Patent Application
20240050686
The invention relates to a gas supply installation comprising a medical ventilator, that is, a medical apparatus for administering gas, and a device or apparatus for delivering gaseous nitric oxide (NO) in order to supply a gas containing NO to a patient, via a main NO delivery system, which installation further comprises an NO emergency dosing system making it possible to supply the gas containing NO at a given backup flow rate in the event of the malfunction of the main NO delivery system, in particular in the event of the loss of the signal coming from the flow rate sensor arranged on the patient circuit supplied by the medical ventilator.
NO is a gas which, when inhaled, dilates the pulmonary vessels and increases oxygenation by improving gas exchange. The properties of NO are used to treat various medical conditions such as persistent pulmonary hypertension of the newborn (PPHN), acute respiratory distress syndrome (ARDS) observed mainly in adults, or pulmonary hypertension in heart surgery, as disclosed in particular by EP-A-560928, EP-A-1516639 or U.S. Pat. No. 10,201,564.
Usually, a small quantity of gaseous NO (i.e. a few ppm by volume), diluted in nitrogen (N2), is injected into a gas flow containing at least 21% by volume of oxygen (O2), which is then inhaled by the patient. The concentration of NO, which corresponds to a dosage, is determined by the physician or similar. Typically, the gas containing oxygen is usually a mixture of N2/O2 or air, such as medical-grade air. Generally, the concentration or dosage of NO in the gas inhaled by the patient, that is, after the NO/N2 mixture has been mixed with the air or an O2/N2 mixture, is between 1 and 80 ppm by volume (ppmv), depending on the population treated, i.e. newborns or adults, and therefore the disease to be treated.
The gas inhaled by the patient can be delivered by way of an NO delivery device associated with a mechanical ventilator, as is described by U.S. Pat. No. 5,558,083. The NO delivery device is fluidly connected to one or more gas cylinders containing an N2/NO mixture, the NO concentration of which is typically between 200 and 800 ppmv. Generally, the NO delivery system comprises an NO injection module placed in the inhalation branch of a patient circuit connected fluidly, on the one hand, to the mechanical ventilator and, on the other hand, to a respiratory interface delivering the NO-enriched gas to the patient, for example a breathing mask, a tracheal intubation tube or similar.
An NO delivery installation also comprises a flow rate sensor that measures the gas flow rate delivered by the mechanical ventilator (i.e. air or N2/O2 mixture) into the patient circuit in order to determine the quantity of NO to be delivered in order to satisfy the dosage set by the physician. It must be noted that this so-called “flow rate” sensor can be of the type that measures and supplies flow rate signals or measurements per se, but also of the type that measures and supplies pressure signals or measurements that are then converted into a flow rate by control means, in particular in a microprocessor.
The NO dosage can be provided by way of a proportional solenoid valve that delivers a continuous flow of NO-containing gas and is associated with a flow rate sensor, referred to as the NO flow rate sensor, these two components being arranged in the NO delivery device, and by an injection line that connects the NO delivery device to the NO injection module arranged on the patient circuit, as described in U.S. Pat. No. 5,558,083.
Other NO delivery devices exist, in which the proportional solenoid valve is replaced by a plurality of “all-or-nothing” solenoid valves, delivering the gas intermittently, that is in the form of pulses, generally at a high frequency, the amplitude and duration of which guarantee the correct quantity of gas circulating in the injection line connected to the NO injection module.
In any event, the known NO delivery installations receive the measurements or signals from the flow rate sensor placed in the inhalation branch of the patient circuit and adjust in real time the quantity of NO to be delivered, according to the desired dosage, by controlling the flow of NO in the injection line. The association of the flow rate sensor placed in the inhalation branch of the patient circuit and the proportional or “all-or-nothing” solenoid valve(s) and the NO flow rate sensor, if present, together with the control means as described below, which are arranged in the NO delivery device, form a main NO delivery system.
Since NO is a therapeutically effective agent, that is, very low concentrations (i.e. a few ppmv) produce a therapeutic effect, its correct dosing is of critical importance, and medical personnel must constantly adjust the dosage according to the condition of the patient. As a result, when the condition of the patient changes, the NO concentration must be gradually reduced or, conversely, increased in order to take into account the condition of the patient. For example, in a situation of withdrawal from a newborn whose condition is improving, it is customary to gradually reduce the dosage, for example in steps of 1 ppm, until a zero value is reached, making it possible then to stop NO delivery. Gradual reduction of the NO concentration makes it possible to avoid a “rebound effect”, which can occur in cases of rapid variation of the concentration, typically in cases of abrupt discontinuation of the treatment, which could seriously worsen the condition of the patient.
NO delivery installations are sophisticated electromedical systems that are susceptible to faults or malfunctions that can have a considerable impact on the therapy being provided. For example, an electronic malfunction or fault, in particular of the control means and/or of the main NO delivery system, can cause the apparatus to fail and therefore NO delivery to stop completely, with the negative consequences mentioned above.
