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Inventors
Gradon, Lewis George
McPhee, Stephen William
Seakins, Paul John
Leonard, Peter John
Application #
097832
Filed
Jun-16-1998
Published
Feb-26-2002
Current US Class
128/203.17
128/204.17
165/295
236/44A
236/44R
261/129
261/131
261/142
261/DIG65
International Classes
A61M 015/00; A61M 016/00; H05B 003/00
Field of Search
128/203.12 128/203.16 128/203.17 128/203.26 128/204.17 128/204.22 261/129 261/130 261/131 261/142 261/DIG. 219/490 219/494 165/222 165/223 165/229 165/230 165/253 165/281 165/287-290 165/295 236/44 392/460-466
Assignee
Fisher & Paykel Limited (Auckland, NZ)
Examiners
Weiss; John G.
Attorney, Agent or Firm
Trexler, Bushnell, Giangiori, Blackstone & Marr, LTD
US Patent References
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Air humidifiers |
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| 4098853 |
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Humidifier and aut... |
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| 4201204 |
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Breathing gas hum... |
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| 4220460 |
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Vapor delivery syst... |
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| 4276243 |
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Vapor delivery cont... |
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| 4393013 |
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Vapor mass flow co... |
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| 4436674 |
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Vapor mass flow co... |
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| 4589409 |
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Heat and humidifi... |
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| 4618462 |
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Humidifier with co... |
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| 4621632 |
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Humidifier system |
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| 4682010 |
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In-line electric heat... |
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| 4705936 |
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Electronically contr... |
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| 4708831 |
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Methods of and/or... |
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| 4921642 |
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Humidifier module... |
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| 5031612 |
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System and method... |
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| 5097424 |
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Constant flow and c... |
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| 5163423 |
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Humidifier |
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| 5249740 |
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Method for regulati... |
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| 5331995 |
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Flow control system... |
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| 5349946 |
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Microprocessor con... |
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| 5537996 |
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Heated respiratory... |
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| 5640951 |
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Humidifier conduit |
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| 5938984 |
|
Temperature regul... |
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| 6050260 |
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Humidifier sleep a... |
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| 6095505 |
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Patient-end humidi... |
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Referenced by:
View Backward References
Citation
Cite This Patent
More From Subclass DIG65
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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 anaesthetic 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).
Claims
What is claimed is:
1. Humidification apparatus for humidifying a gaseous flow to be supplied to a patient or other person in need of such gaseous flow comprising:
humidificaion chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gaseous 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 vapor to said gaseous flow passing through said humidification chamber means,
gaseous flow transportation pathway means connected to said outlet of said humidification chamber means to convey said gaseous flow to said patient or other person in need of such gaseous flow,
flow probe means adapted to sense the flow rate of said gaseous flow,
probe heating means adapted to heat at least a portion of said flow probe means,
temperature sensing means adapted to sense the temperature of said gaseous flow,
user input means to allow a user to set a required temperature of said gaseous flow,
control means which receives input from said flow probe means, said temperature sensing means and said user input means and controls said heating means in response to said inputs to maintain said gaseous flow at said required temperature.
2. Humidification apparatus as claimed in claim 1 said control means is adapted to determine if the humidification apparatus is in a normal operating condition or if abnormal operation has occurred based on said temperature and/or said flow rate, wherein said normal condition in use relating to whether said temperature and/or said flow rate falling with a predetermined range.
3. Humidification apparatus for humidifying a gaseous flow to be supplied to a patient or other person in need of such gaseous flow comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gaseous flow to pass through said humidification chamber means,
gaseous flow transportation pathway means connected to said outlet of said humidification chamber means to convey said gaseous flow to said patient or other person in need of such gaseous flow,
flow probe means adapted to sense the flow rate of said gaseous flow including sensor housing means adapted for positioning in said gaseous flow, said sensor housing means having a longitudinal axis substantially perpendicular to said humidified gaseous flow and a sensing end, sensing means housed within said sensor housing means at or near said sensing end, and at least two projecting tab means extending laterally from said sensor housing means, oppositely positioned around said sensor housing means and aligned parallel to said gaseous flow, wherein liquid condensate is dispersed along the lines of intersection between said sensor housing means and said at least two tab means away from said sensing end of said sensor housing means, there existing a localized area of low surface tension along said lines of intersection,
temperature sensing means adapted to sense the temperature of said gaseous flow,
user input means to allow a user to set a required temperature of said gaseous flow,
control means which receives input from said flow probe means, said temperature sensing means and said user input means and controls said heating means in response to said inputs to maintain said gaseous flow at said required temperature.
