FR3031447A1 - MEDICAL VENTILATOR WITH PROPORTIONAL EXHAUST VALVE ASSOCIATED WITH A BI-DIRECTIONAL FLOW SENSOR - Google Patents

Abstract

The invention relates to a medical respiratory ventilator comprising a source of gas (1) fluidly connected to a pipe (2) for conveying gas, a pipe (2) for conveying gas fluidly connecting the gas source (1) a patient circuit (10) comprising at least one inspiratory limb (10a), an exhaust duct (3) fluidly connected to the gas supply duct (2), an exhaust valve (4a) arranged on said exhaust duct (3), and a gas flow sensor (5a) arranged on the gas supply duct (2). According to the invention, the exhaust valve (4a) is proportional and the gas flow sensor (5a) is bidirectional type.

Description

The present invention relates to a respiratory assistance device or medical ventilator that can be used both for performing light care ventilation and critical care, according to the two modes of invasive and non-invasive ventilation. Certain respiratory conditions or physical conditions require the administration to patients who are suffering from air or a mixture of air enriched with oxygen. This gas administration can be carried out by means of a respiratory assistance device generally called a medical ventilator. Such an apparatus generates a flow of gas at a given pressure and containing a desired proportion of oxygen, namely 21% or more oxygen (% by vol.) And alternates inspiratory and expiratory phases to partially assist. or total breathing of the patient. Depending on the condition of the patient, two types of ventilators can be used, namely: - the light care ventilators found in the recovery room or post-intervention care service to help the patient to recover from a surgical procedure for example and 20 - critical care ventilators found in resuscitation service Among the light care ventilators, there are also known ventilators that allow ventilations to be leaked. These are non-invasive ventilations with gas administration by intentional leakage mask, obtained via one or more leakage orifices arranged in the mask. These fans require a single-branch or single-branched breathing circuit, i.e., the inspiration flow and part of the expiration flow take the same conduit or gas passage. This type of fan benefits both the user, that is to say, the caregiver, by the simplicity of implementation that the patient, through the comfort it provides. However, leaking ventilators can not be used with populations of 30 more critical patients, that is to say in intensive care, because they allow only barometric ventilations. Indeed, the presence of intentional gas leaks prevents accurate delivery of gaseous volume. Conversely, resuscitation or critical care ventilators are designed to provide invasive or non-invasive ventilations with masks without intentional leakage. However, such critical-care ventilators are still provided with double-branched circuits allowing the inhaled air and expired gases of the patient to borrow from different lines or conduits. They can therefore, by construction, function as leakage fans. In other words, there are therefore technical constraints that prevent the use of the same fan according to the two modes of ventilation, i. e. invasive or non-invasive, for light or critical care. This forces users to regularly change devices and causes problems of cost but also safety of use. The problem is therefore to be able to have a single medical ventilator capable of providing both light and critical care ventilations, that is to say according to the two modes of invasive and non-invasive ventilation. invasive. The solution of the invention is a medical ventilator for respiratory assistance comprising: a source of gas fluidly connected to a gas supply pipe, a gas supply pipe connecting fluidically the gas source to a patient circuit comprising at least one inspiratory branch, - an exhaust duct fluidly connected to the gas supply duct, - an exhaust valve arranged on said exhaust duct, and - a gas flow sensor arranged on the duct delivery of gas, characterized in that: - the exhaust valve is proportional and - the gas flow sensor is bidirectional type. In other words, the proportional-operated exhaust valve is associated with a bi-directional flow sensor, this combination allowing the use of the ventilator in the context of ventilations of patients in the context of light and critical care, c that is to say according to the two modes of invasive and non-invasive ventilation. Depending on the case, the medical ventilator of the invention may comprise one or more of the following technical characteristics: it comprises piloting means cooperating with the exhaust valve. - It comprises control means designed to control the exhaust valve, during expiratory phases of the patient, so as to operate a gradual reduction of the passage diameter of the exhaust valve between several positions. 3031447 3 - the exhaust valve is designed or adapted to adopt:. a fully closed position, in which the exhaust passage diameter of the exhaust valve is completely closed and no gas flow can pass through said exhaust valve, 5. a fully open position, in which the exhaust passage diameter of the exhaust valve is completely clear and a maximum flow rate of gas can pass through said exhaust valve, and. at least one partial opening position, in which at least one intermediate gas flow rate lower than the maximum gas flow rate, can pass through said exhaust valve, preferably several partial opening positions. the exhaust valve is of the actuator type. - The exhaust duct comprises a free end or outlet communicating with the ambient atmosphere. the exhaust valve makes it possible to regulate the flow of gas escaping to the atmosphere via the free end or outlet of the exhaust duct, in particular during the expiratory phases of the patient. the bidirectional flow sensor is designed to measure the flow of gas flowing in the pipeline in the direction from the source of gas to the inspiratory branch, and in the opposite direction, that is to say from the inspiratory branch to the source of gas. The bidirectional flow sensor is designed to measure the flow of gas flowing in the pipeline in the direction from the inspiratory branch to the gas source, and to transmit at least one flow measurement signal corresponding to the control means, when the exhaust valve is controlled by said control means to be in full or partial opening position. The exhaust pipe connects fluidly to the gas supply pipe between the gas source and the gas flow sensor. - The gas source comprises a motorized turbine or one or more solenoid valves fluidly connected to one or more gas supplies, in particular to a pipe or a network of air ducts or oxygen (02). The patient circuit comprises: an inspiratory branch and an expiratory branch,. or only an inspiratory branch fluidly connected to a leak rate patient interface, in particular a respiratory mask, typically a nasal or facial mask. - it further comprises a gas pressure sensor arranged on the gas supply pipe. the control means comprise an electronic control card or the like.

