Peripheral muscle composition and health status in patients with COPD

Mortality in individuals with COPD on long-term home non-invasive ventilation

BACKGROUND

Real-world evidence regarding survival of patients with chronic obstructive pulmonary disease (COPD) using chronic non-invasive ventilation (NIV) is scarce.

RESEARCH QUESTION

How do obesity and other factors relate to mortality in patients with COPD on chronic NIV?

STUDY DESIGN

and Methods: We retrospectively analyzed data from COPD patients enrolled in a home ventilation program between 2014 and 2018. Survival was compared between obese and non-obese groups using the Kaplan-Meier method. Factors associated with mortality were identified using multivariable Cox proportional regression analyses with Least Absolute Selection and Shrinkage Operator (LASSO) regularization. Univariable analyses were also done stratified by obesity.

RESULTS

Median survival was 80.0 (95% CI: 71.0-NA) months among obese (n = 205) and 30.0 (95%CI: 19.0-42.0) months in non-obese (n = 61) patients. NIV adherence was high in both groups. Mortality was associated with male gender [HR 1.44], chronic opioids or benzodiazepines use [HR 1.07], home oxygen use [HR 1.82], fixed pressure mode of ventilation [HR 1.55], NIV inspiratory pressure [HR 1.05], and thoracic cancer [HR 1.27]; obesity [HR: 0.43], age [HR 0.99] and NIV expiratory pressure [HR 0.94] were associated with decreased mortality. In the obese, univariable analyses revealed that chest wall disease, thoracic cancer, home oxygen use, FEV1% predicted, and ventilation parameters were associated with mortality. In the non-obese, male gender and respiratory comorbidities were related to mortality.

INTERPRETATION

Obesity is associated with improved survival in COPD patients highly adherent to NIV. Other factors associated with mortality reflect disease severity and ventilator parameters, with differences between obese and non-obese patients.

Responses to incremental exercise and the impact of the coexistence of HF and COPD on exercise capacity: a follow-up study

Our aim was to evaluate: (1) the prevalence of coexistence of heart failure (HF) and chronic obstructive pulmonary disease (COPD) in the studied patients; (2) the impact of HF + COPD on exercise performance and contrasting exercise responses in patients with only a diagnosis of HF or COPD; and (3) the relationship between clinical characteristics and measures of cardiorespiratory fitness; (4) verify the occurrence of cardiopulmonary events in the follow-up period of up to 24 months years. The current study included 124 patients (HF: 46, COPD: 53 and HF + COPD: 25) that performed advanced pulmonary function tests, echocardiography, analysis of body composition by bioimpedance and symptom-limited incremental cardiopulmonary exercise testing (CPET) on a cycle ergometer. Key CPET variables were calculated for all patients as previously described. The [Formula: see text]E/[Formula: see text]CO2 slope was obtained through linear regression analysis. Additionally, the linear relationship between oxygen uptake and the log transformation of [Formula: see text]E (OUES) was calculated using the following equation: [Formula: see text]O2 = a log [Formula: see text]E + b, with the constant 'a' referring to the rate of increase of [Formula: see text]O2. Circulatory power (CP) was obtained through the product of peak [Formula: see text]O2 and peak systolic blood pressure and Ventilatory Power (VP) was calculated by dividing peak systolic blood pressure by the [Formula: see text]E/[Formula: see text]CO2 slope. After the CPET, all patients were contacted by telephone every 6 months (6, 12, 18, 24) and questioned about exacerbations, hospitalizations for cardiopulmonary causes and death. We found a 20% prevalence of HF + COPD overlap in the studied patients. The COPD and HF + COPD groups were older (HF: 60 ± 8, COPD: 65 ± 7, HF + COPD: 68 ± 7). In relation to cardiac function, as expected, patients with COPD presented preserved ejection fraction (HF: 40 ± 7, COPD: 70 ± 8, HF + COPD: 38 ± 8) while in the HF and HF + COPD demonstrated similar levels of systolic dysfunction. The COPD and HF + COPD patients showed evidence of an obstructive ventilatory disorder confirmed by the value of %FEV1 (HF: 84 ± 20, COPD: 54 ± 21, HF + COPD: 65 ± 25). Patients with HF + COPD demonstrated a lower work rate (WR), peak oxygen uptake ([Formula: see text]O2), rate pressure product (RPP), CP and VP compared to those only diagnosed with HF and COPD. In addition, significant correlations were observed between lean mass and peak [Formula: see text]O2 (r: 0.56 p < 0.001), OUES (r: 0.42 p < 0.001), and O2 pulse (r: 0.58 p < 0.001), lung diffusing factor for carbon monoxide (DLCO) and WR (r: 0.51 p < 0.001), DLCO and VP (r: 0.40 p: 0.002), forced expiratory volume in first second (FEV1) and peak [Formula: see text]O2 (r: 0.52; p < 0.001), and FEV1 and WR (r: 0.62; p < 0.001). There were no significant differences in the occurrence of events and deaths contrasting both groups. The coexistence of HF + COPD induces greater impairment on exercise performance when compared to patients without overlapping diseases, however the overlap of the two diseases did not increase the probability of the occurrence of cardiopulmonary events and deaths when compared to groups with isolated diseases in the period studied. CPET provides important information to guide effective strategies for these patients with the goal of improving exercise performance and functional capacity. Moreover, given our findings related to pulmonary function, body composition and exercise responses, evidenced that the lean mass, FEV1 and DLCO influence important responses to exercise.

