Pulmonary Gas Exchange Abnormalities in Mild Chronic Obstructive Pulmonary Disease. Implications for Dyspnea and Exercise Intolerance

Elbehairy, Amany F.; Ciavaglia, Casey E.; Webb, Katherine A.; Guenette, Jordan A.; Jensen, Dennis; Mourad, Sahar; Neder, J. Alberto; O’Donnell, Denis E.

doi:10.1164/rccm.201501-0157oc

Cited by 188 publications

(231 citation statements)

References 47 publications

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“…In COPD patients who fail to be weaned off mechanical ventilation, TTdi is 38% higher than in patients who are successfully weaned off ventilation [26], and higher than 0.15, the critical value above which diaphragmatic fatigue may occur in normal subjects [1] and COPD [20]. During exercise, even patients with mild COPD exhibit increased dead space (Vd) ventilation, leading to compensatory increase in minute ventilation to maintain a constant alveolar ventilation [27], resulting in early exercise intolerance. In fact, in the study of Elbehairy [27] the patient group exhibited levels of PaCO 2 lower than in the control group throughout exercise, suggesting cortical or behavioral input accounting for the hypocapnia [28].…”

Section: Chronic Obstructive Pulmonary Diseasementioning

confidence: 99%

“…During exercise, even patients with mild COPD exhibit increased dead space (Vd) ventilation, leading to compensatory increase in minute ventilation to maintain a constant alveolar ventilation [27], resulting in early exercise intolerance. In fact, in the study of Elbehairy [27] the patient group exhibited levels of PaCO 2 lower than in the control group throughout exercise, suggesting cortical or behavioral input accounting for the hypocapnia [28].…”

Section: Chronic Obstructive Pulmonary Diseasementioning

confidence: 99%

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Breathing Intolerance Index (BIT) and its Relation to Exercise Data: Noninvasive Assessment of Inspiratory Muscle Endurance during Rest and Exercise in Patients with Chronic Obstructive Pulmonary Disease and Cardiovascular Disorders

Baydur¹,

Tran²,

Pallickal³

et al. 2016

Chron Obstruct Pulmon Dis

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Rationale: Diaphragmatic tension-time index [TTdi = (Pdi/Pdimax)(Ti/ Ttot)] assesses inspiratory muscle endurance during rest and exercise. However, the procedure is invasive and not practical for general use. Recently, Tidal Volume/Vital Capacity (Vt/VC) has been substituted for Pdi/Pdimax, to assess need for assisted ventilation in chronic respiratory disorders. This technique has not been used to assess respiratory muscle endurance in other conditions during rest and exercise.Objective: To compare control of ventilation and BIT in cardiorespiratory disorders and controls and to assess their relation to oxygen uptake (V'O 2 ) and annual acute decompensations.Methods: BIT and V'O 2 were assessed in patients with stable CVD (n = 20), RD (n = 20) and C (n = 20) during bicycle ergometry. ANOVA assessed differences in variables amongst cohorts at rest and peak exercise. Results:Resting BIT was [median (25 th , 75 th percentiles)] 0.06 (0.04, 0.07), 0.06 (0.04, 0.09) and 0.04 (0.03, 0.05) for CVD, COPD and controls, respectively. Compared to resting, BIT increased by 3.0-to 4.6-fold at peak exercise in all cohorts (p < 0.0001). V'O 2 max exceeded resting values by 7.5-, 4.6-, and 9.4-fold in COPD, CVD and C, respectively (all p < 0.0001). When corrected for BIT (V'O 2 /BIT), controls exhibited significantly greater (V'O 2 /BIT) max than CVD and COPD (p < 0.0001). Amongst patients who acutely decompensated, BIT was higher only in resting CVD patients (p < 0.019). Conclusions:BIT is useful for evaluating respiratory muscle effort during rest and exercise in CVD and COPD. Oxygen uptake fails to increase in proportion to BIT in these conditions as much as in controls, reflecting impaired oxygen utilization. Its potential usefulness in predicting acute decompensations should be assessed in larger prospective studies.