The invention will now be better understood by means of the following detailed description, given by way of illustration but without limitation, with reference to the appended figures in which: FIG. 1 schematizes the architecture and the operation of an embodiment of FIG. A conventional medical ventilator with a double-branched patient circuit, FIG. 1b schematizes the medical ventilator of FIG. 1 according to a second embodiment in which the patient circuit is single-branched, FIG. 2 schematizes the architecture and the operation of a double branch medical circuit ventilator according to the present invention; and FIG. 3 schematizes the architecture and operation of a single branch medical circuit medical ventilator according to the present invention. Figure la is a schematic representation of the architecture and operation of a conventional medical ventilation ventilator with double-branched patient circuit according to the prior art. A gas source 1, such as a motorized turbine or one or more solenoid valves connected to an air / 02 network, delivers air, possibly enriched with oxygen, to a patient 11 via a pipe. 2 or gas conveying conduit in fluid communication with a patient circuit 10 provided with an inspiratory branch 10a and an expiratory branch 10b. The pipe 2 is provided with a relief valve 4, arranged on an exhaust pipe 3 coming to connect fluidically to the pipe 2, upstream of a unidirectional flow sensor 5. The inspiratory branch 10a conveys the respiratory gas (ie, air or air / 02) to the patient 11, while the exhalation branch 10b is used to evacuate the exhaled gas by the patient 11, which are rich in CO2.

The delivery of the gas by the gas source 1 is effected by alternating inspiratory phases during which the breathing gas is inhaled by the patient 11, and exhaling during which gas is exhaled by the patient 11.

The expiratory limb 10b is provided with a solenoid valve 7 cooperating with an expiratory membrane device 8 so as to allow or prevent a gas outlet of the expiratory limb 10b to the atmosphere. The control of the fan, in particular of the gas source 1, is provided by fan control means 9, such as an electronic control card or the like. The fan and its components are supplied with electrical power from the mains, ie typically between 110 and 220 V, by conventional power supply means, such as cable, socket, connector ... During each inspiratory phase, the gas source 1 delivers to the patient 11 either a given gas volume in the context of a volumetric ventilation, or a given gas pressure in the context of a barometric ventilation. In the context of a volumetric ventilation, a unidirectional flow sensor 5, arranged on the circuit 2, upstream of the inspiratory branch 10a of the patient circuit 10, refers to the control means 9, flow information corresponding to the instantaneous flow rate of gas flowing in the pipe 2, towards the patient 11. The control means 9 then control the gas source 1 so that it adjusts its output rate with respect to a prefixed reference flow rate, if it turns out necessary. The gas delivered by the gas source 1 successively borrows the pipe 2 and the inspiratory branch 10a of the patient circuit 10 which routes it to a patient interface, such as a respiratory mask or an intubation probe, allowing it to be administered to the patient. patient 11. In order that the gas can not escape and be inhaled by the patient, the control card of the control means 9 actuates the solenoid valve 7 so that the expiratory membrane 8 is closed. The exhalation branch 10b of the patient circuit 10 is then obstructed and no gas flow thus escapes to the atmosphere via the membrane 8.

