closed-circuit breathing gas supply system
Patent Information
- Application Number
- FR2023002149
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-03-08
- Publication Date
- 2025-03-14
- Estimated Expiration
- 2043-03-08
Smart Images
Figure 00000024_0000 
Figure 00000024_0001
Abstract
Description
Title of the invention: Installation for supplying breathing gas in a closed circuit
[0001] The present invention relates to a respiratory gas supply installation, operating in a closed circuit, including a system for recycling the gases exhaled by the patient and a system for controlling the concentration of inhaled oxygen, allowing a supply of an oxygen-enriched gas mixture (O2), typically an air / oxygen mixture, to a patient while minimizing the consumption of oxygen from an oxygen source, such as a pressurized oxygen cylinder, supplying the installation.
[0002] The administration of gaseous O2 makes it possible to correct a hypoxemic situation in a human person, i.e. a patient, regardless of their age, i.e. newborns, children, adolescents, adults, elderly people or others, suffering from a respiratory pathology causing an oxyhemoglobin saturation, measured in the blood, lower than a reference value reflecting a “normal” saturation, for example a saturation lower than 90%, for example a respiratory pathology of the type Chronic Obstructive Pulmonary Disease (COPD), Acute Respiratory Distress Syndrome (ARDS) or other.
[0003] Medical grade oxygen is supplied to the "hypoxic" patient either within a hospital or outside of a hospital, for example in a mobile emergency unit (SAMU, ambulances, etc.) or at the home of the patient in question.
[0004] Depending on the case, the oxygen can come either from a gas pipeline, typically from a hospital fluid network, or from a pressurized gas cylinder containing, for example, 400 to 1000 L of O2 (gaseous vol.) compressed to 200 bar abs or more (measured at 1 atm).
[0005] The flow rate of oxygen delivered by a gas cylinder is adjusted according to the intended indication. In the most acute cases, it may be approximately 15 L / min to ensure a high concentration of inhaled oxygen, i.e. close to 100%, such as in an emergency situation involving drowning or carbon monoxide (CO) poisoning. Other indications require a lower flow rate, for example of the order of 6 L / min, in order to correct milder hypoxemia. As a general rule, a flow rate of 6 L / min is equivalent in an adult to an inhaled oxygen concentration of the order of 40% by volume.
[0006] In all cases, the administration of oxygen, whatever the flow rate, is to allow the oxyhemoglobin saturation to return to the normal value, typically at least approximately 90%.
[0007] For reasons of size and weight, many emergency units, such as those of firefighters, international rescuers or military personnel, prefer to use a source of gaseous oxygen as compact as possible, for example a type B2 cylinder, i.e. a cylinder with an internal volume of 2L (equivalent to water) capable of containing oxygen (O2) compressed to 200 bar (full cylinder), which corresponds to a volume of around 400L of oxygen.
[0008] Now, it is understood that the autonomy conferred by such a bottle, that is to say the time of use before it is empty of gas, varies according to the withdrawal flow rate, which itself depends on the seriousness of the pathology to be treated. Thus, for a flow rate of 6 L / min, the autonomy is approximately 1 h, whereas it is less than 30 minutes for a flow rate of 15 L / min.
[0009] It is then understood that the autonomy may prove insufficient, for example during long-term transport, typically during a medical evacuation from one country to another, or from a remote area, such as during a military operation in an external theater of operations, or even during relief for victims in the event of a major disaster, such as an earthquake or other.
[0010] US-A-2021 / 0121649 proposes a system for supplying gas, i.e. oxygen, in closed circuit consisting of a compressed oxygen cylinder equipped with a gas regulator, tubing feeding a gas tank and a module containing soda lime to purify the gases exhaled by the patient (i.e. victim) by trapping the carbon dioxide (CO2) present therein. He then reinhales his own exhaled gases freed from CO2. Knowing that nearly 95% of the inhaled oxygen is exhaled (i.e. not metabolized), purifying the exhaled gases makes it possible to considerably reduce the flow rate provided by the oxygen source, thus increasing autonomy since the flow rate of metabolized oxygen is less than approximately 1 L / min.
[0011] However, such a system is not ideal because it does not allow the concentration of inhaled oxygen to be controlled. Indeed, in this system, the oxygen cylinder delivers a fixed flow rate higher than the metabolic consumption of the patient, for example at approximately IL / min, which can lead to hyperoxic situations, i.e. to deliver an oxygen concentration that is too high to the patient, i.e. close to 100%. This can then result in harmful physiological consequences for certain patients, such as for example those in cardiac arrest, who are ventilated during cardiac massage until return to spontaneous blood circulation (ROSC).
[0012] A problem is therefore to be able to avoid this type of problem by controlling the concentration of oxygen inhaled by the patient, when using a closed-circuit oxygen supply system. In other words, the invention aims to improve closed-circuit oxygen supply systems, such as that described by US-A-2021 / 0121649.
[0013] A solution according to the invention relates to an installation for supplying respiratory gas to a user, i.e. a patient, comprising: - a gas source to provide breathing gas containing oxygen, - a respiratory interface, - a main gas delivery line fluidly connecting the gas source to the respiratory interface, - a gas recovery line in fluid communication with the respiratory interface, - a gas purification system supplied by the gas recovery line, - a gas recycling line fluidly connecting the gas purification system to the main gas delivery line, - and means of control,
[0014] characterized in that it further comprises: - an oxygen sensor arranged to measure the oxygen concentration within the main gas delivery line and provide the oxygen concentration measurement(s) to the control means, - an intake line fluidly connected to the atmosphere and also to the main gas delivery line between the gas source and the oxygen sensor, - a concentration selection device configured to allow a user, typically a healthcare worker, to select or set a target concentration of inhaled O2 and to supply the selected target concentration of inhaled O2 to the control means, - and a first proportional element arranged on the intake line and controlled by the pilot means to control the air circulation in the intake line.
