Prevalence and characteristics of nutritional depletion in patients with stable COPD eligible for pulmonary rehabilitation

Peripheral muscle dysfunction in chronic obstructive pulmonary disease

Peripheral muscle dysfunction is a common systemic complication of moderate to severe COPD and may contribute to disability, handicap, and premature mortality. In contrast to the lung impairment, which is largely irreversible, peripheral muscle dysfunction is potentially remediable with exercise training, nutritional intervention, oxygen, and anabolic drugs. Therapeutic success is often incomplete, however, and a better understanding of the mechanisms involved in the development of peripheral muscle dysfunction in COPD is needed to help develop innovative and more effective therapeutic strategies.

Respiratory muscle function and drive in chronic obstructive pulmonary disease

Respiratory, and particularly inspiratory, muscle function is altered in COPD. Many of these alterations are secondary to a mechanical disadvantage related to hyperinflation. Other factors, including corticosteroid therapy and nutritional depletion, are also deleterious to muscle function. In addition, the load imposed on the respiratory muscles is increased in COPD. Combined with the altered respiratory muscle function, this increase induces important changes in respiratory muscle drive and recruitment. Moreover, the imbalance between respiratory muscle function and load is an important determinant of dyspnea and hypercapnia. Because much of the lung and airway derangements are irreversible in COPD, the respiratory muscles appear to be an attractive target for therapeutic interventions.

Mechanisms and measures of exercise intolerance in chronic obstructive pulmonary disease

The mechanisms for exercise intolerance in chronic obstructive pulmonary disease are complex and multifaceted. Although ventilatory limitation caused by abnormal pulmonary function is a major contributor to this phenomenon, other factors may play an important role in limiting exercise. These other factors include depressed cardiac function, respiratory and peripheral muscle weakness, nutritional imbalances, and psychologic factors. The assessment of the pulmonary patient who complains of decreased functional status must include examination and consideration of all these variables. Only by addressing and treating the combination of these variables as they present in an individual patient will clinicians have the potential to impact that individual's functional status and quality of life.

Nutritional abnormalities and supplementation in chronic obstructive pulmonary disease

Weight loss and muscle wasting commonly occur in patients with chronic obstructive pulmonary disease (COPD). A decreased dietary intake and elevated energy requirements underlie weight loss in these patients. Disturbances in intermediary metabolism caused by altered anabolic and catabolic mediators such as hormones, cytokines, and growth factors, and resulting in disproportionate muscle wasting have been described. Nutritional supplementation in combination with an anabolic stimulus (e.g. exercise) has been shown effective in improving functional capacity, health status, and mortality in most depleted patients. Nutritional or pharmacologic modulation of the catabolic response may further enhance the response in the near future.

Tissue depletion and health related quality of life in patients with chronic obstructive pulmonary disease

The relationship between tissue depletion and decreased exercise performance has been well established in patients with COPD. In this study we investigated the influence of the pattern of tissue depletion on health related quality of life (HRQL) and their mutual relationship with exercise capacity and dyspnoea. Patients with low body weight and/or low fat-free mass (FFM; using bioelectrical impedance) were categorized in three groups according to type of tissue depletion: loss of both FFM and fat mass (FM), and loss of FFM or FM only. Handgrip strength (HGS) was used as a functional outcome measure of tissue depletion. Exercise performance was assessed by 12 min walking distance (12MWD) and dyspnoea by visual analogue scale (VAS). HRQL was measured with the St George's Respiratory Questionnaire (SGRQ) and the Medical Psychological Questionnaire for Lung diseases (MPQL). Patients with depletion of FFM irrespective of body weight showed greater impairment in 12MWD, HGS, the 'activity' and 'impact' scores of the SGRQ and the domain 'invalidity' of the MPQL, in comparison with depleted patients with relative preservation of FFM. Exercise performance and dyspnoea were also significantly related to these subscores of HRQL. In addition, dyspnoea related significantly to the domain 'symptoms' of the SGRQ. Tissue depletion pattern remained significantly related to SGRQ-scores and the domain 'invalidity' of the MPQL when dyspnoea and walking distance were added to the model as a covariates. Tissue depletion is an important determinant of HRQL independent of exercise capacity and dyspnoea.

Serum amino acids in relation to nutritional status, lung function and energy intake in patients with advanced pulmonary disease

Malnutrition, hypoxia and energy deficit may affect protein metabolism. We wanted to evaluate the cross-sectional association between serum amino acids and fat-free mass in a group of hypoxic patients. We also wanted to explore, in the same group of patients, whether the blood amino-acid pattern could possibly be influenced by differences in lung function and energy intake. Serum amino acids were measured in 71 hypoxic underweight and normal-weight patients with advanced pulmonary disease and related to the fat-free-mass index, arterial oxygen (PaO2) and carbon dioxide tension (PaCO2), forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1) and energy intake. Only one amino acid (aspartic acid) remained significantly correlated to the fat-free-mass index after adjustments for age and sex (beta = -0.30, P=0.011). None of the amino acids were significantly correlated to PaO2 but alanine was significantly negatively correlated to PaCO2 (beta = -0.46, P<0.001), phenylalanine to FVC1 (beta = 0.52, P=0.001) and tyrosine to FVC (beta = 0.36, P=0.008). Citrulline and tryptophan were significantly correlated to energy intake (beta = 0.32, P=0.008; beta=0.37, P=0.009 respectively). In conclusion, there was no convincing association between fat free mass and serum amino acids. The negative effect of hypercapnia and reduced lung function on some serum amino acids was suggested and some amino acids were sensitive to reduced energy intake.