There are multiple possible failures, such as for example:
Under such circumstances, the NO delivery device must alert the user, by means of an audible and/or visual alarm signal, that prompt action is required, for example to switch to a backup pneumatic injection mode so as to limit as far as possible the undesirable effects associated with the discontinuation of the therapy caused by the failure.
This switching to backup mode is usually done by manually actuating a rotary knob or similar that commands the change-over from the normal NO administration mode to a backup mode in which there is, for example, continuous delivery of a fixed flow rate of N2/NO mixture, i.e. of the order of 250 ml/min. Such a backup dosing mechanism or system is not without risk, in particular for the following reasons:
It therefore appears that the current backup dosing mechanisms cannot guarantee a satisfactory level of safety and that it would be desirable for the patient, in the event that a backup dose is applied due to malfunction of the NO delivery installation, to be able to maintain NO therapy without interrupting the therapy and without worrying about the type of ventilator, i.e. an HFO or other ventilator, with which the NO delivery system of the NO delivery installation interacts.
In an effort to overcome this, EP-A-3410927 proposes a dosage in response to the loss of the signal, i.e. the data, coming from the flow rate sensor measuring the gas flow rate delivered by the mechanical ventilator, which flow rate sensor is arranged in the patient circuit of the ventilator and subject to multiple stresses from users. The proposed solution relies on operating the proportional solenoid valve of the NO delivery device so as to deliver a constant NO flow rate based on stored historical data previously measured by the flow rate sensor measuring the gas flow rate delivered by the ventilator and stored in a memory of the apparatus.
However, this solution is flawed as it does not make it possible to ensure the delivery of an average NO flow rate in the event of a different type of failure, such as the loss of electrical connection with the solenoid valve(s), or between the NO flow rate sensor and the control means, or even the abrupt loss of the control means themselves.
In other words, one problem is being able to maintain a dosage, that is, the treatment of the patient using NO inhaled at the desired concentration, in the event of the failure or malfunction of the flow rate sensor, which is typically situated in the patient circuit and to which the medical ventilator and the NO delivery device are connected, but also in the event of the other failures mentioned above.
One solution according to the invention relates to an installation for supplying gas to a patient, comprising:
In addition, according to the invention, in the event of the interruption of the reception by the control means of the NO delivery device or apparatus, that is, the loss of the measurement signal supplied by the flow rate sensor:
In the context of the invention:
According to the embodiment in question, the NO supply device or apparatus and/or the installation of the invention can comprise one or more of the following features:
In addition, the installation for supplying gas to a patient further comprises:
The invention also relates to the use of a gas supply installation and/or of the NO delivery device according to the invention, provided with the backup NO dosing system of the invention, which are particularly suitable for use in a therapeutic treatment method including the supply of a gas mixture comprising 1 to 80 ppmv of NO (dosage) and approximately at least 21% by volume of oxygen and generally nitrogen to a patient (i.e. an adult, a child, an adolescent or a newborn) in need thereof, which patient is suffering from pulmonary hypertension and/or hypoxia, which can cause pulmonary vasoconstriction or similar, typically resulting from or caused by pulmonary diseases or disorders such as PPHN (persistent pulmonary hypertension of the newborn) or ARDS (acute respiratory distress syndrome), or resulting from or caused by heart surgery with placement of the patient on extracorporeal circulation (ECC).
The invention will now be better understood from the following detailed description, which is given by way of non-limiting illustration, with reference to the appended figures, in which:
The medical ventilator 2 delivers a respiratory gas containing at least 21% oxygen, such as air or an NO/N2 mixture, into a patient circuit 3, in particular into an inhalation branch 31 of said patient circuit 3, serving to convey and supply the respiratory gas to a patient P during their inhalation phases, that is, to supply respiratory assistance to the patient P, and to transport the gases exhaled by the patient during their exhalation phases.
The medical ventilator 2 is a conventional apparatus comprising for example a motorized blower, also known as a turbine or compressor, delivering the respiratory gas into the patient circuit 3 and the operation of which is controlled by one or more electronic control board(s) or similar. It is supplied with electricity by electrical power supply means, such as the mains (110/22V) and/or an internal battery.
As can be seen in
The inhalation branch 31 and exhalation branch 32 comprise ducts, channels, hoses, passages, tubes or similar, for example flexible polymer hoses that are able and configured to transport the gas flows.
The respiratory gas circulating in the inhalation branch 31 of the patient circuit 3, that is, going from the mechanical ventilator 2 to the patient P, is inhaled by the patient P, whilst the gases exhaled by said patient P, i.e. gases rich in CO2, follow the exhalation branch 32 of the patient circuit 3 towards the mechanical ventilator 2 in order to be released to the atmosphere by the mechanical ventilator 2.
Moreover, a flow rate sensor 100 and an NO injection module 110 are positioned in the inhalation branch 31 of the patient circuit 3. The flow rate sensor 100 is preferably positioned in the inhalation branch 31 between the NO injection module 110 and the mechanical ventilator 2.
The inhalation branch 31 can also comprise a humidifier (not shown) in order to humidify the gas delivered to the patient P. Preferably, the humidifier is placed downstream of the NO injection module 110, that is, between said NO injection module 110 and the respiratory interface 30 supplying the gas to the patient P.
