Thermogenic effect of bronchodilators in patients with chronic obstructive pulmonary disease

Dietary intake of elderly outpatients with chronic obstructive pulmonary disease

PURPOSE

Chronic obstructive pulmonary disease (COPD) is often associated with malnutrition, which is in turn associated with poor outcomes. Accordingly, in COPD patients adequate nutrition might improve several clinical and functional outcomes. Nevertheless, information about nutrient intake of older populations with COPD is still scanty.

MATERIALS AND METHODS

We analysed data of 523 elderly attending a geriatric ambulatory. Of these, 165 had a diagnosis of COPD, while 358 were control participants, matched for demographic characteristics and free from respiratory diseases. COPD was diagnosed according to the global initiative for chronic obstructive lung disease (GOLD) criteria. The intake of micro and macronutrients was recorded using the European prospective investigation into cancer and nutrition (EPIC) questionnaire. Nutrient intake of COPD patients was compared with that of the control group and with recommended dietary allowances RDA.

RESULTS

COPD patients had a lower energy intake, as compared with control participants (29.4 vs 34.4 kcal/kg of ideal weight; P<.0001), due to reduced intake of carbohydrates and proteins. Accordingly, in the energy intake was lower than recommended in 52% of COPD patients, vs 30% of controls (P<.0001). The intake of calcium, potassium, folate, cholecalciferol, retinol, and thiamine was lower than RDA in over 75% of COPD patients.

CONCLUSIONS

The diet of elderly COPD outpatients does not provide the recommended energy intake, nor does it meet the RDA for many micronutrients. Such deficits are more severe than in age matched non- respiratory subjects.

Bronchodilation improves endurance but not muscular efficiency in chronic obstructive pulmonary disease

We hypothesized that bronchodilator treatment not only improves hyperinflation and endurance capacity but also muscular efficiency in stable chronic obstructive pulmonary disease (COPD). We aimed to demonstrate that tiotropium and salmeterol improve muscular efficiency compared with placebo. Twenty-five COPD patients were studied, including 20 males of mean (standard deviation) age 62 years (7 years) with baseline forced expiratory volume in 1 second of 41% (10%) predicted, and maximal workload of 101 Watt (36 Watt). Subjects were randomized for 6-week treatment with tiotropium 18 μg once daily, salmeterol 50 μg twice daily, or placebo using a double-blind, crossover design. Muscular efficiency and endurance time were measured during cycling at 50% of maximal work load. Resting energy expenditure was measured using a ventilated hood. Muscular efficiency after tiotropium, salmeterol, and placebo treatment was 14.6%, 14.4%, and 14.4%, respectively (P > 0.05), and resting energy expenditure was 1485 kcal/24 hours, 1709 kcal/24 hours, and 1472 kcal/24 hours (P > 0.05), respectively. Endurance time after tiotropium treatment was significantly higher than that after placebo (27.0 minutes versus 19.3 minutes [P = 0.02]), whereas endurance time after salmeterol treatment was not higher than that after placebo (23.3 minutes [P = 0.22]). In this small study, we were not able to demonstrate that bronchodilator therapy improved muscular efficiency. Apparently, reduced costs of breathing relative to total energy expenditure were too small to be detected.

Energy expenditure and impact of bronchodilators in COPD patients

28 Consecutive COPD patients performed four 6-minute walking tests (6-MWTs) in 2 different days before and 2, 4 and 6h after the inhalation of formoterol 12microg or tiotropium 18microg, respectively. Physical activity during each 6-MWT was assessed by the SenseWear Armband. At each time also spirometry was performed. Both formoterol and tiotropium induced a significantly sustained bronchodilation and influenced hyperinflation. Formoterol significantly increased distance walked in 6min at 2h and at 4h, whereas tiotropium significantly increased it at all time points. There was a trend to an increase in calories and metabolic equivalents of task (METs) after formoterol and a decrease after tiotropium, but changes were not statistically significant. Total energy expenditure for each 6-MWT was not changed by formoterol, but decreased in significant manner 6h after the inhalation of tiotropium. Active energy expenditure at physical activity level of more than 3 METs decreased significantly after tiotropium at each 6-MWT, but not after formoterol. We did not find any significant correlation between the changes in lung function and those of parameters recorded with SenseWear Armband. Our study seems to indicate that tiotropium, but not formoterol, is able to reduce energy expenditure in COPD patients, although both drugs elicit significant bronchodilation and are able to increase the distance walked in 6min.

Body composition and resting energy expenditure in elderly male patients with chronic obstructive pulmonary disease

STUDY OBJECTIVE

Our study investigates nutritional status, resting energy expenditure (REE) and physical performance in elderly patients with stable COPD to identify any early conditions of hypermetabolism, malnutrition and sarcopenia.

METHODS

Eighty-six males (40 stable COPD and 46 healthy subjects) over 65 years old were studied. All subjects underwent spirometry, blood gas analysis and a 6-min walking test (6MWT). Fat-free mass (FFM) and appendicular skeletal muscle mass (ASMM) were measured by dual energy X-ray absorptiometry (DEXA). REE was measured by indirect calorimetry.

RESULTS

COPD patients had a lower FFM both expressed in kilograms and after correction for height squared. The prevalence of sarcopenia was higher for COPD subjects (38% vs 31%). REE, both in absolute values and adjusted for FFM was significantly higher in COPD patients. Hypermetabolism was found in 60% of COPD cases and 13.7% (P<0.01) of healthy subjects. No relationship was found in COPD patients between the measured/predicted REE ratio (REE(m)/REE(p)) and FEV1. In the hypermetabolic COPD subgroup, the REE(m)/REE(p) ratio correlated with 6MWT.