4. Humidification apparatus as claimed in claim 3 wherein said flow probe means comprise two sensor housing means, a temperature sensor housing means and a flow rate sensor housing means, each comprising a temperature dependent resistance,
and wherein said sensing means of said flow rate sensor housing means is occasionally heated to a predetermined difference temperature above the temperature of said gaseous flow, the power required by said sensor means of said flow rate sensor housing means to maintain said predetermined difference temperature providing an indication of the flow rate of said gaseous flow,
and wherein said sensing means of said flow rate sensor housing means is exposed at or near the sensing end of the flow rate sensor housing means up stream of and spaced across said gaseous flow from the sensing means of said temperature sensor housing means is encapsulated at or near the sensing end of the temperature sensor housing means, in order that heat produced by the sensing means of said flow rate sensor housing means does not effect the sensing means of said temperature sensor housing means.
5. Humidification apparatus as claimed in claim 3 wherein said gaseous flow transportation pathway means has a known cross-sectional area, at least in the region adjacent said flow probe means, and is provided with a sensor entry port adapted to receive said flow probe means, said sensor entry port being provided with a fixed locating depression and said flow probe means being provided with a complimentary fixed locating tooth, the positioning of said temperature and flow rate sensor housing means relative to said gaseous flow being controlled by the interconnection of said locating depression and tooth.
6. Humidification apparatus for humidifying a gaseous flow to be supplied to a patient or other person in need of such gaseous flow comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gaseous 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 vapor to said gaseous flow passing through said humidification chamber means, said heating means utilizing a measurable quantity of power,
gaseous flow transportation pathway means connected to said outlet of said humidification chamber means to convey said gaseous flow to said patient or other person in need of such gaseous flow,
flow probe means adapted to sense the flow rate of said gaseous flow,
control means which receives input from said flow probe means and including storage means which is programmed to:
i.) calculate the power usage required of said heating means in order to humidify said gaseous flow to a predetermined level at the gaseous flow rate sensed by said flow probe means,
ii.) determine the power presently being utilized by said heating means, and
iii.) supply said predetermined level of power to said heating means if the determined present power utilization of said heating means is less than said required power usage.
7. Humidification apparatus as claimed in claim 6 wherein said step of calculating the power usage required of said heating means in order to humidify said gaseous flow comprises sensing the present gaseous flow by said flow probe means and searching in a data storage means for a previously stored power value associated with said sensed gaseous flow rate, said data storage means being previously supplied with flow rate and associated power usage values.
8. Humidification apparatus as claimed in claim 6 or claim 7 wherein said step of calculating the power usage required of said heating means in order to humidify said gaseous flow also comprises the steps of calculating the rate of evaporation required in order to attain said predetermined level at the sensed gaseous flow rate and then determining the power required of said heating means to produce the required said rate of evaporation.
9. Humidification apparatus as claimed in claim 6 or claim 7 wherein said humidification apparatus also comprises a temperature sensing means adapted to sense the temperature of said gaseous flow leaving said humidification chamber means and to supply a temperature signal to said control means and said program stored by said control means includes, between said steps (ii) and (iii), the step of:
a) controlling the energization of said heating means in order to maintain said gaseous flow rate exciting said humidification chamber means at a predetermined temperature.
10. Humidification apparatus as claimed in claim 6 or claim 7 wherein said program stored by said control means also comprise the subsequent step of:
i.) sensing the temperature of the gaseous flow leaving the humidification chamber means and returning to step (c) when the sensed temperature is less than said predetermined temperature.
