Role of diaphragm dysfunction and nutritional status on dyspnea pathogenesis in patients with COPD

Dyspnea is one of the disabling symptoms among COPD patients. The diaphragm is a major muscle of inspiration, and is supposed to play a crucial role in symptoms pathogenesis. The aim of this study was to evaluate the relationship of dyspnea with diaphragm function, exercise capacity, respiratory function, body composition and nutritional status. Forty-seven COPD patients were stratified in two groups according to dyspnea, using modified Medical Research Council Questionnaire (mMRC) as mild (Group-1, mMRC Results show that Group-2 patients had higher prevalence of men and of past smokers, higher CAT, lower FEV1/VC , decreased exercise capacity (i.e. 4MGS p=0.017, and 6MWD , p=0.002), worse MNA (P=0.046) and SGRQ (P=0.001), more respiratory exacerbations (p=0,011) and lower right diaphragm thickening fraction (P=0.011). Multivariate analysis confirmed the association of dyspnea severity with decreased diaphragm thickening fraction (p=0.044). In conclusion, diaphragm dysfunction plays an important role on dyspnea pathogenesis in COPD patients. The evaluation of diaphragm performance together with exercise capacity and nutritional status is important in the multidisciplinary approach and management of COPD.