I: Evaluation of inspiratory fractions of oxygen and endtidal levels of carbon dioxide achieved during continuous supply of oxygen at 1, 2, 3, and 5 L/min by STAIRWAY versus by nasal cannula without STAIRWAY in awake spontaneously breathing healthy volunteer study participants
II: Physiological evaluation of respiratory conditions by continuous volume, flow, pressure, and concentration measurements with STAIRWAY versus biteblock, at defined light, moderate and deep levels of steady-state sedation with propofol in spontaneously breathing healthy volunteer study participants
III: Determination of upper airway volumes by magnetic resonance tomography imaging with STAIRWAY versus no STAIRWAY versus biteblock, at defined light, moderate and deep levels of steady-state sedation with propofol in spontaneously breathing healthy volunteer study participants
IV: Use of manual measures for airway patency, and signs of respiratory depression, with STAIRWAY versus no STAIRWAY during procedural sedation according to standard of care in spontaneously breathing study patients subjected to scheduled ureteral catheterization
V: Use of manual measures for airway patency, and signs of respiratory depression, with STAIRWAY versus no STAIRWAY during scheduled procedural sedation according to standard of care in spontaneously breathing study patients subjected to scheduled colonoscopy