Pathogenesis of hyperinflation in chronic obstructive pulmonary disease

Throughout the continuum of hyperinflation from mild to more severe COPD, the progressive increase in TLC, FRC, and residual volume appears to be exponential with the worsening airflow limitation.

“On the other hand, the progressive increase in TLC, FRC, and residual volume appears to be exponential with the worsening airflow limitation during the course of COPD.40”

• cites [40] Deesomchok A Webb KA Forkert L Lung hyperinflation and its reversibility in patients with airway obstruction of varying severity COPD 2010 7 6 428 437 21166631 sourceSupported

Throughout the continuum of hyperinflation from mild to more severe COPD, vital capacity and inspiratory capacity decrease linearly with the progression of airflow obstruction (FEV1 decline).

“Throughout the continuum of hyperinflation from mild to more severe COPD, vital capacity and IC decrease linearly with the progression of airflow obstruction (FEV1 decline).”

• cites [40] Deesomchok A Webb KA Forkert L Lung hyperinflation and its reversibility in patients with airway obstruction of varying severity COPD 2010 7 6 428 437 21166631 sourceSupported

During exercise, dynamic hyperinflation is already present in patients with mild disease (GOLD stage 1), even when resting hyperinflation is slightly present or absent.

“During exercise, some studies report that dynamic hyperinflation is already present in patients with mild disease (GOLD stage 1), even when resting hyperinflation is slightly present22,23 or absent.24,41–43”

• cites [22] Ofir D Laveneziana P Webb KA Lam YM O’Donnell DE Mechanisms of dyspnea during cycle exercise in symptomatic patients with GOLD stage I chronic obstructive pulmonary disease Am J Respir Crit Care Med 2008 177 6 622 629 18006885 sourceNot checked — no full text of the source
• cites [23] O’Donnell DE Laveneziana P Ora J Webb KA Lam YM Ofir D Evaluation of acute bronchodilator reversibility in patients with symptoms of GOLD stage I COPD Thorax 2009 64 3 216 223 19052054 sourceNot checked — no full text of the source
• cites [24] Gagnon P Saey D Provencher S Walking exercise response to bronchodilation in mild COPD: a randomized trial Respir Med 2012 106 12 1695 1705 22999808 sourceNot checked — no full text of the source
• cites [41] Guenette JA Chin RC Cory JM Webb KA O’Donnell DE Inspiratory capacity during exercise: measurement, analysis, and interpretation Pulm Med 2013 2013 956081 23476765 PMC3582111 sourcePartly supported

  Section 5.1, “Typical Responses in Health and Disease” (page unavailable), says significant dynamic hyperinflation during exercise is detectable even in milder COPD; its cited studies include one on GOLD stage I patients. It does not establish that those patients had slight or no resting hyperinflation, so that qualification is unsupported by our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [42] Guenette JA Webb KA O’Donnell DE Does dynamic hyperinflation contribute to dyspnoea during exercise in patients with COPD? Eur Respir J 2012 40 2 322 329 22183485 sourcePartly supported

  The Abstract and Exercise responses report dynamic hyperinflation during exercise in patients with moderate-to-severe COPD. The Discussion compares resting hyperinflation between exercise hyperinflators and nonhyperinflators, but does not establish the claim for GOLD stage 1 patients with slight or absent resting hyperinflation. Page numbers were not available in our copy. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [43] Chin RC Guenette JA Cheng S Does the respiratory system limit exercise in mild chronic obstructive pulmonary disease? Am J Respir Crit Care Med 2013 187 12 1315 1323 23590271 sourceNot checked — no full text of the source

During exercise, hyperinflation may impede cardiac function in COPD.

“During exercise, hyperinflation may impede cardiac19,20 and respiratory muscle function and increase the work of breathing.21”

• cites [19] Watz H Waschki B Meyer T Decreasing cardiac chamber sizes and associated heart dysfunction in COPD: role of hyperinflation Chest 2010 138 1 32 38 20190002 sourceNot checked — no full text of the source
• cites [20] Tzani P Aiello M Elia D Dynamic hyperinflation is associated with a poor cardiovascular response to exercise in COPD patients Respir Res 2011 12 150 22074289 PMC3225311 sourceSupported

The ability of the respiratory muscles to generate pressure decreases at high lung volumes in humans.

“Indeed, the ability of the respiratory muscles to generate pressure decreases at high lung volumes in humans.58,60”

• cites [58] Similowski T Yan S Gauthier AP Macklem PT Bellemare F Contractile properties of the human diaphragm during chronic hyperinflation N Engl J Med 1991 325 13 917 923 1881417 sourcePartly supported

  The Effects of Acute Change in Lung Volume section (p. 3) reports that twitch transdiaphragmatic pressure decreased as lung volume increased in human patients and controls. The study measured the diaphragm, however, not respiratory muscles generally, so the claim is broader than its evidence. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [60] Polkey MI Hamnegard CH Hughes PD Rafferty GF Green M Moxham J Influence of acute lung volume change on contractile properties of human diaphragm J Appl Physiol 1998 85 4 1322 1328 9760323 sourceNot checked — no full text of the source

In well-characterized COPD patients matched for age, sex, body mass index, and baseline airflow obstruction, hyperinflators did not experience more dyspnea than nonhyperinflators.

“Despite being well matched for age, sex, body mass index, and baseline airflow obstruction, the authors were not able to show that the hyperinflators experienced more dyspnea than the nonhyperinflators.”

• cites [42] Guenette JA Webb KA O’Donnell DE Does dynamic hyperinflation contribute to dyspnoea during exercise in patients with COPD? Eur Respir J 2012 40 2 322 329 22183485 sourceSupported

Collectively, cardiovascular consequences of lung hyperinflation likely contribute, in highly variable combinations, to the reduced cardiac performance observed in some COPD patients during exercise.

“Collectively, these cardiovascular consequences of lung hyperinflation likely contribute, in highly variable combinations, to the reduced cardiac performance observed in some COPD patients during exercise.20,85”

• cites [20] Tzani P Aiello M Elia D Dynamic hyperinflation is associated with a poor cardiovascular response to exercise in COPD patients Respir Res 2011 12 150 22074289 PMC3225311 sourceSupported
• cites [85] Vassaux C Torre-Bouscoulet L Zeineldine S Effects of hyperinflation on the oxygen pulse as a marker of cardiac performance in COPD Eur Respir J 2008 32 5 1275 1282 18550609 sourceNot checked — no full text of the source

Interventions that deflate the lungs and delay the onset of critical VT constraints consistently reduce dyspnea intensity in patients with COPD during exercise.

“Moreover, interventions that deflate the lungs (ie, reduce EILV and EELV) and delay the onset of critical VT constraints consistently reduce dyspnea intensity in patients with COPD during exercise.45,46,55,56”

• cites [45] O’Donnell DE Voduc N Fitzpatrick M Webb KA Effect of salmeterol on the ventilatory response to exercise in chronic obstructive pulmonary disease Eur Respir J 2004 24 1 86 94 15293609 sourcePartly supported

  The Effect on dyspnoea section reports that salmeterol increased inspiratory capacity and tidal-volume expansion with less respiratory discomfort during exercise in patients with COPD; it also describes a later threshold for intolerable dyspnoea. The standardised-time exercise table shows a lower EELV (reflected by higher inspiratory capacity), but does not establish a reduction in EILV. This single-intervention study also does not establish that such effects occur consistently across interventions. Page numbers were not available in our copy. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [46] O’Donnell DE Fluge T Gerken F Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD Eur Respir J 2004 23 6 832 840 15218994 sourceNot checked — no full text of the source
• cites [55] Belman MJ Botnick WC Shin JW Inhaled bronchodilators reduce dynamic hyperinflation during exercise in patients with chronic obstructive pulmonary disease Am J Respir Crit Care Med 1996 153 3 967 975 8630581 sourceNot checked — no full text of the source
• cites [56] O’Donnell DE Hamilton AL Webb KA Sensory-mechanical relationships during high-intensity, constant-work-rate exercise in COPD J Appl Physiol 2006 101 4 1025 1035 16675610 sourceNot checked — no full text of the source

A small proportion of patients with COPD (~15%-20%) do not dynamically hyperinflate during exercise even though they still experience intolerable dyspnea.

“Although dynamic hyperinflation is a cardinal feature of COPD with important physiological consequences, a small proportion of patients (~15%–20%) do not dynamically hyperinflate during exercise even though they still experience intolerable dyspnea.13,42,57”

• cites [13] O’Donnell DE Revill SM Webb KA Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 164 5 770 777 11549531 sourceNot checked — no full text of the source
• cites [42] Guenette JA Webb KA O’Donnell DE Does dynamic hyperinflation contribute to dyspnoea during exercise in patients with COPD? Eur Respir J 2012 40 2 322 329 22183485 sourceSupported
• cites [57] O’Donnell DE Travers J Webb KA Reliability of ventilatory parameters during cycle ergometry in multicentre trials in COPD Eur Respir J 2009 34 4 866 874 19282342 sourceSupported

At peak exercise, notwithstanding the severity of the disease, patients with COPD show a consistent fall of approximately 20% of their resting IC at peak exercise.

