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

Abstract

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.

Diaphragm Ultrasound is an Imaging Biomarker that Distinguishes Exacerbation Status from Stable Chronic Obstructive Pulmonary Disease

“…Air-trapping, which is represented by the value of RV/TLC, is significantly different between stable COPD and AECOPD. 21,22 In the previous study, air-trapping (RV/TLC) is major limiting factor of DUS in COPD patients. 23 Therefore, the status of DUS findings can only be different between AECOPD and stable COPD and that is the reason that DUS imaging biomarkers during maximal breathing showed clinical significance compared to those of tidal breathing.…”

Lower Prevalence of Osteoporosis in Patients with COPD Taking Anti-Inflammatory Compounds for the Treatment of Diabetes: Results from COSYCONET

“…Impaired lung function has been reported to be linked to osteoporosis; 54 this was confirmed in our study, in which RV/TLC, as a marker of trapped air and hyperinflation, was the most robust lung function predictor. RV/TLC is associated with airway obstruction, 55 but its predictive value dominated over that of FEV 1 and FVC. Low BMI was also a risk factor for osteoporosis, although interestingly it is commonly linked to a lower, not a higher value of RV/TLC.…”

The efficacy of manual therapy for chronic obstructive pulmonary disease: A systematic review

“…Spirometry is a means of diagnosing and evaluating COPD by measuring airway obstruction [ 17 ]. RV and TLC also represent hyperinflation, a major feature of COPD [ 40 ]. When at least one item of static and/or dynamic lung volume was reported, it was used to evaluate lung function.…”