Abstract: Systems, apparatus, and methods for providing humidity in a positive airway pressure (PAP) device. In one embodiment, a humidifier is configured to periodically provide vapor to a flow of pressurized gas to produce flows of pressurized gas with added humidity. Each of the flows of pressurized gas with added humidity may be timed to reach a user interface primarily during a first portion of a breath cycle (e.g., during inspiration). Portions of the flow of pressurized gas that reach the user interface during a second portion of the breath cycle (e.g., during expiration) may include little or no added humidity.

Abstract: A system adapted to regulate pressure of a flow of breathable gas generated by a motorized blower fan. The system may include a flow estimation analyzer adapted to receive a speed signal representative of a speed of the fan and estimate a parameter representative of the flow of breathable gas (e.g., a flow rate of the breathable gas). The parameter may be determined by inputting the speed signal into a function (e.g., an equation, matrix, or lookup table), which may be selected from a plurality of predetermined functions. The predetermined function may be selected based upon a specific characteristic of the speed signal as identified at the time of estimation of the parameter representative of flow.