Patent Application
20200261862
This application claims the benefit of priority under 35 U.S.C. § 119 (a) and (b) to European Patent Application No. 19158351, filed Feb. 20, 2019, the entire contents of which are incorporated herein by reference.
The present invention relates to a gas mixing device or gas mixer that can be used in hospitals or similar healthcare facilities for operating precise deliveries of various gas mixtures, especially when fluidly connected to a medical ventilator or to a gas blender device.
Gas mixtures are commonly used for treating respiratory deficiencies or diseases affecting different populations of patients, or for other purposes, such as alleviating pain, neuroprotection . . . .
Medical gas mixtures typically contain 2 or 3 compounds, such as oxygen, inert gases and/or therapeutically-effective gases. For instance He/O2, Xe/O2, N2O/O2, NO/N2/O2 . . . are known mixtures used in hospitals or the like.
Several technical possibilities exist for generating ternary gas mixtures.
For instance, US-A-2009/0205661 discloses a gas mixer that is fluidly connected to the air inlet of a medical ventilator. This gas mixer comprises three gas lines with flow controllers for providing the gas compounds and generating the desired gas mixture in a pressurized vessel, before delivering it to the ventilator. However, such a gas mixer is not ideal as the gaseous mixture delivered by the mixer depends on the O2 concentration set on the ventilator itself. Hence, when the O2 concentration changes, the gaseous mixture has to vary accordingly and the pressurized vessel has to be flushed, which means that gases are wasted.
Further, a precise mixture cannot always be realized as it closely depends on the ventilator itself, especially on the precision of its internal mixer, which may vary from one ventilator to another.
In other words, making a ternary gaseous mixture that keeps the concentration of a therapeutic gas within tight tolerances, regardless of the conditions of operation, e.g. with or without cooperation with a mechanical ventilator, and for variable oxygen concentrations, is not obvious.
Hence, a problem to be solved is to provide an improved gas mixer that can be used for providing ternary gas mixtures containing a therapeutically-effective gas(es) at a concentration within tight tolerances, including when the oxygen concentration varies, and that can be further fluidly connected to a medical ventilator for providing said ternary gas mixtures to said medical ventilator.
A solution according to the present invention is a gas mixer, also called “gas mixing device”, “gas blender” or the like, comprising:
Depending on the embodiment, the gas mixer according to the present invention can comprise one or several of the following features:
The present invention further concerns a mechanical ventilation system comprising a gas mixer according to the present invention in fluid communication with a mechanical ventilator for providing gas or gas mixtures to said mechanical ventilator, especially an argon-containing gas mixture.
The present invention further concerns a ventilation assembly comprising a gas mixer according to the present invention in fluid communication with a blender device for providing gas or gas mixtures to said blender device, especially an argon-containing gas mixture.
A method for manufacturing a ternary gas mixture comprising:
a) providing a gas mixer according to the present invention,
b) providing a first gas, a second gas and a third gas,
c) mixing the first gas, second gas and third gas into the gas mixer according to the present invention, and
d) recovering at least a ternary gas mixture comprising said first, second and third gases.
Depending on the embodiment, the method according to the present invention can comprise one or several of the following features:
The present invention will be explained in more details in the following illustrative description of an embodiment of a gas mixing device or gas mixer according to the present invention, which is made in references to the accompanying drawings among them:
In
The first port 20b is fluidly connected, via a first inlet section 20, to a first source 20a of a first gas, namely a medical O2 source 20a (O2 in
The second port 30b is fluidly connected, via a second inlet section 30, to a second source 30a of a second gas, namely a therapeutically-effective gas (TH in
The third inlet port 10b is fluidly connected, via a third inlet section 10, to a third source 10a of a third gas, namely a medicinal air source (AIR in
According to the present invention, the first 22 and second 32 lines are fluidly connected to two mixing vessels, namely a first mixing vessel 42 and a second mixing vessel 52, for proving said first and second gases to said first and second mixing vessels 42, 52, whereas the third line 12 is in fluid communication only with the second mixing vessel 52, i.e. it is not fluidly connected to the first mixing vessel 42, for providing the third gas, i.e. medicinal air only to the second mixing vessel 52 (i.e. not to the first one 42).