“At peak exercise, notwithstanding the severity of the disease, patients seem to show a consistent fall of approximately 20% of their resting IC at peak exercise.22–24,45–48”

• cites [22] Ofir D Laveneziana P Webb KA Lam YM O’Donnell DE Mechanisms of dyspnea during cycle exercise in symptomatic patients with GOLD stage I chronic obstructive pulmonary disease Am J Respir Crit Care Med 2008 177 6 622 629 18006885 sourceNot checked — no full text of the source
• cites [23] O’Donnell DE Laveneziana P Ora J Webb KA Lam YM Ofir D Evaluation of acute bronchodilator reversibility in patients with symptoms of GOLD stage I COPD Thorax 2009 64 3 216 223 19052054 sourceNot checked — no full text of the source
• cites [24] Gagnon P Saey D Provencher S Walking exercise response to bronchodilation in mild COPD: a randomized trial Respir Med 2012 106 12 1695 1705 22999808 sourceNot checked — no full text of the source
• cites [45] O’Donnell DE Voduc N Fitzpatrick M Webb KA Effect of salmeterol on the ventilatory response to exercise in chronic obstructive pulmonary disease Eur Respir J 2004 24 1 86 94 15293609 sourcePartly supported

  The ‘Effect of salmeterol on ventilation’ section reports that IC fell by 20% of its resting value at peak exercise in this study’s COPD patients. The Subjects section restricts the sample to patients with hyperinflation and significant activity-related dyspnoea; the paper does not establish that the fall is consistent regardless of disease severity. Page numbers were not available in our copy. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [46] O’Donnell DE Fluge T Gerken F Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD Eur Respir J 2004 23 6 832 840 15218994 sourceNot checked — no full text of the source
• cites [47] Neder JA Fuld JP Overend T Effects of formoterol on exercise tolerance in severely disabled patients with COPD Respir Med 2007 101 10 2056 2064 17658249 sourceNot checked — no full text of the source
• cites [48] Maltais F Celli B Casaburi R Aclidinium bromide improves exercise endurance and lung hyperinflation in patients with moderate to severe COPD Respir Med 2011 105 4 580 587 21183326 sourceNot checked — no full text of the source

Obese patients with COPD still hyperinflate to a similar degree (Δ IC from rest to peak exercise capacity) as their normal weight counterparts.

“Obese patients with COPD still hyperinflate to a similar degree (Δ IC from rest to peak exercise capacity) than their normal weight counterparts.126,128,129”

• cites [126] Ora J Laveneziana P Wadell K Preston M Webb KA O’Donnell DE Effect of obesity on respiratory mechanics during rest and exercise in COPD J Appl Physiol 2011 111 1 10 19 21350021 sourceNot checked — no full text of the source
• cites [128] Laviolette L Sava F O’Donnell DE Effect of obesity on constant workrate exercise in hyperinflated men with COPD BMC Pulm Med 2010 10 33 20509967 PMC2891696 sourcePartly supported

  The Results (Dynamic lung volumes) report similar decreases in inspiratory capacity from rest to the end of constant-workrate exercise for normal-BMI and obese patients (421 ± 409 versus 380 ± 487 ml; p = 0.46). This supports similar dynamic hyperinflation in the study’s hyperinflated men with COPD, but the paper measured that change during constant-workrate exercise, not from rest to peak capacity on the incremental test. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [129] Ora J Laveneziana P Ofir D Deesomchok A Webb KA O’Donnell DE Combined effects of obesity and chronic obstructive pulmonary disease on dyspnea and exercise tolerance Am J Respir Crit Care Med 2009 180 10 964 971 19897773 sourceNot checked — no full text of the source

Studies report that obese patients with COPD have either preserved or increased exercise capacity, except when walking is the testing modality.

“Therefore, these studies all report that obese patients with COPD have either preserved or increased exercise capacity,126–129 except when walking is the testing modality.127”

• cites [126] Ora J Laveneziana P Wadell K Preston M Webb KA O’Donnell DE Effect of obesity on respiratory mechanics during rest and exercise in COPD J Appl Physiol 2011 111 1 10 19 21350021 sourceNot checked — no full text of the source
• cites [127] Sava F Laviolette L Bernard S Breton MJ Bourbeau J Maltais F The impact of obesity on walking and cycling performance and response to pulmonary rehabilitation in COPD BMC Pulm Med 2010 10 55 21054892 PMC2987952 sourceSupported
• cites [128] Laviolette L Sava F O’Donnell DE Effect of obesity on constant workrate exercise in hyperinflated men with COPD BMC Pulm Med 2010 10 33 20509967 PMC2891696 sourceSupported
• cites [129] Ora J Laveneziana P Ofir D Deesomchok A Webb KA O’Donnell DE Combined effects of obesity and chronic obstructive pulmonary disease on dyspnea and exercise tolerance Am J Respir Crit Care Med 2009 180 10 964 971 19897773 sourceNot checked — no full text of the source

Respiratory volumes and flows are significantly different between the sexes, as shown by the reference equations for lung function.

“Respiratory volumes and flows are significantly different between the sexes, as shown by the reference equations for lung function.130,131”

• cites [130] Stocks J Quanjer PH Reference values for residual volume, functional residual capacity and total lung capacity. ATS Workshop on Lung Volume Measurements. Official Statement of The European Respiratory Society Eur Respir J 1995 8 3 492 506 7789503 sourcePartly supported

  The Background section (page not supplied) identifies sex as an important determinant of lung volume, and Table 7 gives separate reference equations for boys and girls. The source does not establish a sex difference in respiratory flows, so it supports the volume portion but not the full claim. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [131] Quanjer PH Tammeling GJ Cotes JE Pedersen OF Peslin R Yernault JC Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official Statement of the European Respiratory Society Eur Respir J Suppl 1993 16 5 40 8499054Not checked — no full text of the source

During constant work rate cycle exercise testing at the same relative intensity, women with COPD hyperinflated at a rate similar to that in men (Δ IC).

“During constant work rate cycle exercise testing at the same relative intensity, women with COPD hyperinflated at a rate similar to that in men (Δ IC).138”

• cites [138] Laviolette L O’Donnell DE Webb KA Hamilton AL Kesten S Maltais F Performance during constant workrate cycling exercise in women with COPD and hyperinflation COPD 2009 6 5 340 351 19863363 sourceSupported

Body plethysmography is considered the gold standard for assessing lung volumes in COPD.

“Body plethysmography is considered the gold standard.”

• cites [141] Pellegrino R Viegi G Brusasco V Interpretative strategies for lung function tests Eur Respir J 2005 26 5 948 968 16264058 sourcePartly supported

  The Mixed abnormalities section describes measuring total lung capacity by body plethysmography in patients with airflow obstruction. That supports its use to assess lung volume, but our copy does not call it the gold standard or rank it above other methods for COPD. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

Nitrogen washout and helium dilution techniques underestimate FRC in the presence of severe airflow obstruction or emphysema.

“In contrast, nitrogen washout and helium dilution techniques underestimate FRC in the presence of severe airflow obstruction or emphysema.32,140”

• cites [32] O’Donnell DE Laveneziana P The clinical importance of dynamic lung hyperinflation in COPD COPD 2006 3 4 219 232 17361503 sourcePartly supported

  The measurement passage (indexed as Abstract; page unavailable) equates EELV with FRC and says inert-gas dilution techniques may underestimate lung volumes because of non-communicating airways. It does not name nitrogen washout or helium dilution, specify severe airflow obstruction or emphysema as the conditions, or state that underestimation invariably occurs. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [140] Wanger J Clausen JL Coates A Standardisation of the measurement of lung volumes Eur Respir J 2005 26 3 511 522 16135736 sourceSupported

Radiographic techniques are not commonly used clinically to measure static hyperinflation in COPD because of a lack of standardization.

“Finally, because of a lack of standardization, radiographic techniques144–147 are not commonly used clinically to measure static hyperinflation in COPD.32”

• cites [144] Burki NK Krumpelman JL Correlation of pulmonary function with the chest roentgenogram in chronic airway obstruction Am Rev Respir Dis 1980 121 2 217 223 7362131 sourceNot checked — no full text of the source
• cites [145] Simon G Pride NB Jones NL Raimondi AC Relation between abnormalities in the chest radiograph and changes in pulmonary function in chronic bronchitis and emphysema Thorax 1973 28 1 15 23 4685207 PMC469986 sourceNot checked — no full text of the source
• cites [146] Nakano Y Muro S Sakai H Computed tomographic measurements of airway dimensions and emphysema in smokers. Correlation with lung function Am J Respir Crit Care Med 2000 162 3 Pt 1 1102 1108 10988137 sourceNot checked — no full text of the source
• cites [147] de Jong PA Muller NL Pare PD Coxson HO Computed tomographic imaging of the airways: relationship to structure and function Eur Respir J 2005 26 1 140 152 15994401 sourceNot checked — no full text of the source
• cites [32] O’Donnell DE Laveneziana P The clinical importance of dynamic lung hyperinflation in COPD COPD 2006 3 4 219 232 17361503 sourceSupported

The increase in resting IC caused by bronchodilators causes a parallel downward shift in operating lung volumes during exercise compared with exercise without bronchodilation.

“The resulting increase in resting IC causes a parallel downward shift in operating lung volumes during exercise in comparison with exercise performed without bronchodilation (Figure 3).41,150”

• cites [41] Guenette JA Chin RC Cory JM Webb KA O’Donnell DE Inspiratory capacity during exercise: measurement, analysis, and interpretation Pulm Med 2013 2013 956081 23476765 PMC3582111 sourceSupported
• cites [150] Maltais F Hamilton A Marciniuk D Improvements in symptom-limited exercise performance over 8 h with once-daily tiotropium in patients with COPD Chest 2005 128 3 1168 1178 16162703 sourceNot checked — no full text of the source

The effects of ventilatory support on dyspnea are probably mostly related to unloading of the inspiratory muscles during exercise.

