scholarly journals Variability of within-breath reactance in COPD patients and its association with dyspnoea

2014 ◽  
Vol 45 (3) ◽  
pp. 625-634 ◽  
Author(s):  
Bernt B. Aarli ◽  
Peter M.A. Calverley ◽  
Robert L. Jensen ◽  
Tomas M.L. Eagan ◽  
Per S. Bakke ◽  
...  
Keyword(s):  
Continuous Measurement ◽  
Medical Research Council ◽  
Forced Oscillation ◽  
Chronic Obstructive ◽  
Forced Oscillation Technique ◽  
Flow Limitation ◽  
Oscillation System ◽  
Expiratory Flow Limitation ◽  
Obstructive Pulmonary Disease ◽  
Copd Patients

The forced oscillation technique can identify expiratory flow limitation (EFL) when a large difference in inspiratory and expiratory reactance (ΔXrs) occurs. However, flow limitation can vary from breath to breath, and so we compared a multiple-breath ΔXrs approach to the traditional breath-by-breath assessment of EFL. We investigated the within- and between-day reproducibility and the factors that affect the size of ΔXrs when used as a continuous measurement over multiple breaths. In addition, we examined how multiple-breath ΔXrs relates to the sensation of breathlessness.425 moderate to very severe chronic obstructive pulmonary disease (COPD) patients and 229 controls were included. Spirometry and impedance measurements were performed on a MasterScope CT Impulse Oscillation System.Median ΔXrs approached zero in healthy controls with little variation between measurements. COPD patients generally had higher ΔXrs and higher variability. The COPD patients with ΔXrs >0.1 kPa·L−1·s−1 were prone to be more breathless and had a higher modified Medical Research Council dyspnoea scale score. In controls, the 95th percentile of ΔXrs was as low as 0.07 kPa·L−1·s−1.We describe a new method to assess EFL at a patient level and propose a cut-off, mean ΔXrs >0.1 kPa·L−1·s−1, as a way to identify COPD patients who are more likely to report dyspnoea.

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.

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.

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 Effect of nocturnal EPAP titration to abolish tidal expiratory flow limitation in COPD patients with chronic hypercapnia: a randomized, cross-over pilot study

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Emanuela Zannin ◽  
Ilaria Milesi ◽  
Roberto Porta ◽  
Simona Cacciatore ◽  
Luca Barbano ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Work Of Breathing ◽  
Lung Mechanics ◽  
Intrinsic Peep ◽  
Chronic Obstructive ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Copd Patients ◽  
Ineffective Efforts ◽  
Expiratory Flow

Abstract Background Tidal expiratory flow limitation (EFLT) promotes intrinsic PEEP (PEEPi) in patients with chronic obstructive pulmonary disease (COPD). Applying non-invasive ventilation (NIV) with an expiratory positive airway pressure (EPAP) matching PEEPi improves gas exchange, reduces work of breathing and ineffective efforts. We aimed to evaluate the effects of a novel NIV mode that continuously adjusts EPAP to the minimum level that abolishes EFLT. Methods This prospective, cross-over, open-label study randomized patients to one night of fixed-EPAP and one night of EFLT-abolishing-EPAP. The primary outcome was transcutaneous carbon dioxide pressure (PtcCO2). Secondary outcomes were: peripheral oxygen saturation (SpO2), frequency of ineffective efforts, breathing patterns and oscillatory mechanics. Results We screened 36 patients and included 12 in the analysis (age 72 ± 8 years, FEV1 38 ± 14%Pred). The median EPAP did not differ between the EFLT-abolishing-EPAP and the fixed-EPAP night (median (IQR) = 7.0 (6.0, 8.8) cmH2O during night vs 7.5 (6.5, 10.5) cmH2O, p = 0.365). We found no differences in mean PtcCO2 (44.9 (41.6, 57.2) mmHg vs 54.5 (51.1, 59.0), p = 0.365), the percentage of night time with PtcCO2 > 45 mm Hg was lower (62(8,100)% vs 98(94,100)%, p = 0.031) and ineffective efforts were fewer (126(93,205) vs 261(205,351) events/hour, p = 0.003) during the EFLT-abolishing-EPAP than during the fixed-EPAP night. We found no differences in oxygen saturation and lung mechanics between nights. Conclusion An adaptive ventilation mode targeted to abolish EFLT has the potential to reduce hypercapnia and ineffective efforts in stable COPD patients receiving nocturnal NIV. Trial registration: ClicalTrials.gov, NCT04497090. Registered 29 July 2020—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04497090.

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