Skip to main content

Main menu

  • Home
  • Current issue
  • ERJ Early View
  • Past issues
  • For authors
    • Instructions for authors
    • Submit a manuscript
    • Author FAQs
    • Open access
    • COVID-19 submission information
  • Alerts
  • Podcasts
  • Subscriptions
  • ERS Publications
    • European Respiratory Journal
    • ERJ Open Research
    • European Respiratory Review
    • Breathe
    • ERS Books
    • ERS publications home

User menu

  • Log in
  • Subscribe
  • Contact Us
  • My Cart

Search

  • Advanced search
  • ERS Publications
    • European Respiratory Journal
    • ERJ Open Research
    • European Respiratory Review
    • Breathe
    • ERS Books
    • ERS publications home

Login

European Respiratory Society

Advanced Search

  • Home
  • Current issue
  • ERJ Early View
  • Past issues
  • For authors
    • Instructions for authors
    • Submit a manuscript
    • Author FAQs
    • Open access
    • COVID-19 submission information
  • Alerts
  • Podcasts
  • Subscriptions

Defining the appropriate waiting time between multiple-breath nitrogen washout measurements

Elizabeth R. Salamon, Kevin R. Gain, Graham L. Hall
European Respiratory Journal 2015 45: 1489-1491; DOI: 10.1183/09031936.00198414
Elizabeth R. Salamon
1Respiratory Medicine, Royal Perth Hospital, Perth, Australia
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Kevin R. Gain
1Respiratory Medicine, Royal Perth Hospital, Perth, Australia
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Graham L. Hall
2Respiratory Medicine, Princess Margaret Hospital for Children, Perth, Australia
3Telethon Kids Institute, University of Western Australia, Perth, Australia
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • For correspondence: graham.hall@telethonkids.org.au
  • Article
  • Figures & Data
  • Info & Metrics
  • PDF
Loading

Abstract

Repeated multiple-breath washout tests should be twice the washout time apart to reduce avoidable measurement errors http://ow.ly/HPgW4

To the Editor:

Static lung volume measurements allow objective assessment of total lung capacity (TLC), functional residual capacity (FRC) and residual volume, and assist in the diagnosis and management of lung disease [1, 2]. The use of gas dilution techniques, such as multiple-breath nitrogen washout (MBNW), require minimal patient cooperation and allow FRC to be determined in those individuals unable to complete plethysmographic measurements. The MBNW technique is used clinically and for research, and provides accurate and repeatable measures in both children and adults [3, 4].

The 2005 American Thoracic Society (ATS) and European Respiratory Society (ERS) guidelines recommend waiting between repeated MBNW tests for ≥15 min and that in obstructed patients a period of >1 h may be required [2].

This study aimed to develop an evidence-based recommendation for the wait required between repeated MBNW tests using contemporary equipment and standardised collection protocols.

Children were tested in the Respiratory Laboratory of Princess Margaret Hospital for Children and the adults at the Respiratory Laboratory of Royal Perth Hospital, both located in Perth, Western Australia. The study was approved by the relevant ethics committees (EC LR.2008/127 and EC06-91), and written informed consent obtained from all participants and/or their parents, as relevant.

The study commenced in children between November 2006 and January 2008, and then expanded to the adult population from December 2007 to November 2009. Spirometry was only obtained in participants with lung disease according to current guidelines [5]. All MBNW tests were conducted according to the 2005 ATS/ERS criteria for the MBNW technique [2].

Children attended on a single occasion and were classed as healthy or as having lung disease, including asthma and cystic fibrosis. The initial MBNW (VMax Encore 229; Carefusion, Sydney, Australia) measurement of FRC was obtained for each child (t=0). Children repeated the FRC measurement after waiting for 5 min then after waiting a further 15 min, or after waiting for 15 min then 5 min, with the testing order randomised.