“The effects of these interventions on dyspnea are probably mostly related to unloading of the inspiratory muscles during exercise.155,157–160”

• cites [155] van’t Hul A Gosselink R Hollander P Postmus P Kwakkel G Acute effects of inspiratory pressure support during exercise in patients with COPD Eur Respir J 2004 23 1 34 40 14738228 sourcePartly supported

  The Discussion (page unavailable) says inspiratory pressure support reduces inspiratory-muscle loading during exercise and proposes reduced exertional dyspnoea as a possible mechanism for improved exercise performance. It does not establish that muscle unloading accounts for most of the effect on dyspnoea; the authors say they did not measure that effect in this study. (LLM, conf=0.85)

  Experimental — accuracy not yet measured
• cites [157] O’Donnell DE Sanii R Younes M Improvement in exercise endurance in patients with chronic airflow limitation using continuous positive airway pressure Am Rev Respir Dis 1988 138 6 1510 1514 3059897 sourceNot checked — no full text of the source
• cites [158] Petrof BJ Calderini E Gottfried SB Effect of CPAP on respiratory effort and dyspnea during exercise in severe COPD J Appl Physiol 1990 69 1 179 188 2203722 sourceNot checked — no full text of the source
• cites [159] Maltais F Reissmann H Gottfried SB Pressure support reduces inspiratory effort and dyspnea during exercise in chronic airflow obstruction Am J Respir Crit Care Med 1995 151 4 1027 1033 7697226 sourceNot checked — no full text of the source
• cites [160] Polkey MI Kyroussis D Mills GH Inspiratory pressure support reduces slowing of inspiratory muscle relaxation rate during exhaustive treadmill walking in severe COPD Am J Respir Crit Care Med 1996 154 4 Pt 1 1146 1150 8887619 sourceNot checked — no full text of the source

Reduction of inspiratory reserve volume (IC - VT), reflecting "room to breathe", was even more related to exercise dyspnea than EELV.

“A recent study showed that reduction of the inspiratory reserve volume (IC – VT, Figure 1A and B) reflecting “room to breathe” was even more related to exercise dyspnea than EELV42”

• cites [42] Guenette JA Webb KA O’Donnell DE Does dynamic hyperinflation contribute to dyspnoea during exercise in patients with COPD? Eur Respir J 2012 40 2 322 329 22183485 sourceSupported

FRC calculated by body plethysmography is overestimated because it includes both ventilated and nonventilated lung compartments.

“It seems that the FRC calculated by body plethysmography is overestimated because it includes both ventilated and nonventilated lung compartments.130,142”

• cites [130] Stocks J Quanjer PH Reference values for residual volume, functional residual capacity and total lung capacity. ATS Workshop on Lung Volume Measurements. Official Statement of The European Respiratory Society Eur Respir J 1995 8 3 492 506 7789503 sourcePartly supported

  Section 3.1 reports higher plethysmographic FRC than helium-dilution FRC in newborns and says the discrepancy has been largely attributed to trapped gas that gas-equilibration methods do not detect. But section 3.4 says the methods give the same results in healthy adults. The paper therefore supports a measurement difference in infants, not a general claim that plethysmography overestimates FRC. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [142] Coates AL Peslin R Rodenstein D Stocks J Measurement of lung volumes by plethysmography Eur Respir J 1997 10 6 1415 1427 9192953 sourceNot checked — no full text of the source

The decrease in ventilatory needs after exercise training is probably related to improvements in limb muscle function after training with an accompanying reduced reliance on anaerobic metabolism during exercise.

“This decrease in ventilatory needs is probably related to improvements in limb muscle function after training with an accompanying reduced reliance on anaerobic metabolism during exercise.187,189”

• cites [187] Casaburi R ZuWallack R Pulmonary rehabilitation for management of chronic obstructive pulmonary disease N Engl J Med 2009 360 13 1329 1335 19321869 sourceNot checked — no full text of the source
• cites [189] Troosters T Gosselink R Janssens W Decramer M Exercise training and pulmonary rehabilitation: new insights and remaining challenges Eur Respir Rev 2010 19 115 24 29 20956162 PMC9491643 sourcePartly supported

  The Abstract (page unavailable) links reduced ventilatory needs to delayed lactic acidosis and describes exercise-training approaches that load or adapt skeletal muscle. It does not say that improved limb muscle function after training causes a reduced reliance on anaerobic metabolism and thereby lowers ventilatory needs; its lactic-acidosis explanation concerns supplemental oxygen. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

The positive effects of lung volume reduction surgery on airflow obstruction have been ascribed to increases in lung elastic recoil or to reductions in TLC and residual volume leading to an increased vital capacity and improvements in respiratory muscle function.

“The positive effects of this intervention on airflow obstruction have been ascribed to increases in lung elastic recoil or to reductions in TLC and residual volume leading to an increased vital capacity and improvements in respiratory muscle function.183,184”

• cites [183] Marchand E Gayan-Ramirez G De Leyn P Decramer M Physiological basis of improvement after lung volume reduction surgery for severe emphysema: where are we? Eur Respir J 1999 13 3 686 696 10232448 sourceNot checked — no full text of the source
• cites [184] Fessler HE Scharf SM Ingenito EP McKenna RJ Jr Sharafkhaneh A Physiologic basis for improved pulmonary function after lung volume reduction Proc Am Thorac Soc 2008 5 4 416 420 18453348 PMC2645312 sourceSupported

These studies all found significant differences in endurance time in favor of the hyperoxic helium group.

“These studies all found significant differences in endurance time in favor of the hyperoxic helium group.173–175”

• cites [173] Eves ND Petersen SR Haykowsky MJ Wong EY Jones RL Helium-hyperoxia, exercise, and respiratory mechanics in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2006 174 7 763 771 16840742 sourceNot checked — no full text of the source
• cites [174] Hussain O Collins EG Adiguzel N Langbein WE Tobin MJ Laghi F Contrasting pressure-support ventilation and helium-oxygen during exercise in severe COPD Respir Med 2011 105 3 494 505 20851591 sourceNot checked — no full text of the source
• cites [175] Queiroga F Jr Nunes M Meda E Exercise tolerance with helium-hyperoxia versus hyperoxia in hypoxaemic patients with COPD Eur Respir J 2013 42 2 362 370 23180584 sourceSupported

In three studies, responses to hyperoxic helium (60%-70% helium, 30%-40% oxygen) and oxygen supplementation alone were compared during a constant load cycling task in patients with moderate (nonhypoxemic), severe, and very severe (on long-term oxygen therapy) symptoms.

“In three studies, the responses to hyperoxic helium (60%–70% helium, 30%–40% oxygen) and oxygen supplementation alone were compared during a constant load cycling task in patients with moderate (nonhypoxemic),173 severe,174 and very severe (on long-term oxygen therapy) symptoms.175”

• cites [173] Eves ND Petersen SR Haykowsky MJ Wong EY Jones RL Helium-hyperoxia, exercise, and respiratory mechanics in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2006 174 7 763 771 16840742 sourceNot checked — no full text of the source
• cites [174] Hussain O Collins EG Adiguzel N Langbein WE Tobin MJ Laghi F Contrasting pressure-support ventilation and helium-oxygen during exercise in severe COPD Respir Med 2011 105 3 494 505 20851591 sourceNot checked — no full text of the source
• cites [175] Queiroga F Jr Nunes M Meda E Exercise tolerance with helium-hyperoxia versus hyperoxia in hypoxaemic patients with COPD Eur Respir J 2013 42 2 362 370 23180584 sourceSupported

Positive effects of inspiratory muscle training on operational lung volumes and breathing patterns during exercise have so far only been demonstrated in a single study.

“Positive effects of inspiratory muscle training on operational lung volumes and breathing patterns during exercise have so far only been demonstrated in a single study.197”

• cites [197] Petrovic M Reiter M Zipko H Pohl W Wanke T Effects of inspiratory muscle training on dynamic hyperinflation in patients with COPD Int J Chron Obstruct Pulmon Dis 2012 7 797 805 23233798 PMC3516469 sourcePartly supported

  The Discussion (page not provided) reports improved breathing patterns during exercise, and the Abstract reports an increased inspiratory fraction, indicating reduced dynamic hyperinflation. The paper does not establish that this was the only study to demonstrate those effects. (LLM, conf=0.83)

  Experimental — accuracy not yet measured

For a given level of ventilation, EELV seems not to be altered after exercise training.

“For a given level of ventilation, EELV seems, however, not to be altered after exercise training.187–189”

• cites [187] Casaburi R ZuWallack R Pulmonary rehabilitation for management of chronic obstructive pulmonary disease N Engl J Med 2009 360 13 1329 1335 19321869 sourceNot checked — no full text of the source
• cites [188] O’Donnell DE Ora J Webb KA Laveneziana P Jensen D Mechanisms of activity-related dyspnea in pulmonary diseases Respir Physiol Neurobiol 2009 167 1 116 132 19450767 sourceNot checked — no full text of the source
• cites [189] Troosters T Gosselink R Janssens W Decramer M Exercise training and pulmonary rehabilitation: new insights and remaining challenges Eur Respir Rev 2010 19 115 24 29 20956162 PMC9491643 sourceCould not verify

  The passages from the Abstract discuss ventilation during training, including lower ventilation with interval training, but do not address end-expiratory lung volume (EELV) at a given ventilation level before and after training. Searches for EELV and for unchanged dynamic hyperinflation at the same ventilation level found no passage addressing that comparison; the indexed copy reports no page numbers for these passages. (LLM, conf=0.74)

  Experimental — accuracy not yet measured

During constant work bicycle exercise, a reduction in dyspnea during application of pursed lip breathing was related to changes in EELV and pressure generation of the inspiratory muscles.

