Normal values for maximal static inspiratory and expiratory pressures in healthy children

Respiratory muscular strength in children with mucopolysacaridosis: comparison with predictive equations

BACKGROUND

Mucopolysaccharidoses (MPS) are rare metabolic diseases that impair respiratory function leading to respiratory failure. This study aimed to compare maximal inspiratory and expiratory pressures (MIP and MEP) obtained in children with MPS and compare with predicted values from previous studies involving healthy children.

METHODS

This is a cross-sectional study, in which the chest deformity was evaluated; MIP, MEP through digital manometer, and lung function through spirometry. MIP and MEP were compared with five different predict equations and with a control group of healthy children. Agreement between respiratory muscle weakness regarding absolute values of MIP and MEP in relation to predictive values by the equations included in the study were assessed by Kappa coefficient.

RESULTS

MPS group was composed of 22 subjects. 45.5% had pectus carinatum, 36.4% pectus excavatum, and presented lower MIP (37.14±36.23 cmH2O) and MEP (60.09±22.3 cmH2O) compared with control group (22 healthy subjects) (MIP: 91.45±35.60; MEP: 95.73±22.38). Only the MEP equations proposed by Tomalak et al. were close to those found in our MPS children (P=0.09). In the MPS group it was observed a weak agreement between inspiratory weakness through absolute and predicted values in only two equations: Tomalak et al. and Domenèch-Clar et al. (for both: k=0.35, P value =0.03); and for MEP a moderate agreement was found using all predictive equations.

CONCLUSIONS

In MPS children MRP data should not be normalized using the reference equations for healthy ones, is more coherent to longitudinally follow absolute pressures and lung volumes in this group.

Normal values for maximal respiratory pressures in children and adolescents: A systematic review with meta-analysis

BACKGROUND

The non-invasive assessment of maximal respiratory pressures (MRP) reflects the strength of the respiratory muscles.

OBJECTIVE

To evaluate the studies which have established normative values for MRP in healthy children and adolescents and to synthesize these values through a meta-analysis.

METHODS

The searches were conducted until October 2023 in the following databases: ScienceDirect, MEDLINE, CINAHL, SciELO, and Web of Science. Articles that determined normative values and/or reference equations for maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in children and adolescents published in English, Portuguese, or Spanish regardless of the year of publication were included. Two reviewers selected titles and abstracts, in case of conflict, a third reviewer was consulted. Articles that presented sufficient data were included to conduct the meta-analysis.

RESULTS

Initially, 252 studies were identified, 28 studies were included in the systematic review and 19 in the meta-analysis. The sample consisted of 5798 individuals, and the MIP and MEP values were stratified by sex and age groups of 4-11 and 12-19 years. Values from females 4-11 years were: 65.8 cmH2O for MIP and 72.8 cmH2O for MEP, and for males, 75.4 cmH2O for MIP and 84.0 cmH2O for MEP. In the 12-19 age group, values for females were 82.1 cmH2O for MIP and 90.0 cmH2O for MEP, and for males, they were 95.0 cmH2O for MIP and 105.7 cmH2O for MEP.

CONCLUSIONS

This meta-analysis suggests normative values for MIP and MEP in children and adolescents based on 19 studies.

New reference values for maximum respiratory pressures in healthy Brazilian children following guidelines recommendations: A regional study

OBJECTIVE

To determine reference values for maximum static respiratory pressures in healthy children from a Brazilian region, following recommendations of the European Respiratory Society (ERS) and the Brazilian Society of Pneumology and Tisiology (SBPT).

METHODS

A cross-sectional observational study was conducted with healthy children (6 to 11 years) of both sexes. The maximum inspiratory and expiratory pressures (PImax and PEmax, respectively) were measured using a digital manometer. Each child performed a minimum of three and a maximum of five maneuvers; three acceptable and reproducible maneuvers were considered for analysis. Minimum time for each maneuver was 1.5 seconds, with a one-second plateau, and one minute of rest between them. A stepwise multiple linear regression analysis was conducted for PImax and PEmax, considering correlations between independent variables: age, weight, and sex.

RESULTS

We included 121 children (62 girls [51%]). Boys reached higher values for maximum respiratory pressures than girls. Respiratory pressures increased with age showing moderate effect sizes (PImax: f = 0.36; PEmax: f = 0.30) between the stratified age groups (6-7, 8-9, and 10-11 years). Age and sex were included in the PImax equation (PImax = 24.630 + 7.044 x age (years) + 13.161 x sex; R2 = 0.189). PEmax equations were built considering age for girls and weight for boys [PEmax (girls) = 55.623 + 4.698 x age (years) and PEmax (boys) = 82.617 + 0.612 x weight (kg); R2 = 0.068].

CONCLUSIONS

This study determined new reference equations for maximal respiratory pressures in healthy Brazilian children, following ERS and SBPT recommendations.

The Influence of Surgical Correction of Idiopathic Scoliosis on the Function of Respiratory Muscles

Background and objective: It is important to introduce respiratory exercises to the therapy of patients after the surgical treatment of adolescent idiopathic scoliosis. Surgical correction is the best way to prevent hypoxia in scoliosis, but whether pulmonary rehabilitation increases the effectiveness of scoliosis surgery has not yet been confirmed. Therefore, the aim of the study was to evaluate the function of respiratory muscles after surgical correction of idiopathic scoliosis. Methods: The study involved 24 patients, aged 13.6 ± 0.6. Maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) were measured using the Mikro RPM. In all patients, before the procedure, 7 days after and 3 months after the procedure, the MIP and MEP were measured. Results: MIP was the lowest 7 days after the procedure; it was 45.28 cmH2O and was statistically significantly lower compared to the measurement before the procedure (p < 0.001) and 3 months after the procedure (p < 0.001). Conclusions: The degree of curvature of the spine before the procedure does not significantly affect initial values of the strength of respiratory muscles. The level of MIP is not dependent on the type of surgery.

Inspiratory muscle training in children and adolescents living with neuromuscular diseases: A pre-experimental study

Background

Children with neuromuscular diseases (NMD) are at risk of morbidity and mortality because of progressive respiratory muscle weakness and ineffective cough. Inspiratory muscle training (IMT) aims to preserve or improve respiratory muscle strength, thereby reducing morbidity and improving health-related quality of life (HRQoL).