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Section: Chronic Obstructive Pulmonary Diseasementioning

confidence: 99%

Section: Chronic Obstructive Pulmonary Diseasementioning

confidence: 99%

Breathing Intolerance Index (BIT) and its Relation to Exercise Data: Noninvasive Assessment of Inspiratory Muscle Endurance during Rest and Exercise in Patients with Chronic Obstructive Pulmonary Disease and Cardiovascular Disorders

Baydur¹,

Tran²,

Pallickal³

et al. 2016

Chron Obstruct Pulmon Dis

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“…poor ventilatory efficiency. Thus, an excessive ventilatory response to exertion, likely to compensate for increased physiological dead space, led the patients to reach their mechanical and sensory limits at lower exercise intensities [7][8][9].…”

Section: To the Editormentioning

confidence: 99%

“…The subjects were carefully matched by age, gender, body weight, level of regular physical activity and smoking history ( p>0.05) to 15 smokers with preserved spirometry and normal TLCO (95.3 ±10.5% predicted). Subjects were asked to refrain from smoking during the preceding 4 h. Exercise ventilatory efficiency in response to incremental ramp cardiopulmonary exercise testing (CPET) was determined by the V′E-V′CO 2 slope and the V′E/V′CO 2 ratio nadir [7][8][9].…”

Section: To the Editormentioning

confidence: 99%

Impaired exercise ventilatory efficiency in smokers with low transfer factor but normal spirometry

et al. 2017

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“…As a result, COPD patients become remarkably restricted in their activities, but do not necessarily complain of dyspnoea. Dynamic hyperinflation, together with abnormal gas exchange, can develop even in very mild COPD and can compromise exercise performance 59,60 …”

Section: Clinically Important Chronic Obstructive Pulmonary Diseasementioning

confidence: 99%

The Natural History of COPD: Beyond Fletcher and Peto

Rennard¹,

Agustí²,

Vestbo³

2015

BRN

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The landmark publication of the "British Postal Worker Study" by Fletcher and colleagues in the 1970s established that chronic obstructive pulmonary disease occurs because smoking exposure in susceptible individuals accelerates the decline of lung function that occurs physiologically with age. In the 40 years since Fletcher et al. published the results of their study, subsequent research has advanced our understanding of chronic obstructive pulmonary disease and its natural history. The current review focuses on areas where the proposal by Fletcher et al. require expansion and/or modification, including: (i) the recognition of the role of exposures other than cigarette smoking (or even in its absence where chronic obstructive pulmonary disease may be related to other conditions such as asthma); (ii) that smoking affects a larger percentage of individuals than suggested by Fletcher et al.; (iii) that the benefits of smoking cessation vary with age/disease severity; (iv) that lung function decline does not accelerate with advancing age; (v) that many can develop chronic obstructive pulmonary disease with "normal" rates of lung function decline if they have abnormal lung growth and, therefore, low lung function at early age; (vi) that the relationship between mucus hypersecretion, exacerbations, and lung function decline is more complex than suggested by Fletcher et al.; and, finally, (vii) Corresponding author: Stephen I. Rennard, srennard@unmc.edu

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Pulmonary Gas Exchange Abnormalities in Mild Chronic Obstructive Pulmonary Disease. Implications for Dyspnea and Exercise Intolerance

Cited by 188 publications

References 47 publications

Breathing Intolerance Index (BIT) and its Relation to Exercise Data: Noninvasive Assessment of Inspiratory Muscle Endurance during Rest and Exercise in Patients with Chronic Obstructive Pulmonary Disease and Cardiovascular Disorders

Breathing Intolerance Index (BIT) and its Relation to Exercise Data: Noninvasive Assessment of Inspiratory Muscle Endurance during Rest and Exercise in Patients with Chronic Obstructive Pulmonary Disease and Cardiovascular Disorders

Impaired exercise ventilatory efficiency in smokers with low transfer factor but normal spirometry

The Natural History of COPD: Beyond Fletcher and Peto

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