometry is most useful in the evaluation of obstructive airway disorders but can be a helpful tool in the management of patients with chest restriction or mixed disease. The utility of spirometry depends on reproducibility, standardization, and quality of testing. Accurate interpretation of test results depends on the availability of reference equations applicable to the subject undergoing testing. This paper reviews basic concepts, testing procedures, and interpretation of a single set of spirometry results as well as results obtained over time and gives an overview of previously published reference equations.

Spirometry in an unselected group of 6-year-old children: the DARC birth cohort study

This study presents reference equations for spirometric parameters in 6-year-old children and evaluates the ability of spirometry to discriminate healthy children from children with asthma. Baseline spirometry and respiratory symptoms were assessed in 404 children participating in a longitudinal birth cohort study. Children with known asthma, possible asthma and a control group also performed bronchodilator measurements. At least two acceptable flow-volume curves at baseline were obtained by 368/404 children (91%). The two best values for FEV1 and FVC were within 5% of each other in 88% and 83% of children, respectively. Linear regression analyses for 242 children included in the reference population demonstrated height to be the main predictor of all spirometric indices except FEV1/FVC. FEV1, FEV75, and FVC correlated reasonably to anthropometric data in contrast to flow parameters. Gender differences were found for FEV1, FVC, and FEV75, but not for flow parameters. Asthma was diagnosed in 25/404 children. Baseline lung function in healthy children and children with asthma overlapped, although asthmatic children could be discriminated to some extent. Bronchodilator tests showed a difference in Delta FEV1(mean) between healthy children and children with asthma (3.1% vs. 6.1%, P < 0.05). At a cut-off point of Delta FEV1 = 7.8%, bronchodilator tests had a sensitivity of 46% and a specificity of 92% for current asthma. Spirometry including bronchodilator measurements was demonstrated to be feasible in 6-year-old children and reference values were determined. Spirometry aids the diagnosis of asthma in young children, but knowledge on sensitivity and specificity of these measurements is a prerequisite.

Spirometry in 5-year-olds--validation of current guidelines and the relation with asthma

INTRODUCTION

Spirometry is more frequently measured in younger children. Our primary aim was to validate 2005 ATS-ERS Task Force standards for spirometry in adults and older children among a population of 5-year-old children. Our secondary aim was to relate spirometry to asthma symptoms.

METHODS

Children were participants in a longitudinal cohort study where asthma symptoms and spirometry were assessed.

RESULTS

Of the 827 children assessed, spirometry was obtained in 638 (85 with wheeze). A back-extrapolated volume/FVC ratio of <5% was achieved in 99% of children, the best two FVC were < or =150 ml of each other in 89% and three efforts were obtained within six attempts in 88%. The best two FVC were within 10% of each other in 82% of children. Only 13% achieved a forced expiratory time (FET) of > or =3 sec, whereas 80% had an FET of > or =1 sec. All criteria (including FET > or =1 s and FVC < or =10%) were met in 400 (65%) of the 638 children. Most spirometric indices were reduced in association with current wheeze and a history of asthma; children with current wheeze had a mean reduction of 0.65 FEV(1) z score compared to healthy children, P < 0.001. An FEV(1) z score of -1.0 had 82% sensitivity but only 50% specificity for current wheeze, the corresponding numbers for an FEF(50) z score of -1.0 being 79% and 71%.

CONCLUSIONS

The standards for spirometry are mostly achieved in this age group but are not necessarily valid and require revision. Reliable spirometry is feasible in 5-year-old children where reduced measurements are associated with asthma symptoms and in whom FEF(50) appears to be the most discriminatory variable.

Reference ranges for spirometry across all ages: a new approach

RATIONALE

The Third National Health and Nutrition Examination Survey (NHANES III) reference is currently recommended for interpreting spirometry results, but it is limited by the lack of subjects younger than 8 years and does not continuously model spirometry across all ages.

OBJECTIVES

By collating pediatric data from other large-population surveys, we have investigated ways of developing reference ranges that more accurately describe the relationship between spirometric lung function and height and age within the pediatric age range, and allow a seamless transition to adulthood.

METHODS

Data were obtained from four surveys and included 3,598 subjects aged 4-80 years. The original analyses were sex specific and limited to non-Hispanic white subjects. An extension of the LMS (lambda, mu, sigma) method, widely used to construct growth reference charts, was applied.

MEASUREMENTS AND MAIN RESULTS

The extended models have four important advantages over the original NHANES III analysis as follows: (1) they extend the reference data down to 4 years of age, (2) they incorporate the relationship between height and age in a way that is biologically plausible, (3) they provide smoothly changing curves to describe the transition between childhood and adulthood, and (4) they highlight the fact that the range of normal values is highly dependent on age.

CONCLUSIONS

The modeling technique provides an elegant solution to a complex and longstanding problem. Furthermore, it provides a biologically plausible and statistically robust means of developing continuous reference ranges from early childhood to old age. These dynamic models provide a platform from which future studies can be developed to continue to improve the accuracy of reference data for pulmonary function tests.

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

Recent developments in pulmonary function tests (PFTs) in preschool children (2-5 years of age) have meant that objective assessments of respiratory function are now possible for this age group. However, the application and interpretation of these tests may be limited by the relative paucity of appropriate reference equations. This review summarizes available preschool reference equations, identifies the current gaps and limitations in the methodologies and statistics used and proposes future directions for improving reference data. A PubMed search which included the MeSH terms (preschool [2-5years]), (respiratory function test), and (reference value) yielded 214 publications which were screened to identify 34 publications presenting 36 reference equations for seven techniques. There were considerable differences with respect to population characteristics, recruitment strategies, equipment and methodologies and reported parameters both within and between each measurement technique. Despite an increasing number of reference equations for PFT for preschool children, the extent to which these can be generalized to other populations may be limited in some cases by inclusion of relatively few children less than 5 years of age, a lack of details regarding the sample populations and measurement techniques and/or inappropriate statistical analysis. A fresh approach based on large sample sizes, clearly documented population characteristics, equipment and protocols, and more rigorous modern statistical methods both for developing reference equations and interpreting results could enhance clinical application of these tests. This in turn would maximize the tremendous opportunities to detect early lung disease offered by the recent surge in developing suitable tests for preschool children.