Protein-energy undernutrition in hospital in-patients

Impaired nutritional status has been frequently reported in surveys estimating its prevalence amongst patients in hospital. While there is no doubt that protein-energy undernutrition has serious implications for health, recovery from illness or surgery and hospital costs, lack of nationally or internationally accepted cut-off points and guidelines for most nutrition-related variables make nutritional assessment difficult and proper comparisons between studies impossible. In reviewing published work in which the prevalence of undernutrition has been assessed, it can be seen that each study defined undernutrition, or nutritional risk, using different methodology. This present review aims to highlight the problems which arise when deciphering these studies, and the resulting difficulty in determining the true prevalence of undernutrition and nutritional risk, amongst both general and specific groups of hospital in-patients. It is widely agreed that routine hospital practices can further adversely affect the nutritional status of sick patients in hospital. How this occurs, and the potential effects of impaired nutritional status on clinical outcome are examined. The methods currently available to assess nutritional status are evaluated in the knowledge that such assessments are difficult in clinical practice. The review concludes by proposing that if we want the medical and nursing professions to consider the nutritional status of hospital patients seriously, definitions of undernutrition and nutritional risk, and cut-off values for the nutritional variables measured must be agreed to allow evidence-based practice. Outcome measures which allow clear comparisons between groups and treatments must be used in studies assessing the effects of nutritional interventions.

Nutrition risk factors for institutionalization in a free-living functionally dependent elderly population

Risk factors for institutionalization of frail elderly have been studied but the role of nutritional status has not been addressed. A prospective cohort of 288 frail elderly (81 male; 207 female; mean age: 78.2 +/- 7.6 years) were recruited from the current list of those receiving home help services and followed for 3-5 years. At baseline, height, weight, and arm muscle circumference were measured. Self-reported weight loss prior to baseline, energy, and protein intake were recorded. Covariates included sociodemographic factors, social network variables, functional and health status. Cox's multivariate survival analysis was used to identify independent predictors of institutionalization. Over the period of observation, 46% of subjects were institutionalized. Univariate predictors included weight loss >/=5 kg, functional status, and not living alone. In multivariate analysis, weight loss significantly increased the likelihood of institutionalization [Hazard Ratio (HR) = 1.71 (95% CI: 1.08-2.73)] as did limited functional capacities [HR = 1.26 (95% CI: 1.02-1.55)]. Among the free-living frail elderly, weight loss >/=5 kg is an important predictor of early institutionalization after controlling for social network, health, and functional status.

Skeletal muscle dysfunction in chronic obstructive pulmonary disease and chronic heart failure: underlying mechanisms and therapy perspectives

Low exercise tolerance has a large influence on health status in chronic obstructive pulmonary disease and chronic heart failure. In addition to primary organ dysfunction, impaired skeletal muscle performance is a strong predictor of low exercise capacity. There are striking similarities between both disorders with respect to the muscular alterations underlying the impairment. However, different alterations occur in different muscle types. Histologic and metabolic data show that peripheral muscles undergo a shift from oxidative to glycolytic energy metabolism, whereas the opposite is observed in the diaphragm. These findings are in line with the notion that peripheral and diaphragm muscle are limited mainly by endurance and strength capacity, respectively. In both diseases, muscular impairment is multifactorially determined; hypoxia, oxidative stress, disuse, medication, nutritional depletion, and systemic inflammation may contribute to the observed muscle abnormalities and each factor has its own potential for innovative treatment approaches.

The relationship between chronic hypoxemia and activation of the tumor necrosis factor-alpha system in patients with chronic obstructive pulmonary disease