The adults were classed as healthy, or as having obstructive or restrictive lung disease. On review of the paediatric data and considering that the time to clear gas from the lungs is dependent on disease severity, the protocol for adults was modified such that the time between MBNW tests was determined as a multiple of the initial washout time. An initial MBNW (Medgraphics Corporation, St Paul, MN, USA) was performed (t=0) to provide the baseline washout time. The measurement was then repeated after waiting once, twice and three times their initial washout time, in randomised order.

Data (mean±sd) were normally distributed. Lung function is presented as standardised residuals derived from relevant prediction equations [6–9]. We defined acceptable between-test repeatability as a change in FRC <10%, in line with current MBW testing guidelines [10]. Power analysis showed that group sample sizes of 14 would detect a change of 10% assuming a sd of 0.35 (coefficient of variation, 18.75%). Data were analysed using paired t-tests and a random-effects longitudinal regression model to assess the change in FRC from baseline.

Acceptable and repeatable FRCs were obtained in 19 healthy children and 18 with lung disease (eight with asthma and 10 with cystic fibrosis) aged 7–18 years (mean±sd 12.76±3.18 years). Spirometry (in standardised residuals) in the children with lung disease was: forced expiratory volume in 1 s (FEV1) −1.48±1.75; forced vital capacity (FVC) −0.89±1.13; and FEV1/FVC −1.21±1.51. No clinically (≥10%) or statistically significant differences were detected between baseline FRC (FRC0) and after 5 min (FRC5) or 15 min (FRC15) in either group (table 1). This was confirmed using random-effects regression modelling, with no associations between differences in FRC and waiting time, test order or disease status.

View this table:
  • View inline
  • View popup
TABLE 1

Impact of waiting times on repeat measurements of functional residual capacity (FRC) in children and adults

Measurements of FRC were obtained in 24 healthy adults (aged 35±16.3 years), 16 adults with interstitial lung disease (aged 64.8±8.6 years) and 18 adults with chronic obstructive pulmonary disease (aged 61.6±17.1 years)). Among those with restrictive lung disease, spirometry was: FEV1, −1.66±1.22; FVC, −1.90±1.23; and FEV1/FVC 0.41±1.28. Among those with obstructive lung disease, spirometry was: FEV1 −3.17±1.28; FVC −1.29±1.16; and FEV1/FVC −3.30±1.36. Waiting for the initial washout time had no effect on FRC in the healthy or restrictive lung disease groups. The obstructive lung disease group exhibited a clinically significant fall in FRC of 360 mL (−10.2%; p<0.001) after waiting for the washout time (table 1). This effect was not evident with longer waiting times (table 1). Random-effects regression analysis indicated that obstructive disease severity (assessed by FEV1/FVC) had no effect (p=0.98) on the change in FRC between measurements. Similarly, restrictive disease severity (assessed by predicted TLC) also had no effect (p=0.69) on FRC.

This study investigated the time required for nitrogen levels in the lungs to return to baseline following repeated MBNW testing, thereby avoiding the introduction of measurement errors. To increase the generalisability of our findings, both children and adults were included, with varying degrees of lung disease severity.

In children we found that waiting 5 min (an average of 2.6 times the initial washout time) between measurements allowed nitrogen to return to baseline. In healthy adults and in adults with restrictive lung disease, a wait time of a single washout was sufficient for nitrogen to return to baseline. In adults with obstructive lung disease, a period of twice their initial washout time was required to measure FRC with acceptable repeatability. Nonetheless, waiting twice the initial washout time was, on average, 5.5 min, and significantly shorter than the 15–60 min recommendation in the 2005 ATS/ERS guidelines. Previous infant MBNW testing guidelines [11] and the 2013 ATS/ERS MBNW consensus statement [10] recommend that a wait time of at least twice the washout period be used, and these data support that recommendation.