“Spahija et al192 observed that during constant work bicycle exercise, a reduction in dyspnea during application of pursed lip breathing was related to changes in EELV and pressure generation of the inspiratory muscles.”

• cites [192] Spahija J Marchie M Ghezzo H Grassino A Factors discriminating spontaneous pursed-lips breathing use in patients with COPD COPD 2010 7 4 254 261 20673034 sourcePartly supported

  The Introduction (page not provided) reports that reduced dyspnea with pursed-lips breathing has been related to decreased end-expiratory chest-wall volume. But the Experimental protocol and instrumentation section describes incremental, not constant-work, bicycle exercise; the paper studies spontaneous rather than applied breathing and does not report the claimed relationship with inspiratory-muscle pressure generation. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Hyperinflation contributes to exercise intolerance in patients with COPD.

“Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease.”

Dynamic hyperinflation also occurs in many patients with mild COPD, independently of the presence of resting hyperinflation.

“Dynamic hyperinflation is highly prevalent in the advanced stages of COPD, and new evidence suggests that it also occurs in many patients with mild disease, independently of the presence of resting hyperinflation.”

• Also stated in: § Introduction · plain

  “Finally, this phenomenon can also occur in patients with mild disease,22–24 a category of individuals likely representing a great portion of patients diagnosed with COPD.5”

• cites [22] Ofir D Laveneziana P Webb KA Lam YM O’Donnell DE Mechanisms of dyspnea during cycle exercise in symptomatic patients with GOLD stage I chronic obstructive pulmonary disease Am J Respir Crit Care Med 2008 177 6 622 629 18006885 sourceNot checked — no full text of the source
• cites [23] O’Donnell DE Laveneziana P Ora J Webb KA Lam YM Ofir D Evaluation of acute bronchodilator reversibility in patients with symptoms of GOLD stage I COPD Thorax 2009 64 3 216 223 19052054 sourceNot checked — no full text of the source
• cites [24] Gagnon P Saey D Provencher S Walking exercise response to bronchodilation in mild COPD: a randomized trial Respir Med 2012 106 12 1695 1705 22999808 sourceNot checked — no full text of the source

Hyperinflation contributes to morbidity in patients with COPD.

“Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease.”

• Also stated in: § Introduction · plain

  “Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to the dyspnea8 and morbidity associated with the disease.9”

• cites [9] Soriano JB Visick GT Muellerova H Payvandi N Hansell AL Patterns of comorbidities in newly diagnosed COPD and asthma in primary care Chest 2005 128 4 2099 2107 16236861 sourceNot checked — no full text of the source

In COPD with emphysema, the lung recoil pressure is further reduced by a reduced elastic load related to smoking or α1-antitrypsin deficiency.

“In COPD with emphysema, the lung recoil pressure is further reduced by a reduced elastic load related to smoking or α1-antitrypsin deficiency.29”

• cites [29] Thurlbeck WM Overview of the pathology of pulmonary emphysema in the human Clin Chest Med 1983 4 3 337 350 6357598 sourceNot checked — no full text of the source

Dynamic lung hyperinflation is related to reduced daily physical activity in COPD.

“Moreover, dynamic lung hyperinflation is related to reduced daily physical activity in COPD,11 which is an important component of quality of life.12”

• cites [11] Garcia-Rio F Lores V Mediano O Daily physical activity in patients with chronic obstructive pulmonary disease is mainly associated with dynamic hyperinflation Am J Respir Crit Care Med 2009 180 6 506 512 19542481 sourceNot checked — no full text of the source

Hyperinflation contributes to skeletal muscle limitations in patients with COPD.

“Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease.”

During exercise, hyperinflation may impede respiratory muscle function in COPD.

“During exercise, hyperinflation may impede cardiac19,20 and respiratory muscle function and increase the work of breathing.21”

Dynamic hyperinflation can occur independently of static hyperinflation.

“This is referred to as dynamic hyperinflation, which can occur independently of static hyperinflation.”

During exercise, hyperinflation increases the work of breathing in COPD.

“During exercise, hyperinflation may impede cardiac19,20 and respiratory muscle function and increase the work of breathing.21”

• cites [21] Loring SH Garcia-Jacques M Malhotra A Pulmonary characteristics in COPD and mechanisms of increased work of breathing J Appl Physiol 2009 107 1 309 314 19359620 PMC2711781 sourceNot checked — no full text of the source

Early changes reflecting lung hyperinflation are observed without any apparent reduction in FEV1.

“These early changes reflecting lung hyperinflation are observed without any apparent reduction in FEV1.39”

• cites [39] Corbin RP Loveland M Martin RR Macklem PT A four-year follow-up study of lung mechanics in smokers Am Rev Respir Dis 1979 120 2 293 304 475151 sourceNot checked — no full text of the source

In early COPD, FEV1 may not be the optimal indicator of small airways obstruction.

“In early COPD, the forced expiratory volume in one second (FEV1) may not be the optimal indicator of small airways obstruction.36”

• cites [36] Barnes N Bush A Howling for the moon Thorax 2011 66 8 645 646 21415246 sourceNot checked — no full text of the source

Early changes observed in pulmonary function of heavy smokers without COPD likely imply increased total lung capacity and residual volume because of the loss of elastic recoil.

“Early changes observed in pulmonary function of heavy smokers without COPD likely imply increased total lung capacity (TLC) and residual volume because of the loss of elastic recoil.39”

• cites [39] Corbin RP Loveland M Martin RR Macklem PT A four-year follow-up study of lung mechanics in smokers Am Rev Respir Dis 1979 120 2 293 304 475151 sourceNot checked — no full text of the source

In patients with COPD, the effects of the disease on static and dynamic lung volumes correlate better with patient symptoms and impairment in functional capacity than spirometric indices of the disease.

“In fact, although measurement of expiratory flows is a prerequisite for the diagnosis and staging of COPD, the effects of the disease on static and dynamic lung volumes correlate better with patient symptoms and impairment in functional capacity than spirometric indices of the disease.10”

• cites [10] O’Donnell DE Lam M Webb KA Spirometric correlates of improvement in exercise performance after anticholinergic therapy in chronic obstructive pulmonary disease Am J Respir Crit Care Med 1999 160 2 542 549 10430726 sourceNot checked — no full text of the source

In COPD with emphysema, the elastic recoil pressure of the respiratory system falls to zero at a larger FRC or EELV, resulting in more static hyperinflation.

“Therefore, the elastic recoil pressure of the respiratory system falls to zero at a larger FRC or EELV, resulting in more static hyperinflation.”

In patients with COPD, exhalation may not be completed prior to the onset of the next breath, causing an increase in operational lung volumes and progressive air retention called air trapping.

“As a result, exhalation may not be completed prior to the onset of the next breath, causing an increase in operational lung volumes and progressive air retention called “air trapping”.13,26,34”

• cites [13] O’Donnell DE Revill SM Webb KA Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 164 5 770 777 11549531 sourceNot checked — no full text of the source
• cites [26] O’Donnell DE Laveneziana P Physiology and consequences of lung hyperinflation in COPD Eur Respir Rev 2006 15 100 61 67Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [34] Milic-Emili J Dynamic pulmonary hyperinflation and intrinsic PEEP: consequences and management in patients with chronic obstructive pulmonary disease Recenti Prog Med 1990 81 11 733 737 Italian 2126881Not checked — no full text of the source

Dynamic hyperinflation is highly prevalent in the advanced stages of COPD.

“Dynamic hyperinflation is highly prevalent in the advanced stages of COPD, and new evidence suggests that it also occurs in many patients with mild disease, independently of the presence of resting hyperinflation.”

Dynamic hyperinflation remains a major contributor to exercise limitation consistently observed in COPD.

“While exercise intolerance in patients with COPD is complex and multifactorial,15–17 dynamic hyperinflation remains a major contributor to exercise limitation that is consistently observed in this disease.18”

• cites [18] O’Donnell DE Webb KA The major limitation to exercise performance in COPD is dynamic hyperinflation J Appl Physiol 2008 105 2 753 755 18678624 sourceNot checked — no full text of the source

Hyperinflation contributes to reduced physical activity levels in patients with COPD.

“Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease.”

Exercise intolerance and lung hyperinflation are closely interrelated in COPD.

“Despite the difficulties in establishing a cause-effect relationship, exercise intolerance and lung hyperinflation are closely interrelated in COPD.13,14”

• cites [13] O’Donnell DE Revill SM Webb KA Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 164 5 770 777 11549531 sourceNot checked — no full text of the source
• cites [14] O’Donnell DE Hyperinflation, dyspnea, and exercise intolerance in chronic obstructive pulmonary disease Proc Am Thorac Soc 2006 3 2 180 184 16565429 sourceNot checked — no full text of the source

Dynamic lung hyperinflation is a key mechanistic consequence of expiratory flow limitation.

