Comparison of maximal midexpiratory flow rate and forced expiratory flow at 50% of vital capacity in children

Clinical features and outcomes of small airway disease in ANCA-associated vasculitis

BACKGROUND AND OBJECTIVE

To clarify the prevalence, features and outcomes of small airway disease (SAD) in a Chinese cohort with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) related pulmonary involvement.

METHODS

SAD was recorded when the manifestations of either centrilobular nodules or air trapping were observed according to CT scans, except for infection or other airway-related comorbidities. Baseline and follow-up data were collected retrospectively.

RESULTS

Of the 359 newly diagnosed AAV patients with pulmonary involvement, 92 (25.6%) had SAD, including 79 (85.9%) cases of anti-MPO-ANCA positive, 9 (9.8%) cases of anti-PR3-ANCA positive and 2 (2.2%) cases of double positive. Patients with SAD were more likely to be younger, female, non-smokers, have more ear-nose-throat (ENT) involvement, and have higher baseline Birmingham Vasculitis Activity Score (BVAS) compared to patients without SAD. Several AAV-related SAD patients have improved lung function and CT scans after immunosuppressive therapy. Patients with SAD had a better prognosis compared to those without SAD. When dividing all patients into three groups: isolated SAD (only small airway involvements), SAD with other lower airway involvements, and non-SAD, patients in the SAD with other lower airway involvements group had the highest risk of infection, while patients in the non-SAD group had the worst long-term outcomes. Similar results were observed in anti-MPO-ANCA positive patients when performing subgroup analyses.

CONCLUSION

SAD is a unique manifestation of AAV-related lung involvement and exhibits distinct clinical features. It is vital to focus on SAD because of its association with prognosis and infection in AAV patients, especially in anti-MPO-ANCA positive patients. Moreover, SAD might represent a better response to immunosuppressors.

Serum macrophage migration inhibitory factor as a potential biomarker to evaluate therapeutic response in patients with allergic asthma: an exploratory study

BACKGROUND: Previous studies have shown that macrophage migration inhibitory factor (MIF) is involved in the pathogenesis of asthma. This study aimed to investigate whether serum MIF reflects a therapeutic response in allergic asthma. METHODS: We enrolled 30 asthmatic patients with mild-to-moderate exacerbations and 20 healthy controls, analyzing the parameter levels of serum MIF, serum total immunoglobulin E (tIgE), peripheral blood eosinophil percentage (EOS%), and fractional exhaled nitric oxide (FeNO). Lung function indices were used to identify disease severity and therapeutic response. RESULTS: Our study showed that all measured parameters in patients were at higher levels than those of controls. After one week of treatment, most parameter levels decreased significantly except for serum tIgE. Furthermore, we found that serum MIF positively correlated with EOS% as well as FeNO, but negatively correlated with lung function indices. Receiver operator characteristic (ROC) curve analysis indicated that among the parameters, serum MIF exhibited a higher capacity to evaluate therapeutic response. The area under the curve (AUC) of MIF was 0.931, with a sensitivity of 0.967 and a specificity of 0.800. CONCLUSIONS: Our results suggested that serum MIF may serve as a potential biomarker for evaluating therapeutic response in allergic asthma with mild-to-moderate exacerbations.

Small airways in children with allergic rhinoconjunctivitis: the potential role of a multicomponent nutraceutical

Allergic rhinitis and asthma are closely linked. A progression from rhinitis to overt asthma is common. FEF_25-75 is a spirometry parameter that could reflect small airways patency and could reliably predict early bronchial involvement in allergic rhinitis patients. MEF₅₀ very strongly correlates with FEF_25-75. The aim of this study was to evaluate possible spirometry change in two groups of children suffering from AR over time. The first group took a course of a nutraceutical (Lertal®) before the observation (active group, AG); a second one was considered as control (control group, CG). The children were visited at baseline, at the end of the nutraceutical course, and after 1 year. FEV₁, FVC, and MEF₅₀ were the primary outcomes. After one year, children in AG had significantly higher MEF₅₀ than CG children (p=0.009). In conclusion, the present study showed that a course with a multicomponent nutraceutical could prevent the MEF₅₀ decline in children with allergic rhinoconjunctivitis. (www.actabiomedica.it)

