Patient module for use together with a pressure source , wherein the patient module in terms of flow couples the pressure source to a patient interface that is connectable to the airways of a patient and the patient module is detachably connectable to the patient interface , wherein the patient module comprises at least two valve arrangements with valve drives that are arrangeable outside of the patient module in each case, wherein one of the at least two valve arrangements acts as an expiration valve and one of the valve arrangements acts as an inspiration valve , wherein each valve arrangement comprises a valve drive , a pressure chamber and a control pressure chamber , and the valve drive is fluid-communicatively connected to the control pressure chamber for the purposes of producing a control pressure in the control pressure chamber , wherein the control pressure chamber is separated from the pressure chamber by means of a membrane element having a closure element , wherein the closure element can be used to open and close a first opening in the pressure chamber and the closure element is controllable by means of the control pressure via the membrane element , wherein a piezo-pump acts as a valve drive , wherein, in each valve arrangement acting as an inspiration valve , a branch conduit element fluid-communicatively connects a connecting chamber to exactly one of at least two connection conduit elements that open up in the pressure chamber and wherein the valve drive is arranged such that it pumps gas from the connecting chamber into the control pressure chamber or such that it conveys gas from the connecting chamber into the control pressure chamber in such a way that it brings about a pressure increase in the control pressure chamber. wherein the patient module in terms of flow couples the pressure source to a patient interface that is connectable to the airways of a patient and the patient module is detachably connectable to the patient interface , wherein the patient module comprises at least two valve arrangements with valve drives that are arrangeable outside of the patient module in each case, wherein one of the at least two valve arrangements acts as an expiration valve and one of the valve arrangements acts as an inspiration valve , wherein each valve arrangement comprises a valve drive , a pressure chamber and a control pressure chamber , and the valve drive is fluid-communicatively connected to the control pressure chamber for the purposes of producing a control pressure in the control pressure chamber , wherein the control pressure chamber is separated from the pressure chamber by means of a membrane element having a closure element , wherein the closure element can be used to open and close a first opening in the pressure chamber and the closure element is controllable by means of the control pressure via the membrane element , wherein a piezo-pump acts as a valve drive , wherein, in each valve arrangement acting as an inspiration valve , a branch conduit element fluid-communicatively connects a connecting chamber to exactly one of at least two connection conduit elements that open up in the pressure chamber and wherein the valve drive is arranged such that it pumps gas from the connecting chamber into the control pressure chamber or such that it conveys gas from the connecting chamber into the control pressure chamber in such a way that it brings about a pressure increase in the control pressure chamber. <EOS>