A flow generator for generating a flow of pressurized breathable gas includes a cylindrical housing and a motor supported in the housing. The motor has a shaft having a first end and a second end opposite the first end. The shaft is generally coincident with an axis of the motor. A first impeller is attached to the first end of the shaft and a second impeller is attached to the second end of the shaft. A stator directs an air flow from the first impeller back towards the motor axis. The housing includes an inlet adjacent the first end of the shaft having an inlet axis generally coincident with the motor axis and at least one outlet between the first and second impellers. The at least one outlet has an outlet axis generally tangential to the motor axis.