At the same time, the control card of the control means 9 also controls a backup valve 4, for example a two-position open / closed actuator type valve, in a closed position so that the gas passing through the pipe 2 can escape to the atmosphere through the exhaust duct 3, which duct 2 is connected and in fluid communication with the duct 2.

On the other hand, in the context of a barometric ventilation, a pressure sensor 6 arranged on the pipe 2, between the connection site of the exhaust pipe 3 and the patient circuit 10, replaces the flow sensor 5 so that the control card of the control means 9 processes pressure data to control the gas source 1 accordingly.

During each expiratory phase, the control card of the control means 9 actuates the solenoid valve 7 so as to open the membrane device 8 and thus allow the gases, in particular gases exhaled by the patient 11, to circulate in the chamber. expiratory limb 10b of the patient circuit 10 and their exit to the atmosphere, via the membrane device 8. For therapeutic purposes, the control card of the control means 9 can exploit the pressure signal returned by the pressure sensor 6 in order to control the solenoid valve 7 and, therefore, the membrane 8 and thus ensure that the expiration is at a pressure higher than the ambient pressure, that is to say at a positive expiratory pressure or PEP. At the same time, the control card of the control means 9 controls the source of gas 1 so as to deliver a constant rate, called the bias rate, by exploiting the signal of the flow sensor 5. Such a bias rate is by example between 1 and 10 l / min.

During the expiratory phase, the control card 9 also drives the emergency valve 4, also called exhaust valve 4, in a closed position so that the gas passing through the pipe 2 can not escape via the conduit exhaust 3. However, with this type of fan, there are risk situations that could put the life of the patient 11 in danger.

Thus, a pilot fault of the solenoid valve 7 can prevent the membrane 8 from opening, which makes it impossible for the patient 11 to exhale into the expiratory limb 10b. However, the gas source 1 also does not allow the gas to flow from the inspiratory branch 10a of the patient circuit 10 to the line 2. It then follows a significant risk of barotrauma and / or hypoxia of the patient 11 .

In order to avoid or minimize these risks of barotrauma and / or hypoxia of the patient 11, the emergency valve 4 arranged on the exhaust duct 3 is piloted. Thus, the signal returned by the pressure sensor 6 is exploited. by the control card 9 as explained below. If the instantaneous pressure value measured during the expiratory phase by the pressure sensor 6 passes a predetermined and stored obstruction detection threshold, the control card 9 actuates the emergency valve 4 to open it. The pressurized gas can then borrow the exhaust duct 3, escape to the atmosphere and depressurize the entire circuit 10.

In parallel, the gas source 1 is controlled by the control card 9 so as to stop any delivery of gas. The apparatus is then stopped, that is to say it no longer delivers gas, and the patient 11 must spontaneously breathe ambient air, through the emergency valve or actuator 4, and 5 then expires the CO2-rich gas through said same actuator 4. This is problematic because patients who may be connected to a ventilator, in particular a ventilator used in critical care, have by nature an altered respiratory function. , therefore may have difficulty breathing spontaneously. Typically, the actuator 4 and the pipe 3 have a minimal resistance to flow, typically between 2 and 6 cm of water at a flow rate of 60 l / min. The actuator 4 is therefore in its nominal operation, in a closed position so that no gas can borrow the pipe 3 and on rare occasions, in an open position to depressurize the system. Figure 1b is similar to Figure 1a, except for the replacement of the two-limb patient circuit 10a, 10b, by a single branch patient circuit 10 connected to a patient interface 12, such as a leak-proof breathing mask. intentionally 12a In other words, the patient circuit 10 is here single-branch and the patient interface is an intentional leakage mask 12a serving to promote the elimination of exhaled carbon dioxide by the patient and to generate a pressure drop of approximately 10 cm H 2 O for a flow rate of 24 l / min. However, such a leak is not sufficient to allow the complete expiration of the patient through it, that is to say the evacuation to the atmosphere of the entire volume exhaled by the patient. A part of the expired gases should therefore be able to flow in the opposite direction in the pipe 10 and escape through the source 1.