Reference value for expiratory time constant calculated from the maximal expiratory flow-volume curve

BACKGROUND

The expiratory time constant (RCEXP), which is defined as the product of airway resistance and lung compliance, enable us to assess the mechanical properties of the respiratory system in mechanically ventilated patients. Although RCEXP could also be applied to spontaneously breathing patients, little is known about RCEXP calculated from the maximal expiratory flow-volume (MEFV) curve. The aim of our study was to determine the reference value for RCEXP, as well as to investigate the association between RCEXP and other respiratory function parameters, including the forced expiratory volume in 1 s (FEV1)/ forced vital capacity (FVC) ratio, maximal mid-expiratory flow rate (MMF), maximal expiratory flow at 50 and 25% of FVC (MEF50 and MEF25, respectively), ratio of MEF50 to MEF25 (MEF50/MEF25).

METHODS

Spirometric parameters were extracted from the records of patients aged 15 years or older who underwent pulmonary function testing as a routine preoperative examination before non-cardiac surgery at the University of Tokyo Hospital. RCEXP was calculated in each patient from the slope of the descending limb of the MEFV curve using two points corresponding to MEF50 and MEF25. Airway obstruction was defined as an FEV1/FVC and FEV1 below the statistically lower limit of normal.

RESULTS

We retrospectively analyzed 777 spirometry records, and 62 patients were deemed to have airway obstruction according to Japanese spirometric reference values. The cut-off value for RCEXP was 0.601 s with an area under the receiver operating characteristic curve of 0.934 (95% confidence interval = 0.898-0.970). RCEXP was strongly associated with FEV1/FVC, and was moderately associated with MMF and MEF50. However, RCEXP was less associated with MEF25 and MEF50/MEF25.

CONCLUSIONS

Our findings suggest that an RCEXP of longer than approximately 0.6 s can be linked to the presence of airway obstruction. Application of the concept of RCEXP to spontaneously breathing subjects was feasible, using our simple calculation method.

Chronic obstructive pulmonary disease: an overview

As chronic obstructive pulmonary disease (COPD) is one of the major causes of worldwide mortality, it is important to prevent, diagnose and manage it. COPD creates a huge burden on the NHS and has a significant impact on patients. This is a problem with the increase in morbidity and mortality rates. In primary care there is a lack of knowledge, under-use of quality-assured spirometry and under-diagnosis in about half of all cases. To be able to effectively diagnose, assess and manage COPD, health professionals must understand the physiology and aetiology of the disease. COPD is similar to asthma in its presentation and physiology but management of the condition can differ. The authors therefore looked at the similarities between the two conditions and what tests one can use to make a diagnosis of COPD.

Assessment of Airway Bronchodilation by Spirometry Compared to Airway Obstruction in Young Children with Asthma

A reversibility test by an increase of greater than 12% in FEV1 can support a diagnosis of asthma and alter a patient's treatment plan but may not be applicable to the young ages. We retrospectively gathered spirometric data from 85/271 asthmatic children having mild obstruction (FEV1 > 80% predicted), age 2.6-6.9 years. Spirometry was performed before and 20 min after inhalation of 200 mcg Albuterol. We defined a deviation below -1.64 z scores from control as obstruction and an increased above 1.64 scores from control as a positive response to bronchodilators. Sensitivity of the index was considered significant if it captured >68% of the participants. The sensitivity of detecting airway obstruction in these children by FEV1 was 15.3% and 62.4% by FEF25-75. A positive response to Albuterol was an increase of 9.2% for FEV1 (12% for adults) and 18.5% for FEF25-75. The sensitivity for detecting a response to Albuterol in mild asthma was 64.7% by FEV1 and 91.8% by FEF25-75. Young children having normal spirometry can demonstrate airway reversibility. The response of spirometry parameters to bronchodilators may be more sensitive than obstruction detection and may help to support the diagnosis of asthma and adjust treatment plan.