11. Humidification apparatus as claimed in claim 6 or claim 7 wherein said flow probe means comprises:
sensor housing means adapted for positioning in said gaseous flow, said sensor housing means having a longitudinal axis substantially perpendicular to said humidified gaseous flow and a sensing end,
sensing means housed within said sensor housing means at or near said sensing end, and
at least two projecting tab means extending laterally from said sensor housing means, oppositely positioned around said sensor housing means and aligned parallel to said gaseous flow, wherein liquid condensate is dispersed along the lines of intersection between said sensor housing means and said at least two tab means away from said sensing end of said sensor housing means, there existing a localized area of low surface tension along said lines of intersection.
12. Humidification apparatus as claimed in claim 11 wherein said flow probe means comprise two sensor housing means, a temperature sensor housing means and a flow rate sensor housing means, each comprising a temperature dependent resistance,
and wherein said sensing means of said flow rate sensor housing means is occasionally heated to a predetermined difference temperature above the temperature of said gaseous flow, the power required by said sensor means of said flow rate sensor housing means to maintain said predetermined difference temperature providing an indication of the flow rate of said gaseous flow,
and wherein said sensing means of said flow rate sensor housing means is exposed at or near the sensing end of the flow rate sensor housing means up stream of and spaced across said gaseous flow from the sensing means of said temperature sensor housing means is encapsulated at or near the sensing end of the temperature sensor housing means, in order that heat produced by the sensing means of said flow rate sensor housing means does not effect the sensing means of said temperature sensor housing means.
13. Humidification apparatus as claimed in claim 11 wherein said gaseous flow transportation pathway means has a known cross-sectional area, at least in the region adjacent said flow probe means, and is provided with a sensor entry port adapted to receive said flow probe means, said sensor entry port being provided with a fixed locating depression and said flow probe means being provided with a fixed locating depression and said flow probe means being provided with a complimentary fixed locating tooth, the positioning of said temperature and flow rate sensor housing means relative to said gaseous flow being controlled by the interconnection of said locating depression and tooth.
14. Humidification apparatus for humiditying a gaseous flow to be supplied to a patient or other person in need of such gaseous flow comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gaseous 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 vapor to said gaseous flow passing through said humidification chamber means,
gaseous flow transportation pathway means connected to said outlet of said humidification chamber means to convey said gaseous flow to said patient or other person in need of such gaseous flow,
flow probe means adapted to sense the flow rate of said gaseous flow,
temperature sensing means adapted to sense the temperature of said gaseous flow in or adjacent said humidification chamber means,
user input means to allow a user to select a desired gaseous flow humidity level of said gaseous flow configured such that in use said desired gaseous flow humidity level is substantially on delivery to said patient,
data storage means containing information on target gaseous flow temperatures for various gaseous flow rates for a number of humidification chamber outlet means temperatures,
control means configured to receive input from said temperature sensing means and said user input means and configured to repeatedly obtain corresponding target temperature information from said data storage means corresponding to the desired gaseous flow humidity level in relation to said flow rate and configured to vary the heat provided by said heating means until the sensed temperature is substantially equivalent to said target temperature in order to substantially obtain said desired gaseous flow humidity level on delivery to said patient.
15. Humidification apparatus as claimed in claim 14 wherein said gaseous flow transportation pathway means includes a heating wire means adapted to, upon energization to a setting determined by said control means, supply heat to said gaseous flow between said humidification means outlet and said patient or other person in need to such gaseous flow and wherein said control means thereby controls temperature changes in said gaseous flow along said gaseous flow transportation pathway, said control means adjusting said setting of said heating wire to control the temperature of said gaseous flow delivered to said patient or other person in need of such gaseous flow to a user set desired temperature.
