S49 Identifying patient suitability for lung volume reduction – estimation of gas trapping from spirometry

Elbehairy, AF; Whittaker, H.; Quint, JK; Buttery, Sara C; Jordan, Simon; Polkey, MI

doi:10.1136/thorax-2018-212555.55

Cited by 4 publications

(2 citation statements)

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“…In addition to the RV/TLC ratio, several other parameters, somewhat arbitrarily, are used to rate trapped air and hyperinflation [7], and various approaches have been proposed for their estimation from spirometry, obviating the need for body plethysmography, gas dilution or further techniques [29]. RV % pred can be estimated to detect hyperinflation [30] using two equations published previously [31,32]. Although it appeared that measurement of static lung volumes had little incremental value compared to spirometry regarding the differentiation between asthma and COPD [33], there are other data underlining the value of such measurements.…”

Section: Discussionmentioning

confidence: 99%

Prediction of air trapping or pulmonary hyperinflation by forced spirometry in COPD patients: results from COSYCONET

Alter

Orszag²,

Kellerer

et al. 2020

ERJ Open Res

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BackgroundAir trapping and lung hyperinflation are major determinants of prognosis and response to therapy in chronic obstructive pulmonary disease (COPD). They are often determined by body plethysmography, which has limited availability, and so the question arises as to what extent they can be estimated via spirometry.MethodsWe used data from visits 1–5 of the COPD cohort COSYCONET. Predictive parameters were derived from visit 1 data, while visit 2–5 data was used to assess reproducibility. Pooled data then yielded prediction models including sex, age, height, and body mass index as covariates. Hyperinflation was defined as ratio of residual volume (RV) to total lung capacity (TLC) above the upper limit of normal. (ClinicalTrials.gov identifier: NCT01245933).ResultsVisit 1 data from 1988 patients (Global Initiative for Chronic Obstructive Lung Disease grades 1–4, n=187, 847, 766, 188, respectively) were available for analysis (n=1231 males, 757 females; mean±sd age 65.1±8.4 years; forced expiratory volume in 1 s (FEV1) 53.1±18.4 % predicted (% pred); forced vital capacity (FVC) 78.8±18.8 % pred; RV/TLC 0.547±0.107). In total, 7157 datasets were analysed. Among measures of hyperinflation, RV/TLC showed the closest relationship to FEV1 % pred and FVC % pred, which were sufficient for prediction. Their relationship to RV/TLC could be depicted in nomograms. Even when neglecting covariates, hyperinflation was predicted by FEV1 % pred, FVC % pred or their combination with an area under the curve of 0.870, 0.864 and 0.889, respectively.ConclusionsThe degree of air trapping/hyperinflation in terms of RV/TLC can be estimated in a simple manner from forced spirometry, with an accuracy sufficient for inferring the presence of hyperinflation. This may be useful for clinical settings, where body plethysmography is not available.

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Section: Discussionmentioning

confidence: 99%

Prediction of air trapping or pulmonary hyperinflation by forced spirometry in COPD patients: results from COSYCONET

Alter

Orszag²,

Kellerer

et al. 2020

ERJ Open Res

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“… 61 , 62 Finally, it is possible that the rate of FVC decline could have been impacted by gas trapping; however, hyperinflation or gas trapping information is not available in CPRD. 63 …”

Section: Strengths and Limitationsmentioning

confidence: 99%

<p>Characteristics Associated with Accelerated Lung Function Decline in a Primary Care Population with Chronic Obstructive Pulmonary Disease</p>

Whittaker

Pimenta

Jarvis

et al. 2020

COPD

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Background: Estimates for lung function decline in chronic obstructive pulmonary disease (COPD) have differed by study setting and have not been described in a UK primary care population. Purpose: To describe rates of FEV 1 and FVC decline in COPD and investigate characteristics associated with accelerated decline. Patients and Methods: Current/ex-smoking COPD patients (35 years+) who had at least 2 FEV 1 or FVC measurements ≥6 months apart were included using Clinical Practice Research Datalink. Patients were followed up for a maximum of 13 years. Accelerated rate of lung function decline was defined as the fastest quartile of decline using mixed linear regression, and association with baseline characteristics was investigated using logistic regression. Results: A total of 72,683 and 50,649 COPD patients had at least 2 FEV 1 or FVC measurements, respectively. Median rates of FEV 1 and FVC changes or decline were −18.1mL/year (IQR: −31.6 to −6.0) and −22.7mL/year (IQR: −39.9 to −6.7), respectively. Older age, high socioeconomic status, being underweight, high mMRC dyspnoea and frequent AECOPD or severe AECOPD were associated with an accelerated rate of FEV 1 and FVC decline. Current smoking, mild airflow obstruction and inhaled corticosteroid treatment were additionally associated with accelerated FEV 1 decline whilst women, sputum production and severe airflow obstruction were associated with accelerated FVC decline. Conclusion: Rate of FEV 1 and FVC decline was similar and showed similar heterogeneity. Whilst FEV 1 and FVC shared associations with baseline characteristics, a few differences highlighted the importance of both lung function measures in COPD progression. We identified important characteristics that should be monitored for disease progression.

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S78 Estimating residual volume and predicting presence or absence of significant hyperinflation from spirometry data: validating two described equations

Dawson

Macfarlane

Carlin

2019

An Update in Lung Physiology

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S49 Identifying patient suitability for lung volume reduction – estimation of gas trapping from spirometry

Cited by 4 publications

References 0 publications

Prediction of air trapping or pulmonary hyperinflation by forced spirometry in COPD patients: results from COSYCONET

Prediction of air trapping or pulmonary hyperinflation by forced spirometry in COPD patients: results from COSYCONET

<p>Characteristics Associated with Accelerated Lung Function Decline in a Primary Care Population with Chronic Obstructive Pulmonary Disease</p>

S78 Estimating residual volume and predicting presence or absence of significant hyperinflation from spirometry data: validating two described equations

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