Intramuscular Fat Infiltration Contributes to Impaired Muscle Function in COPD.

UNLABELLED: Muscle weakness is a prevalent complication in chronic obstructive pulmonary disease (COPD). Atrophy does not fully explain muscle weakness in this population. The recent focus on fat infiltration and its clinical implications in age and diseased muscles are important because it may further explain the extent of declining muscle strength and mobility seen in COPD. PURPOSE: The objectives of this study are to quantify fat infiltration (muscle quality) of lower-limb muscles in people with COPD and healthy older adults using magnetic resonance imaging and proton magnetic resonance spectroscopy, and to explore its relationship with muscle strength and walking capacity in COPD. METHODS: T1-weighted magnetic resonance imaging and proton magnetic resonance spectroscopy were performed in people with COPD (n = 10) and control subjects (n = 10) matched for age, gender, and body mass index. Maximal cross-sectional area (muscle size), isokinetic and isometric muscle peak torques, and 6-min walk distance were also assessed. RESULTS: In addition to muscle atrophy (mean between-group differences of 20% to 25%, P < 0.05), COPD group presented with fatty infiltration in thigh and calf muscles that were significantly greater than what was observed in their healthy counterparts (mean between-group differences of 74% to 89%, P = 0.001). There was a strong inverse correlation between intramuscular fat infiltration, muscle peak torque, and walking distance (r = -0.6 to -0.8, P < 0.001) in this group as opposed to fair-to-moderate correlations between muscle size and the same outcomes (r = 0.4-0.6, P < 0.01). CONCLUSION: Poor muscle quality accompanies atrophy in people with COPD. Intramuscular fat infiltration not only appears to have a strong correlation with impaired function but also is more profound than muscle atrophy in this group. Monitoring both muscle size and quality may enable a more comprehensive assessment of exercise programs in COPD.

Statin-induced rhabdomyolysis: a comprehensive review of case reports.

PURPOSE: To identify case reports of statin-induced rhabdomyolysis and summarize common predisposing factors, symptoms, diagnostic findings, functional outcomes, characteristics, treatment, and rehabilitation. METHOD: MEDLINE, CINAHL, SCOPUS, and PEDro databases were searched (1990-2013) for relevant case reports using the search terms "Statins," "Rhabdomyolysis," "Myalgia," "Muscle damage," "Muscle injury," and "Myopathy." Relevance (based on title and abstract) was assessed by one investigator; two investigators independently reviewed the relevant articles to determine inclusion in the review. RESULTS: A total of 112 cases met the inclusion criteria. The majority were in men (70%) and people over 45 years of age (mean 64 [SD 14] years). Simvastatin was the most commonly reported statin (n=55); the majority of cases reported the use of concomitant medications such as fibrates (n=25). Weakness (n=65) and muscle pain (n=64) were the most common symptoms. In 19 cases, the patient was referred to rehabilitation, but the case reports do not include descriptions of the treatment. CONCLUSION: Statin-induced rhabdomyolysis was more commonly reported when statins were used in conjunction with other drugs, which potentiated its effect. Research is needed to identify the role of exercise and rehabilitation following statin-induced rhabdomyoloysis since muscle damage may be severe and may have long-term effects on muscle function.

Objectif : Trouver des rapports de cas portant sur la rhabdomyolyse provoquée par les statines et résumer les facteurs prédisposants communs, les symptômes, les résultats diagnostiques, les résultats fonctionnels, les caractéristiques, le traitement et la réadaptation. Méthodes : On a cherché dans les bases de données MEDLINE, CINAHL, SCOPUS et PEDro (1990­2013) des rapports de cas pertinents en utilisant les termes de recherche Statins, Rhabdomyolysis, Myalgia, Muscle damage, Muscle injury et Myopathy. Un chercheur en a évalué la pertinence (en fonction du titre et du résumé) et deux autres ont revu indépendamment les articles pertinents pour déterminer s'il fallait les inclure dans la recherche. Résultats : Au total, 112 cas répondaient aux critères d'inclusion. La majorité des cas portaient sur des hommes (70 %) et les plus de 45 ans (âge moyen de 64 [ET 14] ans). La simvastatine a été la statine incriminée le plus souvent dans les rapports (n=55), la majorité des cas signalant l'utilisation simultanée de médicaments comme des fibrates (n=25). La faiblesse (n=65) et les douleurs musculaires (n=64) étaient les symptômes les plus courants. Dans 19 cas, le patient a été aiguillé vers la réadaptation, mais les rapports ne décrivent pas le traitement. Conclusion : On a signalé une rhabdomyolyse causée par les statines plus souvent lorsqu'elles étaient conjuguées à d'autres médicaments, ce qui en a accentué l'effet. Des recherches s'imposent pour déterminer le rôle de l'exercice et de la réadaptation à la suite d'une rhabdomyoloyse causée par les statines puisque les dommages musculaires peuvent être graves et qu'elles peuvent avoir des effets à long terme sur la fonction musculaire.

