Patent ID: 8640696
Filing Date: 2014-02-04
Classification: A61M

Abstract:
1. A method of determining humidity of gas delivered to a user, the method comprising: providing a pressure support system that includes a gas flow generator and a patient circuit operatively coupled to an outlet of the gas flow generator, wherein the patient circuit is adapted to carry a flow of gas from the pressure support system to an airway of a patient; providing a humidification system that includes a humidification chamber adapted to hold a quantity of fluid, and a heater adapted to heat the fluid in the humidification chamber, wherein the humidification chamber is provided in-line with the patient circuit; measuring a first humidity level of ambient gas outside the patient circuit; providing ambient gas into the patient circuit using the gas flow generator; determining at least one of the pressure or the flow rate within the patient circuit upstream of the humidification chamber; determining a second humidity level of gas within the patient circuit prior to entering the humidification chamber using at least the first humidity level and one or more of the pressure within the patient circuit upstream of the humidification chamber or the flow rate within the patient circuit upstream of the humidification chamber; causing a gas flow from the gas flow generator to pass through at least a portion of the humidification chamber so as to add vapor to the flow in the patient circuit; determining a rate at which the vapor is added to the gas drawn into the patient circuit; and determining a third humidity level of the gas in the patient circuit downstream from the humidifier based on (a) the second humidity level, (b) one or more of the pressure within the patient circuit upstream of the humidification chamber or the flow rate within the patient circuit upstream of the humidification chamber, and (c) a rate at which the vapor is added to the gas drawn into the patient circuit.