16. Humidification apparatus for humidifying a gaseous flow to be supplied to a patient or other person in need of such gaseous flow comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gaseous 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 vapor to said gaseous flow passing through said humidification chamber means,
gaseous flow transportation pathway means connected to said outlet of said humidification chamber means to convey said gaseous flow to said patient or other person in need of such gaseous flow,
flow probe means adapted to sense the flow rate of said gaseous flow,
temperature sensing means adapted to sense the temperature of said gaseous flow,
user input means to allow a user to select a desired gaseous flow humidity level of said gaseous flow,
data storage means containing information on target gaseous flow temperatures at various gaseous flow rates for a number of humidification chamber outlet means temperatures,
control means which receives input from said temperature sensing means and said user input means and using said flow information from said flow probe means repeatedly obtains corresponding target temperature information from said data storage means corresponding to the desired gaseous flow humidity level and varies the heat provided by said heating means until the sensed temperature is substantially equivalent to said target temperature in order to obtain said desired gaseous flow humidity level,
wherein said flow probe means comprising:
sensor housing means adapted for positioning in said gaseous flow, said sensor housing means having a longitudinal axis substantially perpendicular to said humidified gaseous flow and a sensing end,
sensing means housed within said sensor housing means at or near said sensing end, and
at least two projecting tab means extending laterally from said sensor housing means, oppositely positioned around said sensor housing means and aligned parallel to said gaseous flow, wherein liquid condensate is dispersed along the lines of intersection between said sensor housing means and said at least two tab means away from said sensing end of said sensor housing means, there existing a localized area of low surface tension along said lines.
17. Humidification apparatus as claimed in claim 16 wherein said gaseous flow transportation pathway means includes a heating wire means adapted to, upon energization to a setting determined by said control means, supply heat to said gaseous flow between said humidification means outlet and said patient or other person in need to such gaseous flow and wherein said control means thereby controls temperature changes in said gaseous flow along said gaseous flow transportation pathway, said control means adjusting said setting of said heating wire to control the temperature of said gaseous flow delivered to said patient or other person in need of such gaseous flow to a user set desired temperature.
18. Humidification apparatus as claimed in claims 16 or 17 wherein said flow probe means comprise two sensor housing means, a temperature sensor housing means and a flow rate sensor housing means, each comprising a temperature dependent resistance,
and wherein said sensing means of said flow rate sensor housing means is occasionally heated to a predetermined difference temperature above the temperature of said gaseous flow, the power required by said sensor means of said flow rate sensor housing means to maintain said predetermined difference temperature providing an indication of the flow rate of said gaseous flow,
and wherein said sensing means of said flow rate sensor housing means is exposed at or near the sensing end of the flow rate sensor housing means up stream of and spaced across said gaseous flow from the sensing means of said temperature sensor housing means is encapsulated at or near the sensing end of the temperature sensor housing means, in order that heat produced by the sensing means of said flow rate sensor housing means does not effect the sensing means of said temperature sensor housing means.
19. Humidification apparatus as claimed in claims 16 or 17 wherein said gaseous flow transportation pathway means has a known cross-sectional area, at least in the region adjacent said flow probe means, and is provided with a sensor entry port adapted to receive said flow probe means, said sensor entry port being provided with a fixed locating depression and said flow probe means being provided with a complimentary fixed locating tooth, the positioning of said temperature and flow rate sensor housing means relative to said gaseous flow being controlled by the interconnection of said locating depression and tooth.
20. Humidification apparatus for humidifying a gaseous flow to be supplied to a patient or other person in need of such gaseous flow comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gaseous 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 vapor to said gaseous flow passing through said humidification chamber means,
gaseous flow transportation pathway means connected to said outlet of said humidification chamber means to convey said gaseous flow to said patient or other person in need of such gaseous flow,
flow probe means adapted to sense the flow rate of said gaseous flow, and
control means configured to receive input from said flow probe means and configured to compare the sensed flow rate of said gaseous flow with a predetermined minimum required gaseous flow rate and configured to place the humidification apparatus into a safe mode of operation if the sensed rate is less than said predetermined minimum rate, said safe mode including conditional logic which is configured to choose between a predetermined set of actions at least relating to the energization of said heating means.