The study does have limitations. The protocol differed between the adult and paediatric groups, with the adult protocol informed by the paediatric data. We do not believe this alters our recommendations, as the children had a mean wait time of 2.6 times the initial washout time, which is in line with our recommendation of waiting at least twice the initial washout time in adults. This is further supported by the fact that the adults had more severe obstruction and, therefore, the likelihood of twice the washout time not being adequate in children is low. It should be acknowledged that patients with more severe lung disease that those in this study may require longer wait times and the observation of alveolar nitrogen levels prior to testing commencing, as recently recommended [10], would increase certainty around test commencement. We were not able to measure lung clearance index (LCI). However, errors that affect FRC will also impact LCI and we suggest that studies using ventilation distribution outcomes incorporate these findings into the measurement protocols.

In conclusion, we recommend a uniform approach to waiting time between MBNW tests, and to wait at least twice the initial washout time and to monitor post-test nitrogen levels before repeating the MBNW measurement. Further studies should examine further optimising these recommendations for all MBW outcomes. We believe our recommendation should inform lung function testing practices in paediatric and adult settings and will help optimise the quality of lung volume measurements.

Acknowledgements

This work was presented at the 2010 European Respiratory Society Annual Congress in Barcelona, Spain, as an oral presentation. The authors would like to acknowledge the participants of this study from Princess Margaret Hospital and Royal Perth Hospital (Perth, Australia). They would also like to acknowledge statistician Michael Phillips from the Medical Research Foundation at Royal Perth Hospital for providing statistical analysis.

Footnotes

  • Support statement: G.L. Hall is funded by an Australian National Health and Medical Research Council Fellowship (grant APP1025550). Funding information for this article has been deposited with FundRef.

  • Conflict of interest: None declared.

  • Received September 2, 2014.
  • Accepted December 24, 2014.
  • Copyright ©ERS 2015

References

  1. ↵
    1. Pellegrino R,
    2. Viegi G,
    3. Brusasco V, et al.
    Interpretative strategies for lung function tests. Eur Respir J 2005; 26: 948–968.
    OpenUrlFREE Full Text
  2. ↵
    1. Wanger J,
    2. Clausen JL,
    3. Coates A, et al.
    Standardisation of the measurement of lung volumes. Eur Respir J 2005; 26: 511–522.
    OpenUrlAbstract/FREE Full Text
  3. ↵
    1. Blonshine S,
    2. Foss C,
    3. Mottram C, et al.
    AARC clinical practice guideline: body plethysmography: 2001 revision and update. Respir Care 2001; 46: 506–513.
    OpenUrl
  4. ↵
    1. Newth CJ,
    2. Enright P,
    3. Johnson RL
    . Multiple-breath nitrogen washout techniques: including measurements with patients on ventilators. Eur Respir J 1997; 10: 2174–2185.
    OpenUrlCrossRefPubMedWeb of Science
  5. ↵
    1. Miller MR,
    2. Hankinson J,
    3. Brusasco V, et al.
    Standardisation of spirometry. Eur Respir J 2005; 26: 319–338.
    OpenUrlAbstract/FREE Full Text
  6. ↵
    1. Hall GL,
    2. Thompson BR,
    3. Stanojevic S, et al.
    The Global Lung Initiative 2012 reference values reflect contemporary Australasian spirometry. Respirology 2012; 17: 1150–1151.
    OpenUrlCrossRefPubMedWeb of Science
    1. Quanjer PH,
    2. Stanojevic S,
    3. Cole TJ, et al.
    Multi-ethnic reference values for spirometry for the 3–95-yr age range: the Global Lung Function 2012 equations. Eur Respir J 2012; 40: 1324–1343.
    OpenUrlAbstract/FREE Full Text
    1. Cook CD,
    2. Hamann JF
    . Relation of lung volumes to height in healthy persons between the ages of 5 and 38 years. J Pediatr 1961; 59: 710–714.
    OpenUrlCrossRefPubMedWeb of Science
  7. ↵
    1. Crapo RO,
    2. Morris AH,
    3. Clayton PD, et al.
    Lung volumes in healthy nonsmoking adults. Bull Eur Physiopathol Respir 1982; 18: 419–425.
    OpenUrlPubMedWeb of Science
  8. ↵
    1. Robinson PD,
    2. Latzin P,
    3. Verbanck S, et al.
    Consensus statement for inert gas washout measurement using multiple- and single-breath tests. Eur Respir J 2013; 41: 507–522.
    OpenUrlAbstract/FREE Full Text
  9. ↵
    1. Morris MG,
    2. Gustafsson P,
    3. Tepper R, et al.
    The bias flow nitrogen washout technique for measuring the functional residual capacity in infants. Eur Respir J 2001; 17: 529–536.
    OpenUrlAbstract/FREE Full Text
View Abstract
PreviousNext
Back to top
View this article with LENS
Vol 45 Issue 5 Table of Contents
European Respiratory Journal: 45 (5)
  • Table of Contents
  • Table of Contents (PDF)
  • About the Cover
  • Index by author
Email