Nutritional Status and Body Composition in Patients Suffering From Chronic Respiratory Diseases and Its Correlation With Pulmonary Rehabilitation

As part of an individualized intervention to improve the physical, emotional, and social functioning of patients with chronic respiratory diseases in general and chronic obstructive pulmonary disease in particular, awareness of the presence and consequences of changes in body composition increased enormously during the last decades, and nutritional intervention is considered as an essential component in the comprehensive approach of these patients. This review describes the prevalence and the clinical impact of body composition changes and also provides an update of current intervention strategies. It is argued that body composition, preferentially a three-component evaluation of fat, lean, and bone mass, must become part of a thorough assessment of every patient, admitted for pulmonary rehabilitation.

Pathophysiology of COPD

This article provides an overview of the pathophysiology of chronic obstructive pulmonary disease including the physiological mechanisms that are known precursors. The roles of environmental and genetic causes are considered. α1-Antitrypsin deficiency is also discussed as it relates to the development of airflow obstruction.

Reduced calf circumference is an independent predictor of worse quality of life, severity of disease, frequent exacerbation, and death in patients with chronic obstructive pulmonary disease admitted to a pulmonary rehabilitation program: A historic cohort study

BACKGROUND

Muscle wasting is associated with worse outcomes in chronic obstructive pulmonary disease (COPD) patients. We assessed the association of calf circumference (CC) measurements with clinical outcomes in COPD patients referred to an outpatient pulmonary rehabilitation program (PRP).

METHODS

In this single-center, retrospective study, we analyzed demographic and clinical data ( spirometry tests, comorbidities, COPD exacerbations, dyspnea scoring, exercise capacity, quality-of-life scores, BMI, CC measurements, and all-cause deaths [for 2 years]) from COPD patients PRP medical records. Patients were grouped according to CC into reduced CC (male, ≤34 cm; female, ≤33 cm) or adequate CC groups.

RESULTS

We evaluated 144 patients (aged 64.6 ± 8.5 years; mostly males; forced expiratory volume in 1 s, 40.3% ± 15.8%, predicted). Eighteen patients (12.5%) died during the 2 years of follow-up. Logistic regression showed that patients with reduced CC were more likely to present worse outcomes compared with COPD patients with adequate CC: more advanced disease severity (odds ratio [OR] = 5.09; 95% CI, 2.00-12.96), COPD frequent exacerbators (OR = 2.34; 95% CI, 1.11-4.91), worse total quality-of-life score (OR = 2.70, 95% CI, 1.22-6.00), and higher mortality (OR = 3.69; 95% CI, 1.06-12.87).

CONCLUSION

Reduced CC in COPD patients under initial assessment for PRP admission was associated with disease severity, frequent exacerbation, poor health status, and higher mortality in 2 years of follow-up. Considering its clinical applicability, CC measurement should be introduced in the nutrition assessment of COPD patients admitted to the PRP.

