Patient ventilation device including blower with divided air outlet channels

A respiratory apparatus for treating a patient with a respiratory disorder includes a blower configured to generate a supply of pressurized breathable gas. The blower includes a gas inlet and a gas outlet. The gas outlet is configured to deliver the generated supply of pressurized breathable gas to an outlet of the respiratory apparatus for delivery to the patient. The blower also includes an impeller configured to rotate to generate the supply of pressurized gas. The impeller has a single shroud with a plurality of blades extending from a surface of the shroud in an upstream direction relative to the direction of flow of the pressurized breathable gas. Each of the plurality of blades radiate outwards from a hub in the shroud. The hub is configured to receive a motor shaft. In addition, the outer diameter of the shroud varies between maximum portions with a maximum outer diameter and minimum portions with a minimum outer diameter.