SUPPLY DEVICE AND PROCESS FOR SUPPLYING A PATIENT-SIDE COUPLING UNIT WITH A GAS MIXTURE

Abstract

A device and to a process supply a patient-side coupling unit (9) with a gas mixture. The patient-side coupling unit is connectable to a patient (Pt). A first duct (K.1) guides a first gas component (air) from a first source (2) to a mixing point (8). A second source (20) provides a second gas component, which is guided to a front pressure inlet (V.3) of a pressure reducer (1). The pressure reducer provides the second gas component (O2) at a back pressure outlet (V.2). A time course of pressure at the back pressure outlet follows a time course of pressure at a reference point (11, 28.1) in the first duct. A second duct (K.2) guides the second gas component from the back pressure outlet to the mixing point. An inhalation duct (K.30) guides the gas mixture from the mixing point to the patient-side coupling unit.

Claims

1. A supply device for supplying a patient-side coupling unit with a gas mixture, the gas mixture comprising a first gas component and a second gas component, wherein the patient-side coupling unit is connectable to a patient, the supply device comprising: a first duct with a supply connection element configured to establish a fluid connection with a first source for the first gas component; a second duct; a mixing point; an inhalation duct; and a pressure reducer with a front pressure inlet configured to establish a fluid connection with a second source for the second gas component and with a back pressure outlet connected to the second duct, wherein the first duct is configured to guide the first gas component from the supply connection element to the mixing point, wherein the second duct is configured to guide the second gas component from the back pressure outlet to the mixing point, wherein the pressure reducer is configured to provide the second gas component such that a time course of pressure at the back pressure outlet follows a time course of pressure at a reference point in the first duct, and wherein the inhalation duct is configured to guide a gas mixture generated or emerged at the mixing point to the patient-side coupling unit.

2. A supply device in accordance with claim 1, further comprising: a first valve configured to change a volume flow through the first duct or a pressure in the first duct or both the volume flow through the first duct and the pressure in the first duct; a first sensor configured to measure an indicator of pressure in the first duct or configured to measure an indicator of volume flow through the first duct; and a signal-processing control device configured to carry out a first closed-loop control to actuate the first valve during the first control as a function of measured values of the first sensor and based on a first control gain; the first sensor configured to measure an indicator of pressure and the first control gain being the actual time course of pressure in the first duct to follow a predefined desired pressure time course; or the first sensor configured to measure an indicator of volume flow and the first control gain being the actual time course of volume flow through the first duct to follow a predefined desired volume flow time course.

3. A supply device in accordance with claim 2, further comprising: a second valve configured to change a volume flow through the second duct or a pressure in the second duct or both the volume flow through the second duct and the pressure in the second duct; a second sensor configured to measure an indicator of pressure in the second duct or configured to measure an indicator of volume flow through the second duct; and a signal-processing control device configured to carry out a second closed-loop control to actuate the second valve during the second control as a function of measured values of the second sensor and based on a second control gain: the second sensor configured to measure an indicator of pressure and the second control gain being the actual time course of pressure in the second duct to follow a predefined desired pressure time course; or the second sensor configured to measure an indicator of volume flow and the second control gain being the actual time course of volume flow through the second duct to follow a predefined desired volume flow time course.

4. A supply device in accordance with claim 1, further comprising: a second valve configured to change a volume flow through the second duct or a pressure in the second duct or both the volume flow through the second duct and the pressure in the second duct; and a second sensor configured to measure an indicator of pressure in the second duct or configured to measure an indicator of volume flow through the second duct; and a signal-processing control device configured to carry out a second closed-loop control to actuate the second valve during the second control as a function of measured values of the second sensor and based on a second control gain: the second sensor configured to measure an indicator of pressure and the second control gain of providing the actual time course of pressure in the second duct to follow a predefined desired pressure time course; or the second sensor configured to measure an indicator of volume flow and the second control gain being the actual time course of volume flow through the second duct so as to follow a predefined desired volume flow time course.

5. A supply device in accordance with 1, further comprising a pneumatic control line pneumatically connected to the pressure reducer and pneumatically connected to the first duct at a branch point, wherein: the pneumatic control line establishes a fluid connection between the first duct and the pressure reducer such that a time course of pressure in the pneumatic control line follows a time course of pressure at the branch point; and the pressure reducer is configured to cause the time course of the pressure at the back pressure outlet to follow the time course of the pressure in the pneumatic control line.

6. A supply device in accordance with claim 5, wherein a front pressure chamber connected or connectable to the first source via the front pressure inlet, a back pressure chamber connected to the second duct via the back pressure outlet, and a control pressure chamber are formed in an interior of the pressure reducer; the pneumatic control line is in a fluid connection with the control pressure chamber such that a pressure in the control pressure chamber follows the pressure in the pneumatic control line; and the pressure reducer is configured such that the time course of a pressure at the back pressure outlet follows a time course of the pressure in the control pressure chamber.

7. A supply device in accordance with claim 6, wherein the pressure reducer comprises a partition wall with an opening and a closure for the opening; the partition wall separates the front pressure chamber from the back pressure chamber; the opening in the partition wall connects the front pressure chamber to the back pressure chamber; the closure is configured to selectively release or to close the opening in the partition wall; and the pressure reducer is configured such that the closure releases the opening when a predefined criterion is met and otherwise closes the opening; wherein the criterion depends on pressure in the control pressure chamber or on pressure in the back pressure chamber or on both pressure in the control pressure chamber and pressure in the back pressure chamber.