The flow rate sensor 100 is used to measure the gas flow, i.e. a flow rate, delivered by the mechanical ventilator 2 and circulating in the inhalation branch 31. The flow rate sensor 100 can be a sensor that measures and supplies flow rate signals or measurements per se, for example a mass flow sensor, or that measures and supplies pressure signals or measurements that are then converted into a flow rate by the control means, for example a differential pressure measurement sensor, also known as a differential pressure sensor.
In the embodiment in
As can be seen in
The pressure difference created by the internal restriction 101 is determined by a differential pressure sensor 104 connected to the flow rate sensor 100 by way of the upstream 102 and downstream 103 lines, which form pressure measurement ducts and supply the differential pressure sensor 104 with the pressure measurements of the circulating flow, before and after the pressure drop. Preferably, the differential pressure sensor 104 is integrated into the casing 10 of the NO delivery device 1. The sensor 104 can either be connected electrically to an operating unit 130, also known as control means 130, or can transmit the pressure measurements thereto so that they are processed by computer.
The operating unit 130, i.e. the control means 130, comprises a system for processing data, i.e. measurements, comprising for example one or more microprocessors arranged on one or more electronic boards and implementing one or more algorithms, i.e. one or more computer programs.
In other words, the operating unit 130 is configured to process and/or exploit the pressure measurement signals or the pressure values transmitted by the differential pressure sensor 104 interacting with the flow rate sensor 100.
For example, the operating unit 130 has a pre-recorded lookup table that makes it possible to determine the flow rate of gas circulating in the inhalation branch 31 and the measurement module 100-1 of the flow rate sensor 100, that is, makes it possible to convert a pressure value transmitted by the differential pressure sensor 104 into a value of the flow rate passing through the measurement module 100-1 of the flow rate sensor 100.
Such determining of the flow rate passing through the flow rate sensor 100 then makes it possible to calculate the quantity of NO that must be added to the gas circulating in the inhalation branch 31 before it reaches the patient P.
In other words, using the pressure measurement returned by the differential pressure sensor 104 and the lookup table, the operating unit 130 can determine the gas flow rate issuing from the mechanical ventilator 2 and the quantity of NO that must be added, via the NO injection module 110, in order to obtain the desired concentration of NO, i.e. the dosage defined by the physician, that must be inhaled by the patient P.
Of course, the operating unit 130 can also be configured to operate other electromechanical elements integrated into the casing 10 or outer shell of the NO delivery device 1.
According to another embodiment (not shown), the flow rate sensor 100 could also be a mass flow sensor or similar connected directly to the control means 130, via one or more electrical connections, such as one or more cables or similar, in order to supply them with a signal, such as a voltage, or a measurement of the flow rate passing through the sensor 100. In this case, the differential pressure sensor 104 is removed.
In general, the final gas mixture, i.e. the NO-based respiratory gas that is then administered to the patient by inhalation, obtained in the NO injection module 110 arranged on the inhalation branch 31, then mainly comprises nitrogen (N2), oxygen (O2), typically at a content of approximately at least 21% by volume, and NO, at a content typically between 1 and 80 ppmv, for example of the order of 10 to 20 ppmv.
More specifically, during normal operation, depending on the gas flow rate (i.e. air or N2/O2) circulating in the inhalation branch 31 that has been determined by means of the flow rate sensor 100, the operating unit 130 determines the quantity of NO, typically a mixture of NO and N2, that must be added to the gas circulating in the inhalation branch 31 by the NO injection module 110 in order to obtain the concentration or dosage desired, that is, set by the physician or similar, during normal operation of the gas supply installation 1, 2.
Typically, the concentration or dosage of NO in the gas inhaled by the patient, after the NO/N2 mixture has been mixed with the air or an O2/N2 mixture, is between 1 and 80 ppm by volume (ppmv), for example of the order of 10 to 20 ppmv, depending on the population treated, i.e. newborns or adults, and therefore the disease to be treated.
The NO delivery device 1 is supplied with gaseous NO, typically in an NO/N2 gas mixture, coming from an NO source 250 fluidly connected to the NO delivery device 1, in particular to a high-pressure line 116 of said NO delivery device 1, via a supply line 251, such as a flexible duct or similar.
Typically, the NO source 250 is one or more pressurized gas cylinders holding an NO/N2 mixture containing an NO concentration generally between 100 and 2,000 ppmv, preferably between 200 and 1,000 ppmv, for example of the order of 800 ppmv, and stored at a pressure (when completely full) that can be up to 200 to 250 bar absolute, or even more.
The NO/N2 mixture is supplied to the injection module 110 by the NO delivery device 1 via an injection line 111, such as a flexible gas duct.
The injection line 111 situated in the casing 10 of the NO delivery device 1 is fluidly connected to a high-pressure line 116 of the NO delivery device 1, which high-pressure line 116 has a high-pressure inlet fluidly connected to the NO source in order to be supplied with pressurized NO/N2, that is, at a pressure that can be up to 200 bar absolute.