Eccentric Left Ventricular Hypertrophy and Left and Right Cardiac Function in Chronic Heart Failure with or without Coexisting COPD: Impact on Exercise Performance

Aim

Our aim was to assess: 1) the impact of the eccentric left ventricular hypertrophy (ELVH) on exercise performance in patients diagnosed with chronic heart failure (CHF) alone and in patients with co-existing CHF and chronic obstructive pulmonary disease (COPD) and 2) the relationship between left and right cardiac function measurements obtained by doppler echocardiography, clinical characteristics and primary measures of cardiorespiratory fitness.

Methods

The current study included 46 patients (CHF:23 and CHF+COPD:23) that performed advanced pulmonary function tests, echocardiography and symptom-limited, incremental cardiopulmonary exercise testing (CPET) on a cycle ergometer.

Results

Patients with CHF+COPD demonstrated a lower work rate, peak oxygen uptake (VO₂), oxygen pulse, rate pressure product (RPP), circulatory power (CP) and ventilatory power (VP) compared to those only diagnosed with CHF. In addition, significant correlations were observed between VP and relative wall thickness (r: 0.45 p: 0.03),V_E/VCO₂ intercept and Mitral E/e' ratio (r: 0.70 p: 0.003) in the CHF group. Significant correlations were found between indexed left ventricle mass and RPP (r: -0.47; p: 0.02) and relative VO₂ and right ventricle diameter (r: -0.62; p: 0.001) in the CHF+COPD group.

Conclusion

Compared to a diagnosis of CHF alone, a combined diagnosis of CHF+COPD induced further impairments in cardiorespiratory fitness. Moreover, echocardiographic measures of cardiac function are related to cardiopulmonary exercise performance and therefore appear to be an important therapeutic target when attempting to improve exercise performance and functional capacity.

Multimorbidity in Patients with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a complex disease manifested primarily as airflow limitation that is partially reversible as confirmed by spirometry. COPD patients frequently develop systemic manifestations, such as skeletal muscle wasting and cachexia. COPD patients often develop other comorbid diseases, such as ischemic heart disease, heart failure, osteoporosis, anemia, lung cancer, and depression. Comorbidities complicate management of COPD and need to be evaluated because detection and treatment have important consequences. Novel approaches aimed at integrating the multiple morbidities seen in COPD and other chronic diseases will provide new avenues of research and allow developing more comprehensive and effective therapeutic approaches.

Ultrasonographic assessment of skeletal muscle mass and diaphragm function in patients with chronic obstructive pulmonary disease: A case-control study

BACKGROUND

Although muscle dysfunction is a major contributor to morbidity in chronic obstructive pulmonary disease (COPD), assessment of skeletal muscle, and diaphragm function is not routinely performed in COPD patients.

OBJECTIVES

(1) The aim is to assess muscle dysfunction in COPD by measuring the zone of apposition of diaphragm, diaphragm excursion, thickness of diaphragm, and rectus femoris cross-sectional area (RFCSA) with ultrasonography.(2) To correlate the above assessments with spirometric parameters; notably forced expiratory volume in 1 s (FEV₁).

METHODS

Twenty-four consecutive stable COPD patients and 18 controls were included after obtaining written informed consent. Demographic and clinical data, spirometric values, 6-min walk distance, and sonographic parameters mentioned above were compiled for the analysis.

RESULTS

All included participants were male with a mean age of 62.5 ± 8.4 years. The mean FEV₁in cases was 1.12 ± 0.4 L versus 2.41 ± 0.5 L in controls. The diaphragm thickness (1.8 ± 0.5 mm vs. 2.2 ± 0.6 mm;P = 0.005) and RFCSA was significantly lower in COPD patients (4.8 ± 1.3 cm^[2] vs. 6.12 ± 1.2 cm^[2];P = 0.02). However, diaphragm excursion (5.35 ± 2.8 cm vs. 7 ± 2.6 cm) although lower in COPD patients, was not significantly different between the groups. Correlation between FEV₁and ultrasound diaphragm measurements and RFCSA by Spearman's Rho correlation was poor (ρ= 0.2).