Objectives

To describe the safety and feasibility of a 6-week IMT programme using an electronic threshold device (Powerbreathe®). Any adverse events and changes in functional ability, spirometry, peak expiratory cough flow (PECF), inspiratory muscle strength and HRQoL (Pediatric Quality of Life [PedsQL]) were recorded.

Methods

A convenience sample of eight participants (n = 4 boys; median [interquartile range {IQR}] age: 12.21 [9.63–16.05] years) with various NMD were included in a pre-experimental, observational pre-test post-test feasibility study. Training consisted of 30 breaths, twice daily, 5 days a week, for 6 weeks.

Results

There were significant pre- to post-intervention improvements in upper limb function and coordination (p = 0.03) and inspiratory muscle strength: maximum inspiratory mouth pressure (Pimax) (p = 0.01); strength-index (p = 0.02); peak inspiratory flow (PIF) (p = 0.02), with no evidence of change in spirometry, PECF or HRQoL. No adverse events occurred and participant satisfaction and adherence levels were high.

Conclusion

Inspiratory muscle training (at an intensity of 30% Pimax) appears safe, feasible and acceptable, in a small sample of children and adolescents with NMD and was associated with improved inspiratory muscle strength, PIF and upper limb function and coordination.

Clinical implications

Larger, longer-term randomised controlled trials are warranted to confirm the safety and efficacy of IMT as an adjunct respiratory management strategy in children with NMD.

Respiratory Muscle Strength in Healthy Indian Children of Age 7-17 Years: A Cross-Sectional Study

Purpose

As the values of respiratory muscle strength vary according to race, ethnicity, and geographical area, there is a wide-ranging difference among different populations. Thus, the available reference values may not have an application for use in the Indian paediatric population, creating a need for generating values which will be appropriate for the Indian paediatric context.

Materials and Methods

Assessment of respiratory muscle strength was carried out by assessing maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) and synthesising predictive formulas using anthropometric variables like height, gender and age, which will be suitable for Indian children.

Results

We calculated MIP and MEP of 320 (boys=160 and girls= 160) children in the age range of 7 years to 17 years of Mangaluru city, India. Results stated that mean MIP and MEP for boys were 72.5±32.8 cm H₂O and 73±33.2 cm H₂O, while for the girls it was 67±30.2 cm H₂O and 68±30.1 cm H₂O, respectively.

Conclusion

This study concluded that there is a difference in respiratory pressure values of Indian children with respect to those of other countries. Age, gender, height and BMI have a significant role in determining respiratory muscle strength. Boys demonstrated higher MIP and MEP. As age, height, weight and BMI increases, so does MIP and MEP.

Maximum Expiratory Flow of Children and Adolescents Living at Moderate Altitudes: Proposed Reference Values

(1) Background: Spirometry is useful for diagnosing and monitoring many respiratory diseases. The objectives were: (a) compare maximum expiratory flow (MEF) values with those from international studies, (b) determine if MEF should be evaluated by chronological age and/or maturity, (c) develop reference norms for children, and adolescents. (2) Methods: A cross-sectional study was designed with 3900 subjects ages 6.0 and 17.9 years old. Weight, standing height, sitting height, and MEF were measured. Length of the lower limbs, body mass index (BMI), and age of peak height velocity growth (APHV) were calculated. (3) Results: Values for the curves (p50) for females of all ages from Spain and Italy were higher (92 to 382 (L/min)) than those for females from Arequipa (Peru). Curve values for males from Spain and Italy were greater [70 to 125 (L/min)] than the males studied. MEF values were similar to those of Chilean students ages 6 to 11. However, from 12 to 17 years old, values were lower in males (25 to 55 (L/min)) and in females (23.5 to 90 (L/min)). Correlations between chronological age and MEF in males were from (r = 0.68, R2 = 0.39) and in females from (r = 0.46, R2 = 0.21). Correlations between maturity (APHV) and MEF for males were from (r = 0.66, R2 = 0.44) and for females (r = 0.51, R2 = 0.26). Percentiles were calculated for chronological age and APHV. Conclusion: Differences occurred in MEF when compared with other geographical regions of the world. We determined that maturity may be a more effective indicator for analyzing MEF. Reference values were generated using chronological age and maturity.

How Many Maneuvers Should We Do for Maximal Inspiratory and Expiratory Muscle Pressure Testing in Children: A Retrospective Review in Children with Cystic Fibrosis

OBJECTIVES

Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) could be useful clinical parameters in monitoring many conditions including cystic fibrosis (CF). However, current protocols for undertaking the measurements lack standardization including the number of repeated attempts to achieve best values. We aimed to (a) determine the optimum number of attempts to achieve best MIP/MEP values, and (b) evaluate if the number of attempts is consistent across two different test days.

METHODS

We analyzed data of a previous randomized controlled trial involving the effect of singing on respiratory muscle strength in 35 children with CF. On two different days (T1, T2) children performed MIP/MEP with at least ten attempts each to achieve < 10% repeatability.

RESULTS

All children achieved repeatable MIP/MEP values within 10-11 attempts with 24 (68.6%) and 26 (74.3%) of these achieving best values of MIP and MEP, respectively, at attempts 6-11. Median values of the pressures by three, five, eight and all attempts significantly increased with more attempts (all p < 0.05). At T2, 56% required fewer attempts to achieve best values, but 32% required more attempts, indicating that the number of attempts required was inconsistent between test days.

CONCLUSION

It is likely that at least ten attempts (best two within < 10% variability) is required to achieve best and reliable MIP/MEP in children with CF. A larger sample size in children with CF and various conditions is required to consolidate these findings.

Maximal Static Respiratory and Sniff Pressures in Healthy Children. A Systematic Review and Meta-Analysis

RATIONALE

Respiratory muscle strength in children can be assessed by maximal inspiratory pressures (MIP), maximal expiratory pressures (MEP), and sniff nasal inspiratory pressures (SNIP). However, previous studies involved small cohorts of healthy children and reported wide reference ranges.

OBJECTIVES

To perform a systematic review to summarize existing reference ranges for MIP, MEP, and SNIP tests in healthy children and to conduct a meta-analysis to develop comprehensive prediction equations.

DATA SOURCES

Five databases were searched for relevant studies from database inception to May 29, 2017.

