Objective: This study describes the prevalence and characteristics of an elevated resting energy expenditure (REE) in patients with chronic obstructive pulmonary disease (COPD). Design and setting: Patients were consecutively admitted to an in-patient pulmonary rehabilitation centre. Subjects: The study group consisted of 172 (123<) clinically stable patients with COPD, age mean (s.d. ) 64 (10) y). Interventions: REE was assessed by indirect calorimetry (ventilated hood) and adjusted for the in¯uence of fatfree mass (FFM; measured by bioelectrical impedance analysis) using the linear regression equations of REE on FFM generated in 92 healthy age-matched subjects (58<, age 67 (8) y) for men and women separately. The predicted REE adjusted for FFM (REEFFM) was obtained by using the FFM of each individual patient in the linear regression equation of REE on FFM generated in the healthy control group. Results: 26% of the patients were hypermetabolic (de®ned as REE b 110% REEFFM), characterized by a lower age (60 (10) vs 65 (9) y) and a lower total lung capacity (TLC; 122 (27) vs 139 (28)%pred) compared to normometabolic patients (P`0.001). The prevalence of FFM-depletion was equal among normo-and hypermetabolic patients: 36% vs 33% respectively. Depleted patients expressed however a signi®cantly higher residual volume/TLC ratio and a lower maximal inspiratory mouth pressure independently of hypermetabolism (P`0.05). In contrast, on base of the Harris & Benedict (HB) prediction equations, which do not take body composition into account, 54% of the patients were hypermetabolic (REE b 110% REEHB), characterized by a higher age and a lower body mass and FFM (P`0.05). Conclusions: Hypermetabolism commonly occurs in COPD, characterized by less hyperin¯ation at rest, in contrast to the suggested contribution of an elevated oxygen cost of breathing (OCB) to hypermetabolism in COPD. The higher hyperin¯ation at rest in FFM-depleted patients independently of hypermetabolism suggests a higher OCB during activities, contributing to the elevated total daily energy expenditure previously reported in COPD. The HB-equations overestimate the prevalence of hypermetabolism and link hypermetabolism incorrectly to aging and depletion.

This study investigated the contribution of a single dose of salbutamol by nebulizer to the increased resting energy expenditure (REE) frequently found in patients with chronic obstructive pulmonary disease (COPD) (n = 22), in comparison with a younger (n = 15) and an older healthy (n = 10) control group. The rise in REE after nebulization of 5 mg salbutamol was significantly higher in younger (11.4%) compared to older healthy subjects (5.7%; p < 0.05) and patients with COPD (4.2%; p < 0.001), which also accounted for the increase in heart rate and the drop in the respiratory quotient. No differences in metabolic effects were found between older control subjects and patients with COPD. In conclusion, despite significant improvements in FEV₁ and airway resistance, a significant rise in REE was observed in patients with COPD after nebulization of salbutamol. The metabolic effects of salbutamol were however not sufficient to explain totally the elevated REE seen in these patients.