Although circulating tumor necrosis factor (TNF)-alpha levels have been found to be increased in weight-losing patients with chronic obstructive pulmonary disease (COPD), the main causes for this phenomenon remain to be elucidated. Since hypoxia itself can enhance the production of the TNF-alpha in vitro, we studied the relationship between hypoxemia and activities of the TNF-alpha system, including circulating TNF-alpha and soluble TNF-receptors (sTNF-R; sTNF-R55 and -R75) levels, in 27 COPD patients and 15 age-matched healthy controls. The COPD patients showed a significant weight loss (body mass index = 18.1 +/- 2.8 versus 22.8 +/- 2.2 [mean +/- SD] kg/m(2); p < 0.0001. % fat = 16.3 +/- 5.9 versus 24.3 +/- 4.9 %; p < 0.001), and hypoxemia (Pa(O2 )= 62.2 +/- 9.5 versus 88.6 +/- 5.9 mm Hg; p < 0.0001) as compared with the healthy controls. Serum TNF-alpha (6.15 +/- 1.08 versus 5.41 +/- 1.60 pg/ml; p < 0.05) and plasma sTNF-R55 (1.15 +/- 0.49 versus 0.67 +/- 0.13 ng/ml; p < 0.0001) and sTNF-R75 (3.54 +/- 1.16 versus 2.25 +/- 0.43; p < 0.0001) levels were significantly higher in the COPD patients than in the healthy controls. There were inverse correlations between Pa(O(2)) and circulating TNF-alpha and sTNF-R levels in patients with COPD (TNF-alpha; r = -0.426, p = 0.0297; sTNF-R55: r = -0.587, p = 0.0027; sTNF-R75: r = -0.573, p = 0.0035). In addition, we found inverse correlations between sTNF-R levels and % fat in COPD patients (sTNF-R55: r = -0.442, p = 0.0272; sTNF-R75: r = -0. 484, p = 0.0155). TNF-alpha levels correlated well with sTNF-R levels (sTNF-R55: r = 0.488, p = 0.0127; sTNF-R75: r = 0.609, p = 0. 0019). These relationships were not observed in the healthy controls. These data suggest that systemic hypoxemia noted in patients with COPD is associated with activation of the TNF-alpha system in vivo, which may be a factor contributing to the weight loss in patients with the disease.

Nutritional support for individuals with COPD: a meta-analysis

RATIONALE

Malnutrition in patients with COPD is associated with an impaired pulmonary status, reduced diaphragmatic mass, lower exercise capacity, and higher mortality rate when compared to adequately nourished individuals with COPD. Nutritional support may therefore be a useful part of their comprehensive care.

PURPOSE

To conduct a meta-analysis of randomized controlled trials (RCTs) to clarify whether nutritional supplementation (caloric supplementation for at least 2 weeks) improved anthropometric measures, pulmonary function, respiratory muscle strength, and functional exercise capacity in patients with stable COPD.

METHODS

RCTs were identified from several sources, including the Cochrane Airways Group register of RCTs, a hand search of abstracts presented at international meetings, and consultation with experts. Two reviewers independently selected trials for inclusion, assessed quality, and extracted the data. Within each trial and for each outcome, we calculated an effect size. The effect sizes were then pooled by a random-effects model. Homogeneity among the effect sizes was also tested.

RESULTS

From 272 references, nine RCTs were ultimately included. Six articles were considered as high quality. Only two studies were double blinded. For each of the outcomes studied, the effect of nutritional support was small: the 95% confidence intervals around the pooled effect sizes all included zero. The effect of nutritional support was homogeneous across studies.

CONCLUSION

Nutritional support had no effect on improving anthropometric measures, lung function, or functional exercise capacity among patients with stable COPD.

Skeletal muscle weakness is associated with wasting of extremity fat-free mass but not with airflow obstruction in patients with chronic obstructive pulmonary disease

BACKGROUND

Skeletal muscle weakness is a prominent problem in many patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVE

The aim of the study was to determine the relation between skeletal muscle function, body composition, and lung function in COPD (emphysema and chronic bronchitis) patients and healthy volunteers.

DESIGN

In 50 patients with chronic bronchitis, 49 patients with emphysema, and 28 healthy volunteers, skeletal muscle function was assessed by handgrip and linear isokinetic dynamometry. Whole-body and subregional fat-free mass (FFM) were assessed by dual-energy X-ray absorptiometry.

RESULTS

Whole-body and extremity FFM were significantly lower in patients with emphysema (P < 0.001) and chronic bronchitis (P < 0.05) than in healthy volunteers, but trunk FFM was significantly lower only in patients with emphysema (P < 0.001). Extremity FFM was not significantly different between the COPD subtype groups, despite significantly lower values for whole-body and trunk FFM (P < 0.05) in patients with emphysema. Absolute skeletal muscle function (P < 0. 001) and muscle function per kilogram of whole-body FFM were significantly lower in both COPD subtype groups than in healthy volunteers (P < 0.05), but no significant difference was found between patients with chronic bronchitis and those with emphysema. Muscle function per kilogram of extremity FFM was not significantly different between the 3 groups and was not associated with forced expiratory volume in 1 s.

CONCLUSION

Skeletal muscle weakness is associated with wasting of extremity FFM in COPD patients, independent of airflow obstruction and COPD subtype.