Thank you for your interest in spreading the word on European Respiratory Society .

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Defining the appropriate waiting time between multiple-breath nitrogen washout measurements
(Your Name) has sent you a message from European Respiratory Society
(Your Name) thought you would like to see the European Respiratory Society web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Print
Alerts
Sign In to Email Alerts with your Email Address
Citation Tools
Defining the appropriate waiting time between multiple-breath nitrogen washout measurements
Elizabeth R. Salamon, Kevin R. Gain, Graham L. Hall
European Respiratory Journal May 2015, 45 (5) 1489-1491; DOI: 10.1183/09031936.00198414

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero

Share
Defining the appropriate waiting time between multiple-breath nitrogen washout measurements
Elizabeth R. Salamon, Kevin R. Gain, Graham L. Hall
European Respiratory Journal May 2015, 45 (5) 1489-1491; DOI: 10.1183/09031936.00198414
del.icio.us logo Digg logo Reddit logo Technorati logo Twitter logo CiteULike logo Connotea logo Facebook logo Google logo Mendeley logo
Full Text (PDF)

Jump To

  • Article
    • Abstract
    • Acknowledgements
    • Footnotes
    • References
  • Figures & Data
  • Info & Metrics
  • PDF

Subjects

  • Lung structure and function
  • Tweet Widget
  • Facebook Like
  • Google Plus One

More in this TOC Section

Agora

  • Reply: Is high-dose glucocorticoid beneficial in COVID-19?
  • Is high-dose glucocorticoid beneficial in COVID-19?
  • Corticosteroids in COVID-19: one size does not fit all
Show more Agora

Research letters

  • Self- versus professional-collected swabs for SARS-CoV-2 rapid test
  • Free-breathing MRI for monitoring ventilation changes in paediatric CF
  • Challenges of nasal/pharyngeal swabs during the COVID-19 pandemic
Show more Research letters

Related Articles

Navigate

  • Home
  • Current issue
  • Archive

About the ERJ

  • Journal information
  • Editorial board
  • Reviewers
  • CME
  • Press
  • Permissions and reprints
  • Advertising

The European Respiratory Society

  • Society home
  • myERS
  • Privacy policy
  • Accessibility

ERS publications

  • European Respiratory Journal
  • ERJ Open Research
  • European Respiratory Review
  • Breathe
  • ERS books online
  • ERS Bookshop

Help

  • Feedback

For authors

  • Instructions for authors
  • Submit a manuscript
  • ERS author centre

For readers

  • Alerts
  • Subjects
  • Podcasts
  • RSS

Subscriptions

  • Accessing the ERS publications

Contact us

European Respiratory Society
442 Glossop Road
Sheffield S10 2PX
United Kingdom
Tel: +44 114 2672860
Email: journals@ersnet.org

ISSN

Print ISSN:  0903-1936
Online ISSN: 1399-3003

Copyright © 2021 by the European Respiratory Society