The high-pressure line 116, for example a gas passage or duct, is also arranged in the casing 10 of the NO delivery device 1 and comprises a pressure regulator 115 that reduces the pressure of the NO/N2 mixture to a stable value, for example 4 bar absolute. The outlet port of the pressure regulator 115 supplies a stable pressure in the upstream portion of the injection line 111.
A valve device 113, such as a solenoid valve, preferably a proportional solenoid valve, such as the Parker miniature VSO series for example, is arranged in the device 1 in order to control the flow rate of gaseous NO within the injection line 111. The flow rate of gas circulating in the injection line 111 is measured by a flow rate measurement device 112, also known as an NO flow rate sensor, arranged on the injection line 111, preferably placed downstream of the solenoid valve 113, as can be seen in
The pressure regulator 115, the valve device or solenoid valve 113, the NO flow rate sensor 112 and a portion of the injection line 111 are thus arranged in the casing 10 of the NO delivery device 1.
The valve device 113 is configured so that it is normally in a closed position (i.e. an idle state) in order to prevent any circulation of gas in the injection line 111.
Advantageously, in the idle state, the valve device 113 is not operated by the control means. In other words, when the control means 130 stop/cease commanding the valve device 113, it automatically switches/returns to the idle state, that is, a closed position.
Conversely, in order to switch to an open position, the valve device 113 must be commanded by the control means 130, as is the case during normal operation of the gas supply installation 1, 2.
Moreover, according to the invention a backup NO dosing system 200 is provided, arranged in the casing 10 of the NO delivery device 1 and used in the event of a failure, as set out in detail below.
The backup NO dosing system 200 comprises a backup line 201, also called a bypass line, such as a gas passage, a gas duct or similar. The backup line 201 fluidly connects to the injection line 111 at a first connection site 111a situated upstream of the valve device 113, such as a proportional solenoid valve, and here downstream of the pressure regulator 115, and at a second connection site 111b situated downstream of the valve device 113, and preferably downstream of the NO flow rate sensor 112.
In other words, a valve device 113, such as a proportional solenoid valve, and preferably the NO flow rate sensor 112, are situated between the first and second connection sites 111a, 111b of the emergency line 201, that is the emergency line 201 bypasses the valve device 113 and preferably the NO flow rate sensor 112 situated on the injection line 111. According to another embodiment, the second connection site 111b can be situated downstream of the valve device 113 and upstream of the NO flow rate sensor 112, that is, between these two elements.
The backup line 201 comprises, for its part, a backup solenoid valve 202 and a flow rate control device 210 forming part of the backup dosing system 200 of the invention. This backup solenoid valve 202 is configured so that it is normally in an open position (i.e. an open state) in order to allow gas to circulate in the backup line 201.
The flow rate control device 210 in fact forms a proportional calibrated orifice system 204 that makes it possible to adjust or regulate the backup flow rate of gas, i.e. NO/N2 mixture, circulating in the backup line 201. It can take various forms, i.e. arrangements, in particular the arrangement illustrated in
The backup solenoid valve 202 is preferably an “all-or-nothing” solenoid valve having two possible states, namely an open state and a closed state, for example an IMI Norgren Picosol series solenoid valve.
The backup solenoid valve 202 is normally open, that is, in the absence of an electrical command from the operating unit 130, the backup solenoid valve 202 is in its idle state, i.e. in an open position, which then allows the gas coming from the NO source to follow the backup line 201 from the first connection site 111a towards the second connection site 111b.
In other words, as above for the valve device 113, in its idle state, the backup solenoid valve 202 is not operated by the control means 130. In other words, when the control means 130 stop/cease commanding the backup solenoid valve 202, it automatically switches/returns to the open position that corresponds to its idle state.
Again, it is the control means or operating unit 130 that ensure that the backup solenoid 202 closes, that is, that it switches from the idle state (i.e. open position) to its active state, that is a closed position, as is the case during normal operation of the gas supply installation 1, 2.
In other words, the control means 130, i.e. the operating unit, are configured to interact with the backup solenoid valve 202, the flow rate control device 210, the valve device 113 and the flow rate measurement device 112, during normal operation of the device 1 and the gas supply installation 1, 2.
In the embodiment shown in
However, the flow rate control device 210 constituting the proportional calibrated orifice 204 can take another form, for example a needle valve device or an assembly comprising a pressure regulator arranged upstream of a fixed orifice, said pressure regulator being able to be set to different output pressures, thus generating different flow rates through said fixed orifice.
The actuator means 203, more simply known as an actuator, in
Moreover, here, the movable element 2042 is a sphere. The sphere forming the movable element 2042 can be made from metal, for example stainless steel, and has a through-slot 2043, that is, it is diametrically traversed by an internal hole or passage allowing the passage of the gas. The movable element 2042, i.e. the sphere, is housed in an internal compartment or housing 2041 forming a sphere chamber, which here is generally spherical. The housing 2041 is formed in a part forming a body 2040. The outer diameter of the sphere 2042 is substantially equal to the inner diameter of the internal housing 2041.
The part forming a body 2040 can also be made from metal, for example a steel ball or similar. It comprises an inlet port 201a and an outlet port 201b in fluid communication with the internal housing 2041.