The gas mixer 1 according to the present invention further comprises different electronic elements, such as pressure regulators, solenoid valves and sensors that are controlled by a control unit 70. Control unit 70 comprises a microprocessor, preferably a microcontroller, for instance it comprises a electronic board with microprocessor(s), memory(ies) . . . .
Control unit 70 further provides electric power to the electronic elements and is able to read and to process the measurements provided by the sensors, typically signals. Control unit 70 also embeds/memorizes conversion lookup tables or the like, for determining a flow measurement based on the nature of the gas being measured, for instance medicinal air, O2 and argon as the therapeutic gas.
Control unit 70 is further in electrical communication, via electric line 71, to a command unit 72 operable by a user, such as a keyboard, a touch screen or the like, for setting the desired concentrations of the different gases in the mixture(s) to be realized in vessels 42 and 52.
Third line 12 comprises, arranged in series, downstream of the third inlet port 10b (i.e. air port), a third solenoid valve 11 and a third pressure regulator 13.
Third solenoid valve 11 is preferably a 2:2 normally closed valve that prevents gas losses in case the gas mixer 1 is not in operation, and shuts down the gas supply in case of failure of the gas mixer 1. In normal operation, control unit 70 opens the third solenoid valve 11.
The third pressure regulator 13 is provided for reducing the pressure of the third gas, e.g. air, delivered by the third gas source 10a. The level of the desired lower pressure depends on the settings of the third pressure regulator 13. For instance, if the pressure of the third gas is of about 3.5 bars abs, the pressure level of the third pressure regulator 13 can be set to a lower pressure of 2.5 bars abs (of course, it could be higher or lower) so that the third gas exhibits said lower pressure downstream of the third pressure regulator 13, in downstream line 141. For instance, the third pressure regulator 13 is an electronic pressure regulator, such as the SPV series from Proportion-Air. The downstream pressure is set by control unit 70 and the third pressure regulator 13 keeps this downstream pressure steady without drift overtime, for instance +/−0.25% with respect to the pressure value.
Third pressure regulator 13 can also indicate to control unit 70 that no or insufficient pressure exists in third line 12. This happens for instance when the third source 10a is not connected to the third inlet port 10b.
The gas traversing the third pressure regulator 13 is recovered in a downstream section 141 of third line 12 that comprises a calibrated orifice 14a, preferably made by precision machining, so that its diameter has very tight tolerances. The gas passing through calibrated orifice 14a, is recovered in another section 142 of third line 12. Calibrated orifice 14a is the main restrictive element of sections 141, 142 so that the flow resistance generated in downstream sections 141,142 is negligible in comparison to the flow resistance generated by calibrated orifice 14a.
Similarly, the first gas line 22 and second line 32 comprise, arranged in series, downstream of the first and second inlet ports 20b, 30b (i.e. the O2 port and the therapeutically-effective gas port), first and second solenoid valves 21, 31 and a first and second pressure regulators 23, 33. Further, here again, downstream sections 24, 34 of the first and second lines 22, 32, respectively, comprise each a calibrated orifice 25a, 35a. Said calibrated orifices 25a, 35a are arranged in downstream sections 24, 34 of first and second lines 22, 32 thereby dividing said downstream sections 24, 34 in sub-portions 251, 252; 351, 352, respectively, as shown in
Those elements of first and second lines 22, 32 are the same or similar, and run or are operated the same way as the corresponding ones that are arranged in the third line 12.
As one can see in
Similarly, the first, second and third lines 22, 32, 12 are in fluid communication with the second mixing vessel 52 via a second common line section 50, such a pipe, conduct or the like.
First and second lines 22, 32 are fluidly connected to the second common line section 50 by, respectively, a first additional line 261 and a second additional line 361. In other words, said first and a second additional lines 261, 361 are branched lines fluidly linking said first 22 and second 32 lines to the second common line section 50 for providing gases to the second mixing vessel 52 and mixing them therein.
The first additional line 261 further comprises a solenoid valve 26b that is a normally open 2:2 valve, which can be closed by control unit 70 if need be. In other words, solenoid valve 26b is controlled by the control unit 70.
