Measuring and testing – Volume or rate of flow
Reexamination Certificate
1999-12-09
2001-08-14
Williams, Hezron (Department: 2856)
Measuring and testing
Volume or rate of flow
C073S861010, C073S861020, C073S861030, C073S866500, C128S203160, C128S203170, C128S203260, C128S203270
Reexamination Certificate
active
06272933
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
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.
2. Description of the Prior Art
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 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. It is well known that certain humidity levels are required of gases which are to be administered to a patient. Different humidity values are specifically suitable to intact (for example face mask) or bypassed (intubation delivery of gases) airways. 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 dials adjust the required gases outlet temperature and/or the heating supplied by the heater wire provided within the conduit connecting humidifier to patient (and sometimes also the conduit connecting the patient back to the gases supply). The most important parameter in humidified gases supply to a patient is the humidity of the gases as insufficient humidity can very quickly dehydrate the patient's airways. Accordingly, users have little or no idea where to position the dials to produce the desires result of optimum humidity in the supplied gases at the existing flow rate. An automated system in which the user need only inform the humidification device if the patient receiving the humidified gases has intact or by-passed airways would be a major advance.
Many existing respiratory humidification devices display the gases temperature being supplied to the patient. As previously mentioned, the most important parameter in respiratory humidification systems is the humidity of the gases. 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. It would, therefore, be an advantage if the temperature displayed was in some way related to or indicative of the humidity of the gases being supplied to the patient.
BRIEF SUMMARY OF THE INVENTION
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.
Accordingly, in a first aspect, the invention consists in sensor probe means adapted for positioning in a flow of humidified gases comprising:
sensor housing means adapted for positioning in said gases flow, said sensor housing means having a longitudinal axis substantially perpendicular to said humidified gases flow and a sensing end,
sensing means housed within said sensor housing means at or near said sensing end, and
at least one projecting tab means extending laterally from said sensor housing means, said at least one projecting tab means providing surfaces which enable liquid condensate to disperse away from said sensing end of said sensor housing means.
In a second aspect, the invention consists in humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gases flow to pass through said humidification chamber means,
heating means provided adjacent said humidification chamber means and adapted to provide heat to said quantity of water in said humidification chamber means in order to provide water vapour to said gases flow passing through said humidification chamber means,
gases transportation pathway means connected to said outlet of said humidification chamber means to convey said gases flow to said patient or other person in need of such gases,
flow probe means adapted to sense the flow rate of said gases flow,
temperature sensing means adapted to sense the temperature of said gases flow,
user input means to allow a user to set a required temperature of said gases flow,
control means which receives input from said flow probe means, said temperature sensing means and said user input means and control said heating means in response to said inputs to maintain said gases flow at said required temperature.
In a third aspect, the invention consists in humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gases flow to pass through said humidification chamber means,
heating means provided adjacent said humidification chamber means and adapted to provide heat to said quantity of water in said humidification chamber means in order to provide water vapour to said gases flow passing through said humidification chamber means, said heating means utilising a measurable quantity of power,
gases transportation pathway means connected to said outlet of said humidification chamber means to convey said gases flow to said patient or other person in need of such gases,
flow probe means adapted to sense the flow rate of said gases flow,
control means which receives input from said flow probe means and storing a program which causes the control means to:
i) calculate the power usage required of said heating means in order to humidify said gases flow to a predetermined level at the gases flow rate sensed by said flow probe means,
ii) determine the power presently being utilised by said heating means, and
iii) supply said predetermined level of power to said heating means if the determined present power utilisation of said heating means is less than said required power usage.
In a fourth aspect, the invention consists in humidification apparatus for humidifying a gases flow to be supplied to a patient or other person in need of such gases comprising:
humidification chamber means adapted to hold a quantity of water and having
an inlet and an outlet to allow said gases flow to pass through said humidification chamber means,
heating means provided adjacent said humidification chamber means and adapted to provide heat to said quantity of water in said humidification chamber means in order to provide water vapour to said gases flow passing through said humi
Gradon Lewis George
Leonard Peter John
McPhee Stephen William
Seakins Paul John
Fisher & Paykel Limited
Loo Dennis
Trexler, Bushnell Giangiorgi, Blackstone & Marr, Ltd.
Williams Hezron
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