[0015] Depending on the embodiment considered, the respiratory gas supply installation of the invention may comprise one or more of the following characteristics: - the installation is of the closed circuit type. - the intake line includes a one-way intake valve. - the control means are configured to control the first proportional element, to allow air circulation in the intake line, when the control means determine that at least one measured oxygen concentration measurement is greater than the set or selected target inhaled O2 concentration. - the first proportional element is configured to adopt at least: a. a closed position prohibiting any circulation of air in the intake line, and b. an open position allowing air circulation in the intake line. the control means are configured to control the passage of the first proportional element from the closed position to the open position, or vice versa. the installation further comprises an exhaust line in fluid communication with the gas recovery line and also with the atmosphere. the exhaust line comprises a second proportional element controlled by the control means to control the circulation of gas in the exhaust line. the exhaust line comprises a one-way exhaust valve, the second proportional element is configured to adopt at least: a. a closed position preventing any circulation of gas in the exhaust line, and b. an open position allowing gas to flow into the exhaust line. the control means are configured to control the passage of the second proportional element from the closed position to the open position, or vice versa. the gas recycling line fluidly connects the gas purification system to the main gas supply line, via a buffer tank, the buffer tank is, in addition, fluidly connected to the gas source. the control means comprise at least one microprocessor, that is to say they constitute a control unit with microprocessor(s). the concentration selection device comprises a graphical user interface (GUI). the concentration selection device is integrated into the installation, alternatively, the concentration selection device is independent of the installation. For example, it is a multifunction phone (smartphone), a digital tablet, a laptop or other. the concentration selection device cooperates with the control means. the concentration selection device communicates with the control means. the first proportional element and / or the second proportional element comprise at least one proportional solenoid valve or at least one motorized gas supply valve. - the gas source is configured to supply pure oxygen as the breathing gas. - the gas source comprises a compressed oxygen cylinder, i.e. at a pressure of at least 100 bar, preferably at least 150 bar (absolute bar), i.e. pressure measured when the cylinder is full of gas. - the respiratory interface is configured to administer the respiratory gas to the user, during each inspiratory phase of said user. - the main gas delivery line is configured to deliver breathing gas from the gas source to the breathing interface. - the gas source comprises a compressed oxygen cylinder equipped with an integrated pressure reducing valve or RDI, i.e. comprising gas pressure reducing means arranged in the valve. - the integrated pressure reducing valve or RDI includes a flow outlet and a pressure outlet. - the integrated pressure reducing valve or RDI includes a flow outlet port and a pressure outlet port. - the flow output port allows different flow rates to be delivered, which can be chosen using a flow selector, typically flow rates between 0 and 15L / min. - the pressure outlet port provides a fixed gas pressure, typically around 4 bar. - the integrated pressure reducing valve or RDI, namely the flow outlet port or, as the case may be, the pressure outlet port of the RDI, is fluidically connected to the buffer tank via a gas supply line, such as a flexible hose or similar. - a gas recovery line is configured to recover and convey at least a portion of the exhaled CO2 / O2 gas mixture found in the respiratory interface, during each expiratory phase of the user. - the main gas supply line includes one or more gas passages or conduits or the like. - the gas purification system is supplied with exhaled CO2 / O2 gas mixture through the gas recovery line. - the gas purification system is configured to remove at least a portion of the CO2 contained in the exhaled CO2 / O2 gas mixture and
[0016] obtain a purified gas. - the gas recycling line is configured to convey at least a portion of the purified gas from the gas purification system and reinject it into the main gas conveying line. the gas recycling line comprises one or more gas passages or conduits or the like. the respiratory interface is a respiratory mask, in particular a face mask, i.e. oronasal, covering the user's nose and mouth. the respiratory interface is a respiratory mask comprising an oxygen inlet port for supplying the oxygen-rich gas and an exhaled gas outlet port for discharging the gas mixture exhaled by the user, i.e. the exhaled gas enriched with CO2. The respiratory mask includes a soft cushion that comes into contact with and ensures a fluid seal with the user's face. the respiratory mask comprises a mask body, for example made of rigid polymer, forming a shell delimiting an enclosure for the gas. the soft cushion is mechanically coupled to the mask body, preferably in a detachable manner. the soft cushion includes a central passage within which the user's nose and mouth are housed, when wearing the face mask, the user breathes the gas contained in the enclosure, that is to say inhales and exhales the gas in the enclosure of the mask body. the oxygen inlet port and the exhaled gas outlet port are provided in the mask body. the main gas delivery line and / or the gas recovery line and / or the gas recycling line are or comprise one or more flexible gas pipes, i.e. flexible hoses, for example made of polymer. the main gas delivery line and / or the gas recovery line are connected to the mask body so as to be in fluid communication with the inlet port and the outlet port for exhaled gas, the main gas delivery line is fluidly connected to the inlet port of the respiratory interface so as to introduce respiratory gas into the respiratory interface. the gas recovery line is fluidically connected to the exhaled gas outlet of the respiratory interface so as to extract respiratory gas from the respiratory interface. The gas recycling line supplies the buffer tank with purified gas since the gas recycling line is fluidically connected to the buffer tank. the purified gas conveyed by the gas recycling line contains a proportion (i.e. content) of oxygen less than or equal to the gas coming from the gas source, i.e. pure oxygen, and delivered through the main gas supply line. the buffer tank includes a flexible balloon, bellows or the like. The buffer tank includes an exhaust valve to vent any excess gas to the atmosphere when the buffer