Expiration valve assembly for a respiratory device for artificial ventilation of a patient, comprising - An expiration duct which at one end exhibits an expiration inlet for introducing an expiratory breathing gas flow into the expiration duct and an inlet linkage formation which is configured for linking to an expiration breathing gas line leading to the patient, and which at its other end exhibits an expiration outlet for discharging expiratory breathing gas, where the expiration duct exhibits an expiration valve which through an expiratory breathing gas flow in the expiration direction from the expiration inlet to the expiration outlet is moveable into a feed-through position which lets the expiratory breathing gas flow through, - An inspiration duct which exhibits at one end an inspiration inlet for introducing an inspiratory breathing gas flow into the inspiration duct and an inlet connector formation which is configured for connecting with a breathing gas source supplying inspiratory breathing gas, and which at its other end exhibits an inspiration outlet for letting out inspiratory breathing gas and an outlet connector formation which is configured for connecting with an inspiration breathing gas line leading to the patient, - A control duct which branches off from the inspiration duct at a branching point and leads to the expiration valve in such a way that the expiration valve can be strained by inspiratory breathing gas into a blocking position which blocks the expiratory breathing gas flow, Characterized in that in the inspiration duct there is arranged a one-way valve (60, 60') which allows inspiratory breathing gas flow in the inspiration direction from the inspiration inlet to the inspiration outlet and prevents breathing gas flow in the opposite direction. - An expiration duct which at one end exhibits an expiration inlet for introducing an expiratory breathing gas flow into the expiration duct and an inlet linkage formation which is configured for linking to an expiration breathing gas line leading to the patient, and which at its other end exhibits an expiration outlet for discharging expiratory breathing gas, where the expiration duct exhibits an expiration valve which through an expiratory breathing gas flow in the expiration direction from the expiration inlet to the expiration outlet is moveable into a feed-through position which lets the expiratory breathing gas flow through, - An inspiration duct which exhibits at one end an inspiration inlet for introducing an inspiratory breathing gas flow into the inspiration duct and an inlet connector formation which is configured for connecting with a breathing gas source supplying inspiratory breathing gas, and which at its other end exhibits an inspiration outlet for letting out inspiratory breathing gas and an outlet connector formation which is configured for connecting with an inspiration breathing gas line leading to the patient, - A control duct which branches off from the inspiration duct at a branching point and leads to the expiration valve in such a way that the expiration valve can be strained by inspiratory breathing gas into a blocking position which blocks the expiratory breathing gas flow,