Relation of concavity in the expiratory flow-volume loop to dynamic hyperinflation during exercise in COPD

2016 ◽  
Vol 234 ◽  
pp. 79-84 ◽  
Author(s):  
Janos Varga ◽  
Richard Casaburi ◽  
Shuyi Ma ◽  
Ariel Hecht ◽  
David Hsia ◽  
...  
Keyword(s):  
Dynamic Hyperinflation ◽  
Flow Volume ◽  
Flow Volume Loop ◽  
Expiratory Flow

Evaluation of Major Airway Lesions Using the Flow-Volume Loop

1975 ◽  
Vol 84 (5) ◽  
pp. 635-642 ◽  
Author(s):  
Robert E. Hyatt
Keyword(s):  
Vital Capacity ◽  
Inspiratory Flow ◽  
Flow Volume ◽  
Flow Volume Loop ◽  
Expiratory Flow

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.

Novel method for measuring effects of gas compression on expiratory flow

2004 ◽  
Vol 287 (2) ◽  
pp. R479-R484 ◽  
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.

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

Respirology ◽  
2014 ◽  
Vol 19 (7) ◽  
pp. 1052-1058 ◽  
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

scholarly journals Pulmonary function with expiratory resistive loading in healthy volunteers

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252916
Author(s):  
Jyotika Erram ◽  
Monica Bari ◽  
Antoinette Domingo ◽  
Daniel T. Cannon
Keyword(s):  
Pulmonary Function ◽  
Model Comparison ◽  
Work Of Breathing ◽  
Lung Mechanics ◽  
Dynamic Hyperinflation ◽  
Flow Volume ◽  
Expiratory Flow Limitation ◽  
Volume Relationship ◽  
Expiratory Flow ◽  
Clinically Significant

Expiratory flow limitation is a key characteristic in obstructive pulmonary diseases. To study abnormal lung mechanics isolated from heterogeneities of obstructive disease, we measured pulmonary function in healthy adults with expiratory loading. Thirty-seven volunteers (25±5 yr) completed spirometry and body plethysmography under control and threshold expiratory loading of 7, 11 cmH2O, and a subset at 20 cmH2O (n = 11). We analyzed the shape of the flow-volume relationship with rectangular area ratio (RAR; Ma et al., Respir Med 2010). Airway resistance was increased (p<0.0001) with 7 and 11 cmH2O loading vs control (9.20±1.02 and 11.76±1.68 vs. 2.53± 0.80 cmH2O/L/s). RAR was reduced (p = 0.0319) in loading vs control (0.45±0.07 and 0.47±0.09L vs. 0.48±0.08). FEV1 was reduced (p<0.0001) in loading vs control (3.24±0.81 and 3.23±0.80 vs. 4.04±1.05 L). FVC was reduced (p<0.0001) in loading vs control (4.11±1.01 and 4.14±1.03 vs. 5.03±1.34 L). Peak expiratory flow (PEF) was reduced (p<0.0001) in loading vs control (6.03±1.67 and 6.02±1.84 vs. 8.50±2.81 L/s). FEV1/FVC (p<0.0068) was not clinically significant and FRC (p = 0.4) was not different in loading vs control. Supra-physiologic loading at 20 cmH2O did not result in further limitation. Expiratory loading reduced FEV1, FVC, PEF, but there were no clinically meaningful differences in FEV1/FVC, FRC, or RAR. Imposed expiratory loading likely leads to high airway pressures that resist dynamic airway compression. Thus, a concave expiratory flow-volume relationship was consistently absent–a key limitation for model comparison with pulmonary function in COPD. Threshold loading may be a useful strategy to increase work of breathing or induce dynamic hyperinflation.

Analysis of Maximum Expiratory Flow Volume Curves Using Canonical Correlation Analysis

1985 ◽  
Vol 24 (02) ◽  
pp. 91-100 ◽  
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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