CONCLUSION

Ultrasonographic assessment of the diaphragm and rectus femoris can be used as markers to assess skeletal muscle dysfunction in COPD as diaphragmatic function and RFCSA were lower in COPD patients.

Computed tomography-derived area and density of pectoralis muscle associated disease severity and longitudinal changes in chronic obstructive pulmonary disease: a case control study

BACKGROUND

Muscle wasting is associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). The cross-sectional area of skeletal muscles on computed tomography (CT) could serve as a method to evaluate body composition. The present study aimed to determine the ability of CT-derived pectoralis muscle area (PMA) and pectoralis muscle density (PMD) to determine the severity of COPD and change in longitudinal pulmonary function in patients with COPD.

METHODS

A total of 293 participants were enrolled in this study, a whom 222 had undergone at least two spirometry measurements within 3 years after baseline data acquisition. PMA and PMD were measured from a single axial slice of chest CT above the aortic arch at baseline. The emphysema index and bronchial wall thickness were quantitatively assessed in all scans. The generalized linear model was used to determine the correlation between PMA and PMD measurements and pulmonary function.

RESULTS

PMA and PMD were significantly associated with baseline lung function and the severity of emphysema (P < 0.05). Patients with the lowest PMA and PMD exhibited significantly more severe airflow obstruction (β = - 0.06; 95% confidence interval: - 0.09 to - 0.03]. PMA was statistically associated with COPD assessment test (CAT) score (P = 0.033). However, PMD did not exhibit statistically significant correlation with either CAT scores or modified Medical Research Council scores (P > 0.05). Furthermore, neither PMA nor PMD were associated with changes in forced expiratory volume in 1 s over a 3-year periods.

CONCLUSIONS

CT-derived features of the pectoralis muscle may be helpful in predicting disease severity in patients with COPD, but are not necessarily associated with longitudinal changes in lung function.

Evaluation of body composition in COPD patients using multifrequency bioelectrical impedance analysis

Background

Multifrequency bioelectrical impedance analysis (MF-BIA) is a technique that measures body impedance (Z) at different frequencies (5, 10, 50, 100, and 250 kHz). Body composition may be estimated using empirical equations, which include BIA variables or, alternatively, raw BIA data may provide direct information on water distribution and muscle quality.

Objectives

To compare raw MF-BIA data between COPD patients and controls and to study their relationship with respiratory and functional parameters in COPD patients.

Methods

MF-BIA was performed (Human Im-Touch analyzer) in 212 COPD patients and 115 age- and BMI-matched controls. Fat-free mass (FFM) and fat mass were estimated from BIA data, and low- to high-frequency (5 kHz/250 kHz) impedance ratio was calculated. Physical fitness, lung function and respiratory muscle strength were also assessed in COPD patients.

Results

After adjusting for age, weight, and body mass index, FFM and the 5/250 impedance ratio were lower in COPD patients (P<0.001) and were negatively affected by disease severity. In both male and female patients, the 5/250 impedance ratio was significantly correlated mainly with age (r=−0.316 and r=−0.346, respectively). Patients with a 5/250 impedance ratio below median value had lower handgrip strength (P<0.001), 6-minute walk distance (P<0.005), respiratory muscle strength (P<0.005), forced expiratory volume in 1 second (P<0.05) and vital capacity (P<0.005). Finally, the 5/250 impedance ratio was reduced (P<0.05) in patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) III and IV (compared to those with GOLD I and II) or a BODE index between 6 and 10 points (compared to those with BODE index between 1 and 5 points).

Conclusion

MF-BIA may be a useful tool for assessing body composition and nutritional status in COPD patients. In particular, the impedance ratio could give valuable information on cellular integrity and muscle quality.

