The Effects of Airtrapping on Sleep and Breathing in Non Invasive Ventilation (NIV) in COPD

15 COPD patients will be surveyed in this prospective randomized crossover pilot study concerning non invasive ventilation. Patients will be treated over 2 nights in randomized order with Ventimotion2 (Weinmann) with and without Airtrap Control under Polysomnography (PSG) surveillance including transcutaneous pCO2 measurement. The sleep quality is judged by evaluating the PSG and pCO2 values over night. Target parameters are respiratory rate, sleep quality and influence of Airtrap Control on pCO2 values over night.