Predictors of Body Mass Index in Patients With Moderate to Severe Emphysema

Chronic Obstructive Pulmonary Disease: A 2019 Evidence Analysis Center Evidence-Based Practice Guideline

Chronic obstructive pulmonary disease (COPD) is a progressive lung disorder in which patients are at high risk for both pulmonary and systemic complications of their disease. Medical nutrition therapy by a registered dietitian nutritionist can be an integral component of lifestyle treatment targeted at maintaining and improving outcomes, such as lung function, mortality, and quality of life. The Academy of Nutrition and Dietetics (Academy) convened an expert workgroup to conduct a systematic review to update the COPD Evidence-Based Nutrition Practice Guideline. This publication outlines the Academy's Evidence Analysis Library methods used to complete the systematic review and guideline and examines the recommendations and supporting evidence. A total of 14 recommendations were developed based on evidence from eight conclusions. Using the Nutrition Care Process as a framework for practice, recommendations rated as strong included assessing and monitoring and evaluating body weight and medical nutrition therapy by a registered dietitian nutritionist. Weak recommendations included predicting resting and total energy expenditure. All other recommendations were rated as fair. These included individualizing the calorie prescription and macronutrient composition of the diet; assessing and monitoring and evaluating energy intake, serum 25-hydroxyvitamin D levels, and frequency of exacerbations; and determining need for vitamin D supplementation. Fewer than one-third of the systematic review's conclusions could be used to support the recommendations due to conflicting results or limited or no evidence available. The Evidence Analysis Library 2019 COPD Evidence-Based Nutrition Practice Guideline is a valuable resource for registered dietitian nutritionists and other health care professionals caring for those with COPD.

Lung air trapping lowers respiratory arousal threshold and contributes to sleep apnea pathogenesis in COPD patients with overlap syndrome

STUDY OBJECTIVES

Overlap syndrome occurs when obstructive sleep apnea (OSA) and chronic obstructive pulmonary disorder (COPD) coexist in the same patient. Although several studies highlighted the importance of clinical phenotyping in OSA, the trait contribution to OSA pathogenesis in overlap syndrome has not been investigated. With this pilot study, we aimed to measure OSA determinants and their relationship with functional respiratory parameters in a sample of patients with overlap syndrome. In particular, we hypothesize that patients with COPD have in the low arousal threshold a major contributor for the development of OSA.

METHODS

Ten consecutive non-hypercapnic COPD patients (body mass index<35 kg/m²) suffering from overlap syndrome with no other relevant comorbidities underwent a phenotyping polysomnography. Traits were measured with CPAP dial-downs.

RESULTS

Arousal threshold was found to be inversely associated to functional measures of lung air trapping and static hyperinflation. Particularly, correlations with residual volume (r² = 0.49, p =  0.024) and residual volume to total lung capacity ratio (r² = 0.48, p =  0.026) were evident. Only 20% of patients showed a high upper airway passive collapsibility as single pathological trait. In contrast, among those patients with multiple altered traits (6 out of 10), all had an elevated loop gain and 4 (∼65%) a low arousal threshold.

CONCLUSIONS

High loop gain and particularly low arousal threshold seem important contributors to OSA pathogenesis and severity in patients with COPD. Recognizing in COPD patients these features as key traits may open avenues for personalized medicine in the field of overlap syndrome.

Chronic Obstructive Pulmonary Disease: Clinical Implications for Patients With Lung Cancer

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is the most common smoking-related illness. COPD often is underemphasized as a comorbidity except when considering issues surrounding surgical treatment options.

OBJECTIVES

This article aims to provide nurses with an overview of the pharmacologic and nonpharmacologic treatment implications of COPD.

METHODS

Definitions, differentials, and treatment considerations are provided, and clinical implications and resources are described.

FINDINGS

The added burden of dyspnea, fatigue, and psychological distress related to COPD may affect the overall outcome and quality of life (QOL) of patients with lung cancer. Attention to the prevention, assessment, and treatment of lung cancer and COPD and related symptomatology will help maximize patients' QOL.