Obesity might be a good prognosis factor for COPD patients using domiciliary noninvasive mechanical ventilation

Cachexia is known to be a deteriorating factor for survival of patients with chronic obstructive pulmonary disease (COPD), but data related to obesity are limited. We observed that obese patients with COPD prescribed long-term noninvasive mechanical ventilation (NIMV) had better survival rate compared to nonobese patients. Therefore, we conducted a retrospective observational cohort study. Archives of Thoracic Diseases Training Hospital were sought between 2008 and 2013. All the subjects were prescribed domiciliary NIMV for chronic respiratory failure secondary to COPD. Subjects were grouped according to their body mass index (BMI). The first group consisted of subjects with BMI between 20 and 30 kg/m², and the second group consisted of subjects with BMI >30 kg/m². Data obtained at the first month’s visit for the following parameters were recorded: age, sex, comorbid diseases, smoking history, pulmonary function test, 6-minute walk test (6-MWT), and arterial blood gas analysis. Hospital admissions were recorded before and after the domiciliary NIMV usage. Mortality rate was searched from the electronic database. Overall, 118 subjects were enrolled. Thirty-eight subjects had BMI between 20 and 30 kg/m², while 80 subjects had BMI >30 kg/m². The mean age was 65.8±9.4 years, and 81% were male. The median follow-up time was 26 months and mortality rates were 32% and 34% for obese and nonobese subjects (P=0.67). Improvement in 6-MWT was protective against mortality. In conclusion, survival of obese patients with COPD using domiciliary NIMV was found to be better than those of nonobese patients, and the improvement in 6-MWT in such patients was found to be related to a better survival.

Impact of sleep quality on functional capacity, peripheral muscle strength and quality of life in patients with chronic obstructive pulmonary disease

PURPOSE

The purpose of this study was to assess the impact of quality of sleep on functional capacity, peripheral muscle strength and quality of life in patients with chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS

Forty patients with COPD (61.6 ± 8.28 years) were included in this study. Subjective sleep quality (Pittsburgh sleep quality index), quality of life (Nottingham health profile), quadriceps muscle strength (QMS) and functional capacity (6-min walk test) were assessed.

RESULTS

Poor sleep quality (Pittsburgh sleep quality index total >5) was present in 57% of the patients. Patients with a poor sleep quality had significantly lower QMS and higher exercise heart rate (p < 0.05). The Pittsburgh sleep quality index total score was associated with QMS, Nottingham health profile physical mobility and sleep scores, exercise fatigue and dyspnea (p < 0.05).

CONCLUSION

Sleep quality is affected in a majority of patients with COPD. It is related with symptoms, functional capacity, peripheral muscle strength and general quality of life.

Ultrasonographic assessment of the diaphragm in chronic obstructive pulmonary disease patients: relationships with pulmonary function and the influence of body composition - a pilot study

BACKGROUND

Skeletal muscle weakness with loss of fat-free mass (FFM) is one of the main systemic effects of chronic obstructive pulmonary disease (COPD). The diaphragm is also involved, leading to disadvantageous conditions and poor contractile capacities.

OBJECTIVES

We measured the thickness of the diaphragm (TD) by ultrasonography to evaluate the relationships between echographic measurements, parameters of respiratory function and body composition data.

METHODS

Thirty-two patients (23 males) underwent (1) pulmonary function tests, (2) echographic assessment of TD in the zone of apposition at various lung volumes, i.e. TD at residual volume (TDRV), TD at functional residual capacity (TDFRC) and TD at total lung capacity (TDTLC), and (3) bioelectrical body impedance analysis. The BMI and the BODE (BMI-Obstruction-Dyspnea-Exercise) index values were reported.

RESULTS

TDRV, TDFRC and TDTLC measured 3.3, 3.6 and 6 mm, respectively, with good intraobserver reproducibility (0.97, 0.97 and 0.96, respectively). All the TDs were found to be related to FFM, with the relationship being greater for TDFRC (r(2) = 0.39 and p = 0.0002). With regard to lung volumes, inspiratory capacity (IC) was found to be closely related to TDTLC (r(2) = 0.42 and p = 0.0001). The difference between TDTLC and TDRV, as a thickening value (TDTLCRV), was closely related to FVC (r(2) = 0.34 and p = 0.0004) and to air-trapping indices (RV/TLC, FRC/TLC and IC/TLC): the degree of lung hyperinflation was greater and the TDTLCRV was less. Finally, we found a progressive reduction of both thicknesses and thickenings as the severity of IC/TLC increased, with a significant p value for the trend in both analyses (p = 0.02).

CONCLUSIONS

Ultrasonographic assessment of the diaphragm could be a useful tool for studying disease progression in COPD patients, in terms of lung hyperinflation and the loss of FFM. © 2014 S. Karger AG, Basel.

