scholarly journals Expiratory Flow Limitation and Its Relation to Dyspnea and Lung Hyperinflation in Patients with Chronic Obstructive Pulmonary Disease: Analysis Using the Forced Expiratory Flow-Volume Curve and Critique

2021 ◽  
Vol 11 (03) ◽  
pp. 91-104
Author(s):  
Billy Peng ◽  
Matthew Miller ◽  
Mark Slootsky ◽  
Ravi Patel ◽  
Ahmet Baydur
Keyword(s):  
Chronic Obstructive ◽  
Flow Limitation ◽  
Flow Volume ◽  
Expiratory Flow Limitation ◽  
Obstructive Pulmonary Disease ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Disease Analysis

Detection of expiratory flow limitation during exercise in COPD patients

1997 ◽  
Vol 82 (3) ◽  
pp. 723-731 ◽  
Author(s):  
Nickolaos G. Koulouris ◽  
Ioanna Dimopoulou ◽  
Päivi Valta ◽  
Richard Finkelstein ◽  
Manuel G. Cosio ◽  
...  
Keyword(s):  
Normal Subjects ◽  
Chronic Obstructive ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Obstructive Pulmonary Disease ◽  
Normal Limits ◽  
Volume Curve ◽  
Copd Patients ◽  
Flow Volume Curve ◽  
Expiratory Flow

Koulouris, Nickolaos G., Ioanna Dimopoulou, Päivi Valta, Richard Finkelstein, Manuel G. Cosio, and J. Milic-Emili.Detection of expiratory flow limitation during exercise in COPD patients. J. Appl. Physiol. 82(3): 723–731, 1997.—The negative expiratory pressure (NEP) method was used to detect expiratory flow limitation at rest and at different exercise levels in 4 normal subjects and 14 patients with chronic obstructive pulmonary disease (COPD). This method does not require performance of forced expirations, nor does it require use of body plethysmography. It consists in applying negative pressure (−5 cmH2O) at the mouth during early expiration and comparing the flow-volume curve of the ensuing expiration with that of the preceding control breath. Subjects in whom application of NEP does not elicit an increase in flow during part or all of the tidal expiration are considered flow limited. The four normal subjects were not flow limited up to 90% of maximal exercise power output (W˙max). Five COPD patients were flow limited at rest, 9 were flow limited at one-third W˙max, and 12 were flow limited at two-thirdsW˙max. Whereas in all patients who were flow limited at rest the maximal O2 uptake was below the normal limits, this was not the case in most of the other patients. In conclusion, NEP provides a rapid and reliable method to detect expiratory flow limitation at rest and during exercise.

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.

scholarly journals The Concavity of the Maximal Expiratory Flow–Volume Curve Reflects the Extent of Emphysema in Obstructive Lung Diseases

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Fumi Mochizuki ◽  
Hiroaki Iijima ◽  
Azusa Watanabe ◽  
Naoya Tanabe ◽  
Susumu Sato ◽  
...  
Keyword(s):  
Vital Capacity ◽  
Chronic Obstructive ◽  
Flow Volume ◽  
Obstructive Pulmonary Disease ◽  
Wall Area ◽  
Maximal Expiratory Flow ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Expiratory Flow ◽  
Volume Difference

Abstract A concave-shaped maximal expiratory flow-volume (MEFV) curve is a spirometric feature in chronic obstructive pulmonary disease (COPD). The MEFV curve is characterized by an increase in the Obstructive Index, which is defined as a ratio of forced vital capacity to the volume-difference between two points of half of the peak expiratory flow on the MEFV curve. We hypothesized that the Obstructive Index would reflect the severity of emphysema in patients with COPD and asthma-COPD overlap (ACO). Thus, the aim of this retrospective study was to evaluate whether the Obstructive Index on spirometry is associated with the extent of emphysema on computed tomography (CT) in patients with COPD, ACO, and asthma (N = 65, 15, and 53, respectively). The percentage of low-attenuation volume (LAV%) and wall area (WA%) were measured on CT. The Obstructive Index was higher in patients with COPD and ACO than in those with asthma. Spearman correlation showed that a greater Obstructive Index was associated with a higher LAV%, but not WA%. Multivariate analysis showed that Obstructive Index was associated with LAV% (standardized β = 0.43, P < 0.0001) independent of other spirometric indices. The Obstructive Index is a useful spirometric index that reflects the extent of emphysema.

