Patent Application
20140360501
This application claims the benefit of priority under 35 U.S.C. §119 (a) and (b) to French Patent Application No. 1355204, filed Jun. 6, 2013, the entire contents of which are incorporated herein by reference.
The invention concerns a gas pressure measurement system comprising at least one pressure sensor and a protective membrane, in which a flexible intermediate piece ensures the gastightness of the sensor and of its pressure tapping while protecting them from moisture, in particular the moisture coming from the patient gas circuit of a medical ventilation apparatus of a patient comprising a ventilated gas circuit equipped with such a system.
In some medical appliances for measuring gas flow rate, the air going to the patient is humid. However, pressure sensors are very sensitive to humidity.
Moreover, the sensors have a variable geometry, that is to say with shapes and dimensions that may be substantially different from one sensor version to another.
Consequently the problem that is posed is being able to achieve gastightness of the pressure sensor of a patient circuit and to obtain protection thereof against moisture, whatever the sensor used, that is to say whatever its geometry.
In other words, there exists a requirement for a system making it possible to bring gas, such as air, or a gas pressure to the sensor while preventing leakage to the outside and moreover able to protect the sensor from humidity, or even to provide an antibacterial barrier.
Among the existing solutions, some systems are known using several rigid machined or moulded pieces associated with flexible gaskets and/or glue for holding the membrane protecting the sensor.
However, these solutions give rise to drawbacks or lead to other problems such as difficulties in assembly, impossibility of disassembling in the case where glue is used, a risk of forgetting gaskets during assembly, high costs relating to the number of parts and manipulations thereof, a risk of damage to the membrane, which is sometimes very fragile, by one or other of the rigid pieces used, then giving rise to unexpected leakages, a risk of damage to the gasket during assembly, a weak or even insufficient gastight zone, etc.
Other solutions including sensors having their own connection exist.
In this case, it is necessary then to connect the sensors and to the measuring orifices with connection means, such as pipes, connection bodies, etc.
However, these types of sensor are much more imposing. Thus the size thereof may be 10 to 20 times greater than that of conventional sensors, for example around 1 mm for a conventional sensor as against 10 to 20 mm for sensors with inherent connectivity.
This type of sensor therefore poses problems of insertion and of use of this type of sensor in some medical apparatus, in particular of reduced size, and therefore gives rise to an appreciable increase in the size thereof.
In other words, the existing gas pressure measurement systems are not completely without posing certain problems and giving rise to certain drawbacks.
Consequently the stated problem is to propose a system for measuring gas pressure for a medical apparatus that uses a reduced number of parts, is of low cost, presents less risk of leakage, is easy and rapid to assemble, leads to fewer risks of forgetting during assembly, can be dismantled in production and maintenance, gives rise to fewer risks of leakage with damage to gaskets and/or of damaging the fragile membrane or membranes, etc.
The solution is then a gas pressure measurement system comprising at least one gas circuit and at least one pressure sensor arranged so as to be able to measure the pressure of the gas in at least part of the gas circuit, said at least one pressure sensor being protected by a protective membrane permeable to gas, arranged between said at least one pressure sensor and the gas circuit, characterised in that it further comprises a flexible intermediate piece formed by an elastically deformable material arranged between said at least one pressure sensor and the protective membrane, said flexible intermediate piece comprising an internal passage putting the protective membrane and said at least one pressure sensor in fluid communication.
According to circumstances, the gas pressure measurement system of the invention may comprise one or more of the following technical features:
The invention further concerns a patient ventilation apparatus comprising a gas circuit able to convey a gas between a gas source and a patient, characterised in that it further comprises a gas pressure measurement system according to the invention, in particular as described above.
Preferably the gas pressure measurement system is arranged on the gas circuit, preferably in a casing connected fluidically to said gas circuit or to a bypass line of said gas circuit.
The invention will now be better understood by means of the following detailed description given with reference to the accompanying figures, among which:
The patient circuit 10 conveys the gas issuing from the gas source 23 to a patient interface 21, such as a mask, which delivers the gas flow to a patient (not shown).
In order to be able to determine the pressure of the gas in at least part of the patient circuit 10, a gas pressure measurement system, 6, 16 is conventionally used, comprising one or more pressure sensors 6 and at least one electronic card 16 connected to said pressure sensor or sensors 6.
The pressure tapping or tappings 24 of said pressure sensor or sensors 6 communicate fluidically with the patient circuit 10 via one or more orifices 7a.
It is possible for example to use two pressure sensors 6 arranged in series with the membranes 1 and the deformable pieces 8 arranged in dedicated housings 34, 36.
The sensors 6 have their pressure tappings 24 separated from each other by a means for creating pressure drops, such as a passage restriction 35 for example. Such an arrangement makes it possible in particular to make differential pressure measurements. Such an architecture is illustrated in
In order to simplify understanding, the embodiment described below comprises only one pressure sensor 6 but the invention also aims to apply to pressure measurement systems with several sensors 6, in particular with two sensors.
Depending on the embodiment chosen, the pressure sensor or sensors 6 may be arranged so as to be able to measure the pressure of the gas flowing in the gas circuit 10:
In order to protect the or each pressure sensor 6 from contaminants, such as water vapour (moisture), dust, microorganisms etc., liable to be found in the gas flow and/or in the patient circuit 10, the or each sensor 6 is protected by a protective membrane 1 permeable to the gas, arranged upstream of said sensor 6, in a housing or a bypass line making it possible to take a pressure tapping between the gas circuit 10 and the pressure sensor 6.
