At the start of the study, baseline level for SaO2 and TcPCO2 is recorded, and an arterial blood gas is recorded to calibrate the transcutaneous PCO2 measurement. Thereafter, the registration continues during breathing / blowing until the patient returns to its baseline values. New PEF examination is made after each study arm. At the end of the study we will also measure the effect of 10x3 very deep inspirations and no expiratory no expiratory resistance.