21. Humidificaion apparatus as claimed in claim 20 wherein said predetermined minimum requried gaseous flow rate is about 1.5 liters per minute.
22. Humidification apparatus as claimed in claim 20 or claim 21 wherein heating plate temperature sensing means are also provided and said set of actions includes said control means energizing said heating means in such a way as to ensure that the temperature of said heating means does not exceed a predetermined maximum temperature.
23. Humidification apparatus as claimed in claim 20 or claim 21 wherein said set of actions includes said control means limiting the power supplied to said heating means to a predetermined maximum level.
24. Humidification apparatus for humidifying a gaseous flow to be supplied to a patient or other person in need of such gaseous flow comprising:
humidification chamber means adapted to hold a quantity of water and having an inlet and an outlet to allow said gaseous 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 vapor to said gaseous flow passing through said humidification chamber means,
gaseous flow transportation pathway means connected to said outlet of said humidification chamber means to convey said gaseous flow to said patient or other person in need of such gaseous flow,
flow probe means adapted to sense the flow rate of said gaseous flow, and
control means which receives input from said flow probe means and compares the sensed flow rate of said gaseous flow with a predetermined minimum required gaseous flow rate and places the humidification apparatus into a safe mode of operation if the sensed rate is less than said predetermined minimum rate
wherein said flow probe means comprises:
sensor housing means adapted for positioning in said gaseous flow, said sensor housing means having a longitudinal axis substantially perpendicular to said humidified gaseous flow and a sensing end,
sensing means housed within said sensor housing means at or near said sensing end, and
at least two projecting tab means extending laterally from said sensor housing means, oppositely positioned around said sensor housing means and aligned parallel to said gaseous flow, wherein liquid condensate is dispersed along the lines of intersection between said sensor housing means and said at least two tab means away from said sensing end of said sensor housing means, there existing a localized area of low surface tension along said lines of intersection.
25. Humidification apparatus as claimed in claim 24 wherein said predetermined minimum required gaseous flow rate is about 1.5 liters per minute.
26. Humidification apparatus as claimed in claim 24 or 25 wherein said flow probe means comprise two sensor housing means, a temperature sensor housing means and a flow rate sensor housing means, each comprising a temperature dependent resistance,
and wherein said sensing means of said flow rate sensor housing means is occasionally heated to a predetermined difference temperature above the temperature of said gaseous flow, the power required by said sensor means of said flow rate sensor housing means to maintain said predetermined difference temperature providing an indication of the flow rate of said gaseous flow,
and wherein said sensing means of said flow rate sensor housing means is exposed at or near the sensing end of the flow rate sensor housing means up stream of and spaced across said gaseous flow from the sensing means of said temperature sensor housing means is encapsulated at or near the sensing end of the temperature sensor housing means, in order that heat produced by the sensing means of said flow rate sensor housing means does not effect the sensing means of said temperature sensor housing means.
27. Humidification apparatus as claimed in claims 24 or 25 wherein said gaseous flow transportation pathway means has a known cross-sectional area, at least in the region adjacent said flow probe means, and is provided with a sensor entry port adapted to receive said flow probe means, said sensor entry port being provided with a fixed locating depression and said flow probe means being provided with a complimentary fixed locating tooth, the positioning of said temperature and flow rate sensor housing means relative to said gaseous flow being controlled by the interconnection of said locating depression and tooth.
Description
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 achived.
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 desired 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 trough 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 controls 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 humdifing 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 humidificaton 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 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 select a desired gases humidity level of said gases flow,
data storage means containing information on target gases temperatures at various gases flow rates for a number of humidification chamber outlet means temperatures,
control means which receives input from said temperature sensing means and said user input means and using said flow information from said flow probe means repeatedly obtains corresponding target temperature information from said data storage means corresponding to the desired gases humidity level and varies the heat provided by said heating means until the sensed temperature is substantially equivalent to said target temperature in order to obtain said desired gases humidity level.