Obesity in Bulgarian patients with chronic obstructive pulmonary disease

It has been well defined that obesity is strongly linked with several respiratory symptoms and diseases, but no convincing evidence has been provided for chronic obstructive pulmonary disease (COPD). In the current study, we aim to assess the possible prevalence of obesity in patients with COPD in a cross-sectional case–control study of individuals from the region of Stara Zagora, Bulgaria, and to explore whether the body mass has some effect on the lung function of COPD patients. The study included 158 patients with COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) II, III, and IV stages) and 123 individuals unaffected by the disease (control). A higher frequency of obesity compared to the controls (20.3%) was observed in patients with COPD (29.1%, p = 0.093), especially in those with GOLD II stage (37.7%, p = 0.009). Prevalence of obesity was highest in COPD GOLD II, followed by GOLD III and IV stages ( p = 0.068). When diabetes was considered as confounding factor, we found a significant prevalence of obesity in COPD patients than the controls with diabetes ( p = 0.031). Interestingly, there was a statistically significant moderate positive correlation between the body mass index and forced expiratory volume in one second as a percentage of predicted value in the whole patients’ group ( R = 0.295, p = 0.0002) as well as in the subgroups of GOLD II ( R = 0.257, p = 0.024) and GOLD III COPD ( R = 0.259, p = 0.031).The results of our study propose that the increased body mass, particularly obesity is frequent comorbidity to COPD, especially to less severe diseases. Moreover, the results suggest that the higher body weight may provide some protection against the impairment of lung functions in patients with stable COPD.

COPD elicits remodeling of the diaphragm and vastus lateralis muscles in humans

A profound remodeling of the diaphragm and vastus lateralis (VL) occurs in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). In this mini-review, we discuss the following costal diaphragm remodeling features noted in patients with moderate-to-severe COPD: 1) deletion of serial sarcomeres, 2) increased proportion of slow-twitch fibers, 3) fast-to-slow isoform shift in sarco(endo)plasmic reticulum Ca(2+)-ATPase, 4) increased capacity of oxidative metabolism, 5) oxidative stress, and 6) myofiber atrophy. We then present the sole feature of diaphragm remodeling noted in mild-to-moderate COPD under the heading "MyHC and contractile remodeling noted in mild-to-moderate COPD." The importance of VL remodeling in COPD patients as a prognostic indicator as well as a major determinant of the ability to carry out activities of daily living is well accepted. We present the remodeling of the VL noted in COPD patients under the following headings: 1) Decrease in proportion of slow-twitch fibers, 2) Decreased activity of oxidative pathways, 3) Oxidative and nitrosative stress, and 4) Myofiber atrophy. For each of the remodeling features noted in both the VL and costal diaphragm of COPD patients, we present mechanisms that are currently thought to mediate these changes as well as the pathophysiology of each remodeling feature. We hope that our mechanistic presentation stimulates research in this area that focuses on improving the ability of COPD patients to carry out increased activities of daily living.

Associations between isokinetic muscle strength, high-level functional performance, and physiological parameters in patients with chronic obstructive pulmonary disease

High-level activities are typically not performed by patients with chronic obstructive pulmonary disease (COPD), which results in reduced functional performance; however, the physiological parameters that contribute to this reduced performance are unknown. The aim of this study was to determine the relationships between high-level functional performance, leg muscle strength/power, aerobic power, and anaerobic power. Thirteen patients with COPD underwent an incremental maximal cardiopulmonary exercise test, quadriceps isokinetic dynamometry (isometric peak torque and rate of torque development; concentric isokinetic peak torque at 90°/sec, 180°/sec, and 270°/sec; and eccentric peak torque at 90°/sec), a steep ramp anaerobic test (SRAT) (increments of 25 watts every 10 seconds), and three functional measures (timed up and go [TUG], timed stair climb power [SCPT], and 30-second sit-to-stand test [STS]). TUG time correlated strongly (P < 0.05) with all muscle strength variables and with the SRAT. Isometric peak torque was the strongest determinant of TUG time (r = −0.92). SCPT and STS each correlated with all muscle strength variables except concentric at 270°/sec and with the SRAT. The SRAT was the strongest determinant of SCPT (r = 0.91), and eccentric peak torque at 90°/sec was most significantly associated with STS (r = 0.81). Performance on the SRAT (anaerobic power); slower-velocity concentric, eccentric, and isometric contractions; and rate of torque development are reflected in all functional tests, whereas cardiopulmonary exercise test performance (aerobic power) was not associated with any of the functional or muscle tests. High-level functional performance in patients with COPD is associated with physiological parameters that require high levels of muscle force and anaerobic work rates.