tank is full of gas. The buffer tank is sized to hold 0.5 to 10 liters of gas (in an uncompressed state). the buffer tank is configured to allow a gas mixture to be produced from breathing gas. The buffer tank is configured to supply the main gas supply line with breathing gas. the gas purification system comprises at least one adsorbent having a higher selectivity for CO2 than for O2 so as to adsorb at least a portion of the CO2 contained in the exhaled gas mixture. the gas purification system comprises at least one zeolitic adsorbent. the gas purification system comprises at least one adsorbent selected from silicates. the gas purification system comprises an adsorber containing at least one adsorbent, preferably a zeolitic or silicate adsorbent, or mixtures thereof. the adsorber contains at least one bed of adsorbent. the gas purification system comprises at least one adsorbent for removing CO2 and water vapor (H2O), i.e. the CO2 and water vapor are removed on the same adsorbent bed, for example a single zeolite bed, or on successive beds of different absorbents, for example a silicate bed and a zeolite bed. The adsorber has a cartridge shape. the control means include a microcontroller. an electrical power source (i.e. electrical power supply means) provides electrical power to the installation, for example a connection to the mains current (110 / 220V) such as an electrical cord and connection plug, and / or one (or more) electrical power supply batteries, preferably rechargeable, and / or a current transformer. the electrical current source supplies current to all components requiring current to operate, in particular the control means and / or the oxygen sensor. according to one embodiment, a proportional solenoid metering valve distributor is arranged on the gas supply line. - the gas supply line including the proportional solenoid valve distributor is connected to the pressure outlet of the RDI of the gas source. - the distributor comprises an internal metering line in fluid communication with the gas supply line, in particular with a flexible connection forming an upstream portion of the gas supply line and with a supply line forming a downstream portion of the gas supply line. - the proportional metering solenoid valve is arranged on the internal metering line of the distributor to control the passage of pressurized gas (e.g. of the order of 4 bar), typically oxygen, within the internal metering line. - the proportional metering solenoid valve is controlled by the control means, in particular the opening of the proportional metering solenoid valve and / or the flow rate supplied by the proportional metering solenoid valve. - the proportional metering solenoid valve is naturally closed when not controlled by the control means. - the IGU allows you to adjust or select the opening of the proportional dosing solenoid valve and / or the flow rate supplied by the proportional dosing solenoid valve.
[0017] It should be noted that, in the context of the present invention, the terminology "the exhaled gas" or "the exhaled gases" (i.e. singular or plural) is used interchangeably to designate the gas mixture released by the patient's lungs, which contains O2, CO2 and generally water vapor, or even other constituents, such as argon or nitrogen.
[0018] The invention will now be better understood thanks to the following detailed description, given for illustrative but non-limiting purposes, with reference to the appended figures among which: - [Fig.l] shows schematically an embodiment of an installation for supplying respiratory gas to a user according to the present invention. - [Fig.2] shows a diagram of a variant of the installation method [Fig.l].
[0019] [Fig.l] schematizes an embodiment of a respiratory gas supply installation 50 according to the present invention including a system for recycling exhaled gases with control of the concentration of inhaled oxygen.
[0020] This installation 50 comprises a gas source 3 for supplying a respiratory gas containing oxygen; a main gas delivery line 23, also called a patient circuit; a respiratory interface 21, such as a face mask, for administering the respiratory gas to the user or patient P, during their inspiratory phases; and a system cartridge for purifying exhaled gases 1.
[0021] The gas source 3 may be, for example, a compressed oxygen cylinder 30 equipped with an integrated pressure reducing valve 31 or RDI equipped with two ports (not shown), namely a flow outlet port allowing delivery of different flow rates that can be chosen by means of a flow selector, for example flow rates of 1 to 15 L / min and a pressure outlet port allowing a so-called “high pressure” connection, to provide a fixed gas pressure, typically of the order of 4 bar; this pressure outlet port can also be used to connect the O2 source to a medical ventilator. Preferably, the flow selector makes it possible to adjust the O2 flow rate delivered by the RDI so as to provide a low flow rate, namely of the order of 1 L / min for example, within the scope of the invention.
[0022] The main gas delivery line 23, i.e. the patient circuit, comprises a flexible pipe or conduit which fluidically connects a buffer tank 24 in fluid communication with the lumen of the main gas delivery line 23, via an outlet port 24.1 of the buffer tank 24, serving as a reserve of respiratory gas (i.e. oxygen or an oxygen-enriched mixture), to an orifice or inlet port 22 of the respiratory interface 21 so as to supply the patient P with respiratory gas, typically O2 or an oxygen-rich gas, such as an air / O2 mixture. When the patient P breathes, the buffer tank 24 which is filled with gas satisfies the instantaneous gas demand of the patient P by supplying him with the gas it contains. The buffer tank 24 has a capacity between, for example, 0.5 and 10 L (water equivalent), preferably of the order of 3 L.
[0023] The RDI 31 of the gas source 3 is fluidically connected to the buffer tank 24 via a gas supply line 32, for example a cannula, a flexible hose or a conduit for example made of silicone, supplying a gas supply port 33 of the buffer tank 24.
[0024] Arranged in the main gas delivery line 23 is a one-way inhalation valve 235 allowing the passage of the gas present in the main gas delivery line 23 in only one direction, namely here in the direction going from the buffer reservoir 24 to the inlet port 22 of the respiratory interface 21, preventing any reverse flow of the gas.
[0025] Furthermore, an oxygen sensor 234 is also placed in the main gas delivery line 23, making it possible to measure the concentration of O2 present in the main line 23. The oxygen sensor 234 is preferably of the fast type, i.e. having a fast reaction to a change in oxygen concentration, for example of the order of 1 to 2 seconds. For example, the oxygen sensor referenced FDO2 available from the company Pyroscience GmbH can be used. The oxygen sensor 234 is arranged here upstream of the one-way valve inhalation 235.
