Ventilation heterogeneity in the acinar and conductive zones of the normal ageing lung
- Sylvia Verbanck1,
- Bruce R Thompson2,
- Daniel Schuermans1,
- Harpal Kalsi3,
- Martyn Biddiscombe3,
- Chris Stuart-Andrews2,
- Shane Hanon1,
- Alain Van Muylem4,
- Manuel Paiva4,
- Walter Vincken1,
- Omar Usmani3
- 1Respiratory Division, University Hospital UZ Brussel, Brussels, Belgium
- 2Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, Australia
- 3Imperial College London and Royal Brompton Hospital, National Heart and Lung Institute, London, UK
- 4Respiratory Division, University Hospital Erasme, Université Libre de Bruxelles, Brussels, Belgium
- Correspondence to Dr Sylvia Verbanck, Respiratory Division, University Hospital UZ Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium;
Contributors Study design, data acquisition, analysis, and writing up results: all authors. Interpretation and supervision of final draft: SV, BRT, OSU.
- Received 8 December 2011
- Accepted 28 March 2012
- Published Online First 27 April 2012
Rationale Small airways function studies in lung disease have used three promising multiple breath washout (MBW) derived indices: indices of ventilation heterogeneity in the acinar (Sacin) and conductive (Scond) lung zones, and the lung clearance index (LCI). Since peripheral lung structure is known to change with age, ventilation heterogeneity is expected to be affected too. However, the age dependence of the MBW indices of ventilation heterogeneity in the normal lung is unknown.
Objectives The authors systematically investigated Sacin, Scond or LCI as a function of age, testing also the robustness of these relationships across two laboratories.
Methods MBW tests were performed by never-smokers (50% men) in the age range 25–65 years, with data gathered across two laboratories (n=120 and n=60). For comparison with the literature, the phase III slopes from classical single breath washout tests were also acquired in one group (n=120).
Measurements and main results All three MBW indices consistently increased with age, representing a steady worsening of ventilation heterogeneity in the age range 25–65. Age explained 7–16% of the variability in Sacin and Scond and 36% of the variability in LCI. There was a small but significant gender difference only for Sacin. Classical single breath washout phase III slopes also showed age dependencies, with gender effects depending on the normalisation method used.
Conclusions With respect to the clinical response, age is a small but consistent effect that needs to be factored in when using the MBW indices for the detection of small airways abnormality in disease.
- Small airways function
- acinar airways
- conductive airways
- ventilation distribution
- multiple breath washout
- COPD mechanisms
- asthma mechanisms
- imaging/CT MRI etc
- inhaler devices
- lung physiology
- occupational lung disease
- non-invasive ventilation
- sleep apnoea
- asthma guidelines
- COPD epidemiology
- respiratory measurement
- exhaled airway markers
- lung transplantation
Funding This study was funded by the Fund for Scientific Research—Flanders and supported by the National Institute of Health Research (NIHR) Respiratory Disease Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London. Dr O S Usmani is a recipient of an NIHR Career Development Fellowship. B R Thompson also received financial support through the National Health and Medical Research Council of Australia (grants 486101 and 491103).
Competing interests None.
Ethics approval Research ethics committees of UZ Brussel (B14320097554) and Brompton Hospital (08/H0709/2).
Provenance and peer review Not commissioned; externally peer reviewed.