Flow limitation and dynamic hyperinflation: key concepts in modern respiratory physiology

Calverley, P. M. A.

doi:10.1183/09031936.04.00113204

Cited by 224 publications

(186 citation statements)

References 111 publications

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“…This is likely to provide clinically relevant information, especially during high-intensity, constant work rate exercise test at the limit of tolerance (Tlim), a test format that has been widely used to assess the effects of pharmacological and non-pharmacological interventions in COPD. Assuming, therefore, that any strategy aimed to postpone near-maximum V CW (i.e., a critically reduced inspiratory reserve volume) is likely to be advantageous for these patients (2-5), we tested the following hypotheses: i) dyspnea scores would be higher and Tlim lower in patients with faster kinetics and/or larger increases in EIV CW (and vice versa) and ii) occasional reductions in EEV AB (6,7,10) - conceivably due to the recruitment of expiratory muscles (12-16) - would reduce and slow the increases in V CW thereby being beneficial to breathlessness and exercise tolerance in these patients.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of chest wall volume regulation during constant work rate exercise in patients with chronic obstructive pulmonary disease

Takara¹,

Cunha²,

Barbosa³

et al. 2012

Braz J Med Biol Res

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This study evaluated the dynamic behavior of total and compartmental chest wall volumes [(VCW) = rib cage (VRC) + abdomen (VAB)] as measured breath-by-breath by optoelectronic plethysmography during constant-load exercise in patients with stable chronic obstructive pulmonary disease. Thirty males (GOLD stages II-III) underwent a cardiopulmonary exercise test to the limit of tolerance (Tlim) at 75% of peak work rate on an electronically braked cycle ergometer. Exercise-induced dynamic hyperinflation was considered to be present when end-expiratory (EE) VCW increased in relation to resting values. There was a noticeable heterogeneity in the patterns of VCW regulation as EEVCW increased non-linearly in 17/30 “hyperinflators” and decreased in 13/30 “non-hyperinflators” (P < 0.05). EEVAB decreased slightly in 8 of the “hyperinflators”, thereby reducing and slowing the rate of increase in end-inspiratory (EI) VCW (P < 0.05). In contrast, decreases in EEVCW in the “non-hyperinflators” were due to the combination of stable EEVRC with marked reductions in EEVAB. These patients showed lower EIVCW and end-exercise dyspnea scores but longer Tlim than their counterparts (P < 0.05). Dyspnea increased and Tlim decreased non-linearly with a faster rate of increase in EIVCW regardless of the presence or absence of dynamic hyperinflation (P < 0.001). However, no significant between-group differences were observed in metabolic, pulmonary gas exchange and cardiovascular responses to exercise. Chest wall volumes are continuously regulated during exercise in order to postpone (or even avoid) their migration to higher operating volumes in patients with COPD, a dynamic process that is strongly dependent on the behavior of the abdominal compartment.

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Section: Introductionmentioning

confidence: 99%

Dynamics of chest wall volume regulation during constant work rate exercise in patients with chronic obstructive pulmonary disease

Takara¹,

Cunha²,

Barbosa³

et al. 2012

Braz J Med Biol Res

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“…EFLT plays a central role according to a recent hypothesis on the transition from small airways disease to overt COPD in smokers [6][7][8][9]. EFLT implies inhomogeneity of ventilation distribution, with concurrent impairment of gas exchange and unevenly distributed stress and strain within the lung, which is amplified by tissue interdependence [7,8] and may lead to small airway injury [6][7][8][9].…”

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confidence: 99%

Physiological techniques for detecting expiratory flow limitation during tidal breathing

Koulouris¹,

Hardavella²

2011

Eur Respir Rev

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Patients with severe chronic obstructive pulmonary disease (COPD) often exhale along the same flow-volume curve during quiet breathing as they do during the forced expiratory vital capacity manoeuvre, and this has been taken as an indicator of expiratory flow limitation at rest (EFLT). Therefore, EFLT, namely attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow. EFLT leads to small airway injury and promotes dynamic pulmonary hyperinflation, with concurrent dyspnoea and exercise limitation. In fact, EFLT occurs commonly in COPD patients (mainly in Global Initiative for Chronic Obstructive Lung Disease III and IV stage), in whom the latter symptoms are common, but is not exclusive to COPD, since it can also be detected in other pulmonary and nonpulmonary diseases like asthma, acute respiratory distress syndrome, heart failure and obesity, etc. The existing up to date physiological techniques of assessing EFLT are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, noninvasive, practical and accurate new technique.

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“…6). 52,64,65 It is not surprising, therefore, that regional trapping and its slowly rising waveform signature can be eliminated by raising PEEP.…”

Section: Dynamic Hyperinflation (Air Trapping)mentioning

confidence: 99%

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

Marini

2013

Respir Care

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SummaryRelatively little attention has been directed toward damage inflicted upon the airway network that connects the alveoli, or toward the problems caused by invasive ventilation for patients with severe airflow obstruction. Mechanical ventilation with positive pressure can cause non-edematous barotrauma, inflict airway injury, and promote lung remodeling. Interactions between patient and ventilator, largely mediated through dynamic hyperinflation, include functional consequences for hemodynamics, respiratory muscle function, breathing work load, and patient-ventilator synchrony. Awareness of such associations not only helps to avoid complications during and after the critical phase of obstructive illness, but also opens a window to improved patient comfort and safety. The purpose of this review is to survey the range of structural damages and functional impairments that occur in an "obstructive" context.

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Flow limitation and dynamic hyperinflation: key concepts in modern respiratory physiology

Cited by 224 publications

References 111 publications

Dynamics of chest wall volume regulation during constant work rate exercise in patients with chronic obstructive pulmonary disease

Dynamics of chest wall volume regulation during constant work rate exercise in patients with chronic obstructive pulmonary disease

Physiological techniques for detecting expiratory flow limitation during tidal breathing

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

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