Analysis of water vapor content in a ventilator.
For medical reasons, a humidifier is sometimes used to add moisture and heat to the air supplied by a ventilator to a patient. However, for a fixed mass of water vapor inside a container, the relative humidity of the air inside the container actually goes down when the temperature of the air is increased, since the saturated vapor pressure of water increases with temperature. Hence, for a type of humidifier that is designed to add only a small amount of water vapor to the patient's air intake, the increase in water vapor due to the humidifier may be hard to substantiate. This article presents one method of verifying that the amount of water in the patient circuit has been increased by the humidifier when the air temperature is also increased. An example will be included to illustrate this method.
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Center for Devices and Radiological Health, U.S. Food and Drug Administration, 9200 Corporate Blvd., HFZ-450, Rockville, MD 20850, USA.
D006801:Humans; D006813:Humidity; D008168:Lung / Q000502:physiology; D008954:Models, Biological; D008961:Models, Structural; D013696:Temperature; D012122:Ventilators, Mechanical; D014835:Volatilization; D014867:Water
D014867:Water