Chronic obstructive pulmonary disease is a common respiratory condition that is characterized by inflammation of the large and small peripheral airways , the alveoli and adjacent capillary networks. Severe airflow obstruction that imposes a significant load on the respiratory system is a major manifestation of Chronic obstructive pulmonary disease. The reduced expiratory airflow also causes air trapping at the end of expiration , producing alveolar pressure that are higher than atmospheric pressure before the next breath. This condition is intrinsic positive end-expiratory pressure .

Inclusion Criteria:

• patient with acute exacerbation of Chronic obstructive pulmonary disease and respiratory failure who are intubated and mechanically ventilated.

Exclusion Criteria:

• patient with neuromuscular diseases.
• patient with pulmonary vascular diseases e.g pulmonary embolism.

All patient who diagnosed as chronic obstructive pulmonary disease admitted to the respiratory intensive care unit, chest department, Assiut university hospital, who are mechanically ventilated.