Stage 1: Respiratory Physiology. Aim of this Stage is to investigate the effects of nasal High Flow (NHF) therapy in patients in progressed stages of COPD, by measuring physiologic parameters like tidal volume, breathing frequency and expiratory PCO2 concentration.
Stage 2: Efficacy of short term NHF. Aim of this Stage is to evaluate the efficacy of two flow rates (20 L/min and 35 L/min) regarding alveolar ventilation in overnight therapy. For this reason, patients will have two PSG sleep studies during their hospital stay, under 20 L/min and 35 L/min NHF therapy in randomized order.
Stage 3: Home Care monitoring. Aim of this Stage is to compare long term influences of NHF and LOT on PCO2 levels randomised crossover, 4 weeks each treatment.
Stage 4: Long Term Home Care monitoring . Aim of this stage is the long term follow up (12 month) of patients to examine the compliance of a sufficient NHF therapy. Patients will retain the NHF therapy if they are responders (PCO2 improvement in stage 3 of at least 2 mmHG with NHF versus LOT) and willing and able to use NHF and a patient log.
All patients will be monitored for the next 12 month. After 6 month there will be a control phone call.
