Quantification of single-breath underestimation of lung volume in emphysema

Milite, Fulvia; Lederer, David J.; Weingarten, Jeremy A.; Fani, Pauline; Mooney, Anne M.; Basner, Robert C.

doi:10.1016/j.resp.2008.12.009

Cited by 20 publications

(16 citation statements)

References 22 publications

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“…Chronic obstructive pulmonary disease patients exhibited substantially enlarged P alv – loops ( Figure 1 and Table 3 ). Mechanical heterogeneity should be in fact enhanced in this disease, as well as the presence in the V T range of recruitment/derecruitment, expiratory flow limitation, and possibly gas trapping ( Eltayara et al, 1996 ; D’Angelo et al, 2000 ; Milite et al, 2009 ; Pecchiari et al, 2016 , 2017 ). A connection between A exp and gas trapping could be in fact suggested by the significant negative correlation of A exp with FVC, VC, and IC and the significant positive correlation with RV/TLC ( Table 4 ).…”

Section: Discussionmentioning

confidence: 99%

Plethysmographic Loops: A Window on the Lung Pathophysiology of COPD Patients

et al. 2018

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Plethysmographic alveolar pressure-flow (Palv–F) loops contain potentially relevant information about the pathophysiology of chronic obstructive pulmonary disease (COPD), but no quantitative analysis of these loops during spontaneous breathing has ever been performed. The area of the loop’s inspiratory (Ains) and expiratory portion (Aexp), and the difference between the end-expiratory and end-inspiratory alveolar pressure (ΔPalv) were measured in 20 young, 20 elderly healthy subjects, and 130 stable COPD patients. Ains and ΔPalv increased by 55 and 78% from young to elderly subjects, and by 107 and 122% from elderly subjects to COPD patients, reflecting changes in mechanical heterogeneity, lung-units recruitment/derecruitment, and possibly air trapping occurring with aging and/or obstructive disease. Aexp increased by 38% from young to elderly subjects, and by 198% from elderly subjects to COPD patients, consistent with the additional contribution of tidal expiratory flow-limitation, which occurs only in COPD patients and affects Aexp only. In COPD patients, Aexp and ΔPalv showed a significant negative correlation with VC, FEV1, IC, and a significant positive correlation with RV/TLC. The results suggest that the analysis of plethysmographic Palv–F loops provides an insight of the pathophysiological factors, especially tidal expiratory flow-limitation, that affect lung function in COPD patients.

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Section: Discussionmentioning

confidence: 99%

Plethysmographic Loops: A Window on the Lung Pathophysiology of COPD Patients

et al. 2018

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“…15 Another study suggests that there is a bias between methods, but that the bias is relatively constant and not affected by the degree of obstruction. 16 What is clear is that single-breath methods (such as employed during the single-breath D LCO ) do underestimate lung volumes in subjects who have obstructed airways. Imaging technologies may be able to provide an estimate of lung volume, but the cost and risk of radiation exposure make them less than ideal.…”

Section: Lung Volumesmentioning

confidence: 99%

Pulmonary Function Testing

2012

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Pulmonary function testing is often considered the basis for diagnosis in many categories of pulmonary disease. Although most of the testing methodologies are well established and widely employed, there are still many questions regarding how tests should be performed, how to ensure that reliable data are produced, what reference values and rules should be used, and how pulmonary function tests (PFTs) should be interpreted to best support clinical decision making. This conference was organized around a set of questions aimed at many of these issues. Each presenter was asked to address a specific topic regarding what tests should be done, how those test should be performed to answer a particular clinical question, and to relate test results to an accurate diagnosis and appropriate treatment of the patient. These topics included testing of adults and children, with concentration on important disease entities such as COPD, asthma, and unexplained dyspnea. Special emphasis was given to discussing reference values, lower limits of normal, interpretive strategies to optimize disease classification, and those factors directly affecting data quality. Established techniques for spirometry, lung volumes, diffusing capacity, exercise testing, and bronchial challenges were compared and contrasted with new technologies, and with technologies that might be part of pulmonary function laboratories in the near future.

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“…46,47 Most of these pointed out basic differences in the methodologies (eg, CT performed supine, breathholding at TLC, etc). Milite et al 48 examined differences between single-and multiple-breath dilutional techniques and body plethysmograph in 55 patients with emphysema. In their comparison of He dilution and plethysmographic lung volumes they observed a mean difference of approximately 500 mL, which appeared to be unrelated to the severity of obstruction (P for interaction ϭ .25).…”

Section: Does It Make Any Difference How You Measure Lung Volumes?mentioning

confidence: 99%

What Is the Clinical Value of Lung Volumes?

Ruppel

2012

Respir Care

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Lung volumes are considered part of a complete pulmonary function test, but their value for enhancing clinical decision making is unknown. Unlike spirometry and diffusing capacity of the lung for carbon monoxide (D LCO ), which do contribute to confirming or excluding a diagnosis, there are few clear indications when lung volumes are discriminatory. Confirming "restriction" when vital capacity (VC) or FVC is reduced is perhaps the most important. A restrictive pattern can have many etiologies, and clinicians often use VC or FVC as a primary index of lung volume. This makes "physiologic" sense because, in healthy subjects, and in patients with true restriction, VC comprises most of the total lung capacity (TLC). Mixed obstruction-restriction and the nonspecific pattern (ie, reduced FVC and FEV 1 , normal FEV 1 /FVC and TLC) require measuring TLC to confirm the underlying physiology. In obesity, VC and TLC may remain within normal limits, but functional residual capacity (FRC) can exponentially decrease. Increased lung volumes, particularly residual volume (RV), are commonly observed in airway obstruction. TLC may be normal, but is frequently increased in the late stages of COPD. Hyperinflation and air-trapping are terms commonly used to reflect these changes, but are not well standardized. The variability of lung volumes related to degree of obstruction suggests that measuring gas-trapping may be needed to monitor therapy. Changes in inspiratory capacity, RV, or FRC may be important gauges of response to bronchodilators or other hyperinflation-reducing therapies. How lung volumes are measured may be important, especially in patients who have moderate or severe airway obstruction. Body plethysmography is often considered more accurate than gas dilution methods in the presence of obstruction. However, the differences between techniques are not completely understood. Newer approaches such as computed tomography, although not suitable for routine testing, may help to delineate the true underlying physiology.

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Quantification of single-breath underestimation of lung volume in emphysema

Cited by 20 publications

References 22 publications

Plethysmographic Loops: A Window on the Lung Pathophysiology of COPD Patients

Plethysmographic Loops: A Window on the Lung Pathophysiology of COPD Patients

Pulmonary Function Testing

What Is the Clinical Value of Lung Volumes?

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