Characterization of nonresponse to high caloric oral nutritional therapy in depleted patients with chronic obstructive pulmonary disease

Nutritional support can increase body weight and physiologic function in COPD, but there are some patients who do not respond to nutritional therapy. The aim of this prospective study was to describe the nonresponse to 8 wk of oral nutritional supplementation therapy (500 to 750 kcal/d extra), implemented in an inpatient pulmonary rehabilitation program, with respect to lung function, body composition, energy balance, and systemic inflammatory profile in 24 (16 male) depleted patients with COPD. On the basis of the weight change after 8 wk, patients were divided into three groups (Group 1: weight gain < 2% of baseline body weight, n = 5; Group 2: weight gain 2 to 5%, n = 9; Group 3: weight gain >/= 5%, n = 10). Although no differences were seen in lung function and body composition, Group 1 was characterized by older age, a lower baseline dietary intake/resting energy expenditure (REE) ratio, and a greater number of users of continuous supplemental oxygen when compared with Group 3. In addition, Group 1 exhibited higher baseline concentrations of fasting glucose and LPS-binding protein than did Groups 2 and 3. The concentrations of the soluble TNF- receptors 55 and 75 were elevated in Groups 1 and 2 when compared with Group 3. Furthermore, a significant, inverse correlation coefficient between baseline dietary intake and soluble intercellular adhesion molecule was revealed (r = -0.50, p = 0.016). On linear regression analysis, age, baseline intake/REE ratio, sTNF-receptor 55, and extracellular/intracellular water (ECW/ICW) ratio were selected as independent, significant parameters contributing to a total explained variation of 78% in weight change after nutritional therapy. In conclusion, nonresponse to nutritional therapy in COPD is associated with ageing, relative anorexia, and an elevated systemic inflammatory response. Further research is needed to investigate whether these factors contribute to eventual disturbances in intermediary metabolism as reflected by the increased glucose concentration and ECW/ICW ratio.

Nutrition in chronic obstructive pulmonary disease

Weight loss is a frequently occurring complication in patients with chronic obstructive pulmonary disease (COPD) and is a determining factor of functional capacity, health status, and mortality. Weight loss in COPD is a consequence of increased energy requirements unbalanced by dietary intake. Both metabolic and mechanical inefficiency contribute to the elevated energy expenditure. A disbalance between protein synthesis and protein breakdown may cause a disproportionate depletion of fat-free mass in some patients. Nutritional support is indicated for depleted patients with COPD because it provides not only supportive care, but direct intervention through improvement in respiratory and peripheral skeletal muscle function and in exercise performance. A combination of oral nutritional supplements and exercise or anabolic stimulus appears to be the best treatment approach to obtaining significant functional improvement. Patients responding to this treatment even demonstrated a decreased mortality. Poor response was related to the effects of systemic inflammation on dietary intake and catabolism. The effectiveness of anticatabolic modulation requires further investigation.

The impact of nutritional status on the outcome of lung volume reduction surgery: a prospective study

OBJECTIVES

To study the incidence and clinical significance of nutritional deficiencies in patients with emphysema undergoing lung volume reduction surgery (LVRS).

DESIGN

Prospective observational study.

SETTING

University-based teaching hospital.

PATIENTS

Fifty-one consecutive patients with end-stage emphysema undergoing video-assisted thoracoscopic surgery for LVRS.

INTERVENTIONS

All patients had their body mass index (BMI) and serum nutritional indexes (albumin, transferrin, total protein, cholesterol) measured preoperatively and postoperatively. Various clinical parameters were also compared between two groups.

RESULTS

The BMI was normal in 24 patients (47%), and 27 patients (53%) had a below normal BMI. A preoperative analysis of the serum nutritional indexes revealed no clinically significant differences between the two groups, but postoperative levels were significantly lower in the low BMI group. Anthropometric measurements supported the designation of nutritional status by BMI. Clinically, 26% of the patients in the low BMI group required prolonged ventilatory support (> 24 h), compared to only 4% of the patients with a normal BMI. The hospital length of stay (LOS) also differed, averaging 15.9 days in the low BMI group, compared to an average of 11.8 days in the normal BMI group.

CONCLUSION

Approximately 50% of patients undergoing LVRS for emphysema have a deficient nutritional status identifiable by BMI, but not by standard nutritional indexes. This impaired nutritional status is associated with increased morbidity following LVRS. We suggest that BMI is an accurate determinant of nutritional status in this patient population, and we speculate that preoperative repletion of nutritional deficiencies may decrease hospital morbidity, hospital LOS, and overall costs in the malnourished population undergoing LVRS.

The pulmonary cachexia syndrome: aspects of energy balance

The present paper reviews current knowledge of the pulmonary cachexia syndrome with reference to chronic obstructive pulmonary disease (COPD). Aspects of incidence, aetiology and management are discussed. Malnutrition occurs in approximately one-quarter to one-third of patients with moderate to severe COPD. Both fat mass and fat-free mass become depleted. Loss of fat-free mass is the more important and appears to be due to a depression of protein synthesis. Weight loss is an independent prognostic indicator of mortality, and is associated with increased morbidity and decreased health-related quality of life. The aetiology of malnutrition in COPD is not well understood. Reduced food intake does not seem to be the primary cause. Resting energy expenditure (REE) is elevated in a proportion of patients and probably contributes to negative energy balance. Measurement of actual REE is helpful when considering the adequacy of nutritional supplementation. The underlying reason for a hypermetabolic state is not known. Although weight-losing COPD patients are not catabolic, nutritional supplementation alone does not appear to reverse the loss of fat-free mass. Strategies involving nutritional supplementation in combination with a second intervention are being explored, and there are some encouraging results using anabolic hormones.

