Continuous Positive Airway Pressure Effect on Air Trapping in Chronic Obstructive Pulmonary Disease Patients

Continuous positive airways pressure which prevent small air ways collapse and may also clear secretions. At first stage the optimal pressure for reducing air trapping will be determined. In addition, all patients will undergo a maximal exercise test. A baseline complete pulmonary function test is performed followed by continuous positive air way pressure at the pre-determined pressure. This will be followed by exercise at 60% of maximal obtained previously.