SERIES "STANDARDS FOR INFANT RESPIRATORY FUNCTION TESTING: ERS/ATS TASK FORCE" Edited by J. Stocks and J. Gerritsen Number 6 in this Series Plethysmographic measurements of lung volume and airway resistance J. Stocks*, S. Godfrey # , C. Beardsmore } , E. Bar-Yishay z , R. Castile § , on behalf of the ERS/ATS Task Force on Standards for Infant Respiratory Function Testing Plethysmographic measurements of lung volume and airway resistance. J. Stocks, S. Godfrey, C. Beardsmore, E. Bar-Yishay, R. Castile, on behalf of the ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. #ERS Journals Ltd 2001. ABSTRACT: Functional residual capacity (FRC) is the only static lung volume that can be measured routinely in infants. It is important for interpreting volume-dependent pulmonary mechanics such as airway resistance or forced expiratory flows, and for defining normal lung growth. Despite requiring complex equipment, the plethysmo- graphic method for measuring FRC is very simple to apply and, unlike the gas dilution techniques, enables repeat measures of lung volume to be obtained within a few minutes. This method has the further advantage that with suitable adaptations to the equipment, simultaneous measurements of airway resistance can also be obtained. The aim of this paper is to provide recommendations pertaining to equipment requirements, study procedures and reporting of data for plethysmographic measure- ments in infants. Implementation of these recommendations should help to ensure that such measurements are as accurate as possible and that meaningful comparisons can be made between data collected in different centres or with different equipment. These guidelines cover numerous aspects including terminology and definitions, equipment, data acquisition and analysis and reporting of results and also highlight areas where further research is needed before consensus can be reached. Eur Respir J 2001; 17: 302–312. *Portex Anaesthesia, Intensive Therapy and Respiratory Medicine Unit, Insti- tute of Child Health, London, UK. # Hadassah University Hospital, Mount Scopus, Kiryat Hadassah, Jerusalem, Israel. } Dept of Child Health, Clinical Sciences Building, Leicester Royal Infirmary, Leicester, UK. z Pulmonary Function Laboratories, Hadassah University Hospital, Jerusalem, Israel. § Section of Pulmonary Medicine, Chil- dren9s Hospital, Colombus, OH, USA. Correspondence: J. Stocks, Portex Anaesthesia, Intensive Therapy and Respiratory Medicine Unit, Institute of Child Health, London, UK Fax: 44 2078298634 Keywords: Airways resistance functional residual capacity infant methodology respiratory function tests standardization Received: March 28 2000 Accepted after revision June 14 2000 This work was supported by a grant from the European Respiratory Society, and by donations from GlaxoWellcome (UK) and Glaxo- Wellcome AB (Sweden). The present paper represents one of a series that have been produced by the European Respiratory Society/ American Thoracic Society Task Force on Standards for Infant Respiratory Function Tests. The aim of this paper is to summarize what is currently seen to be good laboratory practice, and to provide recommendations for both users and manufacturers of infant lung function equipment and software with respect to plethysmographic measurements of lung volume and airway resistance in infants. These recommendations have been developed after widespread communication on an international level and are directed towards future Previous articles in this series: No. 1: U. Frey, J. Stocks, A. Coates, P.D. Sly, J. Bates, on behalf of the ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. Specifications for equipment used for infant pulmonary function testing. Eur Respir J 2000; 16: 731 – 740. No. 2: P.D. Sly, R. Tepper, M. Henschen, M. Gappa, J. Stocks, on behalf of the ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. Tidal Forced Expirations. Eur Respir J 2000; 16: 741 – 748. No. 3: U. Frey, J. Stocks, P. Sly, J. Bates, on behalf of the ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. Specifications for signal processing and data handling used for infant pulmonary function testing. Eur Respir J 2000; 16: 1016 – 1022. No. 4: J.H.T. Bates, G. Schmalisch, D. Filburn, J. Stocks, on behalf of the ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. Tidal breath analysis for infant pulmonary function testing. Eur Respir J 2000; 16: 1180 – 1192. No. 5: M. Gappa, A.A. Colin, I. Goetz, J. Stocks, on behalf of the ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. Passive respiratory mechanics: The occlusion techniques. Eur Respir J 2001; 17: 141 – 148. Eur Respir J 2001; 17: 302–312 Printed in UK – all rights reserved Copyright # ERS Journals Ltd 2001 European Respiratory Journal ISSN 0903-1936