In a fifth 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 which may be in one of a predetermined number of states corresponding to one of a number of gases delivery configurations, each configuration optimally requiring a predetermined gases temperature and humidity level,
control means which receives input from said flow probe means, said temperature sensing means and said user input means and controls said heating means to provide said gases flow to said patient or other person in need of such gases at a temperature and humidity level as indicated by said user input means.
In a sixth 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, said gases transportation pathway means having a patient end, distal to said end connected to said outlet of said humidification chamber means,
first temperature sensing means adapted to sense the temperature of said gases flow substantially at said outlet of said humidification chamber means,
second temperature sensing means adapted to sense the temperature of said gases flow substantially at said patient end of said gases transportation pathway means,
display means adapted to display temperature information to a user,
control means which receives input from said first temperature sensing means and outputs a signal to said display means to cause a temperature to be displayed to the user which is the lower of the temperatures sensed by said first and said second temperature sensing means,
In a seventh 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 tie flow rate of said gases flow, and
control means which receives input from said flow probe means and compares the sensed flow rate of said gases flow with a predetermined minimum required gases flow rate and places the humidification apparatus into a safe mode of operation if the sensed rate is less than said predetermined minimum rate.
In an eighth 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, said gases transportation pathway means having a patient end, distal to said end connected to said outlet of said humidification chamber means,
humidity sensing means which senses the humidity of said gases flow being supplied to said patient,
timer means which may be used to time certain humidification apparatus events,
alarm means which may be energised to provide a warning signal after a predetermined alarm time,
storage means which stores said alarm times for a number of associated sensed humidity values, and
control means which stores a program which causes the control means to:
i) receive input of said sensed humidity value from said humidity sensing means,
ii) obtain from said storage means the alarm time associated with said sensed humidity value,
iii) start said timer means,
iv) wait until the time elapsed by said timer means substantially equals said alarm time and
v) energise said alarm means to provide said warning signal.
In a ninth 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 beat 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,
heating means power utilisation sensing means which monitors the level of power being used by said heating means,
heating means temperature sensing means which senses the temperature of said heating 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, said gases transportation pathway means having a patient end, distal to said end connected to said outlet of said humidification chamber means,
alarm means which may be energised to provide a warning signal after a predetermined alarm time, and
control means which stores a program which causes the control means to:
i) determine a difference temperature by subtracting the gases temperature determined by said gases flow temperature sensing means from the heating means temperature sensed by said heating means temperature sensing means,
ii) determine a power requirement value for the heating means from said heating means power utilisation sensing means,
iii) calculate a thermal conductivity value by dividing said power requirement value by said difference temperature,
iv) energise said alarm means if said calculated thermal conductivity value is less than a predetermined minimun allowable thermal conductivity value.
In a tent 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,
gases transportion pathway heating means which are energisable to supply heat to said gases flow along at least a part of the length of said gases transportation pathway means,
gases temperature sensing means which senses the temperature of said gases flow leaving said humidification chamber means,
user input means to allow a user to enter a required temperature offset value which is the required difference in temperature between the said sensed gases temperature and the temperature of the gases flow delivered to said patient,
control means which stores a program which causes the control means to:
i) determine the gases temperature of the gases leaving said humidification chamber means using said gases temperature sensing means,
ii) receive said offset temperature value from said user input means,
iii) calculate an airway set-point temperature by adding said gases temperature to said offset temperature,
iv) energise said gases sportation pathway heating means to increase the temperature of said gases flow by said offset value along the length of said gases transportation pathway means.
To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention consists in the foregoing and also envisages constructions of which the following gives examples only.