Circulating leptin in patients with chronic obstructive pulmonary disease

Unexplained weight loss is common in patients with chronic obstructive pulmonary disease (COPD). Since leptin, an obesity gene product, is known to play important roles in the control of body weight and energy expenditure, we investigated serum leptin levels, along with circulating tumor necrosis factor-alpha (TNF-alpha) and soluble TNF receptor (sTNF-R55 and -R75) levels, in 31 patients with COPD and 15 age-matched healthy controls. The body mass index (BMI) and percent body fat (%fat) were significantly lower in the COPD patients than in the healthy controls (BMI = 18.1 +/- 2.7 kg/m2 versus 22.8 +/- 2.2 kg/m2 [mean +/- SD]; p < 0.0001; %fat = 16.9 +/- 5.8% versus 24.3 +/- 4.9%; p < 0.001). Serum leptin levels were significantly lower in the COPD patients than in the healthy controls (1.14 +/- 1.17 ng/ml versus 2.47 +/- 2.01 ng/ml; p < 0.05). In contrast, serum TNF-alpha levels (6.59 +/- 1.92 pg/ml versus 5.41 +/- 1.60 pg/ml; p < 0.05), plasma sTNF-R55 (1.16 +/- 0.47 ng/ml versus 0.67 +/- 0.13 ng/ml; p < 0.0001) and sTNF-R75 (3.65 +/- 1.29 ng/ml versus 2.25 +/- 0.43 ng/ml; p < 0.0001) levels were significantly higher in the COPD patients than in the healthy controls. Importantly, circulating leptin levels (log transformed) did correlate well with BMI and %fat, but not with TNF-alpha or with sTNF-R levels in the COPD patients. These data suggest that circulating leptin is independent of the TNF-alpha system and is regulated physiologically even in the presence of cachexia in patients with COPD.

Plasma and muscle amino acid levels in relation to resting energy expenditure and inflammation in stable chronic obstructive pulmonary disease

In patients with chronic obstructive pulmonary disease (COPD), muscle wasting can occur independently of fat loss, suggesting disturbances in protein metabolism. In order to provide more insight in amino-acid (AA) metabolism in patients with stable COPD, we examined arterial plasma and anterior tibialis muscle AA levels, comparing 12 COPD patients with eight age-matched healthy control subjects. We also studied relationships between AA levels, the acute phase response as measured by lipopolysaccharide-binding protein (LBP), and resting energy expenditure (REE). In contrast to findings in acute diseases associated with muscle wasting, we found increased muscle glutamine (GLN) levels in our patient group (mean +/- SEM = 10,782 +/- 770 versus 7,844 +/- 293 micromol/kg wet weight, p < 0. 01). Furthermore, muscle arginine, ornithine, and citrulline were significantly increased in the patient group, whereas glutamic acid was decreased. In plasma, the sum of all AA (SumAA) was decreased in the patient group (2,595 +/- 65 versus 2,894 +/- 66 micromol/L, p < 0.01), largely because of decreased levels of alanine (254 +/- 10 versus 375 +/- 25 micromol/L, p < 0.0001), GLN (580 +/- 17 versus 641 +/- 17 micromol/L, p < 0.05), and glutamic acid (91 +/- 5 versus 130 +/- 10 micromol/L, p < 0.01). LBP levels were increased in COPD patients as compared with controls (11.7 +/- 4.5 versus 8.6 +/- 1.0 mg/L, p < 0.05), and showed a positive correlation with REE (r = 0. 49, p = 0.03), a negative correlation with the SumAA in plasma (r = -0.76, p < 0.0001), and no correlation with muscle AA levels. In conclusion, various disturbances in plasma and muscle AA levels were found in COPD patients. A relationship between the observed decreased plasma AA levels and inflammation was suggested.

Peripheral muscle weakness in patients with chronic obstructive pulmonary disease

Peripheral muscle weakness is commonly found in patients with chronic obstructive pulmonary disease (COPD) and may play a role in reducing exercise capacity. The purposes of this study were to evaluate, in patients with COPD: (1) the relationship between muscle strength and cross-sectional area (CSA), (2) the distribution of peripheral muscle weakness, and (3) the relationship between muscle strength and the severity of lung disease. Thirty-four patients with COPD and 16 normal subjects of similar age and body mass index were evaluated. Compared with normal subjects, the strength of three muscle groups (p < 0.05) and the right thigh muscle CSA, evaluated by computed tomography (83.4 +/- 16.4 versus 109.6 +/- 15.6 cm2, p < 0.0001), were reduced in COPD. The quadriceps strength/thigh muscle CSA ratio was similar for the two groups. The reduction in quadriceps strength was proportionally greater than that of the shoulder girdle muscles (p < 0.05). Similar observations were made whether or not patients had been exposed to systemic corticosteroids in the 6-mo period preceding the study, although there was a tendency for the quadriceps strength/thigh muscle CSA ratio to be lower in patients who had received corticosteroids. In COPD, quadriceps strength and muscle CSA correlated positively with the FEV1 expressed in percentage of predicted value (r = 0.55 and r = 0. 66, respectively, p < 0.0005). In summary, the strength/muscle cross-sectional area ratio was not different between the two groups, suggesting that weakness in COPD is due to muscle atrophy. In COPD, the distribution of peripheral muscle weakness and the correlation between quadriceps strength and the degree of airflow obstruction suggests that chronic inactivity and muscle deconditioning are important factors in the loss in muscle mass and strength.