Quantitative Computed Tomography (CT) Assessment of Emphysema in Patients with Severe Chronic Obstructive Pulmonary Disease (COPD) and its Correlation with Age, Sex, Pulmonary Function Tests, BMI, Smoking, and Biomass Exposure

Background

To evaluate the role of HRCT in quantifying emphysema in severe COPD patients and to study the variations in the pattern of emphysema in relation to age, sex, FEV1, smoking index, biomass exposure, and BMI.

Material/Methods

Automatic lung segmentation of HRCT scans in 41 severe COPD patients (GOLD stage III or more) was done using an emphysema protocol. The extent of emphysema was assessed using the density mask method with a threshold of –950 HU (%LAA-950). The percentage of emphysema in each lung lobe and both lungs was correlated with 6 parameters – age, sex, BMI, smoking index, biomass exposure, and FEV₁.

Results

Smoking resulted in homogenously distributed emphysema regardless of the severity of smoking. BMI was inversely correlated with the extent of emphysema. A significant association was found between the percentage of emphysema in the right lower lobe and BMI (P=0.015), between biomass exposure and the percentage of emphysema in RUL, RLL, and both lungs (P values of 0.024, 0.016, and 0.036, respectively). The extent of emphysema was disproportionately low compared to the amount of obstruction on PFTs, indicating an airway predominant variety of COPD with significant biomass exposure.

Conclusions

Smoking is associated with a relatively homogenous distribution of emphysema with no regional predilection. Biomass exposure produces predominantly right-sided emphysema. BMI decreases with increasing levels of emphysema in the right lower lobe. These risk factors of emphysema patterns are helpful in deciding on the management, including surgical options.

A study of chronic obstructive pulmonary disease-specific causes of osteoporosis with emphasis on the emphysema phenotype

BACKGROUND

Osteoporosis, the most common extra-pulmonary complication of chronic obstructive pulmonary disease (COPD), may be related to general causes or COPD-specific causes such as low forced expiratory volume in 1 s (FEV1) and hypoxia. A few studies reported that emphysema is an independent risk factor for osteoporosis. However, other workers considered the association to be confounded by low FEV1 and low body mass index (BMI) which cluster with emphysema.

AIMS

To study the association between osteoporosis and emphysema in a model that includes these potentially confounding factors.

METHODS

We studied prospectively 52 COPD patients with both high resolution computed tomography and carbon monoxide diffusion coefficient as diagnostic markers of emphysema. Dual-energy X-ray absorptiometry was used to measure the bone mass density (BMD) of lumbar vertebrae and neck of the femur. Vertebral fractures were evaluated using the Genant semiquantitative score. Multiple linear regression analysis was used to identify the following independent variables: age, BMI, FEV1% predicted, PaO2, emphysema score, C-reactive protein (CRP), and dyspnea score as related to BMD. P ≤ 0.05 was considered statistically significant.

RESULTS

There was no significant difference in the serum Vitamin D levels, vertebral fracture score, or BMD between the emphysematous and nonemphysematous patients. Multivariate analysis showed that (in a model including age, BMI, FEV1, PaO2, emphysema score, CRP, and dyspnea score) only reduced BMI, FEV1, and PaO2 were independent risk factors for low BMD.

CONCLUSIONS

The emphysematous phenotype is not a risk factor for osteoporosis independently of BMI, FEV1, and PaO2.

Comparison of World Health Organization and Asia-Pacific body mass index classifications in COPD patients

INTRODUCTION

A low body mass index (BMI) is associated with increased mortality and low health-related quality of life in patients with COPD. The Asia-Pacific classification of BMI has a lower cutoff for overweight and obese categories compared to the World Health Organization (WHO) classification. The present study assessed patients with COPD among different BMI categories according to two BMI classification systems: WHO and Asia-Pacific.