[0026] An intake line 231 is fluidically connected to the main gas delivery line 23, upstream of the oxygen sensor 234, i.e. at a site or branch 231a located between the buffer tank 24 and the oxygen sensor 234.
[0027] The intake line 231 comprises a one-way intake valve 232 and a first proportional element 233 for controlling the flow of gas, typically air, in the intake line 231.
[0028] The one-way inlet valve 232 is configured to only allow the passage of gas, i.e. air, in the direction going from the ambient atmosphere A to the main gas delivery line 23, i.e. prohibiting any gas flow in the opposite direction.
[0029] Furthermore, the first proportional element 233 comprises an upstream port 233a in fluid communication with the ambient atmosphere A and a downstream port 233b in fluid communication with the intake line 231. To ensure control of the circulation of gas, i.e. ambient air, the first proportional element 233 is configured to adopt several positions comprising (at least) a closed position and an open position, i.e. partially or totally open, such that: - in the closed position, the upstream port 233a is isolated from the downstream port 233b, that is to say that the fluid communication between them is interrupted and / or prevented; - in the open position, the upstream port 233a communicates with the downstream port 233b, that is to say that fluid communication, total or partial (i.e. proportional opening), between them is possible and / or reestablished.
[0030] The first proportional element 233 is for example a motorized gas supply valve, that is to say with an electric motor, such as that referenced USS-MSV00001 available from the company US. SOLID, or any other suitable control device having a similar operation, for example a proportional solenoid valve with a large passage diameter.
[0031] During operation of the installation 50, the gas exhaled by the patient P, which is rich in CO2 but still contains unmetabolized oxygen, leaves the respiratory interface 21 through an outlet port or orifice 25 provided in the respiratory interface 21, before being recovered and conveyed by a gas recovery line 10 forming an expiratory circuit, such as a flexible gas conduit or pipe, fluidically connected to the outlet port 25 of the respiratory interface 21.
[0032] This gas recovery line 10 makes it possible to recover and convey at least a portion of the exhaled gas mixture found in the respiratory interface 21, during the expiratory phases of the user P. This exhaled gas contains different gaseous compounds, mainly O2 and carbon dioxide (CO2), but also water vapor (H20), and generally also nitrogen (N2), or even argon (Ar).
[0033] In all cases, the expired gas mixture contains a non-zero proportion of CO2 since it results from the patient's breathing and pulmonary exchanges between O2 and CO2, for example a proportion of CO2 of the order of 5% vol.
[0034] The flow of exhaled gas is conveyed by the gas recovery line 10 to an exhaled gas purification system 1, such as one or more adsorption cartridges, within which the CO2 and possibly the water vapor are retained or captured, typically adsorbed, by one or more adsorbent beds preferably containing adsorbent particles, for example arranged in an adsorbent bed. For example, adsorbents of the zeolite or other type may be used.
[0035] The purified gas produced by the purification system 1 essentially contains oxygen and a small, or even negligible, proportion of CO2 and / or water vapor (i.e. humidity) and possibly other residual compounds in the form of traces or unavoidable impurities, such as nitrogen and / or argon.
[0036] In other words, the gas purification system 1 comprising one or more adsorption cartridges, which is supplied with exhaled gas by the gas recovery line 10, makes it possible to eliminate the majority, preferably (almost) all, of the CO2 and water vapor contained in the exhaled gas mixture and thus to obtain a purified gas containing essentially oxygen, or even unavoidable impurities or traces of CO2 or other compound(s).
[0037] For example, an adsorption cartridge of this type comprises at least one adsorbent having a higher selectivity for CO2 than for O2 so as to adsorb at least part of the CO2 contained in the exhaled gas mixture and, preferably, (almost) all of the CO2. The adsorbent may be of the zeolite or silicate type.
[0038] Preferably, the adsorbent is arranged in a bed of adsorbent, such as a bed of zeolite, or in several successive beds, such as for example a bed of silicate and a bed of zeolite, so as to be able to eliminate not only the CO2 but also at least part of the water vapor (H2O), that is to say that the CO2 and the water vapor are eliminated on a single bed of adsorbent, for example a single bed of zeolite, or on successive beds of different absorbents. Of course, other adsorbent materials may be suitable.
[0039] Advantageously, once saturated with CO2, or even with water vapor, the cartridge is replaced with a new cartridge.
[0040] Here again, a one-way exhalation valve 105, arranged in the gas recovery line 10, only allows the circulation of the gas in the direction going from the outlet orifice 25 to the gas purification cartridge 1, that is to say preventing any reverse flow of the gas.
[0041] Furthermore, an exhaust line 101 is also provided in communication fluidic with the gas recovery line 10, coming to connect to each other at a connection site or branch 101a.
[0042] The exhaust line 101 comprises a one-way exhaust valve 102 and a second proportional element 103 similar to the first proportional element 233. The second proportional element 103 also comprises an upstream port 103a in fluid communication with the ambient atmosphere A and a downstream port 103b in fluid communication with the exhaust line 101, and its operation is identical to that of the first proportional element 233, namely that it is configured to adopt several positions comprising (at least) a closed position and an open position, i.e. partially or totally open, in order to prohibit or authorize, respectively, any passage of gas towards the atmosphere, i.e. any escape of gas towards the ambient atmosphere A. The one-way exhaust valve 102 therefore only allows the passage of gas in the direction going from the gas recovery line 10 towards the ambient atmosphere A.
[0043] The installation 50 also comprises, arranged downstream of the gas purification system 1, a gas recycling line 11 fluidly connected, on the one hand, to the gas purification system 1 and, on the other hand, to the buffer tank 24, so as to collect the purified gas leaving the gas purification system 1 and to convey it to the tank 24, into which it enters via the inlet port 12 to which the gas recycling line 11 is fluidly connected.