CONCLUSIONS

Elderly patients with stable COPD develop an increased REE. This hypermetabolism seems to be independent of the severity of the pulmonary obstruction and to influence the patient's physical performance.

Effects of montelukast on airway narrowing from eucapnic voluntary hyperventilation and cold air exercise

BACKGROUND

Exercise induced bronchoconstriction (EIB) is common in elite athletes. Eucapnic voluntary hyperventilation (EVH) is a laboratory test recommended for the identification of EIB in athletes, secondary to a field exercise challenge. Montelukast attenuates EIB, but its protective effect against airway narrowing from EVH has not been investigated.

OBJECTIVE

To examine the effectiveness of montelukast after exercise and after EVH.

METHODS

A randomised, placebo controlled, double blind, crossover study was performed with 11 physically active EIB positive subjects (eight men, three women; mean (SD) age 22.8 (6.8) years). Six hours before each of the following challenges 10 mg montelukast or placebo was ingested: (a) a six minute, cold air (-3 degrees C) maximal effort work accumulation cycle ergometer exercise; (b) EVH, breathing 5% CO(2) compressed air at 85% maximal voluntary ventilation for six minutes. Spirometry was performed before and 5, 10, and 15 minutes after the challenge. At least 48 hours was observed between challenges.

RESULTS

No differences in forced expiratory volume in one second (FEV(1)) were found after the two challenges. Exercise and EVH resulted in falls in FEV(1) of 22.4 (18.0) and 25.6 (16.8) respectively. Falls in FEV(1) after montelukast were less than after placebo (10.6 (10.6) and 14.3 (11.3) after exercise and EVH respectively; p<0.05). Montelukast provided protection against bronchoconstriction (59% and 53%; p<0.05) for eight exercising subjects and 10 EVH subjects; no protection was afforded for three exercising and one EVH challenged subject.

CONCLUSIONS

Both exercise and EVH were potent stimuli of airway narrowing. A single dose of montelukast provided reasonable protection in attenuating bronchoconstriction from either exercise or EVH. The similar protection by montelukast suggests that EVH is a suitable laboratory surrogate for EIB evaluation.

Energetic cost of breathing, body composition, and pulmonary function in horses with recurrent airway obstruction

This study was conducted to determine whether horses with naturally occurring, severe chronic recurrent airway obstruction (RAO) 1) have a greater resting energy expenditure (REE) than control horses, 2) suffer body mass depletion, and 3) have significantly decreased REE after bronchodilation and, therefore, also 4) whether increased work of breathing contributes to the cachexia seen in some horses with RAO. Six RAO horses and six control horses underwent indirect calorimetric measures of REE and pulmonary function testing using the esophageal balloon-pneumotachograph method before and after treatment with ipratropium bromide, a parasympatholytic bronchodilator agent, at 4-h intervals for a 24-h period. Body condition scoring was performed, and an estimate of fat mass was determined via B-mode ultrasonography. O2 and CO2 fractions, respiratory airflow, respiratory rate, and pleural pressure changes were recorded, and O2 consumption, CO2 production, REE, pulmonary resistance, dynamic elastance, and tidal volume were calculated. In addition, we performed lung function testing and calorimetry both before and after sedation in two control horses. RAO horses had significantly lower body condition scores (2.8 ± 1.0 vs. 6.4 ± 1.2) and significantly greater O2 consumption than controls (4.93 ± 1.30 vs. 2.93 ± 0.70 ml·kg−1·min−1). After bronchodilation, there was no significant difference in O2 consumption between RAO horses and controls, although there remained evidence of residual airway obstruction. There was a strong correlation between O2 consumption and indexes of airway obstruction. Xylazine sedation was not associated with changes in pulmonary function but did result in markedly decreased REE in controls.

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.

Sympathoadrenal hyperactivity and the etiology of neuroleptic malignant syndrome

OBJECTIVE

The author's goal was to develop a pathophysiological model for neuroleptic malignant syndrome with greater explanatory power than the alternative hypotheses of hypothalamic dopamine antagonism (elevated set point) and direct myotoxicity (malignant hyperthermia variant).

METHOD

Published clinical findings on neuroleptic malignant syndrome were integrated with data from human and animal studies of muscle physiology, thermoregulation, and autonomic nervous system function.

RESULTS

The data show that the sympathetic nervous system's latent capacity for autonomous activity is expressed when tonic inhibitory inputs from higher central nervous system centers are disrupted. These tonic inhibitory inputs are relayed to preganglionic sympathetic neurons by way of dopaminergic hypothalamospinal tracts. The sympathetic nervous system mediates hypothalamic coordination of thermoregulatory activity and is a primary regulator of muscle tone and thermogenesis, augmenting both of these when stimulated. In addition, the sympathetic nervous system modulates all of the other end-organs that function abnormally in neuroleptic malignant syndrome.

CONCLUSIONS

There is substantial evidence to support the hypothesis that dysregulated sympathetic nervous system hyperactivity is responsible for most, if not all, features of neuroleptic malignant syndrome. A predisposition to more extreme sympathetic nervous system activation and/or dysfunction in response to emotional or psychological stress may constitute a trait vulnerability for neuroleptic malignant syndrome, which, when coupled with state variables such as acute psychic distress or dopamine receptor antagonism, produces the clinical syndrome of neuroleptic malignant syndrome. This hypothesis provides a more comprehensive explanation for existing clinical data than do the current alternatives.