Weight loss is a reversible factor in the prognosis of chronic obstructive pulmonary disease

The objective of the study was to further unravel the prognostic significance of body weight changes in patients with COPD. Two survival analyses were performed: (1) a retrospective study, including 400 patients with COPD none of whom had received nutritional therapy; (2) a post hoc analysis of a prospective study, including 203 patients with COPD who had participated in a randomized placebo-controlled trial. There was no overlap between the patient groups. Baseline characteristics of all patients were collected on admission to a pulmonary rehabilitation center in stable clinical condition. In the prospective randomized placebo-controlled trial, the physiologic effects of nutritional therapy alone (n = 71) or in combination with anabolic steroid treatment (n = 67) after 8 wk was studied in patients with COPD prestratified into a depleted group and a nondepleted group. Mortality was assessed as overall mortality. The Cox proportional hazards model was used to quantify the relationship between the baseline variables age, sex, spirometry, arterial blood gases, body mass index (BMI), smoking, and subsequent overall mortality. Additionally, the influence of treatment response on mortality was investigated in the prospective study. The retrospective study revealed that low BMI (p < 0.001), age (p < 0.0001) and low PaO2 (p < 0.05) were significant independent predictors of increased mortality. After stratification of the group into BMI quintiles a threshold value of 25 kg/m2 was identified below which the mortality risk was clearly increased. In the prospective study, weight gain (> 2 kg/8 wk) in depleted and nondepleted patients with COPD, as well as increase in maximal inspiratory mouth pressure during the 8-wk treatment, were significant predictors of survival. On Cox regression analysis weight change entered as a time-dependent covariate remained an independent predictor of mortality in addition to all variables that were entered in the retrospective study. The combined results of the two survival analyses provide evidence to support the hypothesis that body weight has an independent effect on survival in COPD. Moreover the negative effect of low body weight can be reversed by appropriate therapy in some of the patients with COPD.

Acute oxygen supplementation does not relieve the impairment of respiratory muscle strength in hypoxemic COPD

STUDY OBJECTIVES

To verify whether hypoxemia affects respiratory muscle strength in the absence of malnutrition and whether such effect, if present, is reversible with an acute oxygen supplementation.

DESIGN

Case series analysis, before-after trial.

SETTING

Outpatient pneumology departments of two university hospitals.

PATIENTS

One hundred twenty patients affected by COPD in stable conditions having actual to ideal body weight ratio of > or =90%.

MEASUREMENTS AND RESULTS

Maximal inspiratory pressure (MIP) was measured at functional residual capacity level in the whole sample of subjects and during oxygen supplementation in 58 patients having a PaO2< or =60 mm Hg when breathing in room air. Predictors of MIP were assessed by a multivariate analysis. MIP values before and after oxygen supplementation were compared by a paired t test. MIP was independently correlated with FVC (p<0.001), PaO2 (p<0.01), and age (p<0.01). In the subgroup of hypoxemic patients, MIP values did not change significantly after oxygen supplementation (3.08+/-1.74 vs 3.03+/-1.91 kPa, t=0.43, not significant).

CONCLUSIONS

Hypoxemia is an important negative correlate of MIP even in well-nourished COPD patients. Its effect is not reversible with an acute oxygen supplementation.

Elevated inosine monophosphate levels in resting muscle of patients with stable chronic obstructive pulmonary disease

In order to investigate disturbances in energy metabolism in resting muscle of patients with stable chronic obstructive pulmonary disease (COPD), concentrations of adenine nucleotides and related compounds were examined comparing 34 COPD patients with eight age-matched healthy control subjects. Biopsies were taken from the anterior tibialis muscle. Special attention was paid to the muscle content of inosine monophosphate (IMP), a deamination product of adenosine monophosphate (AMP), because IMP formation is thought to reflect an imbalance between resynthesis and utilization of adenosine triphosphate (ATP). The absolute concentrations of high-energy phosphate compounds did not differ between patients and control subjects, but the ATP/ADP and the phosphocreatine/creatine ratio were significantly lower in the patients. IMP (detection level = 0.06 mmol/kg dry weight) was detected in 25 of 34 patients versus one of eight control subjects (p = 0.001). Mean (SD) IMP level in these patients was 0.18 (0.14) versus 0.06 mmol/kg dry weight in the one control subject. Based on the presence of detectable levels of muscle IMP, the patient group was divided into two subgroups. In IMP-positive patients, ATP/ADP and phosphocreatine/creatine ratios were significantly lower than in IMP-negative patients. IMP-positive patients were furthermore characterized by a significantly lower DL(CO). The results of this study indicate an imbalance between the utilization and resynthesis of ATP in resting muscle of patients with stable COPD.