DATA EXTRACTION

Study inclusion was limited to publications that evaluated MIP, MEP, and SNIP values in healthy children aged 18 years or younger. Studies were also excluded if testing methodology differed greatly from the 2002 American Thoracic Society Statement on Respiratory Muscle Testing. Requests for raw data were made to authors via e-mail.

SYNTHESIS

A total of 18 studies including 3,509 children were systematically reviewed. Diagnostic accuracy of the included studies was assessed using the QUADAS-2 tool, which revealed a high risk of bias for flow and timing and for applicability that may influence the generalizability of our findings. All 18 studies evaluated respiratory pressures in children in seated position. MIP tests were conducted from residual volume, MEP tests from total lung capacity, and SNIP tests from functional residual capacity. The MIP and MEP values in three age groups for boys and girls were summarized using meta-analysis based on individual participant data from five studies containing 1,709 healthy children. Further analyses showed that MIP and MEP were significantly greater in boys than in girls (P < 0.0001). In both sexes, MEP values were always greater than MIP values (P < 0.05). Multivariable random effects models were then performed to establish sex-specific prediction equations. These equations found age, height, and weight to be significant predictor variables. Only two studies with SNIP values from healthy children were included in the review, but they were not part of the meta-analysis.

CONCLUSIONS

We summarized the available reference ranges for MIP, MEP, and SNIP tests based on existing literature, especially for three age groups, and developed prediction equations that can be used in pulmonary function laboratories to aid clinicians. Existing literature on SNIP tests is limited, and future studies are encouraged to explore their use in children. Systematic review registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42017072004).

Inspiratory muscle training in severe spinal muscular atrophy: a case report

Background/Aims

Inspiratory muscle training aims to preserve or improve respiratory muscle strength in children with neuromuscular diseases in order to prevent or minimise pulmonary morbidity. The aim of this study was to determine the effect of inspiratory muscle training on clinical outcomes and health-related quality of life in a child with advanced neuromuscular disease and severe pulmonary restriction.

Methods

A one patient pre-test post-test study design was implemented. General function, spirometry, peak expiratory cough flow and health-related quality of life were measured at baseline and after a 6-week inspiratory muscle training programme. Inspiratory muscle strength (maximal inspiratory mouth pressure and sniff nasal inspiratory pressure) was measured every 2 weeks. The patient used a tapered flow threshold inspiratory training device (POWERbreathe K3) at an intensity of ± 30% of maximal inspiratory mouth pressure twice a day, 5 days per week.

Findings

The non-ambulatory 10-year-old girl with type 2 spinal muscular atrophy initially had a forced vital capacity of 18% predicted and peak expiratory cough flow of 60 litres/minute. A substantial improvement was seen in inspiratory muscle strength between baseline and 4 weeks. Patient health-related quality of life improved and patient satisfaction was high, with a score of 9/10. The patient developed a lower respiratory tract infection towards the end of the inspiratory muscle training period. No other adverse events occurred.

Conclusions

Improved inspiratory muscle strength and health-related quality of life was associated with inspiratory muscle training in a child with advanced spinal muscular atrophy. Controlled clinical trials are recommended to determine the safety and efficacy of inspiratory muscle training in children with advanced spinal muscular atrophy and severe respiratory muscle weakness to inform clinical practice.

Determinants of inspiratory muscle function in healthy children

BACKGROUND

Children are affected by disorders that have an impact on the respiratory muscles. Inspiratory muscle function can be assessed by means of the noninvasive tension-time index of the inspiratory muscles (TTImus). Our objectives were to identify the determinants of TTImus in healthy children and to report normal values of TTImus in this population.

METHODS

We measured weight, height, upper arm muscle area (UAMA), and TTImus in 96 children aged 6-18 years. The level and frequency of aerobic activity was assessed by questionnaire.

RESULTS

TTImus was significantly lower in male subjects (0.095 ± 0.038, mean ± SD) compared with female subjects (0.126 ± 0.056) (p = 0.002). TTImus was significantly lower in regularly exercising (0.093 ± 0.040) compared with nonexercising subjects (0.130 ± 0.053) (p < 0.001). TTImus was significantly negatively related to age (r = -0.239, p = 0.019), weight (r = -0.214, p = 0.037), height (r = -0.355, p < 0.001), and UAMA (r = -0.222, p = 0.030). Multivariate logistic regression analysis revealed that height and aerobic exercise were significantly related to TTImus independently of age, weight, and UAMA. The predictive regression equation for TTImus in male subjects was TTImus = 0.228 - 0.001 × height (cm), and in female subjects it was TTImus = 0.320 - 0.001 × height (cm) .

CONCLUSION

Gender, age, anthropometry, skeletal muscularity, and aerobic exercise are significantly associated with indices of inspiratory muscle function in children. Normal values of TTImus in healthy children are reported.

Reference Values for Respiratory Muscle Strength in Children and Adolescents

BACKGROUND

Measurement of respiratory muscle function is important in the diagnosis of respiratory muscle disease, respiratory failure, to assess the impact of chronic diseases, and/or to evaluate respiratory muscle function after treatment.

OBJECTIVES

To establish reference values for maximal inspiratory and expiratory pressure, and the tension-time index at rest in healthy children and adolescents aged 8-19 years, as well as to present sex- and age-related reference centiles normalized for demographic and anthropometric determinants.

METHODS

In this cross-sectional observational study, demographic, anthropometric, and spirometric data were assessed, as well as data on respiratory muscle strength (PImax and PEmax) and work of breathing at rest (TT0.1), in a total of 251 children (117 boys and 134 girls; mean age 13.4 ± 2.9 years). Reference values are presented as reference centiles developed by use of the lambda, mu, sigma method.

RESULTS

Boys had significantly higher PImax and PEmax values. Next to sex and age, fat-free mass appeared to be an important predictor of respiratory muscle strength. Reference centiles demonstrated a slight, almost linear increase in PImax with age in boys, and a less steep increase with age in girls. TT0.1 values did not differ between boys and girls and decreased linearly with age.

CONCLUSION

This study provides reference values for respiratory muscle strength and work of breathing at rest. In addition to sex and age, fat-free mass was found to be an important predictor of respiratory muscle strength in boys and girls.