“It is dependent on operational lung volumes and expiratory time, and is thus a key mechanistic consequence of expiratory flow limitation.14”

• cites [14] O’Donnell DE Hyperinflation, dyspnea, and exercise intolerance in chronic obstructive pulmonary disease Proc Am Thorac Soc 2006 3 2 180 184 16565429 sourceNot checked — no full text of the source

Various pharmacological and nonpharmacological interventions reduce hyperinflation and delay the onset of ventilatory limitation in patients with COPD.

“Various pharmacological and nonpharmacological interventions have been shown to reduce hyperinflation and delay the onset of ventilatory limitation in patients with COPD.”

In patients with COPD, the airways typically collapse when pleural pressure becomes positive, thereby preventing increased expiratory flow.

“However, in these patients, the airways typically collapse when the pleural pressure becomes positive, thereby preventing increased expiratory flow.33”

• cites [33] Barnes PJ Chronic obstructive pulmonary disease N Engl J Med 2000 343 4 269 280 10911010 sourceNot checked — no full text of the source

With advancing age, damage to the connective tissue of the lung occurs, resulting in a reduction of the lung elastic recoil pressure.

“With advancing age, damage to the connective tissue of the lung occurs, resulting in a reduction of the lung elastic recoil pressure.28”

• cites [28] Pride NB Ageing and changes in lung mechanics Eur Respir J 2005 26 4 563 565 16204583 sourceNot checked — no full text of the source

In a significant proportion of patients with COPD, reduced lung elastic recoil combined with expiratory flow limitation leads to lung hyperinflation during the course of the disease.

“In a significant proportion of patients with COPD, reduced lung elastic recoil combined with expiratory flow limitation leads to lung hyperinflation during the course of the disease.”

• Also stated in: § Introduction · plain

  “In a significant proportion of patients with COPD, reduced lung elastic recoil combined with expiratory flow limitation eventually leads to lung hyperinflation during the course of the disease.7”

• cites [7] [No authors listed] Dyspnea. Mechanisms, assessment, and management: a consensus statement. American Thoracic Society Am J Respir Crit Care Med 1999 159 1 321 340 9872857 sourceNot checked — no full text of the source

In patients with COPD, the combined effects of decreased lung elastic recoil pressure and increased airways resistance result in an increased mechanical time constant for lung emptying in many alveolar units.

“In contrast, the combined effects of decreased lung elastic recoil pressure and increased airways resistance in patients with COPD results in an increased mechanical time constant for lung emptying in many alveolar units.”

Hyperinflation contributes to dyspnea in patients with COPD.

“Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease.”

• Also stated in: § Introduction · plain

  “Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to the dyspnea8 and morbidity associated with the disease.9”

• cites [8] O’Donnell DE Laveneziana P Dyspnea and activity limitation in COPD: mechanical factors COPD 2007 4 3 225 236 17729066 sourceNot checked — no full text of the source

Left ventricular afterload may increase due to the high intrathoracic pressure swings needed to overcome the high elastic and resistive loads encountered by patients with COPD during exercise.

“Left ventricular afterload may also increase due to the high intrathoracic pressure swings needed to overcome the high elastic and resistive loads encountered by patients with COPD during exercise.80”

• cites [80] Montes de Oca M Rassulo J Celli BR Respiratory muscle and cardiopulmonary function during exercise in very severe COPD Am J Respir Crit Care Med 1996 154 5 1284 1289 8912737 sourceNot checked — no full text of the source

In severe COPD, EELV and VT combined with breathing frequency accounted for 61% of the variance in dyspnea intensity.

“In this study, EELV and VT (both components of EILV) combined with breathing frequency accounted for 61% of the variance in dyspnea intensity.”

• cites [54] O’Donnell DE Webb KA Exertional breathlessness in patients with chronic airflow limitation. The role of lung hyperinflation Am Rev Respir Dis 1993 148 5 1351 1357 8239175 sourceNot checked — no full text of the source

Studies that have unloaded the respiratory muscles of hyperinflated patients with bronchodilators or heliox resulted in an improvement in indices of limb muscle fractional oxygen extraction.

“Indeed, studies that have unloaded the respiratory muscles of hyperinflated patients with bronchodilators or heliox resulted in an improvement in indices of limb muscle fractional oxygen extraction.75,76”

• cites [75] Chiappa GR Queiroga F Jr Meda E Heliox improves oxygen delivery and utilization during dynamic exercise in patients with chronic obstructive pulmonary disease Am J Respir Crit Care Med 2009 179 11 1004 1010 19299497 sourceNot checked — no full text of the source
• cites [76] Laveneziana P Palange P Ora J Martolini D O’Donnell DE Bronchodilator effect on ventilatory, pulmonary gas exchange, and heart rate kinetics during high-intensity exercise in COPD Eur J Appl Physiol 2009 107 6 633 643 19711095 sourceNot checked — no full text of the source

There is indirect evidence to suggest that lung hyperinflation is associated with pulmonary hypertension.

“There is also indirect evidence to suggest that lung hyperinflation is associated with pulmonary hypertension.”

Studies in healthy subjects suggest that high levels of respiratory muscle work may result in a sympathetically mediated metaboreflex which causes redistribution of blood flow from the locomotor muscles to the respiratory muscles.

“Studies in healthy subjects suggest that high levels of respiratory muscle work may result in a sympathetically mediated metaboreflex which causes redistribution of blood flow from the locomotor muscles to the respiratory muscles.70–72”

• cites [70] St Croix CM Morgan BJ Wetter TJ Dempsey JA Fatiguing inspiratory muscle work causes reflex sympathetic activation in humans J Physiol 2000 529 Pt 2 493 504 11101657 PMC2270191 sourceNot checked — no full text of the source
• cites [71] Sheel AW Derchak PA Morgan BJ Pegelow DF Jacques AJ Dempsey JA Fatiguing inspiratory muscle work causes reflex reduction in resting leg blood flow in humans J Physiol 2001 537 Pt 1 277 289 11711580 PMC2278925 sourceNot checked — no full text of the source
• cites [72] Dempsey JA Sheel AW St Croix CM Morgan BJ Respiratory influences on sympathetic vasomotor outflow in humans Respir Physiol Neurobiol 2002 130 1 3 20 12380012 sourceNot checked — no full text of the source

Improving operating lung volumes in hyperinflated COPD patients with heliox enhanced oxygen delivery to the quadriceps muscles during exercise by increasing arterial oxygen content and blood flow to the quadriceps muscles.

“For example, Louvaris et al77 recently demonstrated that improving operating lung volumes in hyperinflated COPD patients with heliox enhanced oxygen delivery to the quadriceps muscles during exercise by increasing arterial oxygen content and blood flow to the quadriceps muscles.”

• cites [77] Louvaris Z Zakynthinos S Aliverti A Heliox increases quadriceps muscle oxygen delivery during exercise in COPD patients with and without dynamic hyperinflation J Appl Physiol 2012 113 7 1012 1023 22879534 sourceNot checked — no full text of the source

Some individuals with airflow obstruction can still experience similar critical VT constraints (and thus similar dyspnea ratings), regardless of how they regulate EELV.

“This finding does not necessarily diminish the physiological and sensory significance of dynamic hyperinflation, but rather shows that some individuals with airflow obstruction can still experience similar critical VT constraints (and thus similar dyspnea ratings), regardless of how they regulate EELV.”

Functionally weakened respiratory muscles coupled with increased elastic and threshold loading of the inspiratory muscles results in a substantial increase in the work and oxygen cost of breathing.

“These functionally weakened respiratory muscles coupled with the increased elastic and threshold loading of the inspiratory muscles61 results in a substantial increase in the work and oxygen cost of breathing.21,62”

• cites [21] Loring SH Garcia-Jacques M Malhotra A Pulmonary characteristics in COPD and mechanisms of increased work of breathing J Appl Physiol 2009 107 1 309 314 19359620 PMC2711781 sourceNot checked — no full text of the source
• cites [62] Shindoh C Hida W Kikuchi Y Oxygen consumption of respiratory muscles in patients with COPD Chest 1994 105 3 790 797 8131542 sourceNot checked — no full text of the source

The ventilatory response during exercise of a healthy elderly subject could be similar to that of a patient with GOLD stage 1 COPD.

“Likewise, the ventilatory response during exercise of a healthy elderly subject could be similar to that of a patient with GOLD stage 1 COPD.53”

• cites [53] Laveneziana P Parker CM O’Donnell DE Ventilatory constraints and dyspnea during exercise in chronic obstructive pulmonary disease Appl Physiol Nutr Metab 2007 32 6 1225 1238 18059601 sourceNot checked — no full text of the source

A direct link between dynamic hyperinflation and peripheral muscle function has not been fully established.

“A direct link between dynamic hyperinflation and peripheral muscle function has not been fully established.”

A reduction in locomotor muscle blood flow could result in an accelerated rate of development of limb muscle fatigue during exercise.

“A reduction in locomotor muscle blood flow could result in an accelerated rate of development of limb muscle fatigue during exercise.”

Moderate levels of dynamic hyperinflation can be observed in healthy elderly individuals aged >70 years without any pulmonary disease following normal aging of the lung parenchyma.