The first additional line 261 is terminated by a first end portion 262, whereas the second additional line 361 is terminated by a second end portion 362, said first end portion 262 and second end portion 362 being fluidly connected to downstream section 142 of third line 12 at a second location 50a.
The second additional line 361 further comprises a flow sensor 36b which measures the flow traveling into said second additional line 361. Flow sensor 36b is preferably configured by a lookup table relating to the second gas, such as argon.
The mixer 1 of the present invention is configured for delivering various gas mixtures, especially ternary mixtures, obtained by mixing gases provided by the first, second and third gas sources 20a, 30a, 10a.
For instance, when the mixer 1 is switched on by a user, upon actuation of the solenoid valves 21, 31, 11 by control unit 70, the first, second and third pressure regulators 13, 23, 33 can inform the control unit 70 of the presence of gas sources fluidly connected to the first, second and third ports 20b, 30b, 10b. The solenoid valves 11, 21 and 31 are open when the control unit 70 determined the presence of the gas sources, i.e. when the gases to be mixed are available and provided to the first, second and third ports 20b, 30b, 10b. First and second pressure regulators 23, 33 are set at the same pressure, for instance 2.5 bars, by the control unit 70 so that the gas pressure is the same in all the arranged downstream of said regulators 23, 33, namely in lines 24, 34, 251, 261, 351, 361, as well in calibrated orifices 25a, 35a.
The downstream portions 252, 352 of sub-portions 251, 351 are branched, i.e. connected, at first location 40a, and contain gas at a same pressure. This means that the pressure drops across orifices 25a, 35a are the same. For instance, orifice 25a has an internal diameter of between 0.1 and 3 mm, preferably of about 1 mm, whereas orifice 35a has an inner diameter about 10% larger than the one of orifice 25a. Therefore, the flow spreading into first common line 40 is made of a mixture equivalent to 50% (v/v) Ar and 50% (v/v) O2. This mixture enters into first mixing vessel 42 that is located at the terminal end 40b of first common line 40.
The first mixing vessel 42 has an inner volume typically comprised between 0.1 and 5 L, for example of about 0.5 L, where the gas mixture is stored at a pressure not exceeding the pressure set on pressure regulators 23, 33, e.g. 2.5 bars. First vessel 42 constitutes a mixing chamber for the gases as well as a buffer.
For security reason, an oxygen sensor 41 is arranged in first common line 40, upstream of vessel 42. Oxygen sensor 41 is for example a zirconia based sensor, such as the one referenced KGZ-10 commercialized by the Honeywell, which is designed for operating at pressures up to 3 bar abs. Such an oxygen sensor is linear while operating, meaning that its output is linearly dependent on the oxygen concentration (i.e. from 0 to 100%).
Control unit 70 may rely on the output of oxygen sensor 41 to determine that the gas mixture is correct, e.g. that it contains 50% (v/v) O2, the balance being Ar.
If the measured concentration far differs from 50% (v/v), control unit 70 takes appropriate actions and shut off second solenoid valve 31 to stop the delivery of the therapeutic gas, i.e. argon. Therefore, only O2 from first line 22 is able to travel into first common line section 40 to fill the first mixing vessel 42.
The gas mixture obtained in the first mixing vessel 42 is recovered by a first exit line 43 and delivered by first outlet port 91 located at the end of the first exit line 43.
In the same way, assuming that the third pressure regulator 13 is set at the same pressure than first and second pressure regulators 23, 33, a same gaseous pressure is obtained in downstream line 141 as in downstream portions 261, 361. Further, the downstream line 142 and downstream portions 262, 362, that are branched at second location 50a, also contain a same pressure of gas, i.e. downstream of the calibrated orifices 14a, 26a, 36a, and in the second common line 50.
Calibrated orifices 14a, 26a, 36a are designed so that, for a same pressure drop, and assuming a given volumetric flow (Qar) through calibrated orifice 36a arranged in the second additional line 361, the flow through the first calibrated orifice 26a (i.e. O2) is of about 25% of Qar, whereas the flow through the third calibrated orifice 14a (i.e. air) is of about 75% of Qar. This means that the gas traveling into second common line 50 is a ternary mixture composed of 50% (v/v) Ar, 29% (v/v) N2 (i.e. air) and 21% (v/v) O2.