However, this is not possible because the pressure source 1 is unidirectional and does not allow a gas to cross it in the opposite direction. One solution could be to open the emergency valve 4 during the expiratory phase. However, this solution would not be ideal because the flow from the source 1, necessary to maintain a positive expiratory pressure (PEP) set for example at 5 cm H20, would then be very important, for example greater than 100 l / min. Such a flow would pose problems of oxygen consumption. In addition, the flow sensor 5 is generally in the image of the pneumatic diagram in which it is implemented, so here unidirectional. It can therefore only measure the flows flowing from the gas source 1 to the patient circuit 10. Any gas flow flowing in the opposite direction could not be measured, which would cause problems monitoring the exhaled gas by the patient. . As a result, it is not possible to perform leak ventilation with a critical care appliance as shown in Figure 1b.

Figure 2 shows schematically the architecture and operation, according to a first embodiment, of a double branch medical circuit ventilator according to the present invention. The pneumatic diagram proposed in FIG. 2 is identical to that of FIG. 1a, with the exception of the exhaust valve or actuator 4a, and of the flow sensor 5a.

More precisely, the exhaust valve or actuator 4a is of the proportional operating type, that is to say that it is possible for it to pass from a closed position to an open position by progressively obscuring its passage diameter. . This gradual reduction of the passage diameter of the exhaust valve 4a is controlled by the control means 9 of the fan.

Furthermore, the flow sensor 5a used is bidirectional, that is to say it is designed to be able to measure the gases bidirectionally, that is to say in the direction of the pipe 2 towards the patient 11 and also in the opposite direction, that is to say the patient 11 to the pipe 3, when the actuator 4 is in open safety position. Such a system also makes it possible to avoid any possible overpressure at the level of the patient 11 because the actuator 4a can also be controlled so as to be closed or open, depending on the pressure detected by the pressure sensor 6. then the operating principle described above in connection with Figure la. Furthermore, the pneumatic diagram proposed in FIG. 3 is identical to that of FIG. 1b, with the exception of the actuator 4a and the flow sensor 5a, which have been modified as in the embodiment of FIG. and the operation of the fan which has been adapted to these changes so as to provide so-called "leakage" ventilation. More specifically, in the context of such ventilation, the fan implements a patented single-branch circuit 10a, that is to say mono-branch 10a, associated with a non-invasive mask 12 type leaked interface 12a, as explained above.

Such a ventilation is of the barometric type because the leakage 12a prevents a precise volume of gas being delivered to the patient 11. It alternates inspiratory phases where gas is inspired by the patient 11, and expiratory where gas has expired by the patient 11. During each inspiratory phase, the gas source 1 delivers to the patient 11 a given gas pressure. The pressure sensor 6 measures and sends back to the control card 3031447 9 control means 9, information or a pressure signal measured in the pipe 2. The control card of the control means 9 then drives the gas source 1 so that it adjusts its output accordingly.

The gas delivered by the source 1 borrows the pipe 2 and the branch of the patient circuit 10. At the same time, the control card controls the emergency valve or exhaust valve 4a in a closed position so that the gas borrowing the pipe 2 can not escape into the pipe 3.