“Moderate levels of dynamic hyperinflation can even be observed in healthy elderly individuals aged >70 years without any pulmonary disease following normal aging of the lung parenchyma.50–52”

• cites [50] Johnson BD Dempsey JA Demand vs capacity in the aging pulmonary system Exerc Sport Sci Rev 1991 19 171 210 1936085 sourceNot checked — no full text of the source
• cites [51] Johnson BD Reddan WG Pegelow DF Seow KC Dempsey JA Flow limitation and regulation of functional residual capacity during exercise in a physically active aging population Am Rev Respir Dis 1991 143 5 Pt 1 960 967 2024851 sourceNot checked — no full text of the source
• cites [52] Johnson BD Reddan WG Seow KC Dempsey JA Mechanical constraints on exercise hyperpnea in a fit aging population Am Rev Respir Dis 1991 143 5 Pt 1 968 977 2024852 sourceNot checked — no full text of the source

When comparing two patients with similar FEV1, the one presenting with a reduced diffusion capacity, more severe small airway obstruction, and a higher ventilatory response to exercise will tend to develop more dynamic hyperinflation early during exercise.

“However, when comparing two patients with similar FEV1, the one presenting with a reduced diffusion capacity, more severe small airway obstruction, and a higher ventilatory response to exercise will tend to develop more dynamic hyperinflation early during exercise.13”

• cites [13] O’Donnell DE Revill SM Webb KA Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 164 5 770 777 11549531 sourceNot checked — no full text of the source

In a larger cohort of COPD patients (n=105), the VT/IC ratio was the strongest predictor of exertional dyspnea based on multiple linear regression analysis.

“A subsequent study in a larger cohort of COPD patients (n=105) demonstrated that the VT/IC ratio, an index of EILV and VT constraint, was the strongest predictor of exertional dyspnea based on multiple linear regression analysis.13”

• cites [13] O’Donnell DE Revill SM Webb KA Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 164 5 770 777 11549531 sourceNot checked — no full text of the source

Right ventricular afterload increases during exercise because there is an increase in pulmonary vascular resistance resulting from patients breathing at a high EILV.

“In addition, right ventricular afterload increases during exercise because there is an increase in pulmonary vascular resistance resulting from patients breathing at a high EILV.82,83”

• cites [82] Ranieri VM Dambrosio M Brienza N Intrinsic PEEP and cardiopulmonary interaction in patients with COPD and acute ventilatory failure Eur Respir J 1996 9 6 1283 1292 8804950 sourceNot checked — no full text of the source
• cites [83] Oswald-Mammosser M Apprill M Bachez P Ehrhart M Weitzenblum E Pulmonary hemodynamics in chronic obstructive pulmonary disease of the emphysematous type Respiration 1991 58 5–6 304 310 1792422Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Lung hyperinflation has been shown to adversely affect cardiovascular function in patients with COPD.

“Lung hyperinflation has been shown to adversely affect cardiovascular function in patients with COPD.”

In severe COPD, the change in EILV from baseline was the strongest predictor of the change in Borg dyspnea ratings (r=0.63, P<0.001).

“O’Donnell and Webb54 evaluated 23 patients with severe COPD and found that the change in EILV from baseline was the strongest predictor of the change in Borg dyspnea ratings (r=0.63, P<0.001).”

• cites [54] O’Donnell DE Webb KA Exertional breathlessness in patients with chronic airflow limitation. The role of lung hyperinflation Am Rev Respir Dis 1993 148 5 1351 1357 8239175 sourceNot checked — no full text of the source

Lung hyperinflation reduces right ventricular preload and venous return at rest and during exercise.

“Lung hyperinflation reduces right ventricular preload and venous return at rest and during exercise.78–81”

• cites [78] Mahler DA Brent BN Loke J Zaret BL Matthay RA Right ventricular performance and central circulatory hemodynamics during upright exercise in patients with chronic obstructive pulmonary disease Am Rev Respir Dis 1984 130 5 722 729 6388444 sourceNot checked — no full text of the source
• cites [79] Light RW Mintz HM Linden GS Brown SE Hemodynamics of patients with severe chronic obstructive pulmonary disease during progressive upright exercise Am Rev Respir Dis 1984 130 3 391 395 6476589 sourceNot checked — no full text of the source
• cites [80] Montes de Oca M Rassulo J Celli BR Respiratory muscle and cardiopulmonary function during exercise in very severe COPD Am J Respir Crit Care Med 1996 154 5 1284 1289 8912737 sourceNot checked — no full text of the source
• cites [81] Vizza CD Lynch JP Ochoa LL Richardson G Trulock EP Right and left ventricular dysfunction in patients with severe pulmonary disease Chest 1998 113 3 576 583 9515827 sourceNot checked — no full text of the source

In patients with moderate-to-severe COPD, the level of dynamic hyperinflation is poorly related to FEV1.

“In patients with moderate-to-severe COPD, the level of dynamic hyperinflation is poorly related to FEV1.49”

• cites [49] Calverley PM Koulouris NG Flow limitation and dynamic hyperinflation: key concepts in modern respiratory physiology Eur Respir J 2005 25 1 186 199 15640341 sourceNot checked — no full text of the source

Obese patients consistently have a reduced expiratory reserve volume (or FRC) proportional to the magnitude of obesity.

“Obese patients consistently have a reduced expiratory reserve volume (or FRC) proportional to the magnitude of obesity.99,108,110,113–120”

• cites [99] Jones RL Nzekwu MM The effects of body mass index on lung volumes Chest 2006 130 3 827 833 16963682 sourceNot checked — no full text of the source
• cites [108] Zerah F Harf A Perlemuter L Lorino H Lorino AM Atlan G Effects of obesity on respiratory resistance Chest 1993 103 5 1470 1476 8486029 sourceNot checked — no full text of the source
• cites [110] Rubinstein I Zamel N DuBarry L Hoffstein V Airflow limitation in morbidly obese, nonsmoking men Ann Intern Med 1990 112 11 828 832 2378649 sourceNot checked — no full text of the source
• cites [113] Ladosky W Botelho MA Albuquerque JP Jr Chest mechanics in morbidly obese non-hypoventilated patients Respir Med 2001 95 4 281 286 11316110 sourceNot checked — no full text of the source
• cites [114] Kelly TM Jensen RL Elliott CG Crapo RO Maximum respiratory pressures in morbidly obese subjects Respiration 1988 54 2 73 77 3231898Not matched

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• cites [115] Thomas PS Cowen ER Hulands G Milledge JS Respiratory function in the morbidly obese before and after weight loss Thorax 1989 44 5 382 386 2503905 PMC461837 sourceNot checked — no full text of the source
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• cites [117] Biring MS Lewis MI Liu JT Mohsenifar Z Pulmonary physiologic changes of morbid obesity Am J Med Sci 1999 318 5 293 297 10555090 sourceNot checked — no full text of the source
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Correlative evidence indicates that there is a link between exercise performance and indices of lung hyperinflation.

“Nevertheless, correlative evidence indicates that there is a link between exercise performance and indices of lung hyperinflation.”

Significant variability has been observed when evaluating the effects of obesity on lung volumes.

“While several studies have addressed this issue, significant variability has been observed when evaluating the effects of obesity on lung volumes.”

There is a significant correlation between resting IC and peak work rate and peak oxygen uptake, particularly in patients with demonstrable expiratory flow limitation at rest.

“Work from other groups supports these results by showing a significant correlation between resting IC and peak work rate and peak oxygen uptake, particularly in patients with demonstrable expiratory flow limitation at rest.88”

• cites [88] Diaz O Villafranca C Ghezzo H Role of inspiratory capacity on exercise tolerance in COPD patients with and without tidal expiratory flow limitation at rest Eur Respir J 2000 16 2 269 275 10968502 sourceNot checked — no full text of the source

Voluntary hyperinflation in healthy subjects did not adversely affect cardiac output during exercise.

“For example, Stark-Leyva et al86 found that voluntary hyperinflation in healthy subjects did not adversely affect cardiac output during exercise.”

• cites [86] Stark-Leyva KN Beck KC Johnson BD Influence of expiratory loading and hyperinflation on cardiac output during exercise J Appl Physiol 2004 96 5 1920 1927 14729724 sourceNot checked — no full text of the source

All of these mechanisms of exercise intolerance are related, at least in part, to lung hyperinflation.

“All of these mechanisms are related, at least in part, to lung hyperinflation as previously described.”

Peak VT relative to predicted vital capacity was the best predictor of peak aerobic capacity (r=0.68, P<0.0005) in 105 patients with COPD.

“For example, peak VT relative to predicted vital capacity was found to be the best predictor of peak aerobic capacity (r=0.68, P<0.0005) in 105 patients with COPD.13”

• cites [13] O’Donnell DE Revill SM Webb KA Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 164 5 770 777 11549531 sourceNot checked — no full text of the source

It is difficult to directly demonstrate a cause-effect relationship between hyperinflation and exercise performance because interventions that reduce hyperinflation may also improve any one or a combination of contributory factors to varying degrees.

“Thus, it is difficult to directly demonstrate a cause–effect relationship between hyperinflation and exercise performance because interventions that reduce hyperinflation may also improve any one or a combination of these contributory factors to varying degrees.”

Women with COPD appear to be more susceptible to resting hyperinflation, despite lower tobacco use and younger age.

“Women with COPD appear to be more susceptible to resting hyperinflation, despite lower tobacco use and younger age.135”

• cites [135] Laviolette L Lacasse Y Doucet M Chronic obstructive pulmonary disease in women Can Respir J 2007 14 2 93 98 17372636 PMC2676379 sourceNot checked — no full text of the source

Added weight on the thorax and abdomen (and also the neck) can significantly affect static and dynamic lung volumes along with respiratory mechanics, usually in a dose-response fashion.