Patterns of changes and diagnostic values of FEF50%, FEF25%-75% and FEF50%/FEF25%-75% ratio in patients with varying control of bronchial asthma

BACKGROUND

The pattern of change in FEF50%, FEF25%-75% and FEF50%/FEF25%-75% ratio depends on mechanics of forceful expiration, provided that non-homogenous lung emptying is faithfully recorded in the expiratory flow-volume loops.

OBJECTIVE

To assess the potential clinical value of FEF50%, FEF25%-75% and FEF50%/FEF25%-75% ratio as an indicator of bronchial asthma (BA) control.

METHODOLOGY

The study involved 75 patients with BA matched for age and gender with 45 non-asthmatic subjects. Based on asthma control test (ACT) and spirometry, asthmatic patients were subdivided into controlled and poorly controlled/uncontrolled. The relationship between FEF50% and FEF25%-75% as well as FEF50%/FEF25%-75% ratio and ACT score were assessed using linear regression. ROC curves were used to assess reliability of FEF25%-75% and FEF50% to diagnose BA in patients with different degree of asthma control.

RESULTS

FEF50% correlated strongly with FEF25%-75% (r = 0.989, P < 0.001) and the relationship between the two indices is governed by the formula FEF50% = 1.132* FEF25%-75% - 0.003. There was no significant correlation (r = - 0.159, P = 0.083) between FEF50%/FEF25-75% ratio and ACT score. The diagnostic capability of FEF25%-75% for spirometric diagnosis of BA is only marginally better compared to FEF50% (area under ROC curves were 0.88 and 0.89 respectively, P < 0.001); however, diagnostic power of both spirometric indices deceased with poor BA control.

CONCLUSION

FEF50%/FEF25%-75% has no clinical value as an indicator for BA control. Role of FEF25%-75% in evaluation of BA is marginally better than FEF50%; however, efficiency of both indices declined substantially as BA control worsened.

Diagnostic and prognostic utility of mid-expiratory flow rate in older community-dwelling persons with respiratory symptoms, but without chronic obstructive pulmonary disease

BACKGROUND

The maximal expiratory flow at 50 % of the forced vital capacity (MEF50) is the flow where half of forced vital capacity (FVC) remains to be exhaled. A reduced MEF50 has been suggested as a surrogate marker of small airways disease. The diagnostic and prognostic utility of this easy to assess spirometric variable in persons with respiratory symptoms, but without COPD is unclear.

METHODS

We used data from the UHFO-COPD cohort in which 405 community-dwelling persons aged 65 years or over, and a general practitioner's diagnosis of chronic obstructive pulmonary disease (COPD) underwent pulmonary function testing and echocardiography. In total 161 patients had no COPD according to the spirometric GOLD criteria. We considered MEF50 as reduced if < 60 % of predicted.

RESULTS

Of the 161 patients without COPD (mean age 72 ± 5.7 years; 35 % male; follow-up 4.5 ± 1.1 years), 61 (37.9 %) had a reduced MEF50. They were older, had more pack-years of smoking, more respiratory symptoms, and used more frequently inhaled medication than the remaining 100 subjects. A reduced MEF50 was nearly twice as often associated with newly detected heart failure (HF) at assessment (29.5 % vs. 15.6 %, p = 0.045). In age-and sex-adjusted Cox regression analysis, a reduced MEF50 was significantly associated with episodes of acute bronchitis (hazard ratio 2.54 95 % confidence interval (1.26; 5.13) P = 0.009), and in trend with pneumonia (2.14 (0.98; 4.69) P = 0.06) and hospitalizations for pulmonary reasons (2.28 (0.93; 5.62) P = 0.07).

