Reduction in resting energy expenditure following lung volume reduction surgery in subjects with chronic obstructive pulmonary disease

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.

Variations of inflammatory mediators and alpha1-antitrypsin levels after lung volume reduction surgery for emphysema

RATIONALE

In emphysema, chronic inflammation, including protease-antiprotease imbalance, is responsible for declining pulmonary function and progressive cachexia.

OBJECTIVES

To evaluate variations of inflammatory mediators and alpha(1)-antitrypsin levels after lung volume reduction surgery (LVRS) compared with respiratory rehabilitation.

METHODS

A total of 28 patients with moderate to severe emphysema, who underwent video-assisted thoracoscopic LVRS, were compared with 26 similar patients, who refused operation and followed a standardized rehabilitation program, and to a matched healthy group. Respiratory function, body composition, circulating inflammatory mediators, and alpha(1)-antitrypsin levels were evaluated before and 12 months after treatment. Gene expression levels of inflammatory mediators and protease-antiprotease were assessed in emphysematous specimens from 17 operated patients by matching to normal tissue from resection margins.

MEASUREMENTS AND MAIN RESULTS

Significant improvements were only obtained after surgery in respiratory function (FEV(1), +25.2%, P < 0.0001; residual volume [RV], -19.5%, P < 0.0001; diffusing lung capacity for carbon monoxide, +3.3%, P < 0.05) and body composition (fat-free mass, +6.5%, P < 0.01; fat mass, +11.9%, P < 0.01), with decrement of circulating inflammatory mediators (TNF-alpha, -22.2%, P < 0.001; IL-6, -24.5%, P < 0.001; IL-8, -20.0%, P < 0.001) and increment of antiprotease levels (alpha(1)-antitrypsin, +27.0%, P < 0.001). Supportive gene expression analysis demonstrated active inflammation and protease hyperactivity in the resected emphysematous tissue. Reduction of TNF-alpha and IL-6 and increment of alpha(1)-antitrypsin levels significantly correlated with reduction of RV (P = 0.03, P = 0.009, and P = 0.001, respectively), and partially with increment of fat-free mass (P = 0.03, P = 0.02, and P = 0.09, respectively).

CONCLUSIONS

LVRS significantly reduced circulating inflammatory mediators and increased antiprotease levels over respiratory rehabilitation, also improving respiratory function and nutritional status. Correlations of inflammatory mediators and antiprotease levels with RV and, partly, with body composition suggest that elimination of inflammatory emphysematous tissue may explain clinical improvements after surgery.