scholarly journals Tidal expiratory flow limitation induces expiratory looping of the alveolar pressure-flow relation in COPD patients

2020 ◽  
Vol 129 (1) ◽  
pp. 75-83
Author(s):  
Matteo Pecchiari ◽  
Dejan Radovanovic ◽  
Camilla Zilianti ◽  
Laura Saderi ◽  
Giovanni Sotgiu ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Chronic Obstructive ◽  
Flow Limitation ◽  
Alveolar Pressure ◽  
Expiratory Flow Limitation ◽  
Obstructive Pulmonary Disease ◽  
Copd Patients ◽  
Expiratory Flow ◽  
Spontaneously Breathing

In stable chronic obstructive pulmonary disease (COPD) patients spontaneously breathing at rest, tidal expiratory flow limitation is the major determinant of the occurrence of expiratory looping in the plethysmographic flow-alveolar pressure diagram. In these patients the magnitude and the characteristics of the loop can be used as predictors of the presence of tidal expiratory flow limitation.

scholarly journals Expiratory Flow Limitation Definition, Mechanisms, Methods, and Significance

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Claudio Tantucci
Keyword(s):  
Work Of Breathing ◽  
Chronic Obstructive ◽  
Dynamic Hyperinflation ◽  
Flow Limitation ◽  
Negative Consequences ◽  
Expiratory Flow Limitation ◽  
Obstructive Pulmonary Disease ◽  
Inspiratory Muscles ◽  
Copd Patients ◽  
Expiratory Flow

When expiratory flow is maximal during tidal breathing and cannot be increased unless operative lung volumes move towards total lung capacity, tidal expiratory flow limitation (EFL) is said to occur. EFL represents a severe mechanical constraint caused by different mechanisms and observed in different conditions, but it is more relevant in terms of prevalence and negative consequences in obstructive lung diseases and particularly in chronic obstructive pulmonary disease (COPD). Although in COPD patients EFL more commonly develops during exercise, in more advanced disorder it can be present at rest, before in supine position, and then in seated-sitting position. In any circumstances EFL predisposes to pulmonary dynamic hyperinflation and its unfavorable effects such as increased elastic work of breathing, inspiratory muscles dysfunction, and progressive neuroventilatory dissociation, leading to reduced exercise tolerance, marked breathlessness during effort, and severe chronic dyspnea.

scholarly journals Methods for Assessing Expiratory Flow Limitation during Tidal Breathing in COPD Patients

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Nickolaos G. Koulouris ◽  
Georgios Kaltsakas ◽  
Anastasios F. Palamidas ◽  
Sofia-Antiopi Gennimata
Keyword(s):  
Transpulmonary Pressure ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Exercise Limitation ◽  
Non Invasive ◽  
Airway Injury ◽  
Volume Curve ◽  
Copd Patients ◽  
Flow Volume Curve ◽  
Expiratory Flow

Patients with severe COPD often exhale along the same flow-volume curve during quite breathing as during forced expiratory vital capacity manoeuvre, and this has been taken as indicating expiratory flow limitation at rest (EFLT). Therefore,EFLT, namely, attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow.EFLTleads to small airway injury and promotes dynamic pulmonary hyperinflation with concurrent dyspnoea and exercise limitation. In fact,EFLToccurs commonly in COPD patients (mainly in GOLD III and IV stage) in whom the latter symptoms are common. The existing up-to-date physiological methods for assessing expiratory flow limitation (EFLT) are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure (NEP) has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, non invasive, most practical, and accurate new technique.

Detection of heterogeneous lung emptying by shape of forced expiratory flow-volume curve in asthmatic children

2018 ◽  
Author(s):  
David Richard ◽  
Sabrina Khelil ◽  
Stéphanie Metche ◽  
Aurelie Tatopoulos ◽  
Sébastien Kiefer ◽  
...  
Keyword(s):  
Flow Volume ◽  
Asthmatic Children ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Forced Expiratory Flow ◽  
Expiratory Flow
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