PATIENTS AND METHODS

Patients with COPD aged 40 years or older from the Korean COPD Subtype Study cohort were selected for evaluation. We enrolled 1,462 patients. Medical history including age, sex, St George's Respiratory Questionnaire (SGRQ-C), the modified Medical Research Council (mMRC) dyspnea scale, and post-bronchodilator forced expiratory volume in 1 second (FEV₁) were evaluated. Patients were categorized into different BMI groups according to the two BMI classification systems.

RESULT

FEV₁ and the diffusing capacity of the lung for carbon monoxide (DLCO) percentage revealed an inverse "U"-shaped pattern as the BMI groups changed from underweight to obese when WHO cutoffs were applied. When Asia-Pacific cutoffs were applied, FEV₁ and DLCO (%) exhibited a linearly ascending relationship as the BMI increased, and the percentage of patients in the overweight and obese groups linearly decreased with increasing severity of the Global Initiative for Chronic Obstructive Lung Disease criteria. From the underweight to the overweight groups, SGRQ-C and mMRC had a decreasing relationship in both the WHO and Asia-Pacific classifications. The prevalence of comorbidities in the different BMI groups showed similar trends in both BMI classifications systems.

CONCLUSION

The present study demonstrated that patients with COPD who have a high BMI have better pulmonary function and health-related quality of life and reduced dyspnea symptoms. Furthermore, the Asia-Pacific BMI classification more appropriately reflects the correlation of obesity and disease manifestation in Asian COPD patients than the WHO classification.

The mechanisms of cachexia underlying muscle dysfunction in COPD

Pulmonary cachexia is a prevalent, debilitating, and well-recognized feature of COPD associated with increased mortality and loss of peripheral and respiratory muscle function. The exact cause and underlying mechanisms of cachexia in COPD are still poorly understood. Increasing evidence, however, shows that pathological changes in intracellular mechanisms of muscle mass maintenance (i.e., protein turnover and myonuclear turnover) are likely involved. Potential factors triggering alterations in these mechanisms in COPD include oxidative stress, myostatin, and inflammation. In addition to muscle wasting, peripheral muscle in COPD is characterized by a fiber-type shift toward a more type II, glycolytic phenotype and an impaired oxidative capacity (collectively referred to as an impaired oxidative phenotype). Atrophied diaphragm muscle in COPD, however, displays an enhanced oxidative phenotype. Interestingly, intrinsic abnormalities in (lower limb) peripheral muscle seem more pronounced in either cachectic patients or weight loss-susceptible emphysema patients, suggesting that muscle wasting and intrinsic changes in peripheral muscle's oxidative phenotype are somehow intertwined. In this manuscript, we will review alterations in mechanisms of muscle mass maintenance in COPD and discuss the involvement of oxidative stress, inflammation, and myostatin as potential triggers of cachexia. Moreover, we postulate that an impaired muscle oxidative phenotype in COPD can accelerate the process of cachexia, as it renders muscle in COPD less energy efficient, thereby contributing to an energy deficit and weight loss when not dietary compensated. Furthermore, loss of peripheral muscle oxidative phenotype may increase the muscle's susceptibility to inflammation- and oxidative stress-induced muscle damage and wasting.

Impaired exercise capacity and skeletal muscle function in a mouse model of pulmonary inflammation