CONCLUSIONS

In older community-dwelling persons with pulmonary symptoms but without COPD, a reduced MEF50 may help to uncover unrecognized HF, and identify those at a higher risk for episodes of acute bronchitis, pneumonia and hospitalizations for pulmonary reasons. Echocardiography and close follow-up should be considered in these patients.

The association of forced expiratory volume in one second and forced expiratory flow at 50% of the vital capacity, peak expiratory flow parameters, and blood eosinophil counts in exercise-induced bronchospasm in children with mild asthma

Background

Exercise-induced bronchoconstriction (EIB), which describes acute airway narrowing that occurs as a result of exercise, is associated with eosinophilic airway inflammation, bronchial hyperresponsiveness. The forced expiratory volume in one second (FEV₁) is the most commonly used spirometric test in the diagnosis of EIB in exercise challenge in asthma. Other parameters such as forced expiratory flow at 50% of the vital capacity (FEF_50%) and peak expiratory flow (PEF) are used less often in the diagnosis of EIB.

Objective

The purpose of this study is to evaluate the association of FEV₁ and FEF_50%, PEF parameters, blood eosinophil counts in EIB in children with mild asthma.

Methods

Sixty-seven children (male: 39, female: 28) with mild asthma were included in this study. Pulmonary functions were assessed before and at 1, 5, 10, 15, and 20 minutes after exercise. The values of spirometric FEV₁, FEF_50%, PEF, and blood eosinophil counts were evaluated in EIB in children with mild asthma.

Results

There was a positive correlation between FEV₁ with FEF_50% and PEF values (p<0.05; FEF_50%, r=0.68; PEF, r=0.65). Also, a positive correlation was found between blood eosinophil counts and the values of spirometric FEV₁, FEF_50%, and PEF (p<0.05; FEV₁, r=0.54; FEF_50%, r=0.42; PEF, r=0.26). In addition to these correlations, in the exercise negative group for FEV₁, the FEF_50% and PEF values decreased more than the cutoff values in 3, and 2 patients, respectively.

Conclusion

According to the presented study, eosinophil may play a major role in the severity of EIB in mild asthma. FEF_50% and PEF values can decrease in response to exercise without changes in FEV₁ in mild asthmatic patients.

The effect of vitamin C on bronchoconstriction and respiratory symptoms caused by exercise: a review and statistical analysis

Physical activity increases oxidative stress and therefore the antioxidant effects of vitamin C administration might become evident in people undertaking vigorous exercise. Vitamin C is involved in the metabolism of histamine, prostaglandins, and cysteinyl leukotrienes, all of which appear to be mediators in the pathogenesis of exercise-induced bronchoconstriction (EIB). Three studies assessing the effect of vitamin C on patients with EIB were subjected to a meta-analysis and revealed that vitamin C reduced postexercise FEV1 decline by 48% (95% CI: 33% to 64%). The correlation between postexercise FEV1 decline and respiratory symptoms associated with exercise is poor, yet symptoms are the most relevant to patients. Five other studies examined subjects who were under short-term, heavy physical stress and revealed that vitamin C reduced the incidence of respiratory symptoms by 52% (95% CI: 36% to 65%). Another trial reported that vitamin C halved the duration of the respiratory symptoms in male adolescent competitive swimmers. Although FEV1 is the standard outcome for assessing EIB, other outcomes may provide additional information. In particular, the mean postexercise decline of FEF50 is twice the decline of FEV1. Schachter and Schlesinger (1982) reported the effect of vitamin C on exercise-induced FEF60 levels in 12 patients suffering from EIB and their data are analyzed in this paper. The postexercise FEF60 decline was greater than 60% for five participants and such a dramatic decline indicates that the absolute postexercise FEF60 level becomes an important outcome in its own right. Vitamin C increased postexercise FEF60 levels by 50% to 150% in those five participants, but had no significant effect in the other seven participants. Thus, future research on the effects of vitamin C on EIB should not be restricted to measuring only FEV1. Vitamin C is inexpensive and safe, and further study on those people who have EIB or respiratory symptoms associated with exercise is warranted.