“Added weight on the thorax and abdomen (and also the neck), can significantly affect static and dynamic lung volumes along with respiratory mechanics,92–112 usually in a dose-response fashion.”

• cites [92] Littleton SW Impact of obesity on respiratory function Respirology 2012 17 1 43 49 22040049 sourceNot checked — no full text of the source
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• cites [96] Babb TG Wyrick BL DeLorey DS Chase PJ Feng MY Fat distribution and end-expiratory lung volume in lean and obese men and women Chest 2008 134 4 704 711 18641101 sourceNot checked — no full text of the source
• cites [97] Ofir D Laveneziana P Webb KA O’Donnell DE Ventilatory and perceptual responses to cycle exercise in obese women J Appl Physiol 2007 102 6 2217 2226 17234804 sourceNot checked — no full text of the source
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Not all studies have been able to demonstrate a direct link between dynamic hyperinflation and cardiac performance during exercise.

“However, it should be acknowledged that not all studies have been able to demonstrate a direct link between dynamic hyperinflation and cardiac performance during exercise.”

Obesity alone appears to have a deflationary effect.

“Obesity alone appears to have a “deflationary” effect.”

The increased metabolic load induced by obesity appeared to be compensated by an increased ventilatory efficiency (ie, lower ventilatory equivalent for CO2) in obese patients with COPD.

“Also, the increased metabolic load induced by obesity appeared to be compensated by an increased ventilatory efficiency (ie, lower ventilatory equivalent for CO2) in these patients.”

• cites [126] Ora J Laveneziana P Wadell K Preston M Webb KA O’Donnell DE Effect of obesity on respiratory mechanics during rest and exercise in COPD J Appl Physiol 2011 111 1 10 19 21350021 sourceNot checked — no full text of the source

When restricted to emphysema, women present a different pattern of disease compared with men, ie, smaller airway lumen and thicker airway walls.

“When restricted to emphysema, women also present a different pattern of disease compared with men, ie, smaller airway lumen and thicker airway walls.136,137”

• cites [136] Martinez FJ Curtis JL Sciurba F Sex differences in severe pulmonary emphysema Am J Respir Crit Care Med 2007 176 3 243 252 17431226 PMC1994221 sourceNot checked — no full text of the source
• cites [137] Camp PG Coxson HO Levy RD Sex differences in emphysema and airway disease in smokers Chest 2009 136 6 1480 1488 19617404 sourceNot checked — no full text of the source

Total respiratory system compliance is usually reduced in obese patients.

“Total respiratory system compliance is usually reduced in obese patients.”

These sex differences (mainly smaller lungs and maximal flow rates in women) may affect dynamic volumes because fit women may suffer from expiratory flow limitation that induces an increase in EELV.

“These differences (mainly smaller lungs and maximal flow rates in women) may also affect dynamic volumes because fit women may suffer from expiratory flow limitation that induces an increase in EELV.132–134”

• cites [132] McClaran SR Harms CA Pegelow DF Dempsey JA Smaller lungs in women affect exercise hyperpnea J Appl Physiol (1985) 1998 84 6 1872 1881 9609779 sourceNot checked — no full text of the source
• cites [133] Guenette JA Witt JD McKenzie DC Road JD Sheel AW Respiratory mechanics during exercise in endurance-trained men and women J Physiol 2007 581 Pt 3 1309 1322 17412775 PMC2170830 sourceNot checked — no full text of the source
• cites [134] Deruelle F Nourry C Mucci P Difference in breathing strategies during exercise between trained elderly men and women Scand J Med Sci Sports 2008 18 2 213 220 17490460 sourceNot checked — no full text of the source

Similar results were obtained in another sample of COPD patients.

“Similar results were obtained in another sample of COPD patients.139”

• cites [139] Guenette JA Jensen D Webb KA Ofir D Raghavan N O’Donnell DE Sex differences in exertional dyspnea in patients with mild COPD: physiological mechanisms Respir Physiol Neurobiol 2011 177 3 218 227 21524719 sourceNot checked — no full text of the source

Because TLC remains stable during exercise, a temporary decrease in IC reflects a temporary increase in EELV.

“Because TLC remains stable during exercise,148,149 a temporary decrease in IC reflects a temporary increase in EELV”

• cites [148] Stubbing DG Pengelly LD Morse JL Jones NL Pulmonary mechanics during exercise in subjects with chronic airflow obstruction J Appl Physiol Respir Environ Exerc Physiol 1980 49 3 511 515 7204175 sourceNot checked — no full text of the source
• cites [149] Vogiatzis I Georgiadou O Golemati S Patterns of dynamic hyperinflation during exercise and recovery in patients with severe chronic obstructive pulmonary disease Thorax 2005 60 9 723 729 15964912 PMC1747529 sourceNot checked — no full text of the source

Respiratory muscles in COPD have to overcome higher elastic and threshold loads during exercise, which increases the work and oxygen cost of breathing compared with healthy subjects.

“As previously described, these muscles have to overcome higher elastic and threshold loads during exercise which increases the work and oxygen cost of breathing in comparison with healthy subjects.26,162”

• cites [26] O’Donnell DE Laveneziana P Physiology and consequences of lung hyperinflation in COPD Eur Respir Rev 2006 15 100 61 67Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [162] Rochester DF The respiratory muscles in COPD. State of the art Chest 1984 85 Suppl 6 47S 50S 6373180 sourceNot checked — no full text of the source

More than 80% of patients with moderate-to-severe COPD showed significant increases in EELV during exercise.

“More than 80% of patients with moderate-to-severe COPD showed significant increases in EELV during exercise.11,13,46,150”

• cites [11] Garcia-Rio F Lores V Mediano O Daily physical activity in patients with chronic obstructive pulmonary disease is mainly associated with dynamic hyperinflation Am J Respir Crit Care Med 2009 180 6 506 512 19542481 sourceNot checked — no full text of the source
• cites [13] O’Donnell DE Revill SM Webb KA Dynamic hyperinflation and exercise intolerance in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 164 5 770 777 11549531 sourceNot checked — no full text of the source
• cites [46] O’Donnell DE Fluge T Gerken F Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD Eur Respir J 2004 23 6 832 840 15218994 sourceNot checked — no full text of the source
• cites [150] Maltais F Hamilton A Marciniuk D Improvements in symptom-limited exercise performance over 8 h with once-daily tiotropium in patients with COPD Chest 2005 128 3 1168 1178 16162703 sourceNot checked — no full text of the source

Pressure support provides variable resistive and elastic unloading of the ventilatory muscles.

“while pressure support provides variable resistive and elastic unloading of the ventilatory muscles.156,163”

• cites [156] O’Donnell DE Ventilatory limitations in chronic obstructive pulmonary disease Med Sci Sports Exerc 2001 33 Suppl 7 S647 S655 11462073 sourceNot checked — no full text of the source
• cites [163] Ambrosino N Strambi S New strategies to improve exercise tolerance in chronic obstructive pulmonary disease Eur Respir J 2004 24 2 313 322 15332404 sourceNot checked — no full text of the source

Pharmacological interventions that reduce operating lung volumes and delay the onset of ventilatory limitation consistently reduce the intensity of dyspnea during exercise in patients with COPD.

“Pharmacological interventions that reduce operating lung volumes and delay the onset of ventilatory limitation consistently reduce the intensity of dyspnea during exercise in patients with COPD.46,55,56”

• cites [46] O’Donnell DE Fluge T Gerken F Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD Eur Respir J 2004 23 6 832 840 15218994 sourceNot checked — no full text of the source
• cites [55] Belman MJ Botnick WC Shin JW Inhaled bronchodilators reduce dynamic hyperinflation during exercise in patients with chronic obstructive pulmonary disease Am J Respir Crit Care Med 1996 153 3 967 975 8630581 sourceNot checked — no full text of the source
• cites [56] O’Donnell DE Hamilton AL Webb KA Sensory-mechanical relationships during high-intensity, constant-work-rate exercise in COPD J Appl Physiol 2006 101 4 1025 1035 16675610 sourceNot checked — no full text of the source

Women may be more susceptible to the deleterious effects of COPD because of their smaller respiratory systems compared with men.

“It would appear that women may be more susceptible to the deleterious effects of COPD because of their smaller respiratory systems compared with men.”

Respiratory muscle function is often impaired in patients with COPD.

“Respiratory muscle function is often impaired in patients with COPD.161”

• cites [161] Orozco-Levi M Structure and function of the respiratory muscles in patients with COPD: impairment or adaptation? Eur Respir J Suppl 2003 46 41s 51s 14621106 sourceNot checked — no full text of the source

Ventilatory support techniques will not directly impact either static or dynamic lung hyperinflation.

“The use of ventilatory support techniques will therefore not directly impact either static or dynamic lung hyperinflation.”

Lung volume reduction surgery increases maximal ventilatory capacity as evidenced by increases in both maximal voluntary ventilation and maximal minute ventilation at peak exercise.