The flow sensor 5a measures the flow flowing in the pipe 2 and transmits the information to the control card 9 which draws volume information at the end of the inspiratory phase. This flow rate can be compensated to take account of the leak 12a of the mask and reconstruct the volume a priori really inspired by the patient 11. During the first part of the expiry phase, the control card of the control means 15 opens the actuator 4a so that a portion of the gas exhaled by the patient flows in the patient circuit 10, the pipe 2 and the pipe 3, the other part of the exhaled gas escaping through the mask leak 12a . This actuator 4a will then be controlled proportionally by the control card 9, as in connection with FIG. 2, in order to maintain the desired expiratory pressure by relying on the signal emitted by the sensor 6. At the same time, the control card 9 controls the source of gas 1 so as to stop the delivery of gas and to promote the expiration of the patient 11. It appears that the exhalation flow of the patient 11 passing through the ducts 2 and 3 is known from the card control 9 via the signal transmitted by the sensor 5a. Such a rate is decreasing and is 0 when the patient has completed its expiration. This information can be advantageously used so that the control card 9 controls the source of gas 1 so that it begins to charge again as the flow information approaches 0 to reach a command such as the gas source 1 delivers a flow rate for generating the PEEP set through the leak 12a of the mask 12. Such a fixed control is easy to adjust empirically, for example by prior characterization of the leak 12a or a cycle adjustment to cycle of the command. At the end of the patient expiration the actuator 4a is then completely closed and the gas source 1 placed at a rate guaranteeing the PEEP set. In order to refine this set PEP the control board 9 exploits the pressure information of the sensor 6 in order to control the gas source accordingly. In addition to allowing the system to progressively connect different phases of regulation of the gas source 1 and the actuator 4a, the flow sensor 5a also makes it possible to know the portion of volume exhaled by the patient 11 having borrowed the pipes. 2 and 3. Taking into account the characteristics of the intentional leakage 12a, it is possible to reconstruct the flow a priori actually exhaled by the patient. Any difference between the inspiratory and expiratory volumes thus reconstituted may be the sign of an unintentional leak, that is to say, resulting from gaps between the pad of the mask and the skin of the patient, following a bad fit by example. The measurement of such difference could lead to the generation of an alarm signal to warn the user that action on his part is required. The ventilator or medical device according to the invention can be used to provide light care and critical care ventilation, in invasive or non-invasive ventilation mode.

Claims (10)

REVENDICATIONS1. A medical breathing ventilator comprising: - a gas source (1) fluidly connected to a gas supply pipe (2), - a gas supply pipe (2) fluidly connecting the gas source (1). ) to a patient circuit (10) comprising at least one inspiratory limb (10a), - an exhaust duct (3) fluidly connected to the gas supply duct (2), - an exhaust valve (4a) ) arranged on said exhaust duct (3), and - a gas flow sensor (5a) arranged on the gas conveying pipe (2), characterized in that: - the exhaust valve (4a) is proportional operation and - the gas flow sensor (5a) is bidirectional type. 2. Fan according to the preceding claim, characterized in that it comprises control means (9) cooperating with the exhaust valve (4a). 20 3. Fan according to the preceding claim, characterized in that it comprises control means (9) designed to control the exhaust valve (4a), during expiratory phases of the patient, so as to operate a gradual reduction of the diameter passage of the exhaust valve (4a) between several positions. 25 4. Fan according to one of the preceding claims, characterized in that the exhaust valve (4a) comprises: - a fully closed position, wherein the passage diameter of the exhaust valve (4a) is completely closed and no gas flow can pass through said exhaust valve (4a), - a fully open position, wherein the exhaust valve passage diameter (4a) is completely clear and a maximum gas flow rate can pass through said exhaust valve (4a), and 3031447 12 - at least one partial opening position, in which at least one intermediate gas flow rate lower than the maximum gas flow rate can pass through said exhaust valve (4a) . 5. Fan according to one of the preceding claims, characterized in that the bidirectional flow sensor (5a) is designed to measure the flow of gas flowing in the pipe (2) in the direction from the source (1) of gas to the inspiratory branch (10a), and in the opposite direction. 6. Fan according to one of the preceding claims, characterized in that the bidirectional flow sensor (5a) is designed to measure the flow of gas flowing in the pipe (2) in the direction from the inspiratory branch (10a) to the source (1) of gas, and transmit at least one flow measurement signal corresponding to the control means (9), when the exhaust valve (4a) is controlled by said control means (9) to be in position total or partial opening. 7. Fan according to one of the preceding claims, characterized in that the exhaust duct (3) is fluidly connected to the gas channel (2) between the gas source (1) and the sensor gas flow (5a). 8. Fan according to one of the preceding claims, characterized in that the gas source (1) comprises a motorized turbine or one or more solenoid valves fluidly connected to one or more gas supplies, in particular to an air network or of 02. 9. Ventilator according to one of the preceding claims, characterized in that the patient circuit (10) comprises: - an inspiratory branch (10a) and an expiratory branch (10b), or - only an inspiratory branch (10a) fluidly connected to a patient interface (12) with a leak rate. 10. Fan according to one of the preceding claims, characterized in that it further comprises a gas pressure sensor (6) arranged on the gas channel (2).