Development of a tool to recognize small airways dysfunction in asthma (SADT)

Background

Small airways dysfunction (SAD) contributes to the clinical expression of asthma. The identification of patients who suffer from SAD is important from a clinical perspective, as targeted therapy may improve patients’ well-being and treatment efficacy.

Aims

We aimed to realize the first step in the development of a simple small airways dysfunction tool (SADT) that may help to identify asthma patients having SAD.

Methods

Asthma patients with and without SAD were interviewed. Patients were selected to participate in this study based on FEF_50% and R5-R20 values from spirometry and impulse oscillometry respectively.

Results

Ten in depth interviews and two focus groups revealed that patients with and without SAD perceived differences in symptoms and signs, habits and health related issues. For example, patients with SAD reported to wheeze easily, were unable to breathe in deeply, mentioned more symptoms related to bronchial hyperresponsiveness, experienced more pronounced exercise-induced symptoms and more frequently had allergic respiratory symptoms after exposure to cats and birds. Based on these differences, 63 items were retained to be further explored for the SADT.

Conclusions

The first step of the development of the SADT tool shows that there are relevant differences in signs and respiratory symptoms between asthma patients with and without SAD. The next step is to test and validate all items in order to retain the most relevant items to create a short and simple tool, which should be useful to identify asthma patients with SAD in clinical practice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-014-0155-7) contains supplementary material, which is available to authorized users.

Correlations between pulmonary function and childhood asthma control test results in 5-11-year-old children with asthma

OBJECTIVES

We examined correlations between the two asthma assessment tools, pulmonary function tests, and Childhood Asthma Control Test (C-ACT) scores, in 5-11-year-old children with asthma to determine if the C-ACT scores could predict pulmonary function test results.

MATERIALS AND METHODS

A total of 172 children with asthma aged 5-11 years completed C-ACT questionnaires and underwent pulmonary function testing. Correlations between these test results were examined. Patients were also placed into two groups, C-ACT scores ≤19 and >19, to determine if patients with scores >19 had better pulmonary function test results.

RESULTS

Weak correlations were found between pulmonary function test results and childhood asthma control test scores in 5-11-year-old children with asthma, with or without the use of an asthma controller. These correlations included: 0.061 for FEV1 [confidence interval (CI): -0.022-0.049] and 0.074 for MMEF (CI: -0.013-0.037). The proportions of children with C-ACT test scores ≤19 group and those with scores >19 group were not significantly different.

CONCLUSION

Correlations between C-ACT scores and pulmonary function test results were poor for children aged 5-11 years with asthma. FEV1, FVC, FEF25, FEF50, FEF75, MMEF, and PEFR were not significantly correlated with C-ACT scores.

Pulmonary function testing in children and infants

Pulmonary function testing is performed in children and infants with the aim of documenting lung development with age and making diagnoses of lung diseases. In children and infants with an established lung disease, pulmonary function is tested to assess the disease progression and the efficacy of therapy. It is difficult to carry out the measurements in this age group without disturbances, so obtaining results of good quality and reproducibility is challenging. Young children are often uncooperative during the examinations. This is partly related to their young age but also due to the long testing duration and the unpopular equipment. We address a variety of examination techniques for lung function assessment in children and infants in this review. We describe the measuring principles, examination procedures, clinical findings and their interpretation, as well as advantages and limitations of these methods. The comparability between devices and centres as well as the availability of reference values are still considered a challenge in many of these techniques. In recent years, new technologies have emerged allowing the assessment of lung function not only on the global level but also on the regional level. This opens new possibilities for detecting regional lung function heterogeneity that might lead to a better understanding of respiratory pathophysiology in children.