According to the present invention, as illustrated in
This flexible intermediate piece 8 comprises an internal passage 8a, such as a central passage, putting the protective membrane 1 and the pressure sensor 6 in fluidic communication so as to enable the gas pressure prevailing in the patient circuit 10 to be exerted successively through the membrane 1, in the internal passage 8a and as far as the pressure sensor 6, where the latter can measure it, via the pressure tapping 24 of the sensor 6, which is situated on or in the sensor 6. Here the pressure tapping 24 is an orifice enabling the pressure to enter inside the sensor 6.
As can be seen in
It further comprises an upstream internal recess 8b situated on the same side as the protective membrane 1, and a downstream internal housing 8c situated on the same side as the pressure sensor 6, which are fluidically connected to each other by the internal passage 8a.
Here the upstream internal recess 8b has a frustoconical form, that is to say the inside diameter thereof decreases progressively in the direction of the internal passage 8a.
However, the upstream internal recess 8b may have any other form provided that the fluid is brought to the sensor 6 through the passage 8a, which for its part forms a throttling neck, and the downstream internal housing 8c.
Moreover, concerning the downstream internal housing 8c, it should be emphasised that the sealing may also be done directly on the sensor 6 by modifying the form of said downstream internal housing 8c so as to reduce the volume of this downstream internal housing 8c so that it would form a chamber or a passage in line with the internal passage 8a, a wall expansion 25 of which would project rearwards and would come to bear directly (at 26) around the pressure tapping orifice 24 of the sensor 6 and create therein a gas seal, as illustrated by the particular embodiment in
In the embodiment in
In order to fulfill its function in particular of fluidic seal, the flexible intermediate piece 8 is formed from a polymer or elastomer material, preferably a material of the thermoplastic elastomer type, normally referred to as TPE, or silicone.
In fact, in the embodiment illustrated in
This ensures a fluidic seal between the flexible intermediate piece 8 and the wall 11 carrying the pressure sensor 6, given that the elastic piece 8 deforms slightly in coming to be crushed against the wall 11 (
As shown in
This also provides a fluidic seal between the flexible intermediate piece 8 and the membrane 1. In particular, as illustrated in
In fact, the fluidic seal on the measuring system is provided by compression and deformation of the material of the flexible intermediate piece 8 that is sandwiched and slightly crushed and elastically deformed between the bottom 7c of the casing 7 and the wall 11 carrying the pressure sensor 6, as can be seen in
This deformation and any shapes of revolution such as the fins 17 shown schematically in
This is because, in a particular embodiment, the flexible intermediate piece 8 comprises an external peripheral wall 8d provided with one or more wall expansions 17 projected towards the outside, preferably several wall expansions 17 of revolution arranged in parallel with one another, as shown schematically in
Moreover, the wall 16 carrying the sensor or sensors 6, in particular an electronic card, is fixed by screwing so as to keep the protective membrane 1 and the flexible intermediate piece 8 secured to each other and also to provide a seal.
In fact, the flexible intermediate piece 8 falling within the scope of the present invention makes it possible to press the membrane 1 at the bottom 7c of the casing 7 and/or of a dedicated housing 34, 36, without damaging it, and thus provide a seal between the membrane 1 and the flexible intermediate piece 8 itself, while leaving the possibility for the fluid to pass through the membrane 1 and thus to be filtered.
On the opposite side, the flexible intermediate piece 8 provides a seal at the sensor 6, that is to say in the wall regions 11, 16 surrounding the sensor or sensors 6, that is to say the sensor 6 itself, the support wall or electronic card 16, etc.
Once fitted, the assembly also provides a seal with the outside and provides the pressure, i.e. the gas filtered by the membrane 1, such as air, to the or each pressure sensor 6.
Furthermore, the narrowing constituting all or part of the internal passage 8a of the flexible intermediate piece 8 also guarantees good rigidity of the assembly, which means that the whole of the flexible intermediate piece 8 forms a seal able to maintain an effective contact force on the sealing zones situated on the sides.
More precisely, this casing 7 comprises an internal gas passage 32 forming a part of the gas circuit 10 connecting a gas inlet carried by an inlet connecting piece 30 to a gas outlet carried by an outlet connecting piece 31, between which the respiratory gas delivered by the gas source 23 of the ventilation apparatus 20 flows, supplying a patient via the interface 21 supplied by a flexible pipe forming another part of the gas circuit 10, as illustrated in
In fact, the casing 7 is connected between the apparatus 20 and the flexible pipe 10 as illustrated in
As can be seen in
The deformable pieces 8 for their part are inserted in dedicated housings 34, 36.
Said sensors 6 moreover have their pressure tappings 24 spaced apart from each other while being separated by a pressure-drop creation means, for example a passage restriction 35 placed on the internal gas passage 32, which makes it possible to make differential pressure measurements.
The casing 7 is then closed by a cover 37, as illustrated in
It should be emphasised that the pressure measurements made by the pressure sensor or sensors 6 are processed in a conventional manner by the electronic card 16, in particular by one or more microprocessors or the like.
In all cases, the advantages of a pressure measurement system of an apparatus according to the invention are in particular:
The pressure measurement system and the ventilation apparatus equipped with such a pressure measurement system according to the invention can be used for supplying respiratory gas to patients suffering from respiratory problems, for example those suffering from respiratory pathologies for example of the ARDS or SAS (sleep apnoea) type and/or those that are to observe a treatment of the oxygen therapy or similar type.
It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.
While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.
“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1355204 | Jun 2013 | FR | national |
