Determinants of Lower Limb Muscle Atrophy Induced During an Hospitalization for Exacerbation of COPD

Chronic Obstructive Pulmonary Disease (COPD) is characterized by persistent airway obstruction and inflammatory response of the lungs and bronchi. Episodes of exacerbations contribute to increase the severity and prognosis of the disease. Muscle dysfunction (loss of strength and muscle mass) is one of comorbidities affecting 30% to 60% of patients and playing a key role in their prognosis. Indeed, several studies have shown muscle weakness during hospitalization for exacerbation of COPD by measure of maximal voluntary contraction of quadriceps (MVCQ), but the results are variable from one patient to another. Moreover, no study was interested in the change of muscle mass in patients hospitalized for an exacerbation of COPD. Several mechanisms have been mentioned but not demonstrated: systemics factors (initial amyotrophy, inflammation, oxidative stress, corticotherapy, hypoxia...) but also physical inactivity. In this context, identifying factors associated with the onset of muscle weakness during hospitalization for exacerbation of COPD is a necessary step to better understand the mechanisms and consider a personalized therapeutic approach that can improve the functional and clinical prognosis of disease.

The primary outcome is to identify the clinical and biological determinants associated with the onset of amyotrophy (Measure by ultrasound of sectional area of the Rectus Femoris, CSARF), during hospitalization for exacerbation of COPD. The secondary outcome is to identify the clinical and biological determinants associated with the onset of MVCQ decrease, during hospitalization for exacerbation of COPD.

120 patients hospitalized for exacerbation of COPD will be recruited in two hospitals (CHU Montpellier - CHU Grenoble, FRANCE). The measures of CSARF and MVCQ are carried out on the second, fifth, eighth day of hospitalization, on discharge and on the sixtieth day after hospitalization. A blood test will be performed on the second day of hospitalization to explore different markers of inflammation and oxydative stress. Moreover, to quantify the level of physical activity (number of steps), each patient will carry a pedometer throughout the duration of hospitalization.

At the end of protocol, two groups will be made from the median of CSARF : patients with a small reduction in CSARF compared to patients with a greater reduction in SSRF between the second and eighth days of hospitalization (or between the second day of hospitalization and discharge). Then clinical (comorbidities, severity disease, initial weakness, initial amyotrophy, usual physical activity before hospitalization, treatment, exacerbation number in the previous year...) and biological (markers of inflammation and oxydative stress) determinants were compared between the two groups.

Thus, the identification of the determinants associated with the onset of amyotrophy induced during exacerbation of COPD will guide research for exploration of physiopathological mechanisms of this muscular dysfunction in the exacerbation of COPD as well as to identify a personalized support.