Risk factors for small airway obstruction among Chinese island residents: a case-control study

BACKGROUND

We investigated the prevalence of and risk factors for small airway obstruction (SAO) among Chinese island residents to establish means to prevent and treat SAO.

METHODS

From October 17, 2011 to November 1, 2011, a total of 2,873 residents aged >20 years who lived on the Huangqi Peninsula of Fujian were recruited by random cluster sampling. They were asked to complete a Burden of Obstructive Lung Disease (BOLD) questionnaire and underwent physical examinations and lung function evaluations. SAO was defined as a forced expiratory flow at 50% of vital capacity, Vmax50%, of less than 70% of predicted. Risk factors for SAO were assessed from among demographic and anthropometric variables, blood chemistry results, and questionnaire response items.

RESULTS

A total of 216 (7.52%) Chinese island residents were identified as having SAO (95 males; 121 females). Their survey and test results were compared with 432 age and sex-matched healthy controls (192 males; 240 females) for SAO risk factors. Among numerous factors investigated, only diabetes mellitus (p = 0.039), smoking index (SI, p<0.001 for SI>600), second hand smoke (p = 0.002), and lack of regular exercise (p<0.001) were significant risk factors for SAO.

CONCLUSIONS

The risk factors for SAO among Chinese island residents appeared to be similar to those among people who live in high-density urban environments and impoverished rural areas. Public health policies and medical practices directed toward improving respiratory health for island residents should be comparable to those used for urban and rural dwellers.

Small airway disease in asthma and COPD: clinical implications

Asthma and COPD have a high personal, societal, and economic impact. Both diseases are characterized by airway obstruction and an inflammatory process. The inflammatory process affects the whole respiratory tract, from central to peripheral airways that are <2 mm in internal diameter, the so-called small airways. There is an increased interest in small airway disease, and some new insights have been gained about the contribution of these small airways to the clinical expression of asthma and COPD, as reviewed in this article. Newly developed devices enable drugs to target the small airways, and this may have implications for treatment of patients with asthma, particularly those not responding to large-particle inhaled corticosteroids or those with uncontrollable asthma. The first studies in COPD are promising, and results from new studies are eagerly awaited.

The role of the FEF50%/0.5FVC ratio in the diagnosis of obstructive lung diseases

OBJECTIVE

To evaluate the contribution of a new coefficient, the FEF50%/0.5FVC ratio, obtained from the maximal expiratory flow-volume curve, to the diagnosis of obstructive lung disease (OLD); to test this coefficient in differentiating among patients considered normal, those with OLD and those with restrictive lung disease (RLD); and to determine cut-off points for each functional diagnosis, as well as the probability for each diagnosis based on individual values.

METHODS

A prospective, cross-sectional study analyzing the pulmonary function of patients referred to the Porto Alegre Hospital de Clínicas, in Porto Alegre, Brazil, between January and December of 2003. We collected demographic and spirometric data. The patients were divided into three groups: normal; OLD; and RLD. We calculated the FEV1/FVC and FEF50%/0.5FVC ratios, and we compared the mean FEF50%/0.5FVC values among the groups. We used Pearson's correlation test in order to compare FEF50%/0.5FVC with FEV1/FVC. The patients were again divided into two groups: those with OLD and those without OLD. We calculated the likelihood ratio for different cut-off points.

RESULTS

The mean age of the patients was 55.8 +/- 14.7 years. There were significant differences among the groups in terms of the mean FEF50%/0.5FVC (2.10 +/- 0.82, 2.55 +/- 1.47 and 0.56 +/- 0.29, respectively, for normal, RLD and OLD; p < 0.001). There was a positive correlation between FEF50%/0.5FVC and FEV1/FVC in the OLD group (r = 0.83). We found that an FEF50%/0.5FVC < 0.79 strongly suggests OLD, whereas an FEF50%/0.5FVC > 1.33 practically excludes this diagnosis.

