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Rebuttal From Drs Pellegrino and BrusascoRebuttal From Drs Pellegrino and Brusasco FREE TO VIEW

Riccardo Pellegrino, MD; Vito Brusasco, MD
Author and Funding Information

From the Allergologia e Fisiopatologia Respiratoria (Dr Pellegrino) and Dipartimento di Medicina Interna e Specialità Mediche (Dr Brusasco), Scuola di Scienze Mediche e Farmaceutiche, Università di Genova.

CORRESPONDENCE TO: Riccardo Pellegrino, MD, Allergologia and Fisiopatologia Respiratoria, ASO S Croce e Carle, 12100 Cuneo, Italy; e-mail: pellegrino.r@ospedale.cuneo.it


FINANCIAL/NONFINANCIAL DISCLOSURES: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2014;146(3):541-542. doi:10.1378/chest.14-0811
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There are major reasons for testing acute bronchoreversibility in clinical practice. For instance, finding large increments in FEV1 > 400 mL is of great value to confirm the diagnosis of asthma and support therapy. Evaluating whether airflow obstruction is still reversible is also important, even though normal acute responses do not predict effects of chronic treatment and in no case preclude trials with bronchoactive medications. Drs Hansen and Porszasz1 suggest that with respect to the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines,2 the perceptive threshold is more suitable for evaluating bronchoreversibility. We will try to convince our readers that exploring lung mechanics with various functional parameters capable of identifying the fundamental and complex changes with bronchodilation is more important than debating the concept of threshold.

First, classifying the bronchodilator response is arbitrary by definition in that it is continuous and not dichotomous. Thus, beyond any reasonable discussion on what best represents natural variability and effects of medication, no thresholds properly separate abnormal from normal responses. Drs Hansen and Porszasz1 claim that the perceptibility threshold is more sensitive than that of the ATS/ERS guidelines. We do not deny that this may be true in some patients, and we never suggested that a negative classic response is a marker of fixed airflow obstruction. Yet, the proposed threshold is often within the range of natural variability of the FEV1 and may not be applicable to all disease conditions. For instance, in asthma, the threshold is twice that of COPD and ironically similar3 to that of the ATS/ERS document.2 Second, in asthma, only 20% of the increase in dyspnea is related to airway narrowing or closure,4 whereas the rest has to do with feelings, emotion, and affection. Setting the threshold to low values may, therefore, increase the likelihood of false-positive results, depending on the patient’s personality. Third, data supporting the proposed threshold are scant3 and have never been reproduced by other authors. Fourth, the perceptive approach appears to be applicable only in a minority of patients in whom accuracy and repeatability of the forced expiratory maneuvers are very high. Given that FEV1 is a measurement of whole-lung mechanics inclusive of contrasting mechanisms, such as increase of airway size and airway collapsibility after the bronchodilator, the approach Drs Hansen and Porszasz propose to interpret the bronchodilator responses risks being unrealistic and void of clinical meaning. Fifth, these authors do not bring any evidence that categorizing the response on individual t tests is superior to the ATS/ERS guideline criteria.5 We agree with them that usefulness remains to be shown.

In conclusion, the debate on the choice of the threshold to interpret the acute response to bronchodilators appears to be sterile because the increase in FEV1 with a bronchodilator exhibits continuous and not dichotomous distribution, and any threshold has pros and cons. Instead, we suggest that more effort be spent on examining airway mechanics within time and volume domains by modern technologies that are more sensitive than simple spirometry.6,7

References

Hansen JE, Porszasz J. Counterpoint: is an increase in FEV1and/or FVC ≥12% of control and ≥200 mL the best way to assess positive bronchodilator response? No. Chest. 2014;146(3):538-541.
 
Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26(5):948-968. [CrossRef] [PubMed]
 
Santanello NC, Zhang J, Seidenberg B, Reiss TF, Barber BL. What are minimal important changes for asthma measures in a clinical trial? Eur Respir J. 1999;14(1):23-27. [CrossRef] [PubMed]
 
Antonelli A, Crimi E, Gobbi A, et al. Mechanical correlates of dyspnea in bronchial asthma. Physiol Reports. 2013;1:e00166.
 
Hansen JE, Sun XG, Adame D, Wasserman K. Argument for changing criteria for bronchodilator responsiveness. Respir Med. 2008;102(12):1777-1783. [CrossRef] [PubMed]
 
Baldi S, Dellacà R, Govoni L, et al. Airway distensibility and volume recruitment with lung inflation in COPD. J Appl Physiol (1985). 2010;109(4):1019-1026. [CrossRef] [PubMed]
 
Lall CA, Cheng N, Hernandez P, et al. Airway resistance variability and response to bronchodilator in children with asthma. Eur Respir J. 2007;30(2):260-268. [CrossRef] [PubMed]
 

Figures

Tables

References

Hansen JE, Porszasz J. Counterpoint: is an increase in FEV1and/or FVC ≥12% of control and ≥200 mL the best way to assess positive bronchodilator response? No. Chest. 2014;146(3):538-541.
 
Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26(5):948-968. [CrossRef] [PubMed]
 
Santanello NC, Zhang J, Seidenberg B, Reiss TF, Barber BL. What are minimal important changes for asthma measures in a clinical trial? Eur Respir J. 1999;14(1):23-27. [CrossRef] [PubMed]
 
Antonelli A, Crimi E, Gobbi A, et al. Mechanical correlates of dyspnea in bronchial asthma. Physiol Reports. 2013;1:e00166.
 
Hansen JE, Sun XG, Adame D, Wasserman K. Argument for changing criteria for bronchodilator responsiveness. Respir Med. 2008;102(12):1777-1783. [CrossRef] [PubMed]
 
Baldi S, Dellacà R, Govoni L, et al. Airway distensibility and volume recruitment with lung inflation in COPD. J Appl Physiol (1985). 2010;109(4):1019-1026. [CrossRef] [PubMed]
 
Lall CA, Cheng N, Hernandez P, et al. Airway resistance variability and response to bronchodilator in children with asthma. Eur Respir J. 2007;30(2):260-268. [CrossRef] [PubMed]
 
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