Bronchodilator response of advanced lung function parameters depending on COPD severity
Received 28 April 2016
Accepted for publication 20 September 2016
Published 25 November 2016 Volume 2016:11(1) Pages 2939—2950
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 5
Editor who approved publication: Dr Richard Russell
Linnea Jarenbäck,1 Göran Eriksson,1 Stefan Peterson,2 Jaro Ankerst,1 Leif Bjermer,1 Ellen Tufvesson1
1Respiratory Medicine and Allergology, Department of Clinical Sciences Lund, Lund University, 2Regional Cancer Center South, Skåne University Hospital, Lund, Sweden
Background: COPD is defined as partly irreversible airflow obstruction. The response pattern of bronchodilators has not been followed in advanced lung function parameters.
Purpose: The aim of this study was to investigate bronchodilator response pattern in advanced lung function parameters in a continuous fashion along forced expiratory volume in 1 second (FEV1) percent predicted (%p) in COPD patients and controls.
Patients and methods: Eighty-one smokers/ex-smokers (41 controls and 40 COPD) performed spirometry, body plethysmography, impulse oscillometry and single-breath helium dilution carbon monoxide diffusion at baseline, after salbutamol inhalation and then after an additional inhalation of ipratropium.
Results: Most pulmonary function parameters showed a linear increase in response to decreased FEV1%p. The subjects were divided into groups of FEV1%p <65 and >65, and the findings from continuous analysis were verified. The exceptions to this linear response were inspiratory capacity (IC), forced vital capacity (FVC), FEV1/FVC and expiratory resistance (Rex), which showed a segmented response relationship to FEV1%p. IC and FVC, with break points (BP) of 57 and 58 FEV1%p respectively, showed no response above, but an incresed slope below the BP. In addition, in patients with FEV1%p <65 and >65, response of FEV1%p did not correlate to response of volume parameters.
Conclusion: Response of several advanced lung function parameters differs depending on patients’ baseline FEV1%p, and specifically response of volume parameters is most pronounced in COPD patients with FEV1%p <65. Volume and resistance responses do not follow the flow response measured with FEV1 and may thus be used as a complement to FEV1 reversibility to identify flow, volume and resistance responders.
Keywords: COPD, IOS, body plethysmography, bronchodilation, lung function, reversibility
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