Functional assessment of chronic obstructive pulmonary disease

PURPOSE

To describe available methods for assessing functional capacity in persons with chronic obstructive pulmonary disease (COPD).

DATA SOURCES

An extensive literature review is used to provide pertinent information.

CONCLUSIONS

COPD disease affects millions of Americans and is physically and psychologically distressing. The hallmark of chronic obstructive pulmonary disease is irreversible airflow limitation and dyspnea. Dyspnea is a major contributor to decreased exercise capacity and functional status in this population. Understanding the methods to complete a functional assessment is important for all practitioners caring for this population.

IMPLICATIONS FOR PRACTICE

This paper provides an overview of current methods used to assess functional status, including pulmonary function testing, exercise testing, and anthropomorphic and self-report measurements. In addition, there is discussion of the indications and contraindications for exercise testing in chronic obstructive pulmonary disease and the clinical significance of performing a global composite of functional ability.

Skeletal muscle dysfunction in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a debilitating disease characterized by inflammation-induced airflow limitation and parenchymal destruction. In addition to pulmonary manifestations, patients with COPD develop systemic problems, including skeletal muscle and other organ-specific 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 airflow limitation and dynamic hyperinflation. However, there is mounting evidence to suggest that skeletal muscle dysfunction, independent of lung function, contributes significantly 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 inflammatory processes, nutritional depletion, corticosteroid medications, chronic inactivity, age, hypoxemia, smoking, oxidative and nitrosative stresses, protein degradation and changes in vascular density. This review briefly 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 field.

The mitochondrial phenotype of peripheral muscle in chronic obstructive pulmonary disease: disuse or dysfunction?

RATIONALE

Peripheral muscle alterations have been recognized to contribute to disability in chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To describe the mitochondrial phenotype in a moderate to severe COPD population and age-matched controls.

METHODS

Three primary aspects of mitochondrial function were assessed in permeabilized locomotor muscle fibers.

MEASUREMENTS AND MAIN RESULTS

Respiration rates per milligram of fiber weight were significantly lower in COPD muscle compared with healthy age-matched control muscle under various respiratory states. However, when variations in mitochondrial volume were taken into account by normalizing respiration per unit of citrate synthase activity, differences between the two groups were abolished, suggesting the absence of specific mitochondrial respiratory impairment in COPD. H(2)O(2) production per mitochondrion was higher both under basal and ADP-stimulated states, suggesting that mitochondria from COPD muscle have properties that potentiate H(2)O(2) release. Direct assessment of mitochondrial sensitivity to Ca(2+)-induced opening of the permeability transition pore (PTP) indicated that mitochondria from patients with COPD were more resistant to PTP opening than their counterparts in control subjects.

CONCLUSIONS

Comparison of these results with those of studies comparing healthy glycolytic with oxidative muscle suggests that these differences may be attributable to greater type II fiber expression in COPD muscle, as mitochondria within this fiber type have respiratory function similar to that of mitochondria from type I fibers, and yet are intrinsically prone to greater release of H(2)O(2) and more resistant to PTP opening. These results thus argue against the presence of pathological mitochondrial alterations in this category of patients with COPD.

