Improvement in Pulmonary Function and Elastic Recoil after Lung-Reduction Surgery for Diffuse Emphysema

Sciurba, Frank C.; Rogers, Robert M.; Keenan, Robert J.; Slivka, William A.; Gorcsan, John; Ferson, Peter F.; Holbert, J. Michael; Brown, Manuel L.; Landreneau, Rodney J.

doi:10.1056/nejm199604253341704

Cited by 438 publications

(221 citation statements)

References 23 publications

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“…Regarding TLC25, however, its definition could lead to an artificial overestimation as compared to "voluntary TLC". Indeed, the detrimental effects of hyperinflation on inspiratory-muscle efficiency lead to the inability to develop a transpulmonary pressure in emphysematous subjects as high as that in normal subjects [15]. However, if TLC increased by a 20% margin as is observed in patients, the RV/TLC would still only approach 39%, which remains very low.…”

Section: Discussionmentioning

confidence: 98%

Effects of lung volume reduction surgery in hamsters with elastase-induced emphysema

Marchand¹,

Leyn²,

Gayan‐Ramirez³

et al. 2002

Eur Respir J

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Lung volume reduction surgery (LVRS) has been shown to improve respiratory mechanics in selected patients with severe emphysema. This is thought to be due to an improvement in lung elastic recoil. This study was aimed at gaining further understanding about the effects of LVRS on respiratory mechanics and airway function.Control hamsters instilled with saline (Ctrl; n=8) were compared with emphysematous animals that underwent either a sham operation (Sham; n=7) or an LVRS (LVRS; n=7).As expected, there was a significant increase in the static lung volumes in the Sham as compared to the Ctrl group and a significant decrease of these volumes in LVRS as compared to the Sham group. Surprisingly, emphysema was associated with a significant increase and LVRS with a significant decrease in vital capacity. Despite a tendency toward an increase in lung compliance as compared to Sham, indices of maximal expiratory flows tended to decrease with LVRS. As opposed to humans, there was no change in the distribution of airway diameters in Sham compared to Ctrl.These findings appear to be largely explained by the high compliance of the hamster chest wall. This allows for better matching between the emphysematous lung and the chest-wall sizes than in humans.

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Section: Discussionmentioning

confidence: 98%

Effects of lung volume reduction surgery in hamsters with elastase-induced emphysema

Marchand¹,

Leyn²,

Gayan‐Ramirez³

et al. 2002

Eur Respir J

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“…Early physiologic studies of LVRS focused on increased elastic recoil and decreased airway resistance (13)(14)(15)(16)(17). For example, Gelb and coworkers showed that LVRS increased elastic recoil at a given lung volume (13,14).…”

Section: Increased Lung Elastic Recoilmentioning

confidence: 99%

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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“…reduced airway resistance). In contrast to the situation following lung volume reduction surgery [13], acute BD administration was not associated with increased elastic lung recoil pressure and is not, therefore, likely to affect the statically determined relaxation volume of the respiratory system. The main impact is therefore on the dynamically determined resting EELV through pharmacological manipulation of resistance in the airways upstream from the flow-limiting segments [14,15].…”

mentioning

confidence: 63%

Lung hyperinflation in COPD: the impact of pharmacotherapy

O’Donnell¹,

Laveneziana²

2006

Eur Respir Rev

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Improvement in airway function in response to bronchodilator therapy is generally confirmed by simple spirometry. However, improvements in maximal expiratory flow rates have been shown to correlate poorly with important patient-centred outcomes, such as reduced exertional dyspnoea and improved exercise performance. Recent studies have suggested that attendant reductions in end-expiratory lung volume as a result of bronchodilator-induced improvements in lung emptying may be more closely associated with symptom relief and increased exercise capacity than traditional spirometric indices. To the extent that chronic lung hyperinflation and the superimposition of acute dynamic hyperinflation (in response to increased ventilation or expiratory flow limitation) result in excessive loading and weakening of the inspiratory muscles, then pharmacological lung volume reduction should have important mechanical and sensory benefits for the patient.The present article will examine the mechanisms of lung deflation following short-term bronchodilator therapy. The physiological links between reduced hyperinflation, improved dyspnoea and exercise endurance will be examined, and the emerging evidence for the additive effects of combining various modern pharmacological therapies will be reviewed.

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Improvement in Pulmonary Function and Elastic Recoil after Lung-Reduction Surgery for Diffuse Emphysema

Abstract: Lung-reduction surgery can produce increases in the elastic recoil of the lung in patients with diffuse emphysema, leading to short-term improvement in dyspnea and exercise tolerance.

Cited by 438 publications

References 23 publications

Effects of lung volume reduction surgery in hamsters with elastase-induced emphysema

Effects of lung volume reduction surgery in hamsters with elastase-induced emphysema

Physiologic Basis for Improved Pulmonary Function after Lung Volume Reduction

Lung hyperinflation in COPD: the impact of pharmacotherapy

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