Measurement of activities of daily living in patients with COPD: a systematic review.

BACKGROUND: The objectives of this systematic review were to synthesize the literature on measures of activities of daily living (ADLs) that have been used in individuals with COPD and to provide an overview of the psychometric properties of the identified measures and describe the relationship of the disease-specific instruments with other relevant outcome measures for individuals with COPD and health-care use. METHODS: Studies that included a measure of ADLs in individuals with COPD were identified using electronic and hand searches. Two investigators performed the literature search. One investigator reviewed the study title, abstract, and full text of the articles to determine study eligibility and performed the data extraction and tabulation. In cases of uncertainty, a second reviewer was consulted. RESULTS: A total of 679 articles were identified. Of those, 116 met the inclusion criteria. Twenty-seven ADLs instruments were identified, of which 11 instruments were respiratory disease-specific, whereas 16 were generic. Most instruments combined instrumental ADLs (IADLs) with basic ADLs (BADLs). The majority of the instruments were self-reported; only three instruments were performance based. Twenty-one studies assessed psychometric properties of 16 ADLs instruments in patients with COPD. CONCLUSIONS: Although several ADLs instruments were identified, psychometric properties have only been reported in a few. Selection of the most appropriate measure should focus on the target construct (BADLs or IADLs or both), type of test (disease-specific vs generic and self-reported vs performance-based), depth of information obtained, and psychometric properties of the instruments. Given the relevance of ADLs to the lives of patients with COPD, its assessment should be more frequently incorporated as a clinical outcome in their management.

Gender-associated differences in pulmonary rehabilitation outcomes in people with chronic obstructive pulmonary disease: a systematic review.

PURPOSE: Although there is substantial evidence to support the importance of pulmonary rehabilitation (PR) in the management of chronic obstructive pulmonary disease, there is less evidence for gender-associated differences in the response to PR. The purpose of this review was to systematically identify and synthesize the available literature on whether men and women with chronic obstructive pulmonary disease respond differently to PR. METHODS: A search of 4 electronic databases was conducted (January 1990 to May 2012) for all English language articles where the goal was to assess gender differences in outcomes after PR. RESULTS: Of the 116 articles retrieved, 11 were included. Five studies reported differences between men and women after PR, for the outcomes of dyspnea, health-related quality of life, physical capacity, psychological and functional status, and coping strategies. Six studies reported no difference in response to PR for the same outcomes. No differences in study designs, study quality, participant characteristics, and type and duration of PR programs were observed between studies that showed gender differences and those that did not. CONCLUSION: There was insufficient evidence to support or refute gender-associated differences in PR outcomes. The impact of gender on the outcome of PR and how these differences may affect the delivery of PR programs remains to be defined.

Measurement of peripheral muscle strength in individuals with chronic obstructive pulmonary disease: a systematic review.

PURPOSE: Reduced maximal, peripheral muscle strength is associated with exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). Therefore, it is important to accurately evaluate muscle strength to identify patients with muscle weakness and to prescribe adequate loads for resistance training. The objective here was to systematically identify and summarize the literature on measurement of peripheral muscle strength in individuals with COPD and to make recommendations for strength testing in clinical and research settings. METHODS: A literature search was conducted of electronic databases between 1999 and 2009 of all English language articles utilizing muscle strength measurements. RESULTS: The search resulted in retrieval of 178 articles, of which 66 were reviewed. Isometric muscle strength was measured using handgrip (n = 30), strain gauge (n = 15), computerized dynamometer (n = 13), magnetic stimulation (n = 8), handheld dynamometer (n = 6), or manual testing (n = 3). Isotonic muscle strength was measured using a hydraulic system (n = 3) or 1-repetition maximum (n = 9), and isokinetic muscle strength was measured using computerized dynamometer (n = 16). Methodological issues such as limb position, number of trials, subject familiarization, test instructions, rest periods, and muscle group tested were all identified as important variables to consider when developing a strength-testing protocol. CONCLUSION: Muscle strength has been measured in people with COPD using similar methods as in other clinical populations. Each method presents advantages and disadvantages that need to be considered when selecting the most relevant measure. Standardization of the test procedures is essential in both clinical and research settings to obtain valid and reliable measurements of muscle strength.