CONCLUSIONS

The FEF50%/0.5FVC ratio is a potentially useful parameter in the differential diagnosis of OLD and correlates positively with the FEV1/FVC ratio.

Effects of scoliosis on respiratory muscle strength in patients with neuromuscular disorders

BACKGROUND CONTEXT

Neuromuscular disorders (NMD) are characterized by loss of lung volume and respiratory muscle weakness, but the effects of scoliosis on lung function are unclear.

PURPOSE

To compare pulmonary function and respiratory muscle strength in patients with NMD with and without scoliosis as well as in healthy controls.

STUDY DESIGN/SETTING

Prospective comparison of pulmonary function testing and respiratory muscle strength were made at the pediatric pulmonology and cardiopulmonary rehabilitation units of a university hospital.

PATIENT SAMPLE

Twenty-two patients with NMD and scoliosis, 17 patients with NMD without scoliosis, and 24 age- and sex-matched healthy controls. Outcome measures were compared in patients with NMD with and without scoliosis and healthy subjects using Student t test, Mann-Whitney U test, chi-square test, one-way analysis of variance (ANOVA), Kruskal-Wallis one-way ANOVA, Pearson correlation coefficients, and Spearman rank correlation, as appropriate.

OUTCOME MEASURES

1) Pulmonary function: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV(1)), peak expiratory flow rate (PEF), forced expiratory flow between 25% and 75% of FVC (FEF(25-75%)), and maximum expiratory flows at 75%, 50%, and 25% of FVC (MEF(75), MEF(50), and MEF(25), respectively); 2) oxygen saturation: pulse oxymeter reading; and 3) respiratory muscle strength: maximal inspiratory mouth pressure (MIP) and maximal expiratory mouth pressure (MEP).

METHODS

Pulmonary function, oxygen saturation, MIP, and MEP were measured and compared in patients with NMD, patients with and without scoliosis, and in healthy subjects.

RESULTS

The patients with NMD, both with and without scoliosis, had significantly lower PEF, MIP, MEP, % predicted MIP (%MIP), and % predicted MEP (%MEP) than those of healthy subjects (p<.05). The patients with NMD and scoliosis had significantly lower values than those with NMD without scoliosis and controls (p<.05) for FVC, FEV(1), and FEF(25-75%).

CONCLUSION

Both inspiratory and expiratory muscle strength were diminished in patients with NMD compared with healthy controls. Significant differences were also noted in pulmonary function in patients with NMD with or without scoliosis. This suggests that NMD may impact respiratory function independently of the effects of scoliosis. Clinicians treating patients with NMD should be aware of the possibility of compromised respiratory function in these patients to address possible complications.

[Involvement of distal airways in asthma: lessons from pediatric cohorts]

INTRODUCTION

Prospective studies of paediatric cohorts contribute to our knowledge of changes in pulmonary function in children with asthma.

STATE OF THE ART

Asthma is associated with a significant impairment of the distal airways which is more pronounced when asthma has started early, before 5 years of age, or when asthma is persistent. In utero exposure to tobacco smoke allergenic sensitization and persistent bronchial hyperresponsiveness are the main factors associated with an unfavourable respiratory function outcome. This impairment may persist despite the disappearance of symptoms. Distal airway alterations are also poorly responsive to conventional inhaled corticosteroid therapy. This could be due to early remodelling phenomenon or non-optimal deposition of the drugs on distal airways.

PERSPECTIVES AND CONCLUSIONS

The medium and long term clinical implications of distal airway involvement in paediatric asthma and the impact of treatment need to be evaluated.

Spirometry in Early Childhood in Cystic Fibrosis Patients

BACKGROUND

Spirometry data in cystic fibrosis (CF) patients in early childhood is scarce, and the ability of spirometry to detect airways obstruction is debatable.