Impact of sports activities on respiratory function and mechanics in children

Abstract Introduction: Being physically active in childhood may improve the quality of life in adulthood. So, it is extremely important to evaluate the respiratory function and mechanics of children who participate in sports activities, in order to determine the impact of physical activity on airway resistance. Objective: To analyze measures of respiratory function and mechanics in children who participate (PG) and who do not participate (CG) in sports activities regularly, as well as to compare and correlate the results. Methods: This is a cross-sectional analytical study of healthy school-aged children aged 6 to 12 years, assessed by impulse oscillometry tests (IOS) and spirometry. The sample was divided into PG and CG. The Student’s t-Test or Mann-Whitney test was used to compare the groups according to normality of data tested by the Shapiro-Wilk test. The correlation between the tests and age, sex, weight, height and body mass index (BMI) was performed using Pearson’s and Spearman correlation coefficient. Statistical data were processed by the SPSS® software, considering significance level at p < 0.05. Results: Forty children participated in the study, 20 in each group, with no differences regarding age, sex, weight, height and BMI. There were significant differences in FEF25-75% (CG: 94.19% ± 13.08 x PG: 101.75% ± 17.44, p = 0.049), and oscillometry data did not differ between both groups. Sex correlated with total airway resistance (R5 - p = 0.049, r = 0.314). Conclusion: In the group with children who participated in sports activities, FEF25-75% was higher, compared to the control group.

Predictive equations for maximal respiratory pressures of children aged 7-10

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Predictive equations allow comparisons between children with or without changes in respiratory muscle strength.

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Predictive equations facilitate the monitoring and control of physical therapy interventions.

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Age and biometric measurements had little influence on the values of maximal respiratory pressures.

Background

Measurements of respiratory muscle strength are widely used for assessment in children; however, clearly defined predictive equations for the Brazilian pediatric population have yet to be established.

Objective

To determine the prediction equations for maximal respiratory pressures in healthy children.

Method

Cross-sectional observational study with normal-weight students aged 7–10 years (n = 399, 198 boys) with health attested by the (International Study of Asthma and Allergies in Childhood) questionnaire and medical history. Biometric data were evaluated (weight, height, and body mass index) as predictors. Spirometry and maximal expiratory pressure values were measured according to the recommendations of the American Thoracic Society. To verify data normality, the Shapiro–Wilk test was applied, and Pearson's test was used to verify the correlation between variables. The models were developed using simple linear regression and multivariate analyses. For all tests, the significance level was p < 0.05.

Results

Boys showed higher values of maximal respiratory pressures than girls, both increasing with age. For boys, these values had moderate correlation with age, weight, and height and weak correlation with body mass index. For girls, maximum inspiratory pressure had a weak correlation with age and moderate correlation with biometric data. Maximum expiratory pressure had a moderate correlation with age and biometric measures. The best predictive models were found in boys: Log(MIP) = 1.577 + 0.006 × weight (kg) (R²_aj = 14.1%) and Log(MEP) = 1.282 + 0.409 × height (m) (R²_aj = 13.9%); and for girls: Log(MIP) = 1.548 + 0.006 × weight (kg) (R²_aj = 15.0%) and Log(MEP) = 1.524 + 0.012 × age (years) + 0.005 × weight (kg) (R²_aj = 21.6%).

Conclusion

Prediction equations for maximal respiratory pressures were developed for boys and girls. The biometric measurements were shown to have a weak influence on the results.

Analysis of Pulmonary Function Test in Korean Patients With Duchenne Muscular Dystrophy: Comparison of Foreign and Korean Reference Data

Objective

To determine the abnormal pulmonary function value in Korean Duchenne muscular dystrophy (DMD) patients, we performed a comparative analysis of the patients' pulmonary function value expressed as % of the overseas reference data and Korean healthy children and adolescent reference data.

Methods

We performed pulmonary function test (PFT) in a total of 27 DMD patients. We compared the patients' FVC% and FEV1% of the overseas reference data with those of the Korean children and adolescent reference data. Also, we compared the patients' MIP% and MEP% of the prediction equation data with those of the Korean children and adolescent reference data.

Results

Age of the subjects ranged from 8 to 16 years (12.03±2.27 years). The mean maximal expiratory pressure (MEP), maximal inspiratory pressure (MIP), vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak cough flow (PCF) were 36.93±9.5 cmH₂O, 45.79±17.46 cmH₂O, 1.4±0.43 L, 1.45±0.45 L, 1.40±0.41 L, and 206.25±61.21 L/min, respectively. The MIP%, MEP%, and FVC% of the Korean children and adolescent reference data showed statistically significant higher values than those of the prediction equation data.

Conclusion

We observed a clear numeric difference between Korean DMD patients' pulmonary function value expressed as % of the overseas data and inland data. To perform a precise assessment of respiratory function and to determine appropriate respiratory therapy, pulmonary function values of Korean DMD patients should be interpreted taking into account the inland normal pulmonary function test data.

Reference Equation for Respiratory Pressures in Pediatric Population: A Multicenter Study

Previous studies have proposed only one prediction equation for respiratory muscle strength without taking into consideration differences between ages in pediatric population. In addition, those researches were single-center studies. The objective of this study was to establish reference equations for maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax) in children and teenagers. In a multicenter study, 450 healthy volunteers were evaluated (aged 6–18yrs). There were included volunteers with normal lung function. We excluded volunteers who could not perform the tests; participated in physical activity more than twice a week; were born prematurely; smokers; chronic respiratory, cardiologic, and/or neurologic diseases; had acute respiratory disease during the prior three weeks. The volunteers were divided into two groups: Group 6–11 (6–11yrs) and Group 12–18 (12–18yrs). PImax and PEmax were measured according to statement. The mean PImax value was 85.6 (95%IC 83.6–87.6 cmH₂O), and PEmax 84.6 (95%IC 85.5–86.2 cmH₂O). The prediction equations for PImax and PEmax for Group 6–11 were 37.458–0.559 + (age * 3.253) + (BMI * 0.843) + (age * gender * 0.985); and 38.556 + 15.892 + (age * 3.023) + (BMI * 0.579) + (age * gender * 0.881), respectively (R² = 0.34 and 0.31, P<0.001). The equations for Group 12–18 were 92.472 + (gender * 9.894) + 7.103, (R² = 0.27, P = 0.006) for PImax; and 68.113 + (gender * 17.022) + 6.46 + (BMI * 0.927), (R² = 0.34, P<0.0001) for PEmax. This multicenter study determined the respiratory muscle strength prediction equations for children and teenagers.

