Left ventricular failure (LVF) is a common cause of acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

This association is frequently underestimated with regard to the difficulty of clinical diagnosis .

The investigators expect that Valsalva Maneuver (VM) could be useful in this issue.

Inclusion Criteria

• We included in this group, patients with a history (previous history) of COPD who consulted the emergency room for an exacerbation of COPD defined by a respiratory rate> 25c/min and a pH <7.35 and a PaCO2 >6 KPa.
• This group is also divided into two groups according to clinical expert assessment and the BNP value: Group1 : BNP> 400pg/ml, Group2 : BNP <400PG / ml

Exclusion Criteria:

• We excluded from this study patients with Prominent cardiac arrest
• Rhythm disorders including severe tachycardia arrhythmia
• Auricular fibrillation
• Hemodynamic instability requiring the use of vasoactive drugs and a contre indications of non invasive ventilation such us consciousness disorders with a Glasgow score <12/15,a swallowing disorder
• A significant bronchial obstruction ,the upper airway obstruction , in upper gastrointestinal bleeding in progress, an extreme obesity and Cirrhosis or cancer.
• We are also excluded patients who did not cooperate and those who refused the study.