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From the authors

¹ University of Rome Tor Vergata, Internal Medicine, Unit of Respiratory Diseases, Rome, and ² Dept of Internal Medicine, University of Genoa, Genova, Italy. ³ Dept of Internal Medicine, University of Michigan Health-System, Ann Arbor, MI, USA.

We thank D. Stanescu for his interest in our paper 1 and for giving us the opportunity to clarify an important methodological issue. First of all, we would like it to be remembered that our document was intended for use in designing clinical trials on pharmacological treatments of chronic obstructive pulmonary disease. The point we wanted to make clear is that, because of the well known potential errors inherent to dilution methods and body plethysmography 2–4, they should not be used interchangeably within a clinical trial. We are aware that keeping the panting frequency below 1 Hz helps reduce overestimation of lung volumes measured by body plethysmography in the presence of airflow obstruction 5, 6, but this has to be confirmed in very severe chronic obstructive pulmonary disease and it may not be easily feasible in large multicentre clinical trials. Notwithstanding, we agree that, whenever possible, the plethysmographic method should be adopted, not only because it is less time consuming, but also because it allows assessment of repeatability of measurements within sessions and, thus, better quality control.

Statement of interest

Statements of interest for M. Cazzola and V. Brusasco can be found at www.erj.ersjournals.com/misc/statements.shtml

REFERENCES

1. Cazzola M, MacNee W, Martinez FJ, et al. Outcomes for COPD pharmacological trials: from lung function to biomarkers. Eur Respir J 2008;31:416–469.[Abstract/Free Full Text]
2. Mitchell MM, Renzetti AD Jr. Evaluation of a single-breath method of measuring total lung capacity. Am Rev Respir Dis 1968;97:571–580.[Web of Science][Medline] [Order article via Infotrieve]
3. Mikus JP, Robins AG, Burke GW, Lyons LD, Epler GR, Smith AA. Comparison of 5 methods for determination of FRC and TLC in 100 persons: appendix 6 of the American Thoracic Society Epidemiology Standardization Project. Am Rev Respir Dis 1978;118:92–104.
4. Rodenstein DO, Stanescu DC. Reassessment of lung volume measurement by helium dilution and by body plethysmography in chronic air-flow obstruction. Am Rev Respir Dis 1982;126:1040–1044.[Web of Science][Medline] [Order article via Infotrieve]
5. Rodenstein DO, Stanescu DC, Francis C. Demonstration of failure of body plethysmography in airway obstruction. J Appl Physiol 1982;52:949–954.[Abstract/Free Full Text]
6. Rodenstein DO, Stanescu DC. Frequency dependence of plethysmographic volume in healthy and asthmatic subjects. J Appl Physiol 1983;54:159–165.[Abstract/Free Full Text]

This Article Full Text (PDF) An erratum has been published Alert me when this article is cited Alert me if a correction is posted Permissions Request Permissions Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Cazzola, M. Articles by Martinez, F. J. Search for Related Content PubMed Articles by Cazzola, M. Articles by Martinez, F. J.