Background: There are times in clinical practice when it would be useful to be able to assess the severity of airways obstruction from tidal breathing. Three indices of airways obstruction derived from analysis of resting tidal expiratory flow have previously been described: (1) Tme/TE = time to reach maximum expiratory flow/expiratory time; (2) Krs = decay constant of exponential fitted to tidal expiratory flow versus time curve; and (3) EV = extrapolated volume--that is, area under the curve when the fitted exponential is extrapolated to zero flow. In this paper a further index--dtr/TE, time from the beginning of expiration till the rapid decay of flow begins/expiratory time--is evaluated. The aim of this study was to assess the ability of these indices to detect mild airways obstruction.
Methods: A histamine bronchial provocation test was performed in 20 adult patients with a diagnosis of asthma or symptoms of cough and/or shortness of breath. Baseline forced expiratory volume in one second (FEV1), functional residual capacity (FRC), and specific inspiratory conductance (sGaw) were measured and the measurements repeated after the final inhalation of histamine. Expiratory flow patterns during quiet breathing over five consecutive representative breaths were analysed before and after histamine. The test was concluded in 12 subjects when FEV1 had decreased by 20% of the post saline value, and in the remaining eight after inhalation of 16 or 32 mg/ml histamine.
Results: FEV1, sGaw, FRC, Krs, EV, and dtr/TE were all different after histamine (paired t test). For Tme/TE no difference was shown. Change in EV detected change in end tidal volume but underestimated it compared with the change measured by body plethysmography. Percentage fall in Krs after histamine correlated with percentage fall in FEV1 (r = 0.527, Pearson correlation coefficient). This was of a similar order to the correlation between the percentage fall in sGaw and in FEV1 (r = 0.543).
Conclusions: Analysis of expiratory tidal flow-time patterns predicted a decrease in FEV1 following histamine challenge as did measurement of sGaw. This analysis of tidal breathing would be useful in circumstances where forced expiratory manoeuvres are unreliable or inapplicable.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC474272 | PMC |
| http://dx.doi.org/10.1136/thx.50.4.346 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Comparing spirometry, impulse oscillometry with computed tomography for assessing small airway dysfunction in subjects with and without chronic obstructive pulmonary disease.
BMC Pulm Med
January 2025
State Key Laboratory of Respiratory Disease & National Clinical Research Center for Respiratory Disease & National Center for Respiratory Medicine & Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510120, China.
Background: Studies on consistency among spirometry, impulse oscillometry (IOS), and histology for detecting small airway dysfunction (SAD) remain scarce. Considering invasiveness of lung histopathology, we aimed to compare spirometry and IOS with chest computed tomography (CT) for SAD detection, and evaluate clinical characteristics of subjects with SAD assessed by these three techniques.
Methods: We collected baseline data from the Early COPD (ECOPD) study.
The efficacy and safety of Fluticasone Furoate/Umeclidinium/Vilanterol (FF/UMEC/VI) on cough symptoms in adult patients with asthma, A randomized double-blind, placebo-controlled, parallel group study: Chronic Cough in Asthma (COCOA) study.
J Asthma
January 2025
Division of Respiratory Medicine and Allergology, Department of Medicine, School of Medicine, Showa University, Tokyo, Japan.
Persistent cough bothers many patients with asthma because it worsens their quality of life; therefore, it must be remedied immediately. The efficacy of triple therapy as a first-line treatment for cough remains unclear. To evaluate the effectiveness and safety of the triple therapy againts persistent cough, the clinical effect of regular treatment with fluticasone furoate/umeclidinium/vilanterol (FF/UMEC/VI) or placebo in adult patients with asthma was investigated.
View Article and Find Full Text PDFEnhanced breathing effort in pulmonary function tests by CO2/O2 gas mixture and barometric whole-body plethysmography in healthy and feline lower airway disease cats.
Am J Vet Res
January 2025
National Taiwan University Veterinary Hospital, National Taiwan University, Taipei, Taiwan.
Objective: Enhancing ventilatory effort during pulmonary function testing can help reveal flow limitations not evident in normal tidal breathing. This study aimed to assess the efficacy and tolerability of using a CO2/O2 gas mixture to enhance tidal breathing with a barometric whole-body plethysmography system in both healthy cats and those with feline lower airway disease (FLAD).
Methods: This prospective study included healthy cats and those with FLAD, which underwent pulmonary function testing and were exposed to a 10% CO2/90% O2 gas mixture in a barometric whole-body plethysmography chamber, with CO2 concentrations maintained within the target range of 5% to 10%.
Influence of lung function on macro- and micro-structural brain changes in mid- and late-life.
Int J Surg
January 2025
Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
Introduction: Lung function has been associated with cognitive decline and dementia, but the extent to which lung function impacts brain structural changes remains unclear. We aimed to investigate the association of lung function with structural macro- and micro-brain changes across mid- and late-life.
Methods: The study included a total of 37 164 neurologic disorder-free participants aged 40-70 years from the UK Biobank, who underwent brain MRI scans 9 years after baseline.
Residing in areas with high residential greenspace is associated with increased COPD risk and decreased lung function of adults in eastern China.
Heart Lung
January 2025
Department of Preventive Medicine, Shantou University Medical College, Shantou, Guangdong 515041, China. Electronic address:
Background: Evidence for a relation between residential greenspace and respiratory health is scarce and controversial.
Objectives: The purpose of this study was to explore the association between residential greenspace and its interaction with particulate matter (PM) and risk of chronic obstructive pulmonary disease (COPD) and lung function.
Methods: A total of 3,759 adults were recruited from Wenzhou in this study.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!