Analysis of the metabolic and ventilatory response to self-paced 12-minute treadmill walking in patients with severe chronic obstructive pulmonary disease

BACKGROUND

The 12-minute walking test is frequently used to measure exercise capacity in patients with severe chronic obstructive pulmonary disease. However, the physiological response to this test has been the subject of limited investigation.

METHODS

In this study, the metabolic and ventilatory consequences of a self-paced 12-minute treadmill walking test (WT) were measured in 17 patients with severe chronic obstructive pulmonary disease (FEV1: 40 +/- 9%) and evaluated using the physiological response to symptom-limited cycle ergometry (CE). During exercise testing, heart rate, transcutaneous oxygen saturation, and lactate concentration were measured, and oxygen consumption, carbon dioxide production, tidal volume, and breathing frequency were recorded breath by breath.

RESULTS

After 4 minutes walking, the peak oxygen consumption (VO2) was already 99 +/- 11% of last-minute walking VO2. Walking speed was chosen within 2 minutes and remained stable throughout the test. The WT and CE showed similar (end-) test results for all measurements, except for a higher carbon dioxide production, venous lactate concentration, and respiratory quotient after CE. However, lactate concentration was also significantly increased after WT. Severe and prolonged desaturation was shown during walking in most patients.

CONCLUSIONS

The physiological stress evoked during the WT is close to the stress developed at an incremental symptom-limited test and the relatively high metabolic and ventilatory stress is sustained from at least 4 to 12 minutes during the WT. This study has shown that anaerobic metabolism not only occurs during incremental cycle ergometry, but also during the WT.

Verbal memory impairment in COPD: its mechanisms and clinical relevance

STUDY OBJECTIVES

Identification of mechanisms accounting for verbal memory impairment in patients with severe COPD; assessing the relationship between verbal memory and the overall cognitive performance; verifying if verbal memory impairment affects medication adherence.

DESIGN

Case-comparison study.

SETTING

Outpatient Departments of Pneumology and Neurology, Day Hospital of General Surgery.

PATIENTS

Forty-two COPD ambulatory patients, age 70+/-9.7 years, with hypoxemia and hypercarbia (group A); 27 normal subjects of comparable age and educational level (group B); 31 patients with Alzheimer's disease (group C); and 26 older normal subjects (group D).

MEASUREMENTS AND RESULTS

The overall cognitive function and verbal memory were evaluated by the Mental Deterioration Battery and 14 indexes of verbal memory. Defective retrieval and recognition mechanisms distinguished group A from group B. According to discriminant analysis, verbal memory profile of COPD patients was group specific in 38.1% of cases and conformed to that of group B, C, and D in 19%, 16.7%, and 26.2% of cases, respectively. In COPD patients, both immediate and delayed recall, the strongest determinants of the discriminant function, were significantly correlated with the overall cognitive performance (rho=0.64, p=0.001; rho=0.61, p=0.001, respectively). Poor adherence to medication regimen was significantly associated with abnormal delayed recall score (82.3% vs 36% in subjects with normal delayed recall, p<0.008).

CONCLUSIONS

Decline of verbal memory parallels that of the overall cognitive function in COPD patients and is due to the impairment of both active recall and passive recognition of learned material. It could be an important determinant of the level of medication adherence.

Decreased mechanical efficiency in clinically stable patients with COPD

BACKGROUND

It has recently been reported that total daily energy expenditure (TDE) is increased in patients with chronic obstructive pulmonary disease (COPD) and it was hypothesised that these patients may have a decreased mechanical efficiency during activities. The purpose of the present study was to measure the mechanical efficiency of submaximal leg exercise, and to characterise patients with a potentially low efficiency in terms of body composition, resting energy expenditure, lung function, and symptom limited exercise performance.

METHODS

Metabolic and ventilatory variables were measured breath by breath during submaximal cycle ergometry exercise performed at 50% of symptom limited achieved maximal load in 33 clinically stable patients with COPD (23 men) with forced expiratory volume in one second (FEV1) of 40 (12)% predicted. Net mechanical efficiency was calculated adjusting for resting energy expenditure (REE).

RESULTS

Median mechanical efficiency was 15.5% and ranged from 8.5% to 22.7%. Patients with an extremely low mechanical efficiency (< 17%, n = 21) demonstrated an increased VO2/VE compared with those with a normal efficiency (median difference 4.7 ml/l, p = 0.005) during submaximal exercise. There was no difference between the groups differentiated by mechanical efficiency in blood gas tensions at rest, airflow obstruction, respiratory muscle strength, hyperinflation at rest, resting energy expenditure or body composition. There was a significant difference in total airways resistance (92% predicted, p = 0.03) between the groups differentiated by mechanical efficiency.

