The contractile properties of the elderly human diaphragm.

Polkey, MI; Harris, Mark; Hughes, Philip D.; Hamnegärd, C H; Lyons, D.; Green, M; Moxham, John

doi:10.1164/ajrccm.155.5.9154857

Cited by 178 publications

(107 citation statements)

References 23 publications

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“…Indeed, maximum transdiaphragmatic pressure (Pdi max ) measured at various lung volumes is reportedly to be approximately 25% lower in elderly subjects as compared to that measured in young subjects (Tolep et al 1995). Similarly, 13% and 23% reductions in sniff Pdi and twitch Pdi (generated by phrenic stimulation) have been observed in elderly subjects, as compared to young subjects (Polkey et al 1997). These studies clearly indicate that aging contributes to poor skeletal muscle contractile performance in COPD patients.…”

Section: Agementioning

confidence: 77%

Skeletal Muscle Dysfunction in Patients with Chronic Obstructive Pulmonary Disease

2010

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Chronic obstructive pulmonary disease (COPD) is a debilitating disease characterized by infl ammation-induced airfl ow limitation and parenchymal destruction. In addition to pulmonary manifestations, patients with COPD develop systemic problems, including skeletal muscle and other organ-specifi c dysfunctions, nutritional abnormalities, weight loss, and adverse psychological responses. Patients with COPD often complain of dyspnea on exertion, reduced exercise capacity, and develop a progressive decline in lung function with increasing age. These symptoms have been attributed to increases in the work of breathing and in impairments in gas exchange that result from airfl ow limitation and dynamic hyperinfl ation. However, there is mounting evidence to suggest that skeletal muscle dysfunction, independent of lung function, contributes signifi cantly to reduced exercise capacity and poor quality of life in these patients. Limb and ventilatory skeletal muscle dysfunction in COPD patients has been attributed to a myriad of factors, including the presence of low grade systemic infl ammatory processes, nutritional depletion, corticosteroid medications, chronic inactivity, age, hypoxemia, smoking, oxidative and nitrosative stresses, protein degradation and changes in vascular density. This review briefl y summarizes the contribution of these factors to overall skeletal muscle dysfunction in patients with COPD, with particular attention paid to the latest advances in the fi eld. Keywords: skeletal muscles, chronic obstructive pulmonary disease, diaphragm, quadriceps, fatigue, disuse, atrophy, smoking, exercise It has long been recognized that COPD is a systemic disease in which several extrapulmonary manifestations, including cachexia and skeletal muscle dysfunction, contribute to morbidity and mortality. Functionally, skeletal muscle dysfunction in COPD patients is characterized by signifi cant reduction in muscle strength and endurance. It is structurally characterized by loss of muscle mass and cross-sectional area (muscle atrophy), fi ber type distribution (reduction in the proportion of oxidative fi bers and increases in the proportion of glycolytic fi bers), oxidative metabolic capacity (attenuation of mitochondrial enzyme activities and expression) and capillary distribution (signifi cant loss of capillary density). Although disuse and inactivity are important contributors to the pathogenesis of skeletal muscle dysfunction in COPD patients, several other systemic and local factors are also involved. These include systemic infl ammation, malnutrition, corticosteroid usage, hypoxemia, aging, smoking and local factors such as the production of reactive oxygen (ROS) and nitrogen species (RNS) and enhanced protein degradation inside muscle fi bers, a result of increased activities of the proteasomal and lysosomal pathways and activation of calpains and caspases. Evidence of skeletal muscle dysfunction in patients with COPDIt has been well established that skeletal muscle function (strength and endurance) and s...

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Section: Agementioning

confidence: 77%

Skeletal Muscle Dysfunction in Patients with Chronic Obstructive Pulmonary Disease

2010

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“…The diaphragm is the most important inspiratory muscle in mammals and plays a critical role in the maintenance of adequate alveolar ventilation. Unfortunately, diaphragmatic force-generating capacity decreases with age (Bou-Resli et al, 1991;Criswell et al, 1997;Gosselin et al, 1994;Polkey et al, 1997;Tolep et al, 1995). Mitochondrial function in diaphragm may be reduced with age due to the high metabolic activity of this muscle, producing high ROS generation and subsequent oxdiative damage.…”

Section: Discussionmentioning

confidence: 99%

Improved mitochondrial function and increased life span after chronic melatonin treatment in senescent prone mice

Rodríguez

Escames

López

et al. 2008

Experimental Gerontology

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“…The measurement of transdiaphragmatic pressure (TP), maximum voluntary ventilation (MVV) and maximum inspiratory pressure (MIP) reflects the contractile status of the diaphragm. All these variables decline with age (13)(14)(15), also the anatomical structure of the lung parenchyma changes. A progressive senile hyperinflation is observed (16) with enlarged air spaces, degeneration of the elastic fibers and reduction of the peribronchial support opposing to the premature closure of small airways during forced expiration and even normal breathing.…”

Section: Aging: Physiologic Changesmentioning

confidence: 98%