This invention relates to a breathing sensing device, comprising a diaphragm (100) having a first pressure chamber (120) on one side and a second pressure chamber (121) on a second side, wherein said first and second pressure chambers (120, 121) are connected to a system pressure (L1) by means of flow passages (143, 153) having different cross sectional passage area (Ar, Af) arranged to facilitate detection of a pressure drop due to breathing, wherein the relation of cross sectional passage area between the cross sectional passage area (Ar) providing a restricted flow passages (143) to and/or from the second pressure chamber (121) is in the range of 1/50- 1/200 in relation to the cross sectional passage area (A f) providing a flow passage to and/or from the first pressure chamber (120).
