Abstract: Shown and described is a user unit (1) for determining output parameters from respiratory gas analyses, particularly for use in spiroergometry devices, with a preferably replaceable breathing tube (2) and a housing part (3), wherein the breathing tube (2), also preferably, can be inserted into the housing part (3) in order to put the user unit into a measuring mode. A provision is made according to the invention that a nose clip (4) connected to the housing part (3) and designed to seal the nose of a user (5) during the determination of the output parameters is provided on the top side of the housing part (3).