As indicated, here, the actuator means 203 is a stepping motor 2030 rotating the shaft 2031 and thus the sphere 2042. In response to a command coming from the operating unit 130, the stepping motor 2030 will adopt a different position and cause the rotation of the shaft 2031, which will then also rotate the sphere 2042.
Considering that the operating unit 130 is able to vary the command value proportionally, it follows that the shaft 2031 can undergo greater or lesser rotational movements in a proportional manner, for example between 0 and 90°. In other words, the rotational movement undergone by the shaft 2031 is therefore transmitted to the sphere 2042, which pivots in response, within its housing 2041, as illustrated in
In
In this so-called closed position, the axis AA of the through-slot 2043 of the sphere 2042 is (quasi) perpendicular to the axis BB passing through the inlet port 201a and outlet port 201b, so that no passage of gas takes place through the through-slot 2043 and therefore in the backup line 201.
Between
However, the operating unit 130 is also configured to be able to issue, in a proportional manner, commands causing the rotation of the shaft 2031 and of the sphere 2042 between these two extreme angular positions, i.e. 0° and 90° rotation, that is, an angle that is not zero but is less than 90°.
In the so-called intermediate positions, the axis AA of the through-slot 2043 of the sphere 2042 and the axis BB passing through the inlet port 210a and outlet port 201b form between them a variable angle, here strictly between 0 and 90°, so that the passage of gas through the through-slot 2043, therefore in the backup line 201, is limited/reduced but not zero, nor the maximum, that is, depending on the desired opening O of the calibrated orifice 204.
Depending on the command imposed on the actuator 203 by the operating unit 130, the level of opening O defined by the intersection of the inlet port 201a, the outlet port 201b and the hollow part 2043 of the sphere 2042 thus varies from a zero value (
It will be readily appreciated that each level or value of opening O corresponds to an equivalent calibrated orifice the gas flow area of which depends on the positioning of the sphere 2042 and consequently on the command sent by the operating unit 130, i.e. the control means, to the actuator 203.
As has already been stated, this assembly therefore forms a proportional calibrated orifice, since its diameter or level of opening O depends on the angular position adopted by the sphere 2042 within the body 2040 of the calibrated orifice 204.
The pressure prevailing in the upstream portion of the backup line 201, that is, upstream of the calibrated orifice 204, is stable and known, since it corresponds to the relief pressure of the pressure regulator 115, set for example at 4 bar absolute. The flow rate of gas circulating in the downstream portion of the backup line 201, that is, downstream of the calibrated orifice 204, therefore depends on the level of opening O.
The operating unit 130 can thus have a lookup table linking a given command level to a level of opening and to a flow rate of gas passing through the calibrated orifice 201 towards the injection line 111 and accessing the second connection site 111b.
For reasons of simplification, the pressure level prevailing in the inhalation branch 31 of the patient circuit 3, and therefore in the NO injection module 110 and the injection line 111, is considered to be negligible with regard to the relief pressure of the pressure regulator 115 and therefore has no impact on the accuracy of the measurements of the flow rate circulating in the backup line 201 taken by the operating unit 130.
Of course, according to a particular embodiment, supplementary measuring means, such as an additional pressure measurement device arranged to measure pressure downstream of the calibrated orifice 204 of the backup line 201, can be implemented, i.e. used, for compensation purposes, without changing the object of the present invention in any way.
Finally, it must be noted that the choice of a stepping motor is particularly recommended since, in contrast to the solenoid valves 202, 113, which will adopt an idle position if the power is cut, namely an open position for the all-or-nothing solenoid valve 202 and a closed position for the proportional solenoid valve 113, the position of the stepping motor remains permanent and fixed according to the last command imposed. In other words, the calibrated orifice 204 has a fixed level of opening corresponding to the last command value received by the stepping motor, i.e. the last command originating from the control means 130.
Of course, the present invention is not limited to an actuator in the form of a stepping motor. Any other actuator that keeps its position if the electrical power supply fails and that can be coupled to a mechanical mechanism making it possible to define a calibrated orifice of variable size can be used, for example a linear motor or similar.
Moreover, the NO delivery device 1 is supplied with electricity by an electrical power supply, for example the mains (110/220V) or an internal battery, in order to permit the correct operation of the components thereof that require electrical current in order to function, in particular the actuator 203, such an electric stepping motor, the operating unit 130, the solenoid valves 202, 113, or other components.
In addition, the NO delivery device 1 also comprises storage means, such as a computer memory, for storing data, information or similar, for example one or more lookup tables, the gas flow rate measurements taken by the flow rate measurement device 112 or coming from the flow rate sensor 100 and/or processed by the control means 130, or other data.
According to the invention, in the event that the operation of the installation 1, 2 fails as a result of a loss of signal, i.e. the measurements, coming from the flow rate sensor 100, for example in the event of the disconnection of the upstream 103 and/or downstream 102 pressure measurement lines, which can be mechanically coupled, it must be possible to continue to treat the patient with inhaled NO despite the malfunction.