“Lung volume reduction surgery increases maximal ventilatory capacity as evidenced by increases in both maximal voluntary ventilation and maximal minute ventilation at peak exercise.176–178,180–182”

• cites [176] O’Donnell DE Webb KA Bertley JC Chau LK Conlan AA Mechanisms of relief of exertional breathlessness following unilateral bullectomy and lung volume reduction surgery in emphysema Chest 1996 110 1 18 27 8681624 sourceNot checked — no full text of the source
• cites [177] Benditt JO Wood DE McCool FD Lewis S Albert RK Changes in breathing and ventilatory muscle recruitment patterns induced by lung volume reduction surgery Am J Respir Crit Care Med 1997 155 1 279 284 9001325 sourceNot checked — no full text of the source
• cites [178] Martinez FJ de Oca MM Whyte RI Stetz J Gay SE Celli BR Lung-volume reduction improves dyspnea, dynamic hyperinflation, and respiratory muscle function Am J Respir Crit Care Med 1997 155 6 1984 1990 9196106 sourceNot checked — no full text of the source
• cites [180] Benditt JO Lewis S Wood DE Klima L Albert RK Lung volume reduction surgery improves maximal O2 consumption, maximal minute ventilation, O2 pulse, and dead space-to-tidal volume ratio during leg cycle ergometry Am J Respir Crit Care Med 1997 156 2 Pt 1 561 566 9279240 sourceNot checked — no full text of the source
• cites [181] Cordova F O’Brien G Furukawa S Kuzma AM Travaline J Criner GJ Stability of improvements in exercise performance and quality of life following bilateral lung volume reduction surgery in severe COPD Chest 1997 112 4 907 915 9377952 sourceNot checked — no full text of the source
• cites [182] Keller CA Ruppel G Hibbett A Osterloh J Naunheim KS Thoracoscopic lung volume reduction surgery reduces dyspnea and improves exercise capacity in patients with emphysema Am J Respir Crit Care Med 1997 156 1 60 67 9230727 sourceNot checked — no full text of the source

The improvements observed at a given level of exertion with oxygen supplementation are not caused by a direct effect on static or dynamic hyperinflation.

“The improvements observed at a given level of exertion are therefore not caused by a direct effect on static or dynamic hyperinflation.”

It is generally accepted that exercise training, unlike bronchodilators, does not have an impact on resting pulmonary mechanics.

“It is generally accepted that exercise training, unlike bronchodilators, does not have an impact on resting pulmonary mechanics.190”

• cites [190] Porszasz J Emtner M Goto S Somfay A Whipp BJ Casaburi R Exercise training decreases ventilatory requirements and exercise-induced hyperinflation at submaximal intensities in patients with COPD Chest 2005 128 4 2025 2034 16236851 sourceNot checked — no full text of the source

Two papers evaluating dyspnea at isotime during an endurance cycling task consistently showed significant reductions in perception of dyspnea with heliox.

“Two papers evaluating dyspnea at isotime during an endurance cycling task however consistently showed significant reductions in perception of dyspnea.171,173”

• cites [171] Palange P Valli G Onorati P Effect of heliox on lung dynamic hyperinflation, dyspnea, and exercise endurance capacity in COPD patients J Appl Physiol 2004 97 5 1637 1642 15234959 sourceNot checked — no full text of the source
• cites [173] Eves ND Petersen SR Haykowsky MJ Wong EY Jones RL Helium-hyperoxia, exercise, and respiratory mechanics in chronic obstructive pulmonary disease Am J Respir Crit Care Med 2006 174 7 763 771 16840742 sourceNot checked — no full text of the source

The response with regard to exercise capacity to heliox seems to be correlated with the magnitude of change in EELV during exercise.

“The response with regard to exercise capacity seems to be correlated with the magnitude of change in EELV during exercise.171”

• cites [171] Palange P Valli G Onorati P Effect of heliox on lung dynamic hyperinflation, dyspnea, and exercise endurance capacity in COPD patients J Appl Physiol 2004 97 5 1637 1642 15234959 sourceNot checked — no full text of the source

Similar to the acute effects of oxygen supplementation, exercise training reduces ventilatory needs for a given level of exertion.

“Similar to the acute effects of oxygen supplementation, exercise training reduces ventilatory needs for a given level of exertion.170,190,191”

• cites [170] Dolmage TE Evans RA Goldstein RS Defining hyperinflation as ‘dynamic’: moving toward the slope Respir Med 2013 107 7 953 958 23478191 sourceNot checked — no full text of the source
• cites [190] Porszasz J Emtner M Goto S Somfay A Whipp BJ Casaburi R Exercise training decreases ventilatory requirements and exercise-induced hyperinflation at submaximal intensities in patients with COPD Chest 2005 128 4 2025 2034 16236851 sourceNot checked — no full text of the source
• cites [191] Puente-Maestu L Abad YM Pedraza F Sanchez G Stringer WW A controlled trial of the effects of leg training on breathing pattern and dynamic hyperinflation in severe COPD Lung 2006 184 3 159 167 16902841 sourceNot checked — no full text of the source

Effects of heliox on dyspnea are likely but less clearly documented in the current literature.

“Effects on dyspnea are likely but less clearly documented in the current literature.172”

• cites [172] Hunt T Williams MT Frith P Schembri D Heliox, dyspnoea and exercise in COPD Eur Respir Rev 2010 19 115 30 38 20956163 PMC9491633 sourceNot checked — no full text of the source

Besides the effects on static hyperinflation, lung volume reduction surgery also exerts a direct effect on dynamic hyperinflation during exercise.

“Besides the effects on static hyperinflation, it seems that the intervention also exerts a direct effect on dynamic hyperinflation during exercise.176–178”

• cites [176] O’Donnell DE Webb KA Bertley JC Chau LK Conlan AA Mechanisms of relief of exertional breathlessness following unilateral bullectomy and lung volume reduction surgery in emphysema Chest 1996 110 1 18 27 8681624 sourceNot checked — no full text of the source
• cites [177] Benditt JO Wood DE McCool FD Lewis S Albert RK Changes in breathing and ventilatory muscle recruitment patterns induced by lung volume reduction surgery Am J Respir Crit Care Med 1997 155 1 279 284 9001325 sourceNot checked — no full text of the source
• cites [178] Martinez FJ de Oca MM Whyte RI Stetz J Gay SE Celli BR Lung-volume reduction improves dyspnea, dynamic hyperinflation, and respiratory muscle function Am J Respir Crit Care Med 1997 155 6 1984 1990 9196106 sourceNot checked — no full text of the source

Oxygen supplementation during exercise delays the attainment of ventilatory limitation and accompanying intolerable symptoms of dyspnea by reducing ventilatory demand.

“Oxygen supplementation during exercise delays the attainment of ventilatory limitation and accompanying intolerable symptoms of dyspnea during exercise by reducing ventilatory demand.168,169”

• cites [168] O’Donnell DE D’Arsigny C Webb KA Effects of hyperoxia on ventilatory limitation during exercise in advanced chronic obstructive pulmonary disease Am J Respir Crit Care Med 2001 163 4 892 898 11282762 sourceNot checked — no full text of the source
• cites [169] Somfay A Porszasz J Lee SM Casaburi R Dose-response effect of oxygen on hyperinflation and exercise endurance in nonhypoxaemic COPD patients Eur Respir J 2001 18 1 77 84 11510809 sourceNot checked — no full text of the source

From the available data, it also appears that, unlike heliox breathing or lung volume reduction surgery, exercise training does not have a direct effect on the rate of increase in EELV (dynamic hyperinflation) during exercise.

“From the available data, it also appears that, unlike heliox breathing or lung volume reduction surgery, exercise training does not have a direct effect on the rate of increase in EELV (dynamic hyperinflation) during exercise.170”

• cites [170] Dolmage TE Evans RA Goldstein RS Defining hyperinflation as ‘dynamic’: moving toward the slope Respir Med 2013 107 7 953 958 23478191 sourceNot checked — no full text of the source

Heliox supplementation improves exercise intensity and endurance in patients with COPD in comparison with room air breathing.

“Heliox supplementation has been shown to improve exercise intensity and endurance in patients with COPD in comparison with room air breathing.172”

• cites [172] Hunt T Williams MT Frith P Schembri D Heliox, dyspnoea and exercise in COPD Eur Respir Rev 2010 19 115 30 38 20956163 PMC9491633 sourceNot checked — no full text of the source

The improvements in dyspnea and exercise capacity during constant load cycling tasks after properly conducted exercise training programs are larger than those observed with any of the previously described interventions.

“The improvements in dyspnea and exercise capacity during constant load cycling tasks after properly conducted exercise training programs are larger than those observed with any of the previously described interventions.185,186”

• cites [185] Lacasse Y Guyatt GH Goldstein RS The components of a respiratory rehabilitation program: a systematic overview Chest 1997 111 4 1077 1088 9106590 sourceNot checked — no full text of the source
• cites [186] Casaburi R Porszasz J Reduction of hyperinflation by pharmacologic and other interventions Proc Am Thorac Soc 2006 3 2 185 189 16565430 sourceNot checked — no full text of the source

A recent study by Collins et al used a computerized ventilation feedback intervention aimed at slowing respiratory rate in combination with an exercise training program and showed reductions in respiratory rate, ventilation, and dynamic hyperinflation at isotime during a constant load cycling task.

“A recent study by Collins et al195 used a computerized ventilation feedback intervention aimed at slowing respiratory rate in combination with an exercise training program and showed reductions in respiratory rate, ventilation, and dynamic hyperinflation at isotime during a constant load cycling task.”

• cites [195] Collins EG Langbein WE Fehr L Can ventilation-feedback training augment exercise tolerance in patients with chronic obstructive pulmonary disease? Am J Respir Crit Care Med 2008 177 8 844 852 18202351 sourceNot checked — no full text of the source