An exhalation valve device (22) for a ventilator apparatus for the artificial respiration of patients can be flowed through in an exhalation flow direction (E) and comprises: - an upstream breathing gas duct (54), which extends along a first duct path (K1) and is or can be connected to a section of the exhalation line coming from the patient, - a downstream breathing gas duct (58), which extends along a second duct path (K2) and is or can be connected to a breathing gas sink (U), - a valve assembly (63) having a valve body (64) and a valve seat (66), which valve assembly is provided between the upstream and the downstream breathing gas ducts (54, 58) such that, in the event of a predetermined first breathing gas overpressure in the upstream gas duct (54) relative to the downstream gas duct (58), said valve assembly permits an exhalatory breathing gas flow from the upstream breathing gas duct (54) to the downstream breathing gas duct (58) and, in the event of a predetermined second breathing gas overpressure in the downstream breathing gas duct (58) relative to the upstream breathing gas duct (54), said valve assembly blocks a gas flow from the downstream breathing gas duct (58) to the upstream breathing gas duct (54). According to the invention, the exhalation valve arrangement (22) has a bypass chamber (74) that communicates via flow mechanics with the upstream breathing gas duct (54) and extends from the upstream breathing gas duct (54) to the region of the downstream breathing gas duct (58) and there is designed for coupling a gas pressure sensor (80).