To this end, in the event that the control means (130) lose the signal(s) coming from the flow rate sensor 100, the backup solenoid valve 202 ceases to be commanded by the control means 130 as it is during normal operation of the installation 1, 2, so that it automatically switches to an open position, that is, its idle state, to allow the circulation of a backup gas flow (i.e. NO/N2 mixture) in the backup line 201 and, at the same time, the valve device 113 also ceases to be commanded by the control means 130, so that it switches to a closed position, that is, its idle state, in order to stop any circulation of gas (i.e. NO/N2 mixture) in the injection line 111, which makes it possible to supply the gas (i.e. NO/N2 mixture) at a backup gas flow rate, via the backup line 201 and the flow rate control device 210, even if the signal is lost.
In this case, the backup gas flow rate corresponds to a gas flow rate pre-regulated in the flow rate control device 210 forming a proportional calibrated orifice system, during the normal operation of the installation, that is, before the loss of signal from the flow rate sensor 100.
More specifically, the backup gas flow rate corresponds to the “last” flow rate calculated by the control means 130 on the basis of the last measurement signal(s) corresponding to the flow rate(s) of respiratory gas (e.g. air or N2/O2) in the inhalation branch, having been supplied by the flow rate sensor 100 of the patient circuit 3 to the control means 130, before said interruption of reception of said signal, and also on the basis of the desired NO dosage, which is typically between 1 and 80 ppmv. The desired NO dosage or concentration in the final mixture is set by the medical staff, e.g. a physician or similar, and can be stored in the NO delivery device 1.
Preferably, the backup gas flow is calculated on the basis of a plurality of flow rate values measured by the flow rate sensor 100 within the inhalation branch of the patient circuit 3, during normal operation of the installation 1, 2. Said flow rate values are averaged by the control means, that is, the control means 130 calculate an average gas flow rate or “average flow rate” over a given period of time, during which the values were read, for example for several seconds or tens of seconds. The backup gas flow rate is then pre-regulated in the flow rate control device 210 forming the proportional calibrated orifice system, also during normal operation of the installation 1, 2.
In other words, during normal operation of the installation 1, 2 prior to the malfunction, the backup gas flow rate is determined by the control means 130 on the basis of the last gas flow rate measurement(s) supplied by the flow rate sensor 100, in particular an average flow rate, as explained above, and optionally stored, and of course on the basis of the desired dosage, i.e. the NO content in the final mixture. The control means 130 can then act immediately, that is before any future loss of signal, on the flow rate control device 210 of the NO supply device 1 in order to adjust the calibrated orifice thereof so that it is able to immediately deliver a backup gas flow (i.e. NO/N2 mixture) at the desired backup gas flow rate via the backup line 201, as soon as a loss of signal is detected and the control means 130 cease or stop commanding the backup solenoid valve 202 and the valve device 113, which then switch to their respective idle states, namely to an open position for the backup solenoid valve 202 and to a closed position for the valve device 113 so as to ensure the circulation of the NO/N2 gas mixture in the backup line 201 but prevent or stop any circulation of gas in the injection line 111.
The control means 130 therefore determine the backup gas flow rate, before any loss of signal, on the basis of the desired NO dosage and the last gas flow rate measurement(s) supplied by the flow rate measurement device 100, during normal operation, that is before any interruption of the signal, and act on the flow rate control device 210 in order to pre-regulate this backup gas flow rate, for example by adjusting the diameter or level of opening O acting on the angular position adopted by the sphere 2042 within the body 2040 of the calibrated orifice 204, as explained above. Preferably, the last flow rate measurements are used by the control means 130 to calculate an average flow rate over a given duration of a few seconds or tens of seconds preceding the malfunction and this average flow rate is used to determine the backup gas flow rate making it possible to obtain the desired dosage.
More specifically, the operation of the backup NO dosing system 200 of the NO delivery device 1 of the invention is generally as follows.
As illustrated in
These flow rate measurements allow the operating unit 130 to determine, in real time, the flow rate of NO, i.e. the backup flow rate, that must be injected into the injection line 111 and the NO injection module 110 in order to satisfy the desired concentration or dosage of NO in the gas supplied to the patient, namely between 1 and 80 ppmv, typically between 5 and 80 ppmv, for example of the order of 10 to 20 ppmv.
In normal operation, the operating unit 130 commands the valve device 113, preferably a proportional solenoid valve, to an open position (i.e. active state) to allow the circulation of the NO/nitrogen mixture in the injection line 111. Conversely, so as not to introduce an additional flow coming from the backup line 201 into the injection line 111, the operating unit 130 commands the solenoid valve 202, which is preferably an all-or-nothing solenoid valve, to a closed position (i.e. active state) and, in parallel, will operate the actuator 203, i.e. the stepping motor, in order to pre-regulate the calibrated orifice 204 by defining a given level of opening O, and therefore a backup flow rate.
This is carried out as follows by the operating unit 130, on the basis of one or preferably a plurality of measurements of the flow rate of respiratory gas (e.g. air or N2/O2, or even O2) coming from the ventilator 2, which circulates in the inhalation branch 31 of the patient circuit 3 at a flow rate(s) determined by the flow rate sensor 100, which is transmitted to the control means 130.