Second pressure vessel 52 is similar to and works as the first pressure vessel 42, i.e. same volume and gas pressure (e.g. 2.5 bar abs), for mixing the gases and storing them (i.e. buffer). Similarly, another oxygen sensor 51a is located in second common line 50, preferably upstream of vessel 52 for ensuring that the amount of O2 is of at least 21% (v/v).
Further, flow sensors 36b measures the therapeutic gas flow provided by second additional line 361, whereas an additional flow sensor 51b of the second common line 50, measures the total flow of gas circulating in said second common line 50.
Control unit 70 receives the measurement signals from said flow sensors 36b, 51b and, if need be, applies appropriate lookup tables, to determine that the flow measured by flow sensor 51b is twice the flow measured by flow sensor 36b, meaning that the concentration of argon is of 50% (v/v). In other words, based on these measurements, it can be determined that the mixture generated is correct and contains 50% (v/v) Ar, 29% (v/v) N2 and 21% (v/v) O2.
If the measured concentration far differs from 50% (v/v) Ar or 21% (v/v) O2, control unit 70 takes appropriate actions and shut off second solenoid valve 31 to stop the delivery of the therapeutic gas and solenoid valve 26b to stop the delivery of O2 into second common line 50. Consequently, only air can fill the second mixing vessel 52.
The gas mixture obtained in the second mixing vessel 52 is recovered by a second exit line 53 and delivered by second outlet port 92 located at the end of the second exit line 53.
In this embodiment, the first inlet 91A of ventilator 9 receives a mixture of 50% (v/v) Ar and 50% (v/v) O2 at a pressure greater than 2 bars provided by the first outlet orifice 91 of the mixer 1, whereas the second inlet 92A of ventilator 9 receives a mixture of 50% (v/v) Ar, 21% (v/v) O2 and 29% (v/v) N2 provided by the second outlet orifice 92 of the mixer 1.
Further, ventilator 9 is equipped with control means 90, such as a man-machine interface, for instance a keyboard, a touch screen or the like, allowing setting the O2 concentration to be delivered to the patient, i.e. of between 21 and 50 vol. %.
With the mixer 1 of the present invention, various gas mixtures can be made and supplied to ventilator 9, for instance:
Thanks to the mixer 1 of the present invention, the therapeutic gas (e.g. argon) can be precisely delivered to patient 8 regardless of the imprecisions of ventilator 9.
Further, whatever the set O2 concentration, there is no need to flush the mixing vessels 42, 52 as the therapeutic gas concentration remains steady.
Furthermore, the mixer 1 of the present invention can be connected to any type of ventilator 9, e.g. neonatal, adults, transport ventilators.
For some patients, the use of medical ventilator as shown in
This can be done with the gas mixer 1 according to the present invention and a gas blender device as shown in
In this embodiment, the gas outlets 91, 92 of the gas mixer 1 are connected to the inlets 101, 102 of a blender device 10 comprising a rotatable dial 100, an indicator 100a, such as an arrow or any other marking, and O2 concentration scale 100b arranged around the rotatable dial 100.
The position of the indicator 100a, relative to the O2 concentration scale 100b, i.e. O2 concentration range, determines the quantity of gases passing through inlets 101,102.
For instance, indicator 100a pointing to:
Consequently, a continuous flow is delivered to a patient 8, at the right therapeutic level (e.g. 50% (v/v) Ar), independently of the O2 concentration set by dial 100.
Of course, according to another embodiment (not shown), blender device 10 can also be directly integrated into the housing of gas mixer 1.
Generally speaking, an improved gas mixer according to the present invention can be used for providing ternary gas mixtures containing a therapeutically-effective gas(es), such as argon, at a concentration within tight tolerances, including when the oxygen concentration varies, and can be further fluidly connected to a medical ventilator or to a blender device for providing said ternary gas mixtures to said medical ventilator or to said blender device.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19158351.7 | Feb 2019 | EP | regional |
