A patient module (20) is intended for use together with a pressure source (12). The patient module (20) couples the pressure source (12) for flow to a patient interface (14) that can be connected to the airways of a patient. The patient module (20) includes at least one valve device (30), which can be controlled by means of a piezo pump, which acts as a valve drive (34) and can preferably be operated at a high frequency. The at least one valve device (30) acts as an exhalation valve (28).