The operating unit 130 uses the respiratory gas flow rate measurements to preferably calculate an average flow rate over a given duration, for example a few seconds, and then evaluate the NO flow rate value (in 1/min) that makes it possible to obtain or come close to the desired NO concentration or dosage, e.g. between 1 and 80 ppmv, for example of the order of 10 to 20 ppmv, after the flow of NO/nitrogen mixture conveyed by the injection line 111 has been mixed with the respiratory gas circulating in the inhalation branch 31 of the patient circuit 3. In other words, the calculation of the NO flow rate value takes into account, during normal operation of the installation, the respiratory gas flow rate measured in the patient circuit 3 by the flow rate sensor 100, in particular an average flow rate calculated by the control means 130.
More specifically, when the backup flow rate value has been determined, the operating unit 130 carries out a conversion by way of a stored lookup table so as to command the actuator 203 of the flow rate control device 210 and consequently define a level of opening of the calibrated orifice 204 in order to set a flow rate of NO that can circulate in the backup line 201 equal to the calculated average NO value set, that is, corresponding to the pre-set backup flow rate. It must be emphasized that this activity has no physical effect, i.e. no flow of gas circulates in the backup line 201, because the all-or-nothing solenoid valve 202 is closed during normal operation of the installation 1, 2, that is, before any loss of signal coming from the flow rate sensor 100.
Conversely, in the event that the signal coming from the flow rate sensor 100 is interrupted, the valve device 113, typically a proportional solenoid valve, returns to its idle state, namely switches to its closed position preventing any passage of gas, while the solenoid valve 202 simultaneously returns to its idle state, namely its open position, permitting the gas coming from the NO source to pass into the backup line 201 and circulate as far as the second connection site 111b and then the downstream part of the injection line 111. The operating unit 130 has ceased to operate the valve device 113 and the backup solenoid valve 202, which have automatically returned to their idle state.
In other words, the valve device 113, typically a proportional solenoid valve, and/or the solenoid valve 202 switch naturally to their idle state, that is, independently of any command from the control means 130. These idle states are in fact “default” states of the valve device 113 and the solenoid valve 202.
The NO/N2 mixture can then circulate in the backup line 201 at a backup flow rate calculated as explained above and set out below, which is controlled by the calibrated orifice of the flow rate control device 210. The flow of NO/N2 at the backup flow rate reaches the injection line 111 (at 111b) and can then be injected into the inhalation branch 31 of the patient circuit 3 via the NO injection module 110, as already explained, in order to obtain the final mixture to be administered to the patient, which is at the desired NO dosage, that is, usually between 1 and 80 ppmv of NO, for example of the order of 10 to 20 ppmv.
It will therefore be understood that, according to the invention, the flow rate control device 210 is configured, i.e. pre-regulated during normal operation of the installation 1, 2 to supply, in the event of a malfunction with loss of signal from the flow rate sensor 100, the gas, i.e. NO/N2, at a backup gas flow rate determined by the control means 130 on the basis of one or more gas flow rate measurement(s) supplied by the flow rate sensor 100, for example via the upstream and downstream lines 103, 102, and the differential pressure sensor 104 before any malfunction, preferably the last flow rate value of the respiratory gas coming from the ventilator 2 and measured before the malfunction, caused for example by the inadvertent or accidental disconnection of the upstream and downstream lines 103, 102, or even the abrupt failure of the flow rate sensor 100.
The NO flow rate value is therefore pre-regulated within the flow rate control device 210 by the control means 130, for example by acting on the angular position adopted by the sphere 2042 within the body 2040 of the calibrated orifice 204 of the flow rate control device 210 in order to vary the diameter or level of opening O therein, as explained above, by command of said flow rate control device 210 by the control means 130, said pre-regulation taking place, that is to say being performed or realised, during said normal operation of the device 1.
Of course, injecting a continuous flow rate of NO into the inhalation branch 31 of the patient circuit 3 does not guarantee the same accuracy of the inhaled NO concentration as when the NO delivery system 1 is operating normally, that is by adjusting the flow rate of NO according to the flow rate passing through the flow rate sensor 100, but the buffer volume generated by the portion of the inhalation branch 31 situated downstream of the NO injection module, which is optionally augmented by the volume of the humidification chamber when it is present, makes it possible to smooth the variations in the concentration of NO inhaled by the patient and to come close to the desired target value, that is to say the NO dosage.
In any event, being able to come close to the desired target value of NO, by virtue of the backup NO dosing system 200 integrated into the NO delivery device 1 of the invention, considerably improves the safety for the patient by comparison with a fixed backup NO flow rate (for example of 250 ml/min) usually delivered by the safety system of the NO delivery devices of the prior art.
By way of comparison, while the backup NO dosing system 200 integrated into the NO delivery device 1 of the invention makes it possible to guarantee an NO concentration substantially equal to the desired dosage, with a backup system based on a fixed flow rate of 250 ml/min, as conventionally used in the NO delivery devices of the prior art:
In both cases, the considerable departures from the dosage can bring about situations that are unacceptable and dangerous for the patient, in contrast to the backup NO dosing system 200 integrated into the NO delivery device 1 of the invention, which makes it possible to comply with the desired dosage.
