scholarly journals Heliox breathing equally influences respiratory mechanics and cycling performance in trained males and females

2015 ◽  
Vol 118 (3) ◽  
pp. 255-264 ◽  
Author(s):  
Sabrina S. Wilkie ◽  
Paolo B. Dominelli ◽  
Benjamin C. Sporer ◽  
Michael S. Koehle ◽  
A. William Sheel
Keyword(s):  
Exercise Performance ◽  
Respiratory Mechanics ◽  
Work Of Breathing ◽  
Time Trial ◽  
Whole Body ◽  
Flow Limitation ◽  
Maximal Aerobic Capacity ◽  
Expiratory Flow Limitation ◽  
Ventilatory Capacity ◽  
Expiratory Flow

In this study we tested the hypothesis that inspiring a low-density gas mixture (helium-oxygen; HeO2) would minimize mechanical ventilatory constraints and preferentially increase exercise performance in females relative to males. Trained male ( n = 11, 31 yr) and female ( n = 10, 26 yr) cyclists performed an incremental cycle test to exhaustion to determine maximal aerobic capacity (V̇o2max; male = 61, female = 56 ml·kg−1·min−1). A randomized, single-blinded crossover design was used for two experimental days where subjects completed a 5-km cycling time trial breathing humidified compressed room air or HeO2 (21% O2:balance He). Subjects were instrumented with an esophageal balloon for the assessment of respiratory mechanics. During the time trial, we assessed the ability of HeO2 to alleviate mechanical ventilatory constraints in three ways: 1) expiratory flow limitation, 2) utilization of ventilatory capacity, and 3) the work of breathing. We found that HeO2 significantly reduced the work of breathing, increased the size of the maximal flow-volume envelope, and reduced the fractional utilization of the maximal ventilatory capacity equally between men and women. The primary finding of this study was that inspiring HeO2 was associated with a statistically significant performance improvement of 0.7% (3.2 s) for males and 1.5% (8.1 s) for females ( P < 0.05); however, there were no sex differences with respect to improvement in time trial performance ( P > 0.05). Our results suggest that the extent of sex-based differences in airway anatomy, work of breathing, and expiratory flow limitation is not great enough to differentially affect whole body exercise performance.

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.

Lung volumes and expiratory flow limitation during exercise in interstitial lung disease

1994 ◽  
Vol 77 (2) ◽  
pp. 963-973 ◽  
Author(s):  
D. D. Marciniuk ◽  
G. Sridhar ◽  
R. E. Clemens ◽  
T. A. Zintel ◽  
C. G. Gallagher
Keyword(s):  
Interstitial Lung Disease ◽  
Lung Disease ◽  
Lung Volume ◽  
Total Lung Capacity ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Ventilatory Capacity ◽  
Expiratory Flow

Lung volumes were measured at rest and during exercise by an open-circuit N2-washout technique in patients with interstitial lung disease (ILD). Exercise tidal flow-volume (F-V) curves were also compared with maximal F-V curves to investigate whether these patients demonstrated flow limitation. Seven patients underwent 4 min of constant work rate bicycle ergometer exercise at 40, 70, and 90% of their previously determined maximal work rates. End-expiratory lung volume and total lung capacity were measured at rest and near the end of each period of exercise. There was no significant change in end-expiratory lung volume or total lung capacity when resting measurements were compared with measurements at 40, 70, and 90% work rates. During exercise, expiratory flow limitation was evident in four patients who reported stopping exercise because of dyspnea. In the remaining patients who discontinued exercise because of leg fatigue, no flow limitation was evident. In all patients, the mean ratio of maximal minute ventilation to maximal ventilatory capacity (calculated from maximal F-V curves) was 67%. We conclude that lung volumes during exercise do not significantly differ from those at rest in this population and that patients with ILD may demonstrate expiratory flow limitation during exercise. Furthermore, because most patients with ILD are not breathing near their maximal ventilatory capacity at the end of exercise, we suggest that respiratory mechanics are not the primary cause of their exercise 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.