[0044] The inlet port 12 and the gas supply port 33 are placed close to each other in order to improve the homogenization of the gases in the buffer tank 24.
[0045] An exhaust valve 26 allowing any excess gas within the buffer tank 24 to be evacuated to the ambient atmosphere when it is full.
[0046] In order to ensure recycling of exhaled gases with control of the concentration of inhaled oxygen, the installation 50 further comprises control means 15 comprising an electronic control card 150 and a microprocessor control unit 151, typically a microcontroller or the like.
[0047] The control means 15 make it possible to control or command all the electromechanical elements of the installation 50 of the invention. More precisely, the control card 150 preferably integrates the control unit 151 and is configured to control and also analyze the signals coming from the different components of the installation 50, such as valves, sensors, etc.
[0048] The electrical power supply of the installation 50 of the invention is provided by a source of electrical current and / or electrical power supply means (not shown), for example a connection to the mains current (110 / 220V) of the electrical cord and connection socket type, and / or one (or more) electrical power supply batteries, preferably rechargeable, and / or a current transformer.
[0049] The control means 15 and other components of the installation 50 are arranged in a rigid external casing or housing (not shown), for example made of polymer.
[0050] As already stated, the gas purification system 1 of the installation 50 makes it possible to purify and then recycle the exhaled gases by removing the CO2 and preferably the water vapor (H2O) that they contain, instead of releasing them into the atmosphere and thus wasting the oxygen that is still there.
[0051] Indeed, recovering the majority of the O2 contained in the gases exhaled by patient P and recycling it after purification makes it possible to avoid wasting it, and therefore to limit the flow of oxygen supplied by the O2 source 3.
[0052] Thus, for example, if we consider that the metabolic consumption of O2 of a human being is of the order of 0.5 L / min, which corresponds to a minute ventilation of 10 L / min, i.e. 10 L of gas (100% O2) inhaled by the patient for one minute, a quantity of approximately 9.5 L of O2 is exhaled, the remainder, i.e. approximately 0.5 L / min being formed of CO2 and water vapor. The installation 50 of the invention therefore makes it possible to recover approximately 9.5 L of O2. By adjusting the RDI 31 of the bottle 30 to a flow rate of 1 L / min and by recycling the O2 by mixing it with the O2 coming from the bottle 30, the flow rate of O2 recovered exceeds the minute ventilation of the patient.
[0053] It is considered, firstly, that the control means 15 control the first and second proportional elements 233, 103 in the closed position so as to isolate the intake and exhaust lines 231, 101 from the ambient atmosphere A.
[0054] Furthermore, the gas source 3 is adjusted so as to provide a constant flow rate of 1 L / min of oxygen, while the patient P has a metabolic consumption of O2 of the order of 0.5 L / min and the buffer tank 24 is filled with O2 (100% content), coming from the gas source 3.
[0055] During an inspiratory phase, that is to say when the patient P inhales gas, the inhaled gas leaves the buffer reservoir 24 and travels in the main gas delivery line 23 to the inlet port 22 of the respiratory interface 21.
[0056] Conversely, during an expiratory phase (following the inspiratory phase), the gas exhaled by the patient P leaves the respiratory interface 21 via the outlet port 25 and is recovered in the gas recovery line 10 to then be conveyed to the system 1 for purifying exhaled gases, where the CO2 is eliminated (and preferably the water vapor, or even other compounds present, with the exception of oxygen). The purified gas obtained is conveyed via the gas recycling line 11 and refills the buffer tank 24 via its inlet port 12.
[0057] In order to better understand the invention, it is considered that the buffer tank 24 here contains a volume of 3L of pure O2 (i.e. 100% vol.), and that the lungs of the patient P have a total volume of the order of 5L and that they contain air (i.e. a mixture of 21% O2 and nitrogen; argon and other possible gases in trace form are neglected), before the first inhalation of oxygen. From then on, the whole has a total volume of around 8 L and the initial O2 concentration is around 50% and is homogeneous between the buffer reservoir 24 and the lungs of patient P.
[0058] The purified gas, after passing through the purification system 1, is essentially formed of oxygen and nitrogen but it no longer contains CO2, knowing that the volume of CO2 exhaled per minute is always less than or equal to the metabolic consumption of O2 of a patient, also called “respiratory quotient”.
[0059] The gas source 3 being set at a constant flow rate greater than the metabolic consumption of the patient P (i.e. here 1 L / min of supply for a metabolic consumption of 0.5 L / min), the O2 supply by the gas source 3 is then in excess and the buffer reservoir 24 reaches its maximum capacity during the expiration of the patient P. The purified gas entering the buffer reservoir 24, via its inlet port 12, will quickly homogenize with the O2 coming from the gas source 3 via the gas supply port 33.
[0060] Therefore, the excess volume discharged to the atmosphere by the exhaust valve 26, when the buffer tank 24 is full, contains nitrogen and O2. Over time, that is to say successive inhalation and exhalation phases, the overall volume of nitrogen (N2) remaining in the patient P / installation 50 assembly tends to decrease, given that the nitrogen is gradually replaced by O2 supplied by the gas source 3, that is to say pure oxygen. It follows that after a given time, the O2 concentration reaches approximately 100% and remains at this level (possible presence of traces of residual nitrogen or unavoidable impurities).
[0061] However, as already explained, such a high concentration of oxygen is not desirable from a medical point of view because it can cause hyperoxic situations in certain patients.
[0062] To remedy this, according to the invention, the control means 15 of the installation of the invention 50 are configured to allow the healthcare personnel to select a target concentration of inhaled O2, via concentration selection means or device 300, typically a target concentration of inhaled O2 less than or equal to 100% vol.