Pulmonary TNFα has been linked to reduced exercise capacity in a subset of patients with moderate to severe chronic obstructive pulmonary disease (COPD). We hypothesized that prolonged, high expression of pulmonary TNFα impairs cardiac and skeletal muscle function, and both contribute to exercise limitation. Using a surfactant protein C promoter-TNFα construct, TNFα was overexpressed throughout life in mouse lungs (SP-C/TNFα+). TNFα levels in wild-type (WT) female serum and lung were two- and threefold higher than in WT male mice. In SP-C/TNFα+ mice, TNFα increased similarly in both sexes. Treadmill exercise was impaired only in male SP-C/TNFα+ mice. While increases in lung volume and airspace size induced by TNFα were comparable in both sexes, pulmonary hypertension along with lower body and muscle mass were evident only in male mice. Left ventricular (LV) function (cardiac output, stroke volume, LV maximal pressure, and LV maximal pressure dP/dt) was not altered by TNFα overexpression. Fatigue measured in isolated soleus and EDL was more rapid only in soleus of male SP-C/TNFα+ mice and accompanied by a loss of oxidative IIa fibers, citrate synthase activity, and PGC-1α mRNA and increase in atrogin-1 and MuRF1 expression also only in male mice. In situ gastrocnemius fatigue resistance, reflecting both oxygen availability and contractility, was decreased similarly in female and male SP-C/TNFα+ mice. These data indicate that male, but not female, mice overexpressing pulmonary TNFα are susceptible to exercise limitation, possibly due to muscle wasting and loss of the oxidative muscle phenotype, with protection in females possibly due to estrogen.

Chronic airflow limitation in a rural Indian population: etiology and relationship to body mass index

Purpose

Respiratory conditions remain a source of morbidity globally. As such, this study aimed to explore factors associated with the development of airflow obstruction (AFO) in a rural Indian setting and, using spirometry, study whether underweight is linked to AFO.

Methods

Patients > 35 years old attending a rural clinic in West Bengal, India, took a structured questionnaire, had their body mass index (BMI) measured, and had spirometry performed by an ancillary health care worker.

Results

In total, 416 patients completed the study; spirometry was acceptable for analysis of forced expiratory volume in 1 second in 286 cases (69%); 16% were noted to exhibit AFO. Factors associated with AFO were: increasing age (95% confidence interval (CI) 0.004–0.011; P = 0.005), smoking history (95% CI 0.07–0.174; P = 0.006), male gender (95% CI 0.19–0.47; P = 0.012), reduced BMI (95% CI 0.19–0.65; P = 0.02), and occupation (95% CI 0.12–0.84; P = 0.08). The mean BMI in males who currently smoked (n = 60; 19.29 kg/m²; standard deviation [SD] 3.46) was significantly lower than in male never smokers (n = 33; 21.15 kg/m² SD 3.38; P < 0.001). AFO was observed in 27% of subjects with a BMI <18.5 kg/m², falling to 13% with a BMI ≥18.5 kg/m² (P = 0.013). AFO was observed in 11% of housewives, 22% of farm laborers, and 31% of cotton/jute workers (P = 0.035).

Conclusion

In a rural Indian setting, AFO was related to advancing age, current or previous smoking, male gender, reduced BMI, and occupation. The data also suggest that being under-weight is linked with AFO and that a mechanistic relationship exists between low body weight, smoking tobacco, and development of AFO.

Effect of obesity on constant workrate exercise in hyperinflated men with COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and a high body mass index (BMI) can both affect pulmonary volumes as well as exercise tolerance, but their combined effect on these outcomes is not well known. The aim of this study was to investigate the effects of increased BMI during constant workrate cycle ergometry in patients with COPD.

METHODS

Men with COPD and hyperinflation were divided according to World Health Organization BMI classification: 84 normal BMI (NBMI), 130 overweight (OW) and 64 obese (OB). Patients underwent spirometric and lung volumes assessment and an incremental cycling exercise test. This was followed by a constant workrate exercise test (CET) at 75% of peak capacity. Inspiratory capacity and Borg dyspnea scores were measured at baseline, during and at the end of CET.

RESULTS AND DISCUSSION

FEV1 % predicted was not different across BMI classes. Total lung capacity and functional residual capacity were significantly lower in OB and OW compared to NBMI patients. Peak VO2 in L x min(-1) was significantly higher in OB and OW patients than in NBMI patients. CET time was not different across BMI classes (p = 0.11). Changes in lung volumes and dyspnea during CET were not different between BMI categories.

CONCLUSIONS

OB and OW patients with COPD had a higher peak VO2 than their lean counterparts. Endurance time, dyspnea and changes in lung volumes during CET were similar between BMI categories.