Chest
Clinical InvestigationsPULMONARY FUNCTION TRAITSValidity of the American Thoracic Society and Other Spirometric Algorithms Using FVC and Forced Expiratory Volume at 6 s for Predicting a Reduced Total Lung Capacity
Section snippets
Materials and Methods
The Canterbury Ethics Committee, New Zealand, approved the study. Consecutive patients referred for testing in the Respiratory Physiology Laboratory at Christchurch Hospital between December 2000 and December 2001 were considered for the study. Patients scheduled for spirometry alone or spirometry and lung volumes were approached, the study was explained, and informed consent was sought. Two hundred nineteen patients referred for spirometry and lung volume measurements signed consent forms and
Results
Subject recruitment is summarized in Table 2. Eligible patients were approached if the laboratory workload allowed the time necessary to get informed consent. Workload issues resulted in only 27% of the spirometry-only patients and 30% of the spirometry and lung volume patients being approached. Of those approached, 67% of the spirometry-only and 61% of the spirometry-only and lung volume groups consented. The effects of workload and lack of consent, the causes of the low percentage of
Discussion
This study confirms the results of Aaron et al3 and Glady et al,4 who found that spirometry patterns could not reliably predict a reduced TLC but could reliably predict a TLC at or above the normal level (NPV = 99 to 100%). The NPV of these patterns was not affected by the reference set used, and substituting FEV6 for FVC led to equivalent outcomes. These findings are consistent with a previous report6 of good performance of FEV6 as a surrogate for FVC in establishing obstructive and
Summary
Clinicians can be confident in spirometry-based algorithms that predict a normal TLC, but restriction cannot be reliably diagnosed with spirometry alone. FEV6 is equivalent to FVC for excluding a low TLC. There was no evidence of ascertainment bias in the selection of patients to get TLC measurements.
ACKNOWLEDGMENT
The authors thank Debbie Murray, Kelly Sallaway, and Fiona McClymont for technical assistance and Janet Embry for editorial assistance.
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Cited by (44)
Prevalence of restrictive lung function in children and adults in the general population
2023, Respiratory MedicineLung Function Tests in Clinical Decision-Making
2012, Archivos de BronconeumologiaCitation Excerpt :There are no data to document the use of FRC or RV categories in airflow obstruction or TLC in pulmonary restriction in order to classify severity, as done in spirometry. Cases of low TLC and normal VC are exceptional3,6,35–37; therefore these measurements are generally not very useful in subjects with normal VC. Its use has not been demonstrated in the differential diagnosis between emphysema and chronic bronchitis, or between COPD and asthma.36,38
Prognostic significance of surrogate measures for forced vital capacity in an elderly population
2010, Journal of the American Medical Directors AssociationCitation Excerpt :Indeed, this measure could not be measured in only 15 of our patients, and in patients not attaining the FVC, who tended to be older and frailer,10 it was significantly associated with mortality. For diagnostic purposes, FEV1/FEV6 is a well-recognized alternative to FEV1/FVC for the diagnosis of bronchial obstruction and FEV6 is an acceptable alternative to FVC for the diagnosis of restriction.11,12,18–20 The proposed index, SFVC, is unlikely to have noticeable diagnostic and classificatory properties because it provides a very approximate estimate of the vital capacity and its repeatability is suboptimal, but further studies should investigate this issue, especially in the elderly.
Changes in management of chronic obstructive pulmonary disease (COPD) in primary care: EMMEPOC study
2010, Respiratory MedicineCitation Excerpt :Vandevoorde et al.23 calculated the values of FEV1/FEV6 and FEV6 that would best match an FEV1/FVC of 0.70 of predicted values, and they found FEV1/FEV6 and FEV6 suitable for screening purposes in primary care. These data established cutoffs for the detection of obstructive spirometric patterns and were consistent with previous studies stressing the importance of spirometry in primary care, using portable airflow monitoring devices.17,23–25 Despite the fact that the KoKo Peak Pro 6 spirometer used was not validated to the spirometer standards of either the American Thoracic Society or the European Thoracic Society,26 it provides an easily reproducible test and involves measures such as PEF, FEV1% and FEV6%, which are simple to interpret in general practice.
When the Heart Is Not to Blame: Managing Lung Disease in Adult Congenital Heart Disease
2018, Progress in Cardiovascular DiseasesCitation Excerpt :A normal FVC has high negative predictive value in excluding restrictive lung impairment. However, as mentioned above, an abnormally low FVC has modest positive predictive value, and referral for pulmonary function testing with body plethysmography is ideally needed to confirm the diagnosis of restrictive lung disease by demonstrating a reduction in lung volumes.17 DLCO measured during pulmonary function testing may also elucidate the etiology behind the low FVC, by differentiating an intrinsic or parenchymal lung abnormality (low DLCO) from extrinsic restrictive causes (normal DLCO).
This work was performed at the Respiratory Physiology Laboratory, Christchurch Hospital, Christchurch, New Zealand.