CONCLUSIONS

It is concluded that many patients with severe COPD have decreased mechanical efficiency. Furthermore, based on the results of this study it is hypothesised that an increased oxygen cost of breathing during exercise contributes to the decreased mechanical efficiency.

Impact of nutritional support on functional status during an acute exacerbation of chronic obstructive pulmonary disease

The impact of oral nutritional supplementation during an acute exacerbation of COPD on functional status was assessed through measuring change in lung function, strength testing, and general well-being. Subjects hospitalized for an acute exacerbation of COPD (n = 33) were randomized to extra nutritional support or the regular hospital care. They consumed an additional 10 kcal/kg/d. Outcome measures were measured at 2 wk as change scores. Forced vital capacity (% predicted) improved in the treatment group as compared with the control group (+8.7% versus -3.5%, p = 0.015), and change in FEV1 was in the same direction but not significantly different (p = 0.099). There were no changes in handgrip strength or respiratory muscle strength, but there was a trend towards more improvement in the general well-being score (+11.96 versus -10.25, p = 0.066). Almost all subjects were in negative nitrogen balance, indicating muscle wasting. The degree of muscle wasting was strongly correlated with the dose of corticosteroids (r = 0.73, p < 0.005). In conclusion, it is difficult to prevent important muscle wasting in patients with COPD treated with corticosteroids, but some small gains were observed with increased dietary intake.

Nutritional support in advanced lung disease. The pulmonary cachexia syndrome

Patients with advanced lung disease (ALD) demonstrate changes in body composition characteristically manifested by a progressive loss of body weight. The mechanisms of this pulmonary cachexia syndrome are multifactorial, and treatment must be comprehensive in nature. This article addresses our current knowledge regarding the relationship between nutrition and ALD.

Evidence for a relation between metabolic derangements and increased levels of inflammatory mediators in a subgroup of patients with chronic obstructive pulmonary disease

BACKGROUND

An increase in resting energy expenditure (REE) commonly occurs in patients with chronic obstructive pulmonary disease (COPD), the cause of which is as yet unknown. The objective of this study was to assess the relationship between REE, acute phase proteins, and inflammatory mediators in patients with COPD.

METHODS

Thirty patients were studied and 26 healthy age-matched subjects served as controls. REE was measured by indirect calorimetry and adjusted for fat-free mass (FFM) by bioelectrical impedance analysis. Tumour necrosis factor alpha (TNF-alpha), soluble tumour necrosis receptor (sTNF-R)55 and sTNF-R75, interleukin (IL)-6, IL-8, and lipopolysaccharide binding protein (LBP) were measured by ELISA.

RESULTS

Fourteen patients had a normal REE and in 16 it was raised. The mean body mass index and fat mass were significantly lower in the latter but pulmonary function data were similar in the two groups. In the 30 patients with COPD the mean (SD) sTNF-R75 was 1.7 (1.0) ng/ml compared with 1.1 (0.4) ng/ml in the controls; C-reactive protein (CRP) was detectable (> 5 micrograms/ml) in eight patients compared with none of the control subjects, and LBP was 13.2 (7.7) micrograms/ml compared with 8.6 (3.1) micrograms/ml in the controls. The patients with a raised REE had increased mean levels of CRP compared with the patients with a normal REE (median 5.5 micrograms/ml (range 5-193) and < 5 micrograms/ml, respectively); the same was true for LBP (median 12.4 micrograms/ml (range 8.1-39.1) and 9.5 micrograms/ml (range 5.0-16.6), respectively), but sTNF-R55 and R75 and IL-8 were similar in the two groups. Of the 16 patients with a raised REE, the CRP level was increased in eight and normal in eight. In those with an increased level of CRP the FFM was decreased and LBP, IL-8, and sTNF-R55 and R75 were increased compared with those with normal CRP levels.

CONCLUSIONS

A subset of patients with COPD with an increased REE and decreased FFM have increased levels of acute phase reactant proteins and inflammatory cytokines in their serum; these phenomena may be causally related.

[Artificial nutrition in patients with chronic respiratory insufficiency undergoing surgery]

Denutrition is a common finding in patients with chronic respiratory failure (CRF). Preoperative denutrition increases the risk of nosocomial pneumonia and difficulties in weaning from mechanical ventilation. A preoperative nutritional support may have beneficial effects on respiratory muscles performance. However, prospective studies need to be carried out in patients with CRF to substantiate this hypothesis. Postoperative nutritional support is indicated if weaning from the ventilator is expected to require more than several days, in order to preserve the diaphragmatic function. Lipid-enriched nutrition may have a beneficial effect, when energy supply is high, as the resulting decrease in CO2 production may facilitate the weaning from the ventilator. A beneficial effect of branched-chain amino acid-enriched solutions has not been demonstrated in patients with CRF.