J Stocks

Specifications for signal processing and data handling used for infant pulmonary function testing

The aim of this present paper is to define minimal performance criteria for the separate items comprising signal processing and data handling used to measure respiratory function in infants. These guidelines cover numerous aspects including: signal processing, data handling and subsequent analysis, reporting of results, demographics and handling of reference values. Adherence to these guidelines should ensure that infant lung function measurements can be performed with an acceptable degree of safety, precision, and reproducibility. Furthermore, they will facilitate multicentre collection of data and the performance of clinical investigations.

New aspects of airway mechanics in pre-term infants

High-frequency respiratory impedance data measured noninvasively by the high-speed interrupter technique (HIT), particularly the first antiresonance frequency (far,1), is related to airway wall mechanics. The aim of this study was to evaluate the feasibility and repeatability of HIT in unsedated pre-term infants, and to compare values of far,1 from 18 pre-term (post-conceptional age 32–37 weeks, weight 1,730–2,910u2005g) and 18 full-term infants (42–47 weeks, 3,920–5,340u2005g). Among the pre-term infants, there was good short-term repeatability of far,1 within a single sleep epoch (mean (sd) coefficient of variance: 8 (1.7)%), but 95% limits of agreement for repeated measures of far,1 after 3–8u2005h were relatively wide (−41u2005Hz; 37u2005Hz). far,1 was significantly lower in pre-term infants (199 versus 257u2005Hz), indicating that wave propagation characteristics in pre-term airways are different from those of full-term infants. The present authors suggest that this is consistent with developmental differences in airway wall structure and compliance, including the influence of the surrounding tissue. Since flow limitation is determined by wave propagation velocity and airway cross-sectional area, it was hypothesised that the physical ability of the airways to carry large flows is fundamentally different in pre-term than in full-term infants.

Population-specific reference equations?

To the Editors: nnThe recent paper by Chinn et al. 1, published in the European Respiratory Journal , describing sources of variation of forced expiratory volume in one second (FEV1) and forced vital capacity in the large multicentre European Community Respiratory Health Survey trial, raises important issues in the ongoing debate over the misuse of reference equations in respiratory medicine. The authors demonstrate potentially important population differences, which call into question the application of ethnicity-specific reference equations.nnHowever, we believe it is likely that much of the population heterogeneity …

Internal consistency of reference equations

From the authors:nnThe summary equations published by the European Community for Steel and Coal (ECSC), and the European Respiratory Society (ERS) [1, 2] are an average of prediction equations published before 1983; arising from this they have serious deficiencies. All ECSC studies were paid for by levies on coal and steel, thus lacked adequate studies in females. Since no appropriate data existed for females, and no funds were available for a new study, the working party used published prediction equations derived from healthy nonsmokers to generate a new database, and then used this to derive a new equation. The limitations of this technique are quite obvious, some of these were …

Optimal lung function tests for monitoring cystic fibrosis, bronchopulmonary dysplasia, and recurrent wheezing in children less than 6 years of age

Although pulmonary function testing plays a key role in the diagnosis and management of chronic pulmonary conditions in children under 6 years of age, objective physiologic assessment is limited in the clinical care of infants and children less than 6 years old, due to the challenges of measuring lung function in this age range. Ongoing research in lung function testing in infants, toddlers, and preschoolers has resulted in techniques that show promise as safe, feasible, and potentially clinically useful tests. Official American Thoracic Society workshops were convened in 2009 and 2010 to review six lung function tests based on a comprehensive review of the literature (infant raised-volume rapid thoracic compression and plethysmography, preschool spirometry, specific airway resistance, forced oscillation, the interrupter technique, and multiple-breath washout). In these proceedings, the current state of the art for each of these tests is reviewed as it applies to the clinical management of infants and children under 6 years of age with cystic fibrosis, bronchopulmonary dysplasia, and recurrent wheeze, using a standardized format that allows easy comparison between the measures. Although insufficient evidence exists to recommend incorporation of these tests into the routine diagnostic evaluation and clinical monitoring of infants and young children with cystic fibrosis, bronchopulmonary dysplasia, or recurrent wheeze, they may be valuable tools with which to address specific concerns, such as ongoing symptoms or monitoring response to treatment, and as outcome measures in clinical research studies.