[Respiratory muscle strength test: is it realistic in young children?]

Objective:

To determine the success rate of the manovacuometry test in children between 4 and 12 years of age.

Methods:

Cross-sectional study involving children and adolescents from 4 to 12 years of age, enrolled in three basic education schools. All subjects had the anthropometric and respiratory muscle strength (maximum inspiratory pressure and maximum expiratory pressure) data measured. Students whose parents did not authorize participation or who did not want to undergo the test were excluded. The test was considered successful when the subject reached acceptability (no air leaks) and reproducibility (variation <10% between the two major maneuvers) criteria established by guidelines. Failure was defined when subjects did not meet the above criteria. Data were expressed as mean and standard deviation and the categorical variables in absolute and relative frequency. The comparison between proportions was performed using the chi-square test.

Results:

We included 196 children and adolescents, mean age of 8.4±2.5 years, 53.1% female. The success rate of the manovacuometry test in children and adolescents evaluated was 92.3%. When comparing the differences between the success rates of preschool children with those children and adolescents of school age, there was a significantly lower success rate in the pre-school (85.1%) group compared to the school group (94.6%) (p=0.032). However, no significant differences (p=0.575) were found when gender comparisons were performed.

Conclusions:

The manovacuometry test showed a high success rate in both preschool and school population assessed. Furthermore, the rate of success appears to be related to aging.

Maximal respiratory pressures of healthy children: comparison between obtained and predicted values

PURPOSE

To compare maximal inspiratory and expiratory pressures (PImax and PEmax, respectively) obtained in Brazilian children who are healthy with reference and predicted values from previous studies.

METHODS

Respiratory muscle strength of 144 children (63 boys), aged 7 to 11 years, was assessed. A digital manovacuometer was used to measure PImax and PEmax from residual volume and total lung capacity, respectively. Children were assessed in the sitting position while wearing a nose clip.

RESULTS

Mean values of PImax for boys and girls were 81.6 ± 20.2 and 66.1 ± 19.5 cmH2O, respectively. Mean values of PEmax in boys and girls were 95.6 ± 21.1 and 78.9 ± 19.7 cmH2O, respectively.

CONCLUSIONS

Published reference values demonstrated a wide diversity across age groups studied, and published equations were not successful in predicting maximal respiratory pressures; thus, the assessment of respiratory muscle strength of children should consider the minimization of ethnic and methodological differences.

Normal values for inspiratory muscle function in children

Assessment of inspiratory muscle function (IMF) is limited in children with neuromuscular disorders, because respiratory muscle tests are poorly standardized and valid normative data are unavailable. We investigated maximum inspiratory pressure after exhalation to residual volume (MIP), mouth occlusion pressure (P0.1) and time of inspiration during quiet breathing and derived inspiratory muscle load (P0.1/MIP), and tension time index (TTI) in 301 healthy schoolchildren 6-16 years old. Gender-specific and age-dependent percentile curves for MIP were drawn with the median, 5%, 10%, 25%, 75% and 95% percentile. P0.1 was equal in boys and girls (0.23  ±  0.11 kPa), while MIP was significantly higher in boys (6.8  ±  2.2 versus 5.8  ±  2.4 kPa). Consequently, P0.1/MIP (4.8% ± 3.2% versus 4.0% ± 3.1%) and TTI (0.2  ±  0.14 versus 0.16  ±  0.14) were significantly higher in girls. MIP was 2.90 + 0.36 × age (kPa) and 3.19 + 0.24 × age (kPa) in boys and girls, respectively. The 95% confidence intervals for boys and girls, respectively, were MIP, 6.3-7.3 kPA and 5.4-6.2 kPa; P0.1/MIP, 3.5%-4.5% and 4.3%-5.3%; TTI, 0.14-0.18 and 0.18-0.22; and P0.1, 0.20-0.24 kPa for both. IMF in children has a wide interindividual variability; however percentile curves facilitate a longitudinal assessment of individual patients. Furthermore, narrow confidence intervals allow for comparisons of study populations, making IMF an appropriate endpoint for clinical trials.

Equações internacionais superestimam a força muscular ventilatória em crianças e adolescentes com fibrose cística

O objetivo deste estudo foi comparar os resultados da normalização dos dados de força muscular ventilatória utilizando-se três equações de referência internacionais e uma nacional em crianças e adolescentes com fibrose cística (FC). Estudo retrospectivo, no qual foram incluídos pacientes com FC, idade entre 8 e 12 anos e acompanhamento ambulatorial regular. Foram coletados dados demográficos e variáveis antropométricas. Todos os pacientes incluídos deveriam ter realizado teste de força muscular ventilatória e espirometria nos últimos 12 meses. A normalização dos resultados foi realizada utilizando-se as variáveis preditoras requeridas em cada equação estudada. Os dados foram comparados utilizando-se uma ANOVA de uma via. Foram incluídos 24 pacientes, 62,5% masculinos, média de idade 10,5±1,53 anos, estatura 138,0±0,08 cm, massa corporal 34,6±9,07 kg, VEF1 93,29±29,02% e CVF 103,78±26,12%. As pressões (cmH2O) inspiratória (PIMAX) e expiratória (PEMAX) máximas encontradas foram 92,1±22,8 e 98,9±24,5, respectivamente. Após a normalização pelas diferentes equações, demonstrou-se que as internacionais tendem a superestimar os achados para a nossa população. A equação nacional apresentou valores médios previstos significativamente (p<0,05) menores para PIMAX e PEMAX em comparação com as equações internacionais, sendo que estas classificariam a PIMAX como acima do normal (>100%) em 91,6, 79,1, e 75,0% dos sujeitos e a PEMAX em 66,6, 87,5 e 50%, enquanto a equação nacional estimaria apenas 50,0 e 37,5% dos indivíduos, respectivamente. A normalização dos resultados de força muscular ventilatória em crianças e adolescentes entre 8 e 12 anos com FC utilizando-se equações internacionais superestimam os valores das pressões respiratórias máximas.

