The main objective of the study is to evaluate the predictive factors of the endothelial function to the waning of an acute exacerbation in COPD. It will act to do a multivariate analysis to determine the respective weight of the parameters of the systemic inflammation, of the oxidative stress of the functional respiratory parameters and then functional respiratory parameters.

In exacerbated Chronic Obstructive Pulmonary Disease (COPD) patients, there is augmentation of hypoxia and the obstructive ventilatory disorders is more important. This is correlated with an increase in C-reactive Protein (CRP) and of inflammatory cytokines and oxidative stress. It has been demonstrated that there is an endothelial dysfunction in answer to hypoxia. Since the exacerbated COPD patients are hypoxic in most cases , we suppose they have an endothelial dysfunction during exacerbation. So we think we will find an augmentation of vascular resistances ,shown by a peripheral arterial tone too high. And this, certainly, play a part in physiopathology of the COPD exacerbation.

We want to judge the improvement of the endothelial function remotely to the acute exacerbation (6 weeks). And then we would like to correlate this improvement with the variations of oxidative stress, muscle strength, respiratory function and systemic inflammation.

We also would like to find a relation between the new hospitalizations for respiratory exacerbation and the initial value of endothelial function.

Then we would like to evaluate the relationship between the cardiovascular risk and the COPD severity.

Inclusion Criteria:

• COPD patients with the waning of exacerbation:
• Male or Female more than 18 years old
• VEF1/FCV < 70% or COPD already knew
• At the moment of the respiratory failure, the day of the enter in hospital:
• Respiratory frequency >25
• PaCO2 > 45 mmHg
• pH < 7.35
• The day of the inclusion in our study:
• PH > 7.33 at the end of the respiratory failure, or 2 days of continuation, 3 to 7 days post acute exacerbation of continuation
• Fever < 38.5
• Patients who have signed the inform consent form
• Stable COPD patients:
• Men or women more than 18 years old
• VEF1/FCV < 70% or COPD already knew
• Patients who have signed the inform consent form

Exclusion Criteria:

• Evolutive obvious infection or CRP > 100 at inclusion Cardiac failure considered like the major cause of the exacerbation or cardiac insufficiency with FEVG < 45 %
• Smoker > 10 cigarettes a day Antioxidant catch: N-acetyl-cystein, selenium, ascorbic acid, alpha tocopherol acetate…
• Evolutive neoplasia
• Antioxidant catch: N-acetyl-cystein, selenium, ascorbic acid, alpha tocopherol acetate…
• pregnant women
• patient under supervision or trusteeship
• patient taking part in another clinical trial
• claustrophobia, patients allergic to contrast agents like Gadolinium, presence of material dissuading the realization of a MRI (pacemaker, implantable defibrillator, insulin pump, ferrometallic clips or foreign bodies in brain or eyes)

Patients with exacerbated (50) or stable (195) COPD