Respiratory humidification system

Abstract

A flow probe for use in a humidification system is disclosed. The flow probe is adapted to be positioned in a humidified gases flow (for example oxygen or anesthetic gases) such as that which is provided to a patient in a hospital environment. The flow probe is designed to provide both temperature and flow rate sensing of the gases flow by incorporating two sensors (preferably thermistors) and the shape and alignment of the probe enables accurate readings by reducing the occurrence of condensation on the sensors. A number of possible applications are disclosed wherein the flow sensor is included in humidification control systems which provide a patient with a desired humidity level or simplify the amount of user input required or wherein the flow sensor provides a controller with flow information which may then be used to determine certain, possibly dangerous, conditions (such as incorrect flow sensor placement, breathing circuit disconnected, no water in the humidification chamber or humidity out of required limits).

Description

[0001]This is a divisional of copending application Ser. No. 09 / 097,832 filed Jun. 16, 1998.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to gases distribution systems and in particular, though not solely, to respiratory humidifier systems which humidify gases for a patient, or other person in need of such gases, to breathe.[0004]2. Description of the Prior Art[0005]Many, if not all, existing respiratory humidification systems which deliver humidified gases (such as oxygen or anaesthetic gases) to a patient, or other person in need of such gases, operate as temperature controllers. That is, the temperature of the gases leaving the humidification device in the breathing circuit is monitored and the heat source controlled in response to changes in that temperature to achieve a desired outgoing humidified gases temperature. An example of this type of humidifier control system is disclosed in our prior U.S. Pat. No. 5,558,084. This method of cont...

AI Technical Summary

Benefits of technology

[0012]It is, therefore, an object of the present invention to provide a respiratory humidifier system which will go at least some way towards overcoming the above disadvantages or which at least provide the industry with a useful choice.

Problems solved by technology

This method of control has a number of disadvantages including:In situations with high incoming gases temperature (approaching the desired outgoing gases temperature) little heat is necessarily supplied to the gases by the humidification process to achieve the required temperature.

Accordingly, little humidification of the gases is also achieved.The dependency on temperature sensors in this control method means that incorrect placement or connection of the temperature sensors can lead to impaired performance of the entire humidification and breathing system.Lack of flow sensors which, if provided, would enable certain breathing circuit conditions to be easily recognised and appropriate action to be taken by the humidification device (and / or the gases supply).

Flow sensors have previously not been utilised in humidification systems due to insufficient robustness and problems of condensation occurring on the flow sensor, leading to incorrect flow readings.Gases being supplied to the patient at a pressure / humidity combination which is inappropriate.

Temperature sensing alone can not ensure that these required temperature / humidity values are achieved.Some existing respiratory humidification devices require users to adjust dials which have little or no intuitive relationship to the actual physical parameters they are intended to control.

Often, the temperature displayed has no relationship to the actual humidity of the gases being supplied to the patient due to heating in the delivery circuit and can therefore be misleading to the average health care professional.

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