Maximal respiratory pressure reference values for Navajo children ages 6-14

BACKGROUND

Since anthropometric variables are critical to the creation of pulmonary nomograms for FVC, FEV1, and other volumes and capacities, it is logical that anthropometric variables also influence the values of the maximal respiratory pressures (MRPs). Since nomograms are race-specific, it is important that tribe-specific tables of normal maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) be developed. To date normal tables for MRPs do not exist for Navajo children.

OBJECTIVE

Therefore the purpose of this study was to derive MRP normative reference values for Navajo children in the age range of 6-14 years.

METHODS-PARTICIPANTS AND MEASUREMENTS

A cross-sectional study was undertaken with a representative sample of 534 healthy children, ages 6-14 years, attending Navajo Nation elementary schools in Arizona. MIP and MEP were measured.

RESULTS

Test results from 275 girls and 259 boys met American Thoracic Society quality control standards and showed that MRPs all increased with height. Mean MIP in cm H2 O was 77 for boys and 67 for girls with lower limits of 44 and 40, respectively. Mean MEP in cm H2 O was 75 for boys and 66 for girls with the lower limits of 42 and 38, respectively.

CONCLUSION

Since the data were collected from the population of interest, the resulting MIP and MEP reference equations should be used when testing Navajo children ages 6-14 years.

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.

Relationships between respiratory muscle strength and daily living function in children with cerebral palsy

Cerebral palsy (CP) is a common childhood disorder characterized by motor disability. Children with CP are at risk of developing significant respiratory problems associated with insufficient respiratory muscle strength. It is crucial to identify important factors which are associated with the limitations in daily living function in such children. Hence, the aim of this study was to investigate the relationship between respiratory muscle strength and daily living function in children with CP. The participants were 30 children with CP (M±SD age, 8.7±2.1 years) and 30 children with typical development (M±SD age, 8.3±0.9 years). Respiratory muscle strength was measured by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) for the both groups of children. Children with CP were also assessed on daily living function with the subscales of Pediatric Evaluation of Disability Inventory (PEDI), the Functional Skills Scales (PEDI-FSS) and the Caregiver Assistance Scale (PEDI-CAS). Results show that, compared to the children with typical development, the MIP and MEP in the CP group were significantly lower (p=.003 and p=.001, respectively). In the CP group, MIP and MEP were correlated to two of the three PEDI-FSS domain scores (r=.43-.53, p<.05) but not with the three PEDI-CAS domain scores. MET explained 19% of the variance in the self-care domain score of PEDI-FSS. MEP also explained 15% of the variance in the social domain score of PEDI-FSS. The results of this study demonstrate that respiratory muscle strength in children with CP is correlated positively to their capability levels of daily living self-care and social function, and we suggest this should be taken into account when planning intervention to improving ability of daily living function for children with CP.

Comparação das pressões respiratórias máximas entre escolares das redes pública e privada

OBJETIVO: Comparar os valores obtidos das pressões inspiratórias máximas (PImáx) e pressões expiratórias máximas (PEmáx) entre estudantes das redes pública e privada de ensino. MÉTODOS: Estudo observacional do tipo descritivo transversal. Foram avaliadas 144 crianças nas duas redes de ensino. As pressões respiratórias máximas foram mensuradas com o MVD300 (Globalmed®). Aplicou-se o teste t de Student não pareado para comparar as médias das variáveis estudadas e o teste do qui-quadrado para comparar a frequência de crianças que realizavam ou não atividade física. RESULTADOS: Os alunos das escolas privadas e públicas apresentaram, respectivamente, média de PImáx 77,0±21,5 e 65,7±18,7cmH2O (p=0,002) e PEmáx 90,1±22,5 e 79,4±19,0cmH2O (p=0,005). Os meninos, das escolas privadas e públicas, apresentaram médias de PImáx 85,0±20,8 e 74,4±17,1cmH2O (p=0,051) e PEmáx 98,5±2,5 e 89,2±16,3cmH2O (p=0,103), respectivamente. As meninas, das escolas privadas e públicas, apresentaram médias de PImáx 70,0±19,8 e 60,2±17,8cmH2O (p=0,027) e PEmáx 82,6±20,0 e 73,2±18,1cmH2O (p=0,035), respectivamente. Aproximadamente 40% dos alunos da rede pública e 95% dos alunos da rede privada realizavam atividade física. As crianças que realizavam ou não atividade física apresentaram PImáx 76,0±20,7 e 63,2±20,0cmH2O (p=0,002) e PEmáx 89±21,6 e 77,4±20,5cmH2O (p=0,006), respectivamente. CONCLUSÕES: A força muscular respiratória dos alunos da rede privada foi significativamente superior à dos alunos da rede pública, especialmente entre as meninas. Possivelmente, essa diferença esteja relacionada à prática de atividade física, mais frequentemente observada nas escolas privadas.

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.

Changes in the FEV₁/FVC ratio during childhood and adolescence: an intercontinental study

In children, the ratio of forced expiratory volume in 1 s (FEV₁) to forced vital capacity (FVC) is reportedly constant or falls linearly with age, whereas the ratio of residual volume (RV) to total lung capacity (TLC) remains constant. This seems counter-intuitive given the changes in airway properties, body proportions, thoracic shape and respiratory muscle function that occur during growth. The age dependence of lung volumes, FEV₁/FVC and RV/TLC were studied in children worldwide. Spirometric data were available for 22,412 healthy youths (51.4% male) aged 4-20 yrs from 15 centres, and RV and TLC data for 2,253 youths (56.7% male) from four centres; three sets included sitting height (SH). Data were fitted as a function of age, height and SH. In childhood, FVC outgrows TLC and FEV₁, leading to falls in FEV₁/FVC and RV/TLC; these trends are reversed in adolescence. Taking into account SH materially reduces differences in pulmonary function within and between ethnic groups. The highest FEV₁/FVC ratios occur in those shortest for their age. When interpreting lung function test results, the changing pattern in FEV₁/FVC and RV/TLC should be considered. Prediction equations for children and adolescents should take into account sex, height, age, ethnic group, and, ideally, also SH.

Effects of inspiratory muscle training in cystic fibrosis: a systematic review

OBJECTIVE

We performed a systematic review to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and endurance, exercise capacity, dyspnoea and quality of life for adolescents and adults living with cystic fibrosis.

