Bronchodilation increases exercise endurance in COPD patients with sustained concavity in the spontaneous expiratory flow volume loop

The flow-volume (FV) loop is another way of representing spirometric data from combinations of forced expiratory and forced inspiratory vital capacity breaths. The FV loop is of use in identifying, and often localizing, lesions of the larynx and the trachea (down to the carina). Three general patterns have been recognized. When the lesion behaves in a fixed fashion (as might occur with an artificial orifice), maximal expiratory and inspiratory flows are almost equally compromised. This results in a rectangular FV loop, irrespective of whether the lesion is located intrathoracically or extrathoracically. When the lesion behaves in a variable fashion, two distinct patterns are seen, depending on the location of the lesion (intrathoracic or extrathoracic). The variable lesion acts as a fixed lesion during one phase of forced respiration only. The extrathoracic variable lesion results in a predominant reduction in forced inspiratory flow, with little effect on expiratory flow, whereas the intrathoracic variable lesion produces a characteristic reduction in expiratory flow. These patterns reflect the transmural forces existing at the site of the lesion.

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Novel method for measuring effects of gas compression on expiratory flow

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00573.2003 ◽

2004 ◽

Vol 287 (2) ◽

pp. R479-R484 ◽

Cited By ~ 8

Author(s):

Amir Sharafkhaneh ◽

Todd M. Officer ◽

Sheila Goodnight-White ◽

Joseph R. Rodarte ◽

Aladin M. Boriek

Keyword(s):

Normal Subjects ◽

Chronic Obstructive ◽

Flow Limitation ◽

Flow Volume ◽

Expiratory Flow Limitation ◽

Obstructive Pulmonary Disease ◽

Flow Volume Loop ◽

Gas Compression ◽

Novel Method ◽

Expiratory Flow

During forced vital capacity maneuvers in subjects with expiratory flow limitation, lung volume decreases during expiration both by air flowing out of the lung (i.e., exhaled volume) and by compression of gas within the thorax. As a result, a flow-volume loop generated by using exhaled volume is not representative of the actual flow-volume relationship. We present a novel method to take into account the effects of gas compression on flow and volume in the first second of a forced expiratory maneuver (FEV1). In addition to oral and esophageal pressures, we measured flow and volume simultaneously using a volume-displacement plethysmograph and a pneumotachograph in normal subjects and patients with expiratory flow limitation. Expiratory flow vs. plethysmograph volume signals was used to generate a flow-volume loop. Specialized software was developed to estimate FEV1 corrected for gas compression (NFEV1). We measured reproducibility of NFEV1 in repeated maneuvers within the same session and over a 6-mo interval in patients with chronic obstructive pulmonary disease. Our results demonstrate that NFEV1 significantly correlated with FEV1, peak expiratory flow, lung expiratory resistance, and total lung capacity. During intrasession, maneuvers with the highest and lowest FEV1 showed significant statistical difference in mean FEV1 ( P < 0.005), whereas NFEV1 from the same maneuvers were not significantly different from each other ( P > 0.05). Furthermore, variability of NFEV1 measurements over 6 mo was <5%. We concluded that our method reliably measures the effect of gas compression on expiratory flow.

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Area under flow-volume loop may predict severe exacerbation in COPD patients with high grade of dyspnea

Respiratory Physiology & Neurobiology ◽

10.1016/j.resp.2021.103771 ◽

2021 ◽

pp. 103771

Author(s):

Celal Satici ◽

Mustafa Asim Demirkol ◽

Burcu Arpinar Yigitbas ◽

Aysegül Erinc ◽

Ayse Filiz Kosar

Keyword(s):

Severe Exacerbation ◽

High Grade ◽

Flow Volume ◽

Flow Volume Loop ◽

Copd Patients

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Prevalence and correlates of a ‘knee’ pattern on the maximal expiratory flow-volume loop in young adults

Respirology ◽

10.1111/resp.12352 ◽

2014 ◽

Vol 19 (7) ◽

pp. 1052-1058 ◽

Cited By ~ 2

Author(s):

Hayden H. Shin ◽

Malcolm R. Sears ◽

Robert J. Hancox

Keyword(s):

Young Adults ◽

Flow Volume ◽

Maximal Expiratory Flow ◽

Flow Volume Loop ◽

Expiratory Flow

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Analysis of Maximum Expiratory Flow Volume Curves Using Canonical Correlation Analysis

Methods of Information in Medicine ◽

10.1055/s-0038-1635359 ◽

1985 ◽

Vol 24 (02) ◽

pp. 91-100 ◽

Cited By ~ 3

Author(s):

W. van Pelt ◽

Ph. H. Quanjer ◽

M. E. Wise ◽

E. van der Burg ◽

R. van der Lende

Keyword(s):

Correlation Analysis ◽

Canonical Correlation Analysis ◽

Canonical Correlation ◽

Flow Volume ◽

Non Linear ◽

Maximum Expiratory Flow ◽

Expiratory Flow ◽

Relationship Of ◽

The Relationship ◽

Age And Sex

SummaryAs part of a population study on chronic lung disease in the Netherlands, an investigation is made of the relationship of both age and sex with indices describing the maximum expiratory flow-volume (MEFV) curve. To determine the relationship, non-linear canonical correlation was used as realized in the computer program CANALS, a combination of ordinary canonical correlation analysis (CCA) and non-linear transformations of the variables. This method enhances the generality of the relationship to be found and has the advantage of showing the relative importance of categories or ranges within a variable with respect to that relationship. The above is exemplified by describing the relationship of age and sex with variables concerning respiratory symptoms and smoking habits. The analysis of age and sex with MEFV curve indices shows that non-linear canonical correlation analysis is an efficient tool in analysing size and shape of the MEFV curve and can be used to derive parameters concerning the whole curve.

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