Extra-pulmonary features in COPD patients entering rehabilitation after stratification for MRC dyspnea grade

Experts have stated that referral for rehabilitation of patients with chronic obstructive pulmonary disease (COPD) becomes appropriate when these patients become aware of their disability (e.g. usually grade 3 to 5 on the Medical Research Council (MRC) dyspnea scale). However, patients with MRC dyspnea grade 1/2 may also suffer from extra-pulmonary features, such as abnormal body composition, exercise intolerance and reduced disease-specific health status. In the present study, we have studied whether and to what extent chronic obstructive pulmonary disease (COPD) patients with MRC dyspnea grade 1/2 have extra-pulmonary features compared to patients with grade 3, 4 or 5? Pulmonary function, body composition, 6-min walking distance, peak exercise capacity, anxiety, depression and disease-specific health status have been assessed in 333 outpatients who had been referred for pulmonary rehabilitation. On average, patients with MRC dyspnea grade 1/2 had a better exercise tolerance and disease-specific health status compared to patients with grade 4 or 5. Nevertheless, grade 1/2 patients had a higher prevalence of muscle mass depletion. In addition, these patients did still have aberrant values in one or more of the aforementioned outcomes. On average, patients with MRC dyspnea grade 1/2 may clearly suffer from extra-pulmonary features, indicating the necessity to refer these patients for rehabilitation. Therefore, MRC dyspnea scale alone does not appear to be a suitable measure to identify most patients with COPD who have to be referred for rehabilitation.

Muscle fibre type shifting in the vastus lateralis of patients with COPD is associated with disease severity: a systematic review and meta-analysis

BACKGROUND

Skeletal muscle dysfunction is a common feature in chronic obstructive pulmonary disease (COPD) which is associated with intrinsic muscular abnormalities. One of the most consistently reported alterations is a shift from fibre type I to II in the vastus lateralis of these patients. Surprisingly, the relationship between this shift and the severity and phenotype of COPD remains unclear. A study was conducted to determine whether vastus lateralis muscle fibre type proportions are associated with COPD disease severity and to provide reference values for the proportions of fibre types in the vastus lateralis in COPD.

METHODS

A systematic review and a meta-analysis were conducted in which muscle fibre type data and markers of disease severity were collected from the literature.

RESULTS

The forced expiratory volume in 1 s (FEV(1)), the ratio of FEV(1) to forced vital capacity (FVC) and body mass index were positively associated with the proportion of type I fibres in COPD. A proportion of 51% for vastus lateralis fibre type I and 13% for fibre type IIX were calculated from the combined data as normal values for patients with typical GOLD stage 3-4 COPD aged 60-70 years. Based on these reference values, a proportion of fibre type I <27% and of fibre type IIX >29% were defined as pathologically abnormal.

CONCLUSIONS

This review sheds new light on the relationship between skeletal muscle abnormalities and important hallmarks of the disease in severe COPD, and identifies absence of data in GOLD stages 1-2. This review also provides reference values on fibre type composition for diagnostic purposes in COPD.

Skeletal muscle structure and function in response to electrical stimulation in moderately impaired COPD patients

STUDY OBJECTIVE

To determine the structural and functional consequences of high-frequency neuromuscular electrical stimulation (hf-NMES) in a group of moderately impaired outpatients with chronic obstructive pulmonary disease (COPD).

DESIGN

A prospective, cross-over randomized trial.

SETTING

An university-based, tertiary center.

PATIENTS AND MATERIALS

Seventeen patients (FEV(1)=49.6+/-13.4% predicted, Medical Research Council dyspnoea grades II-III) underwent 6-weeks hf-NMES (50Hz) and sham stimulation of the quadriceps femoris in a randomized, cross-over design. Knee strength was measured by isokinetic dynamometry (peak torque) and leg muscle mass (LMM) by DEXA; in addition, median cross-sectional area (CSA) of type I and II fibres and capillary-fibre ratio were evaluated in the vastus lateralis. The 6-min walking distance (6MWD) was also determined.

RESULTS

At baseline, patients presented with well-preserved functional capacity, muscle strength and mass: there was a significant relationship between strength and type II CSA (P<0.05). NMES was not associated with significant changes in peak torque, LMM or 6MWD as compared to sham (P>0.05). At micro-structural level, however, electrical stimulation increased type II, but decreased type I, CSA; no change, however, was found in the relative fibre distribution or capillary:fibre ratio (P<0.05). There was no significant association between individual changes in structure and function with training (P>0.05). Post-NMES increase in type II CSA was inversely related to baseline mass and strength (P<0.05).

CONCLUSION

NMES may promote a modest degree of type II muscle fibre hypertrophy in COPD patients with well-preserved functional status. These micro-structural changes, however, were not translated into increased volitional strength in this sub-population.