Effect of surgical lung volume reduction on respiratory muscle function in pulmonary emphysema

Teschler, Helmut; Stamatis, Georgios; Farhat, Ahmed; Meyer, F. Joachim; Costabel, Ulrich; Konietzko, N.

doi:10.1183/09031936.96.09091779

Cited by 93 publications

(50 citation statements)

References 28 publications

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“…LVRS increases the maximal force of contraction of the inspiratory muscles at RV or FRC, the expected result of decreased lung volumes (27,28). This has also been shown specifically for the diaphragm, measured by maximal transdiaphragmatic pressure during sniffs, inspiratory/expulsive maneuvers, and phrenic stimulation (19).…”

Section: Respiratory Muscle Functionmentioning

confidence: 87%

Physiologic Basis for Improved Pulmonary Function after Lung Volume Reduction

Fessler¹,

Scharf²,

Ingenito³

et al. 2008

Proceedings of the American Thoracic Society

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It is not readily apparent how pulmonary function could be improved by resecting portions of the lung in patients with emphysema. In emphysema, elevation in residual volume relative to total lung capacity reduces forced expiratory volumes, increases inspiratory effort, and impairs inspiratory muscle mechanics. Lung volume reduction surgery (LVRS) better matches the size of the lungs to the size of the thorax containing them. This restores forced expiratory volumes and the mechanical advantage of the inspiratory muscles. In patients with heterogeneous emphysema, LVRS may also allow space occupied by cysts to be reclaimed by more normal lung. Newer, bronchoscopic methods for lung volume reduction seek to achieve similar ends by causing localized atelectasis, but may be hindered by the low collateral resistance of emphysematous lung. Understanding of the mechanisms of improved function after LVRS can help select patients more likely to benefit from this approach.Keywords: lung mechanics; emphysema surgery; lung recoil; airflow limitation; respiratory muscles PHYSIOLOGIC BASIS FOR IMPAIRMENT WITH EMPHYSEMAInflammatory changes associated with chronic obstructive pulmonary disease (COPD) initiate the changes in lung mechanical properties that characterize emphysema. Inflammation leads to destruction of elastin, which contributes to lung elasticity, and collagen, which provides tensile strength. Although recent interest has focused on the cellular and molecular mechanisms contributing to emphysema, the study of lung mechanical stresses, one of the earliest postulated causes of emphysema (1), has received less attention. Weakened lung parenchyma is more likely to fracture during respiratory stress, and coalescence of a few alveoli can increase stress on adjacent units in a way that favors formation of large, localized cysts similar to the pattern seen in patients with advanced emphysema (2-4). Effects of Emphysema on Expiratory FlowThese sequelae of inflammation ultimately decrease lung elastic recoil and small airway caliber, contributing to characteristic airflow limitation. The three classic determinants of expiratory flow limitation are lung elastic recoil, the propensity for airways to close, and airway resistance (5). Loss of elastic recoil in emphysema decreases the upstream pressure that drives expiratory flow, thereby decreasing maximal flows at any lung volume. Loss of elastic recoil also increases the unstressed volume of the lung (the volume remaining when elastic recoil is zero). Loss of radial traction on airways from lung parenchyma contributes to airway closure at higher lung volumes (increased trapped volume) because a higher transmural pressure is required to maintain airway patency. In addition, airway caliber at any lung volume is decreased (6). Coexisting small airway inflammation and fibrosis further increase airway resistance (7,8). These changes collectively reduce the rate of lung emptying.The rate of lung emptying may be expressed as its time constant, the time necessary for approximately 63% o...

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Section: Respiratory Muscle Functionmentioning

confidence: 87%

Physiologic Basis for Improved Pulmonary Function after Lung Volume Reduction

Fessler¹,

Scharf²,

Ingenito³

et al. 2008

Proceedings of the American Thoracic Society

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“…In fact, not only is the denominator of this ratio increased after LVRS, but the numerator is also reduced (see below). Nevertheless, no correlation has been found between the increase in maximal inspiratory muscle strength and the improvement in dyspnoea after LVRS [51,62].…”

Section: Respiratory Muscle Strength and Interactionmentioning

confidence: 91%

“…Besides FEV1, more specific indices of airflow obstruction have been reported less frequently. Three groups reported improved FEV1/VC ratios, using stapling techniques and with most patients operated on bilaterally [52,61,62]. Others found a lack of significant improvement in FEV1/VC [4,48,53,59].…”

Section: Pathophysiological Basis Of Functional Impairment In Emphysemamentioning

confidence: 99%

“…One study did not show any significant improvement in maximal inspiratory pressure [48] but it was not designed to specifically address respiratory muscle function. Diaphragmatic strength evaluated by maximal inspiratory [51] or sniff nasal transdiaphragmatic pressure [62] improved after surgery. These results are generally ascribed to a reduction of hyperinflation as reflected by the lowered FRC observed after LVRS.…”

Section: Respiratory Muscle Strength and Interactionmentioning

confidence: 99%

“…Global inspiratory muscle strength, as measured by mouth pressure during maximal inspiratory efforts [51,53,62] or sniff nasal inspiratory pressure [62], has been shown to increase significantly after LVRS. One study did not show any significant improvement in maximal inspiratory pressure [48] but it was not designed to specifically address respiratory muscle function.…”

Section: Respiratory Muscle Strength and Interactionmentioning

confidence: 99%

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Physiological basis of improvement after lung volume reduction surgery for severe emphysema: where are we?

Marchand¹,

Gayan‐Ramirez²,

Leyn³

et al. 1999

Eur Respir J

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Physiological basis of improvement after lung volume reduction surgery for severe emphysema: where are we? E. Marchand, G. Gayan-Ramirez, P. De Leyn, M. Decramer. #ERJ Journals Ltd 1999. ABSTRACT: Lung volume reduction surgery has become an accepted therapeutic option to relieve the symptoms of selected patients with severe emphysema. In a majority of these patients, it causes objective as well as subjective functional improvement. A proper understanding of the physiological determinants underlying these beneficial effects appears very important in order to better select patients for the procedure that is currently largely carried out on an empirical basis.Lung volume reduction surgery has two distinct effects. Firstly, it causes an increased elastic recoil, which at least partially explains the enhanced maximal expiratory flow. Secondly, it is associated with a reduction of hyperinflation which allows for an increase in global inspiratory muscle strength and in diaphragmatic contribution to tidal volume as well as a decrease in the inspiratory elastic load imposed by the chest wall. Taken together, these effects result in a reduced work of breathing and in an enhanced maximal ventilation which both contribute to the increased exercise capacity and reduced dyspnoea after surgery. The improved lung recoil and the reduced hyperinflation after volume reduction surgery were the primary postulates upon which the usual selection criteria for the procedure were based. It is now likely that these are correct. Nevertheless, some patients do not benefit from lung volume reduction surgery and the current literature does not allow for a refinement of the selection process from a physiological point of view.The exact mechanisms underlying the improvement in lung recoil, lung mechanics, and respiratory muscle function remain incompletely understood. Moreover, the effects of lung volume reduction surgery on gas exchange and pulmonary haemodynamics still need to be more fully investigated. An analysis of the characteristics of patients who do not benefit from the procedure and the development of an animal model for lung volume reduction surgery would probably help address these important issues. Eur Respir J 1999; 13: 686±696.

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