Determinants of exercise performance in normal men with externally imposed expiratory flow limitation

2002 ◽  
Vol 92 (5) ◽  
pp. 1943-1952 ◽  
Author(s):  
Iacopo Iandelli ◽  
Andrea Aliverti ◽  
Bengt Kayser ◽  
Raffaele Dellacà ◽  
Stephen J. Cala ◽  
...  
Keyword(s):  
Exercise Performance ◽  
Valsalva Maneuver ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Optoelectronic Plethysmography ◽  
Expiratory Flow ◽  
The Difference ◽  
Blood Volume Shift ◽  
Normal Men ◽  
Gas Volume

To understand how externally applied expiratory flow limitation (EFL) leads to impaired exercise performance and dyspnea, we studied six healthy males during control incremental exercise to exhaustion (C) and with EFL at ∼1. We measured volume at the mouth (Vm), esophageal, gastric and transdiaphragmatic (Pdi) pressures, maximal exercise power (W˙max) and the difference (Δ) in Borg scale ratings of breathlessness between C and EFL exercise. Optoelectronic plethysmography measured chest wall and lung volume (Vl). From Campbell diagrams, we measured alveolar (Pa) and expiratory muscle (Pmus) pressures, and from Pdi and abdominal motion, an index of diaphragmatic power (W˙di). Four subjects hyperinflated and two did not. EFL limited performance equally to 65%W˙max with Borg = 9–10 in both. At EFLW˙max, inspiratory time (Ti) was 0.66s ± 0.08, expiratory time (Te) 2.12 ± 0.26 s, Pmus ∼40 cmH2O and ΔVl-ΔVm = 488.7 ± 74.1 ml. From Pa and Vl, we calculated compressed gas volume (Vc) = 163.0 ± 4.6 ml. The difference, ΔVl-ΔVm-Vc (estimated blood volume shift) was 326 ml ± 66 or 7.2 ml/cmH2O Pa. The high Pmus and long Te mimicked a Valsalva maneuver from which the short Ti did not allow recovery. Multiple stepwise linear regression revealed that the difference between C and EFL Pmus accounted for 70.3% of the variance in ΔBorg. ΔW˙di added 12.5%. We conclude that high expiratory pressures cause severe dyspnea and the possibility of adverse circulatory events, both of which would impair exercise performance.

Endurance exercise performance in acute hypoxia is influenced by expiratory flow limitation

2015 ◽  
Vol 115 (8) ◽  
pp. 1653-1663 ◽  
Author(s):  
Joshua C. Weavil ◽  
Joseph W. Duke ◽  
Jonathon L. Stickford ◽  
Joel M. Stager ◽  
Robert F. Chapman ◽  
...  
Keyword(s):  
Endurance Exercise ◽  
Exercise Performance ◽  
Acute Hypoxia ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Expiratory Flow

Modeling expiratory flow from excised tracheal tube laws

1999 ◽  
Vol 87 (5) ◽  
pp. 1973-1980 ◽  
Author(s):  
Nikolai Aljuri ◽  
Lutz Freitag ◽  
José G. Venegas
Keyword(s):  
Static Pressure ◽  
Pressure Recovery ◽  
High Frequency Ventilation ◽  
Flow Limitation ◽  
Flow Conditions ◽  
Expiratory Flow Limitation ◽  
Elastic Tubes ◽  
Viscous Losses ◽  
Forced Expiratory Flow ◽  
Expiratory Flow

Flow limitation during forced exhalation and gas trapping during high-frequency ventilation are affected by upstream viscous losses and by the relationship between transmural pressure (Ptm) and cross-sectional area ( A tr) of the airways, i.e., tube law (TL). Our objective was to test the validity of a simple lumped-parameter model of expiratory flow limitation, including the measured TL, static pressure recovery, and upstream viscous losses. To accomplish this objective, we assessed the TLs of various excised animal tracheae in controlled conditions of quasi-static (no flow) and steady forced expiratory flow. A tr was measured from digitized images of inner tracheal walls delineated by transillumination at an axial location defining the minimal area during forced expiratory flow. Tracheal TLs followed closely the exponential form proposed by Shapiro (A. H. Shapiro. J. Biomech. Eng. 99: 126–147, 1977) for elastic tubes: Ptm = K p[( A tr/ A tr0)− n − 1], where A tr0 is A tr at Ptm = 0 and K p is a parametric factor related to the stiffness of the tube wall. Using these TLs, we found that the simple model of expiratory flow limitation described well the experimental data. Independent of upstream resistance, all tracheae with an exponent n < 2 experienced flow limitation, whereas a trachea with n > 2 did not. Upstream viscous losses, as expected, reduced maximal expiratory flow. The TL measured under steady-flow conditions was stiffer than that measured under expiratory no-flow conditions, only if a significant static pressure recovery from the choke point to atmosphere was assumed in the measurement.

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