[0063] Depending on the embodiment, the concentration selection device 300 can be integrated into the installation, such as a GUI or graphical user interface comprising selection keys or the like and a display, or be independent of it, for example the concentration selection device 300 can be a multifunction telephone (i.e. smartphone), a digital tablet, a laptop or another communicating device 301, remotely or not, with the control means 15, via a communication protocol of the Bluetooth® type or other.
[0064] In all cases, the installation of the invention 50 cooperates with the device of concentration selection 300 which allows the healthcare personnel to choose or set a target concentration of inhaled O2 and to supply the selected or set target concentration of inhaled O2 to the control means 15 of the installation of the invention 50 which act in response to the reception of this selected target concentration of inhaled O2, as explained below.
[0065] Reception means are therefore provided, such as a Bluetooth® receiver, integrated or cooperating with the control means to receive the target concentration of inhaled O2 selected or fixed via the concentration selection device 300.
[0066] If the closed circuit formed in particular by the main gas delivery line 23, the gas recovery line 10 and the gas recycling line 11, makes it possible to limit the consumption of the O2 source 3, and therefore to increase the autonomy of care of the patient P, it is clinically desirable to allow the user, i.e. the nursing staff, to be able to select a desired inhaled oxygen concentration in order to meet the specific physiological needs of the patient P in question, typically a target inhaled O2 concentration less than or equal to 100% vol.
[0067] Thus, if the user desires an inhaled O2 concentration equal to 40% for example, he sets it or selects it or chooses it via the concentration selection device 300 and this desired target content or concentration of inhaled O2 is then supplied to the control means 15 in the form of a signal or other.
[0068] When the control means 15 receive the signal corresponding to this choice of desired concentration, i.e. here 40%, they process it and also interact with the oxygen sensor 234, periodically, for example every 0.5 seconds, to carry out a measurement of the O2 concentration within the main gas delivery line 23.
[0069] The O2 concentration measurement(s) (i.e. value or signal) are provided by the oxygen sensor 234 to the control means 15 which process them, in particular compare them to the desired concentration, i.e. 40%.
[0070] A measured concentration higher than the concentration choice made (i.e. 40%), for example equal to 100%, is an indication for the control means 15 that the current measured concentration is higher than the desired target concentration, and therefore is too high, and must therefore be adjusted to avoid or minimize the aforementioned problems.
[0071] In response, the control means 15 control the first proportional element 233 to move it into an at least partially open position, which creates fluid communication between the ambient atmosphere A and the intake line 231, as explained previously, and therefore allows a supply of ambient air.
[0072] During inhalation by the patient P, the gas from the buffer tank 24 passing through the upstream portion 23a of the main gas delivery line 23, containing of 100% O2, will then be added (i.e. diluted by) air passing through the intake line 231, during the inspiration of the patient P, to thus form an air / O2 gas mixture of given O2 concentration, i.e. less than 100% (due to the dilution carried out), in a downstream portion 23b of the main gas delivery line 23, located downstream of the branch site 213a.
[0073] The O2 concentration obtained in the air / O2 gas mixture is then measured by the oxygen sensor 234. It depends on the ratio between the volume of gas coming from the buffer tank 24 and the volume of gas (i.e. ambient air) coming from the intake line 231, and therefore also on the opening level of the first proportional element 233.
[0074] The control means 15 can then determine, by means of one or more stored algorithms, what level of opening to give to the first proportional element 233, for example by analyzing the difference between the measurement of the O2 concentration by the oxygen sensor 234 and the target oxygen concentration selected or set by the user, and by taking into account the volume of the buffer tank 24.
[0075] In other words, the opening level of the first proportional element 233 is proportional in particular to the difference between the O2 concentration provided by the oxygen sensor 234 and the desired target oxygen concentration.
[0076] When the patient P exhales, knowing that the second proportional element is still in the closed position, (almost) all of the gases exhaled by the patient P exit the respiratory interface 21, are conveyed by the gas recovery line 10, and are treated by the purification system 1 to retain the CO2 (and water). The purified gas will refill the buffer tank 24, knowing that it then contains a concentration or content of O2 less than 100%, for example of the order of 60%.
[0077] Due to the mixing of the purified gas with the gaseous content of the buffer tank 24 and with the oxygen coming from the oxygen source 3, the residual concentration in the buffer tank 24 will become less than 100%, for example of the order of 80%.
[0078] Therefore, during the next inhalation by the patient P, the gas passing through the upstream portion 23a of the main gas delivery line 23 has an O2 concentration of less than 100%, for example of the order of 80%.
[0079] Advantageously, the control means 15 anticipate this drop in O2 concentration by means of one or more specific algorithms and adjust, accordingly, the opening level of the first proportional element 233 so that the air supply circulating in the intake line 231, mixing with the gas circulating in the upstream portion 23a of the main gas delivery line 23, has an average concentration in the downstream portion 23b of the main gas delivery line 23, measured by the O2 sensor, approaching even more closely the desired target O2 concentration.
[0080] It is understood that due to the succession of inhalations and exhalations of gas by the patient P over time, by measuring the O2 concentration in the downstream portion 23b of the main gas delivery line 23 and by precisely controlling the opening level of the first proportional element 233, the control means 15 can progressively cause the actual (i.e. measured) inhaled O2 concentration to converge towards the target O2 concentration desired by the user.
[0081] Once the target O2 concentration has been reached, the control means 15 preferably enter into so-called “maintenance” mode by precisely controlling, i.e. by closing or slightly opening, the first proportional element 233 in order to maintain the concentration of O2 inhaled by the patient P equal to or (very) close to the target O2 concentration desired by the healthcare personnel.
