A transfer unit (20), for a ventilator (1), is provided for carrying out a ventilation process of a patient. A ventilator (1) for carrying out a ventilation process of a patient, is provided that includes a ventilation unit (10) with a pneumatic unit (16) for carrying out the ventilation process as well as the transfer unit (20) mounted reversibly at the ventilation unit (10). A ventilation system (100) for carrying out a ventilation process of a patient, is provided including a transfer unit (20) and at least two ventilation units (10). A process for changing a ventilator (1) is provided for the ventilation process of a patient, wherein the transfer unit (20) can be mounted in the ventilation system (100) at a first ventilation unit (10) for forming a first ventilator (1) and at a second ventilation unit (10) for forming a second ventilator (1).