OBJECTIVE

To evaluate the ability of spirometry to detect airflow obstruction in CF patients in early childhood.

METHODS

CF children (age range, 2.5 to 6.9 years) in stable clinical condition were recruited from five CF centers. The children performed guided spirometry (SpiroGame; patented by Dr. Vilzone, 2003). Spirometry indices were compared to values of a healthy early childhood population, and were analyzed with relation to age, gender, and clinical parameters (genotype, pancreatic status, and presence of Pseudomonas in sputum or oropharyngeal cultures).

RESULTS

Seventy-six of 93 children tested performed acceptable spirometry. FVC, FEV1, forced expiratory flow in 0.5 s (FEV0.5), and forced expiratory flow at 50% of vital capacity (FEF50) were significantly lower than healthy (z scores, mean +/- SD: - 0.36 +/- 0.58, - 0.36 +/- 0.72, - 1.20 +/- 0.87; and - 1.80 +/- 1.47, respectively; p < 0.01); z scores for FEV1 and FVC were similar over the age ranges studied. However, z scores for FEV0.5 and forced expiratory flow at 25 to 75% of vital capacity were significantly lower in older children compared to younger children (p < 0.001), and a higher proportion of 6-year-old than 3-year-old children had z scores that were > 2 SDs below the mean (65% vs 5%, p < 0.03). Girls demonstrated lower FEF50 than boys (z scores: - 2.42 +/- 1.91 vs - 1.56 +/- 1.23; p < 0.001). Clinical parameters evaluated were not found to influence spirometric indices.

CONCLUSIONS

Spirometry elicited by CF patients in early childhood can serve as an important noninvasive tool for monitoring pulmonary status. FEV0.5 and flow-related volumes might be more sensitive than the traditional FEV1 in detecting and portraying changes in lung function during early childhood.

Mid-expiratory flow versus FEV1 measurements in the diagnosis of exercise induced asthma in elite athletes

BACKGROUND

A fall in FEV(1) of > or =10% following bronchoprovocation (eucapnic voluntary hyperventilation (EVH) or exercise) is regarded as the gold standard criterion for diagnosing exercise induced asthma (EIA) in athletes. Previous studies have suggested that mid-expiratory flow (FEF(50)) might be used to supplement FEV(1) to improve the sensitivity and specificity of the diagnosis. A study was undertaken to investigate the response of FEF(50) following EVH or exercise challenges in elite athletes as an adjunct to FEV(1).

METHODS

Sixty six male (36 asthmatic, 30 non-asthmatic) and 50 female (24 asthmatic, 26 non-asthmatic) elite athletes volunteered for the study. Maximal voluntary flow-volume loops were measured before and 3, 5, 10, and 15 minutes after stopping EVH or exercise. A fall in FEV(1) of > or =10% and a fall in FEF(50) of > or =26% were used as the cut off criteria for identification of EIA.

RESULTS

There was a strong correlation between DeltaFEV(1) and DeltaFEF(50) following bronchoprovocation (r = 0.94, p = 0.000). Sixty athletes had a fall in FEV(1) of > or =10% leading to the diagnosis of EIA. Using the FEF(50) criterion alone led to 21 (35%) of these asthmatic athletes receiving a false negative diagnosis. The lowest fall in FEF(50) in an athlete with a > or =10% fall in FEV(1) was 14.3%. Reducing the FEF(50) criteria to > or =14% led to 13 athletes receiving a false positive diagnosis. Only one athlete had a fall in FEF(50) of > or =26% in the absence of a fall in FEV(1) of > or =10% (DeltaFEV(1) = 8.9%).

CONCLUSION

The inclusion of FEF(50) in the diagnosis of EIA in elite athletes reduces the sensitivity and does not enhance the sensitivity or specificity of the diagnosis. The use of FEF(50) alone is insufficiently sensitive to diagnose EIA reliably in elite athletes.