[0082] Conversely, situations may arise where patient P inhales a given concentration, for example 40%, but his condition deteriorates to the point that the healthcare staff wishes to increase the level of O2 concentration inhaled by patient P, for example to 90% (instead of 40% for example).
[0083] In this case, the control means 15 can command a closure of the first proportional element 233 to prevent any entry of air and therefore allow the O2 concentration present in the main gas delivery line 23 to gradually reach the desired value (i.e. 90%) thanks to the supply of O2 by the gas source 3 which is in excess (i.e. much greater than) compared to the metabolic consumption of the patient P, to then return to the maintenance phase by slightly closing or opening the first proportional element 233 in order to maintain the O2 concentration inhaled by the patient P close to the desired target O2 concentration, as explained above.
[0084] However, the time required to reach such a state may sometimes be too long, or even clinically unacceptable because it is not compatible with the state of the patient to be treated. In this case, the control means 15 are configured to control the installation to accelerate the increase in oxygen concentration in the gas flow supplied to the patient P via the respiratory interface 21.
[0085] To do this, the control means 15 are configured to determine the O2 concentration prevailing in the main gas delivery line 23, thanks to the measurements made by the O2 sensor 234, in particular determined if this measured O2 concentration is lower than the desired target O2 concentration.
[0086] If this is the case, the control means 15 control the first proportional element 233 in the closed position to prohibit or interrupt, within the conduit 231, any circulation of air coming from the ambient atmosphere, and in parallel control the second proportional element 103 in the open position (i.e. partially or totally open) and thus create a fluid communication between line exhaust 101 and the ambient atmosphere A, as explained previously.
[0087] Thus, when the patient P exhales, the gas circulating in the upstream portion 10a of the gas recovery line 10, having an O2 concentration of 40% for example (therefore containing approximately 60% nitrogen and possibly other unavoidable impurities, such as argon or water vapor) divides, at the branch 101a, into two gas flows.
[0088] More precisely, a portion of the gas (i.e. first flow) circulating in the upstream portion 10a of the gas recovery line 10 passes through the exhaust line 101 to escape, i.e. be discharged, into the ambient atmosphere A, while the remainder of the gas (i.e. second flow) passes through the downstream portion 10b of the gas recovery line 10 to be conveyed to the exhaled gas purification system 1, where the CO2 is eliminated. The purified gas which emerges therefrom via the gas recycling line 11 will refill the buffer tank 24 via its inlet port 12.
[0089] The volume ratio (i.e. respective quantities) between the gas flow using the exhaust line 101 and the gas flow using the downstream portion 10b of the gas recovery line 10 depends on the opening level of the second proportional element 103. The control means 15 are configured to determine, by means of one or more specific algorithms, for example by analyzing the difference between the measurement of the O2 concentration by the O2 sensor 234 and the target O2 concentration, what opening level to give to the second proportional element 103.
[0090] In all cases, the volume of gas conveyed to the buffer tank 24 is less than the volume of gas having circulated in the upstream portion 10a of the gas recovery line 10.
[0091] Schematically, if IL of exhaled gas has passed through the exhaust line 101 to be discharged into the atmosphere A, the patient P and installation 50 assembly can be assimilated to a total volume of 7L at an O2 concentration of 40%, supplemented by IL of O2 at 100% from the gas source 3. The resulting O2 concentration relative to the volume of 8L is then of the order of 47.5%. Of course, the pure O2 supplement from the gas source 3 cannot be delivered instantaneously due to the initial setting of IL / min, which implies that the buffer reservoir 24 empties progressively according to the successive inhalations and exhalations of the patient P.During these, depending on the measurement of the O2 concentration in the main gas supply line 23, the control means 15 determine the degree of opening to be given to the second proportional element 103 so that part of the gases exhaled by the patient P are evacuated to the atmosphere A via the exhaust line 101.
[0092] In the context of an increase in the target O2 concentration, the user, e.g. the healthcare staff, may be asked via the control interface 300, such as an IGU, to manually increase the flow rate from the gas source 3, for example to set it at 6L / min, so as to ensure that the buffer tank 24 does not empty completely. The second proportional element 103 makes it possible to "purge" the nitrogen more quickly than the single exhaust valve 26 of the buffer tank 24, which makes it possible to reach the new target O2 concentration more quickly, when this is higher than the concentration prevailing in the main gas delivery line 23.
[0093] Once the target O2 concentration has been reached, the control means 15 enter into maintenance mode by closing the second proportional element 103 and by slightly closing or opening the first proportional element 233 in order to maintain the O2 concentration inhaled by the patient P at a level close to the target O2 concentration.
[0094] It is therefore understood that the installation 50 according to the invention makes it possible to precisely regulate the oxygen content sent to the patient P as a function of one (or more) target oxygen content or concentration set by the care staff as a function of the needs of the patient P in question, in particular by adjusting the supply of ambient air or the evacuation of gas from the circuit to the ambient atmosphere A.
[0095] A variant of the installation 50 according to the invention is presented in [Fig.2]. The overall architecture of the installation 50 of [Fig.2] is identical to that of [Fig.l] and will not be detailed to avoid unnecessary repetitions.
[0096] This variant of the installation 50 makes it possible to further reduce, or even optimize, the time required to obtain a target concentration of inhaled O2 set by the user when this is higher than the concentration of inhaled O2.
[0097] To do this, the “high pressure” port of the RDI 31 of the gas source 3 is preferably used, which contains compressed oxygen, which is connected, via a connecting hose 34 forming an upstream portion of the gas supply line 32, to the upstream port 8a of a distributor 8 which is then supplied with oxygen at 4 bar supplied by the connecting hose 34.
[0098] The distributor 8 comprises a proportional metering solenoid valve 82 controlled by the control means 15, which is arranged on an internal metering line 81 which is in fluid communication with the connecting hose 34 forming the upstream portion of the gas supply line 32.