DATA SOURCES

MEDLINE, EMBASE and CINAHL electronic databases were searched up to January 2008.

REVIEW METHODS

We performed a systematic review using the methodology outlined in the Cochrane Collaboration protocol. Articles were included if: (1) participants were adolescents or adults with cystic fibrosis (> 13 years of age); (2) an IMT group was compared to a sham IMT, no intervention or other intervention group; (3) the study used a randomized controlled trial or cross-over design; and (4) it was published in English. Data were abstracted and methodological quality was assessed independently by two reviewers.

RESULTS

The search strategy yielded 36 articles, of which two met the inclusion criteria. Both studies used a targeted or threshold device for IMT. Meta-analyses were limited to forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC), which showed no difference in effect between the IMT group and the sham and/or control group. Individual study results were inconclusive for improvement in inspiratory muscle strength. One study demonstrated improvement in inspiratory muscle endurance.

CONCLUSION

The benefit of IMT in adolescents and adults with cystic fibrosis for outcomes of inspiratory muscle function is supported by weak evidence. Its impact on exercise capacity, dyspnoea and quality of life is not clear. Future research should investigate the characteristics of the subgroup of people with cystic fibrosis that might benefit most from IMT.

Cough peak flows: standard values for children and adolescents

OBJECTIVE

We describe the distribution of cough peak flows (CPFs) in a random population of healthy children and adolescents.

DESIGN

Spirometric and peak expiratory flows including CPF data were collected on 649 (341 females, 308 males) healthy children ages 4-18 yrs, using a portable spirometer and a peak flow meter. CPFs were related to anthropometric characteristics, age, and gender by linear multiple regression analysis. Reference values for CPF were estimated through regression models and calculation of empirical percentiles of data distribution.

RESULTS

Other than peak expiratory flow rate, which was normally distributed, all other variables required logarithmic transformation to attain normal distribution. Significant relationships were found between CPF and gender, height, and body mass surface (P < 0.001) in both males and females. Age, even if correlated with CPF, does not add predictive value to the model. Fiftieth percentiles were from 147 to 488 liters/min and from 162 to 728 liters/min in females and males, respectively, through an age range of 4-18 yrs, with levels in males being generally higher than those in females at any particular age. CPF values also significantly correlated with other respiratory variables.

CONCLUSIONS

The availability of reference levels for CPF in the pediatric population, as provided by this study, could be useful for establishing the risk of acute respiratory complications for young patients with weak coughs, particularly those with neuromuscular disease and restrictive pulmonary syndromes.

Avaliação da força muscular respiratória em crianças e adolescentes com sobrepeso/obesos

OBJETIVO: Avaliar a força muscular respiratória de crianças e adolescentes com sobrepeso ou obesidade. MÉTODOS: Estudo transversal com crianças e adolescentes entre quatro e 15 anos de idade de duas instituições de ensino fundamental e uma clínica de nutrição. As crianças foram avaliadas e classificadas em dois grupos, de acordo com a curva proposta pelo National Center for Health Statistics: sobrepeso/obesos (GSO, índice de massa corpórea (IMC) em relação à idade e ao sexo acima do percentil 85) e eutróficos (GE, IMC entre percentil 5 e 85). Para avaliar as pressões inspiratória máxima (PImax) e expiratória máxima (PEmax) foram realizadas três medidas com um manovacuômetro, considerando-se a maior medida a partir da capacidade máxima inspiratória e expiratória. Aplicou-se o teste t para as variáveis quantitativas e o qui-quadrado para as qualitativas. Para ajuste das covariáveis, foi feita a análise de covariância, sendo significante p<0,05. RESULTADOS: Foram avaliadas 69 crianças: 37 (54%) do GSO e 32 (46%) eutróficos. O GSO apresentou menor idade (9,8±2,3 versus 10,9±1,9 anos; p=0,03). A PImax foi 71,4±24,9cmH2O no GSO e 89,6±19,6cmH2O nos eutróficos (p=0,002). A PEmax foi 71,9±24,8cmH2O no GSO e 95,6±19,6cmH2O nos eutróficos (p<0,001). Não houve diferenças quanto ao sexo e à prática de atividade física. Ajustando-se os valores em relação à idade, somente a PEmax manteve-se diferente entre os grupos (p=0,003). CONCLUSÕES: A força muscular expiratória mostrou-se diminuída nesta amostra de crianças e adolescentes com sobrepeso/obesidade, indicando que a obesidade pode comprometer a mecânica pulmonar dessa população.

[Respiratory dynamics measurements in children with four to ten years of age]

BACKGROUND

respiratory dynamics measurements are frequently used in the speech-language pathology practice, but few are the scientific data for children.

AIM

to study the respiratory dynamics in children with nasal breathing.

METHOD

the study was performed with a stratified random sample of 106 nasal breathing children, male and female, from schools of the city of Marília-SP, with ages between four and ten years. The following measurements were obtained: vital capacity (VC) in both standing and sitting positions, with and without nasal occlusion; maximum phonation time (MPT) of sustained vowels and consonants and also of speech when counting numbers.

RESULTS

the mean values for VC in the standing position with and without nasal occlusion were of 1515.56ml and 1538.67ml respectively and for the sitting position of 1524ml and 1539.15ml respectively. MPT of vowels in seconds were: /a/ = 8.32, /i/ = 8.61 and /ul = 8.42; of consonants: /s/ = 6.64 and /z/ = 7.65; and when counting numbers: 7.76. It was observed that the mean values of these measurements progressively increased according to age. There was a statistically significant difference (p<0.05) not only for the MPT of vowels but also for the MPT of consonants in older children, i.e. between 4 and 10 year olds, 4 and 9 year olds and 4 and 8 year olds. There was no significant statistical difference for the VC values in consecutive age groups. There was a strong association between VC and the child's physical development.

CONCLUSION

this study presented respiratory dynamics measurements in children that can be used for the spech-language diagnosis and therapy. Other studies should be developed in order to bring additional information on the subject.

Measurement of maximal pressures and the sniff manoeuvre in children

Maximal static inspiratory and expiratory pressures are simple, noninvasive tests that evaluate global inspiratory and expiratory muscle strength. But these tests may be difficult or impossible to perform in young children. The sniff is a natural maneuver which many children find easier to perform than maximal pressures. The measurement of the nasal inspiratory pressure represents a valuable inspiratory muscle test which allows the extension of inspiratory muscle testing to a younger and larger paediatric population.