In other words, the backup NO dosing system 200 of the invention has undeniable advantages by increasing patient safety by:
Of course, the switch-over to the backup NO dosing system 200 of the invention is only temporary, that is, it lasts only for the time needed to replace the faulty equipment or component that triggered the audible and/or visual alarm alerting the medical staff.
In order to avoid erroneous activation of the backup NO dosing system 200, the operating unit 130 is further configured to carry out suitable start-up and shut-down sequences. For example, if the NO therapy is deliberately stopped by the user, the operating unit 130 can command the actuator 203 in order to close the calibrated orifice 204. In the event of a deliberate shut-down and therefore the opening of the solenoid valve 202, the “closed” configuration of the calibrated orifice 204 thus then prohibits any circulation of NO flow in the backup line 201, while the NO delivery device 1 is shut down.
In general, according to the invention, in the event of the failure of the flow rate sensor 100 measuring the gas flow rate issuing from the mechanical ventilator 2 accompanied by the loss of the measurement signal, for example in the event of the disconnection of the upstream 103 and/or downstream 102 pressure measurement lines connected to the flow rate measurement module 100-1 of the flow rate sensor 100, the operating unit 130 retains its ability to command the actuators of the NO delivery device 1.
In this case, the operating unit 130 can detect the loss of signal from the flow rate sensor 100 and then immediately “activate” the backup dosing system 200 by stopping the operation of the proportional solenoid valve 113 and the solenoid valve 202 so that the proportional solenoid valve 113 switches to an idle position, that is a closed position, and the solenoid valve 202 of the backup line 201 simultaneously switches to its idle position, namely an open position permitting the circulation of the gas coming from the NO source in the backup line 201 and through the flow rate control device 210, which then delivers the NO/N2 flow at the pre-regulated flow rate, as explained above.
The flow of NO/N2 mixture can then follow the backup line 201 at the flow rate pre-set by the flow rate control device, for example a calibrated orifice or similar, before any loss of signal due to a malfunction, namely the backup flow rate determined by the operating unit 130 on the basis of the last respiratory gas flow rate measurement obtained before the malfunction and on the basis of the desired dosage, that is, the desired NO content after the NO/N2 flow has been mixed with the respiratory gas coming from the ventilator 2, such as air or an N2/O2 mixture, said mixing taking place in the inhalation branch 31 in the NO injection module 110, so as to obtain the final mixture to be administered to the patient containing the desired NO dosage, typically between 1 and 80 ppmv, for example of the order of 10 to 20 ppmv.
In other words, the NO/N2 flow coming from the backup line 201 will then join the injection line 111 (at 111b) in order to be injected into the inhalation branch 31 of the patient circuit 3 via the NO injection module 110, and mix therein with the respiratory gas flow, such as air or a nitrogen/oxygen mixture, containing oxygen, typically approximately at least 21% by volume of oxygen, coming from the ventilator 2, as already explained.
Of course, such a situation in which the operating unit 130 detects a loss of signal from the flow rate sensor 100, can be resolved and then return to normal, for example when the user reconnects the upstream 103 and/or downstream 102 pressure measurement lines of said flow rate sensor 100, if it/they has/have been unintentionally disconnected so as to cause the malfunction and the loss of signal.
Next, when the operating unit 130 determines that the signal from the flow rate sensor 100 is valid again, i.e. reception of the signal is restored, it can return to a normal operating state of the NO delivery device 1, that is by commanding the solenoid valve 202 back to a closed position in order to isolate the backup dosing system 200 from the injection line 111, and by commanding the proportional solenoid valve 113 again in order to deliver the NO flow rate that must be injected into the injection line 111 and the NO injection module 110 in order to satisfy the desired concentration of NO in the gas supplied to the patient.
Similarly, although this occurrence is rarer, the operating unit 130 can also determine that an internal failure of the NO flow rate sensor 112 has occurred, such as the breakage of its power supply cable, caused by vibrations during patient transport, for example.
In this case, the operating unit 130 is configured to operate in an identical way to the preceding case resulting from a loss of signal from the flow rate sensor 100 due to the accidental disconnection of the upstream 103 and/or downstream 102 lines, in order to activate the backup dosing system 200. However, such an internal failure of the sensor 112 is generally permanent and irreversible, and therefore requires technical intervention to replace the damaged, i.e. malfunctioning, elements.
The NO delivery device 1 provided with a backup NO dosing system 200 of the invention is particularly suitable for supplying a gas mixture comprising 1 to 80 ppmv of NO (dosage) and at least 21% by volume of oxygen to patients (adults, children, adolescents or newborns) suffering from pulmonary hypertension and/or hypoxia, which can cause pulmonary vasoconstriction or similar, for example caused by pulmonary diseases or disorders such as PPHN (persistent pulmonary hypertension of the newborn) or ARDS (acute respiratory distress syndrome), or those caused by heart surgery with placement of the patient on extracorporeal circulation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2208243 | Aug 2022 | FR | national |
