Module 2
CPET (MasterScreen CPX®, Vyaire Medical GmbH, Höchberg, Germany) was performed using a standard silicone CPET mask (Hans Rudolph™ mask) on a bicycle ergometer according to current recommendationsBefore each examination (modules 1 and 2), the measuring device was calibrated with the specific mask adapter and the specific dead-space volume (consisting of the volumes of the mask adapter and of the CPET mask) was recorded in the system. However, this dead-space volume was very similar to the dead-space volume of any face mask worn under real-life conditions (modules 3 and 4).