Influência do método Reequilíbrio Toracoabdominal sobre a força muscular respiratória de pacientes com fibrose cística

OBJETIVO: Avaliar o efeito do método Reequilíbrio Toracoabdominal na força dos músculos respiratórios de pacientes com fibrose cística, acompanhados no Ambulatório de Fibrose Cística da Universidade Católica de Brasília. MÉTODOS: A amostra, constituída de 29 fibrocísticos, foi caracterizada com base em dados antropométricos, genéticos e de colonização bacteriana. Espirometria, manovacuometria e antropometria foram realizadas antes e depois do tratamento fisioterapêutico, no qual se utilizou o método Reequilíbrio Toracoabdominal, duas vezes por semana, durante quatro meses. RESULTADOS: Houve aumento da pressão inspiratória máxima e da pressão expiratória máxima após o tratamento fisioterapêutico em todos os pacientes, naqueles sem distúrbio ventilatório obstrutivo e naqueles com distúrbio ventilatório obstrutivo leve (p < 0,05). Foi encontrada correlação positiva entre a idade e a pressão expiratória máxima para a maioria dos grupos. A pressão inspiratória máxima só apresentou correlação positiva com a idade no grupo com distúrbio ventilatório obstrutivo leve (p = 0,012; r = 0,817). Para o sexo feminino e para o grupo sem distúrbio ventilatório obstrutivo houve correlação negativa entre a pressão expiratória máxima e a colonização por Pseudomonas aeruginosa (p = 0,036; r = -0,585). CONCLUSÃO: Para os fibrocísticos avaliados, o método Reequilíbrio Toracoabdominal aumentou a força dos músculos respiratórios, o que reafirma a importância do tratamento fisioterapêutico para estes pacientes.

Effect of body position on maximal expiratory pressure and flow in adults with cystic fibrosis

Maximum expiratory pressure (MEP) and peak expiratory flow rate (PEFR) are used as surrogate measures of cough and huff strength. Some body positions (particularly head-down tilt) significantly affect these measures in people with normal respiratory function and with chronic obstructive pulmonary disease. This may have implications for people with cystic fibrosis (CF), who use coughing and huffing and may use gravity-assisted drainage positions for airway clearance. Previous research concluded that body position does not affect MEP in people with CF, although head-down tilt was not examined and PEFR was not measured. This study investigated the effect of body position on MEP and PEFR in 20 adults with stable CF. Repeated measures of MEP and PEFR were performed across seven positions (standing, chair-sitting, sitting in bed with backrest vertical, sitting in bed with backrest at 45 degrees , supine, side-lying, and side-lying with head-down tilt 20 degrees ) in random order. During testing, reflux sensation and oxygenation were monitored. MEP was significantly reduced in side-lying and in the head-down tilt position. PEFRs were significantly reduced in the three-quarters sitting, supine, side-lying, and head-down positions. Oxygenation and reflux scores were worst in the head-down position. Despite statistical significance, the differences observed between positions in this stable population were of small magnitude. The effect of body position on MEP and PEFR may be more relevant during airway clearance treatments of the acutely unwell person with CF.

Formoterol delivered via a new multi-dose dry powder inhaler (Certihaler) is as effective and well tolerated as the formoterol dry powder inhaler (Aerolizer) in children with persistent asthma

The Certihaler is a new multi-dose dry powder inhaler for the delivery of formoterol (Foradil), a long-acting beta(2)-agonist. This dose-ranging study compared the efficacy and safety of formoterol 5, 10, 15 and 30 microg and placebo administered via the Certihaler or formoterol 12 microg via a single-dose dry powder inhaler (Aerolizer) in children with persistent asthma. This was a randomized, placebo-controlled, double-blind, double-dummy, incomplete block crossover, dose-finding and pharmacokinetic study. Children (5-12 years, n = 77) received four of the active treatments twice weekly (BID) for 1 week separated by 1-week single-blind washouts. The primary efficacy variable was 12-h AUC of FEV(1) after 1 week's treatment. Secondary variables included serial 12-h FEV(1). A subset of patients (n = 37) participated in a pharmacokinetic analysis. All formoterol doses resulted in significant increases in 12-h AUC of FEV(1) compared with placebo, and there was no difference between active treatments. The onset of action of formoterol was <3 min for all active treatments. Doses of formoterol > or =10 microg via the Certihaler increased FEV(1) significantly for up to 12 h compared with placebo. The 5 microcg dose via the Certihaler and 12 microg dose via the Aerolizer had a significant effect up to 8 and 7 h post-dose, respectively. Urinary excretion of formoterol via the Certihaler increased in a dose-proportional manner. All formoterol doses were well tolerated, but some patients experienced tremor at the 15 and 30 microg doses. Despite the lack of significant differences between the active doses in the overall bronchodilation, formoterol 10 microg BID via the Certihaler was the dose that provided the best balance between efficacy and tolerability: its duration of action was sustained over 12 h, contrary to that the lower dose (5 microg BID), whereas its tolerability, especially with regard to tremor, was better than the higher doses (15 and 30 microg BID). Overall, Certihaler 10 microg BID was not significantly different from formoterol 12 microg BID via Aerolizer.

Reference values for forced inspiratory flows in children aged 7-15 years

In order to construct reference equations, we attempted to measure forced inspiratory flows, i.e., peak inspiratory flow (PIF) and maximal inspiratory flow at 50% of FVC (MIF50%FVC) in 332 healthy schoolchildren aged 7-15 years during flow-volume loop measurements, using an electronic spirometer. In 255 children (122 boys and 133 girls), the results were satisfactory. Statistical analysis revealed that the only predictive variables were sex and height. The best fit of the data was obtained with the power model (Y = A * H(B)); the coefficients of correlation between flows and height ranged from 0.66-0.77, and were slightly greater for boys. Forced inspiratory flows in children increase with height, and the variability is higher than for forced expiratory flows. Reference values for forced inspiratory flows can be useful in assessing the ability of children to generate affective inspiratory flows for choosing an inhalation device, or in resolving diagnostic problems, e.g., extrathoracic obstruction.