Value of Spirometry in Detecting Volume Restriction in Interstitial Lung Disease Patients

Abstract

Background: Restriction is a typical functional abnormality in interstitial lung disease (ILD) patients, but is not always present, especially in the early stage of the disease. The greater reduction of vital capacity (VC; %pred.) than total lung capacity (TLC; %pred.) is regarded as a typical pattern of lung function disturbances in ILD patients. Study Objectives: To explore the diagnostic value of spirometry in a detection restrictive pattern the relative volume loss assessed by TLC and VC in large series of patients with a diagnosis of ILD referred for lung function tests was evaluated. Methods: Retrospective, cross-sectional analysis of pulmonary function data was done. The sampleconsisted of 1,173 patients with the diagnosis of different interstitial lung diseases investigated during a period of 5 years. Only patients without airway obstruction (normal FEV1%VC) were included. In all cases spirometry and whole body plethysmography were performed by experienced staff using MasterLab – ‘Jaeger’ equipment according to ERS standards. Reference values according to ERS guidelines were applied. Results: The mean value of TLC expressed as %pred. was significantly (p < 0.001) lower than VC in all patients (93.7 ± 18.6 vs. 98.0 ± 21.4%pred.). The frequency of abnormal (lowered) TLC results was also higher than lowered VC (22.8 vs. 17.8%). Sensitivity of VC reached 69.3% and the positive predictive value was 88.5% in detecting volume restriction as compared to TLC measurement. Conclusion: The relative loss of TLC was greater than VC in our large group of patients. Measurement of TLC should be part of functional assessment of ILD patients, irrespective of whether they present or do not present a restrictive pattern in spirometry.

Impaired lung compliance and DL,CO but no restrictive ventilatory defect in sarcoidosis

“…Previous investigators have also reported normal lung volumes in the majority of patients with stage I or II sarcoidosis [15,26]. The cause of a restrictive ventilatory defect in sarcoidosis patients may be more complex and respiratory muscle weakness should also be considered [27].…”

Implications of adopting the Global Lungs Initiative 2012 all-age reference equations for spirometry

“…In a general population, where a reduced total lung capacity is rare, the positive predictive value of this test result will be very small. There is therefore little to be said for measurement of the total lung capacity if a restrictive pattern or mixed pattern is diagnosed on the basis of spirometry alone, unless there is a priori clinical evidence of a condition that might cause lung restriction, such as interstitial lung disease [36]. The underlying principle should be to treat the patient, not the numbers [37].…”

Health hazard evaluation report: HETA-2008-0155-3131, lung function (spirometry) testing in employees at a flavorings manufacturing plant - Indiana.

“…Still, without medical testing in addition to spirometry, we cannot be sure whether spirometric restriction reflects lung disease. It should be noted that in a case series of patients with documented restrictive lung diseases, the combination of restrictive spirometry and low total lung capacity were quite insensitive [Boros et al 2004]. Thus, if true restrictive lung disease is shown to exist in some employees with restrictive spirometry, all employees may need to have other diagnostic tests performed to assess for interstitial lung disease.…”