One preferred form of the present invention will now be described with reference to the accompanying drawings in which;
FIG. 1 is a front elevation of a flow probe constructed according to one preferred embodiment of the present invention,
FIG. 2 is a view from below of the flow probe of FIG. 1,
FIG. 3 is a cross-sectional side elevation of a breathing circuit showing the flow probe of FIG. 1 installed within the conduit,
FIG. 4 is a cross-sectional view from below of the breathing circuit of FIG. 3 showing the flow probe of FIG. 1 installed in the conduit,
FIG. 5 is a schematic diagram of a respiratory humidification system incorporating the flow probe of FIG. 1,
FIG. 6 is a flow diagram of one preferred embodiment of a humidity and temperature control system utilised in the respiratory humidification system shown in FIG. 5,
FIG. 7 is a graph of the target outlet temperature required (for a desired humidity level) versus flow rate illustrating one preferred embodiment of a humidity and/or temperature control system utilsed in the respiratory humidification system shown in FIG. 5, and
FIG. 8 is a graph of humidity (or dewpoint) versus time to alarm in an example humidification system such as that shown in FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to the accompanying drawings and in particular to FIG. 5, an example humidification apparatus or respiratory humidification system incorporating preferred embodiments of the present invention is illustrated. Included in the respiratory humidification system is a ventilator or gases supply means or blower 1 having an outlet 2 which supplies gases (for example oxygen, anaesthetic gases or air) to te inlet 3 of a humidification chamber means 4 via a conduit 6. Humidification chamber means 4 may, for example comprise a plastics formed chamber having a metal base 7 sealed thereto. Humidification chamber 4 is adapted to bold a volume of water 8 which is heated by a heater plate means 9 under the control of controller or control means 11 of a humidification device or humidifier 10.
As the water within chamber 4 is heated it will slowly evaporate, mixing water vapour wit the gases flow through the humidification chamber from ventilator 1. Accordingly, humidified gases leave humidification chamber 4 via outlet 12 and are passed to a patient or other person in need of such gases 13 through a gases transportation pathway or inspiratory conduit 14. In order to reduce condensation within the inspiratory conduit 14 and to raise the temperature of the gases provided to the patient 13 a heating wire means 15 may be provided which may be energised under the control of control means 11.
In FIG. 1 a gases mask 16 is shown over the patient's nose and mouth (referred to as "Intact Airways" gases delivery) however it should be understood that many gases delivery configurations exist such as intubation in which a delivery tube is positioned in the patient's trachea to by-pass the patient's airways (known as "Intubated Airways" gases delivery). It is also possible to provide a return path for the patient's exhaled gases back to ventilator 1. In this case a suitable fitting such as a "Y-piece" may be attached between the patient (13), inspiratory conduit (14) and an expiratory conduit (not shown) which is connected to an inlet (not shown) of ventilator 1.
Control means 11 may for example comprise a microprocessor or logic circuit with associated memory or storage means which holds a software program which, when executed by control means 11, controls the operation of the humidification system in accordance with instructions set in the software and also in response to external inputs. For example, control means 11 may be provided with input from heater plate 9 so that control means 11 is provided with information on the temperature and/or power usage of the heater plate 9. In addition, control means 11 could be provided with inputs of temperature of the gases flow, for example a temperature sensing means or temperature probe 17 may be provided at or near the patient to indicate the gases temperature being received by the patient and a further temperature probe 18 may be provided to indicate to control means 11 the temperature of the humidified gases flow as it leaves outlet 12 of humidification chamber 4. Furthermore, a flow sensing means or flow probe 19 may be provided anywhere in the breating circuit ("the breating circuit" comprises the parts of the humidification apparatus through which the gases flow passes). The flow probe 19 is shown in FIG. 5 in the same position as temperature probe 18 as the two devices may both be provided in one probe as will described below.
A still further input to control means 11 may be a user input means or switch 20 which could be used to allow a user (such as a health care professional or the patient themselves) to set a desired gases temperature of gases to be delivered or a desired gases humidity level to be delivered or alternatively other functions could be controlled by switch 20 such as control of the heating delivered by heater wire 15 or selecting from a number of automatic gases delivery configurations (which will be described below).
A number of preferred embodiments of the system (or parts thereof) set out above will now be described in more detail.
Flow Probe
With reference to FIGS. 1 and 2, the preferred form of flow probe 19 is shown. Flow probe 19 is preferably formed by moulding in a plastics material such as polycarbonate and comprises a base por |