[0099] The proportional metering solenoid valve 82 is naturally closed when not controlled by the control means 15 so that no flow of O2 coming from the RDI 31 of the gas source 3 circulates in the metering line 81, and does not enter the buffer tank 24 via the O2 supply port 33, via a supply line 35 forming a downstream portion of the gas supply line 32, connected to the downstream port 8b of the distributor 8. The supply line 35 is for example a flexible pipe.
[0100] The proportional metering solenoid valve 82 may, for example, be the one referenced “VSO LowPro” available from the Parker company or any other equivalent or similar solenoid valve.
[0101] During operation of the installation 50, the control means 15 determine an opening level of the proportional metering solenoid valve 82 so that it delivers a flow rate of the order of IL / min, called the basic flow rate, as described above with reference to [Fig.l]. Knowing the expansion pressure of 4 bar, the operating position of the proportional metering solenoid valve 82 can be determined. Of course, additional elements, such as a flow rate sensor, pressure sensor, etc., can be used to regulate such a basic flow rate.
[0102] The IGU 300 communicating with the control means 15 can also allow the basic flow rate to be adjusted by the nursing staff, preferably approaching the patient's assumed metabolism, for example a flow rate of 0.5 L / min, IL / min or more. In this case, the proportional metering solenoid valve 82 delivers the basic flow rate which circulates in the supply line 35 and fills the buffer tank 24.
[0103] The advantage of such a distributor 8 lies in particular in the transient phases, in particular when setting a target O2 concentration higher than the O2 concentration inhaled by the patient. Indeed, in this case, the control means 15 can fully open the second proportional element 103 so that the majority, or even all of the exhaled gases circulating in the gas recovery line 10, escape to the ambient atmosphere A, via the exhaust line 101, in order to allow rapid evacuation of the nitrogen present in the installation 50.
[0104] At the same time, the control means 15 can control the proportional metering solenoid valve 82 so as to increase its flow rate, for example to 6L / min or more, in order to fill the buffer tank 24 and prevent it from emptying.
[0105] Once the target concentration of inhaled O2 is reached, the control means 15 can control the proportional metering solenoid valve 82 so that it again delivers a preset basic flow rate. Such operation then makes it possible to improve (i.e. reduce) the convergence time towards a new target concentration when this is higher than the concentration of inhaled O2, to improve the O2 flow rate by automating a task to be carried out by the user and, ultimately, to reinforce the overall safety of the installation 50.
[0106] The respiratory gas supply installation 50 according to the present invention makes it possible to control the concentration of O2 inhaled by a patient P while significantly limiting the consumption of O2 coming from the gas source 3, thus increasing its autonomy.
Claims
Claims
1. Installation for supplying (50) respiratory gas to a user (P) comprising: - a gas source (3) for supplying a breathing gas containing oxygen, - a respiratory interface (21), - a main gas delivery line (23) fluidly connecting the gas source (3) to the respiratory interface (21), - a gas recovery line (10) in fluid communication with the respiratory interface (21), - a gas purification system (1) supplied by the gas recovery line (10), - a gas recycling line (11) fluidly connecting the gas purification system (1) to the main gas delivery line (23), - and control means (15), characterized in that it further comprises: - an oxygen sensor (234) arranged to measure the oxygen concentration within the main gas delivery line (23) and provide the oxygen concentration measurement(s) to the control means (15), - an intake line (231) fluidly connected to the atmosphere and also to the main gas delivery line (23) between the gas source (3) and the oxygen sensor (234), - a concentration selection device (300) configured to allow a user to select or set a target concentration of inhaled O2 and to supply the selected target concentration of inhaled O2 to the control means (15), and - a first proportional element (233), arranged on the intake line (231), controlled by the control means (15) to control the circulation of air in the intake line (231).
2. Installation according to claim 1, characterized in that the line inlet (231) comprises a one-way inlet valve (232).
3. Installation according to claim 1, characterized in that the control means (15) are configured to control the first proportional element (233), to authorize a circulation of air in the intake line (231), when the control means (15) determine that at least one measurement of oxygen concentration measured is higher than the target concentration of inhaled O2 fixed or selected.
4. Installation according to claim 1 or 3, characterized in that the first proportional element (233) is configured to adopt at least: - a closed position preventing any circulation of air in the intake line (231), and - an open position allowing circulation of air in the intake line (231), said control means (15) being configured to control the passage of the first proportional element (233) from the closed position to the open position, or vice versa.
5. Installation according to claim 1, characterized in that it further comprises an exhaust line (101) in fluid communication with the gas recovery line (10) and furthermore with the atmosphere, said exhaust line (101) comprising a second proportional element (103) controlled by the control means (15) to control the circulation of gas in the exhaust line (101).
6. Installation according to claim 5, characterized in that the exhaust line (101) comprises a one-way exhaust valve (102).
7. Installation according to claim 5, characterized in that the second proportional element (103) is configured to adopt at least: - a closed position preventing any circulation of gas in the exhaust line (101), and - an open position allowing circulation of gas in the exhaust line (101), the control means (15) being configured to control the passage of the second proportional element (103) from the closed position to the open position, or vice versa.
8. Installation according to claim 1, characterized in that the gas recycling line (11) fluidly connects the gas purification system (1) to the main gas supply line (23), via a buffer tank (24), the buffer tank (24) being, in addition, fluidly connected to the gas source (3).
9. Installation according to claim 1, characterized in that the control means (15) comprise at least one microprocessor.
10. Installation according to claim 1, characterized in that the first proportional element (233) and / or the second proportional element (103) comprise at least one proportional solenoid valve or at least one motorized gas supply tap.