8. A supply device in accordance with claim 7, wherein: the pressure reducer comprises a housing and a wall separates the back pressure chamber from the control pressure chamber; the wall between the back pressure chamber and the control pressure chamber is movable relative to the pressure reducer housing or is flexible or is both movable and flexible such that a volume of the back pressure chamber and a volume of the control pressure chamber are variable; and the movable or flexible wall is in a functional connection with the closure for the opening in the partition wall.

9. A supply device in accordance with 1, further comprising: a pressure sensor configured to measure an indicator of pressure at a measuring point in the first duct; and a signal-processing pressure-reducing control device configured to cause, depending on a signal of the pressure sensor, the time course of the pressure at the back pressure outlet to follow a time course of pressure at the reference point in the first duct.

10. A supply device in accordance with claim 9, wherein: a back pressure chamber that is connected via the back pressure outlet to the second duct is formed in an interior of the pressure reducer; the pressure reducer comprises an actuatable pressure reducer actuator; the pressure-reducing control device is configured: to actuate the pressure reducer actuator depending on a signal of the pressure sensor; and to cause, by the actuation, a time course of pressure in the back pressure chamber to follow the time course of the pressure at the reference point in the first duct.

11. A supply device in accordance with claim 10, wherein: the pressure reducer comprises: a front pressure chamber connectable to the first source via the front pressure inlet; a partition wall with an opening; and a closure for the opening; wherein the partition wall separates the front pressure chamber from the back pressure chamber; wherein the opening in the partition wall connects the front pressure chamber to the back pressure chamber; wherein the closure is configured to selectively release or close the opening in the partition wall; and the pressure reducer actuator is in a functional connection with the closure.

12. A supply device in accordance with claim 10, wherein a wall of the back pressure chamber is movable relative to another wall of the back pressure chamber such that a volume of the back pressure chamber is variable; and the pressure reducer actuator is in a functional connection with the movable wall.

13. A supply device in accordance with claim 1, in combination with a first source configured to provide the first gas component and a second source configured to provide the second gas component to form a supply system for supplying the patient-side coupling unit with the gas mixture comprising the first gas component and the second gas component.

14. A supply device combination in accordance with claim 13, wherein the second source provides the second gas component with a higher pressure compared to pressure with which the first source provides the first gas component.

15. A ventilation system for artificial ventilation of a patient with a gas mixture, the gas mixture comprising a first gas component and a second gas component, wherein at least one of the two gas components is oxygen or contains oxygen, the ventilation system comprising: a fluid delivery unit; a patient-side coupling unit connectable to a patient; and a supply device comprising: a first duct with a supply connection element configured to establish a fluid connection with a first source for the first gas component; a second duct; a mixing point; an inhalation duct; and a pressure reducer with a front pressure inlet configured to establish a fluid connection with a second source for the second gas component and with a back pressure outlet, the back pressure outlet being connected to the second duct, wherein the first duct is configured to guide the first gas component from the supply connection element to the mixing point, wherein the second duct is configured to guide the second gas component from the back pressure outlet to the mixing point, wherein the pressure reducer is configured to provide the second gas component such that a time course of pressure at the back pressure outlet follows a time course of pressure at a reference point in the first duct, wherein the inhalation duct is configured to guide a gas mixture generated or emerged at the mixing point to the patient-side coupling unit, and wherein the ventilation system is configured to carry out ventilation strokes and to guide during each ventilation stroke a respective quantity of the gas mixture through the inhalation duct to the patient-side coupling unit.

16. A ventilation system in accordance with claim 15, further comprising: a first valve configured to change a volume flow through the first duct; and a signal-processing control device configured: to derive a desired volume flow time course of the first gas component depending on a predefined desired time course of the volume flow of the gas mixture; and to actuate the first valve based on a control gain, the control gain being the actual volume flow through the first duct being equal to the derived desired time course of the volume flow of the first gas component.

17. A ventilation system in accordance with claim 15, further comprising: a second valve configured to change a volume flow through the second duct; and a signal-processing control device configured: to derive a desired volume flow time course of the second gas component depending on a predefined desired time course of the volume flow of the gas mixture; and to actuate the second valve based on a control gain, the control gain being the actual volume flow through the second duct being equal to the derived desired time course of the volume flow of the second gas component.

18. A supply process for supplying a patient-side coupling unit with a gas mixture, the gas mixture comprising a first gas component and a second gas component, wherein the patient-side coupling unit is connectable to a patient, the supply process being carried out with a supply device comprising a first duct with a supply connection element, a second duct, a mixing point, an inhalation duct, and a pressure reducer with a front pressure inlet and with a back pressure outlet, the supply process comprises the steps of: providing the first gas component at the supply connection element; providing the second gas component at the front pressure inlet of the pressure reducer; the pressure reducer providing the second gas component at its back pressure outlet; causing a time course of a pressure at the back pressure outlet to follow a time course of pressure at a reference point in the first duct; guiding the first gas component from the supply connection element to the mixing point with the first duct; guiding the second gas component from the back pressure outlet of the pressure reducer to the mixing point with the second duct; the gas mixture is generated or emerged at the mixing point; and guiding the gas mixture comprising the first gas component and the second gas component from the mixing point through the inhalation duct to the patient-side coupling unit.

19. A supply process in accordance with claim 18, wherein: the supply device comprises a pneumatic control line; the pneumatic control line is pneumatically connected to the pressure reducer and at a branch point to the first duct; a time course of a pressure in the pneumatic control line follows a time course of a pressure at the branch point; a time course of a pressure at the back pressure outlet follows the pneumatic control line pressure time course; and thereby the back pressure outlet pressure time course follows the time course of pressure at the reference point.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In the drawings:

[0075] FIG. 1 is a schematic view showing how a patient is ventilated mechanically with a gas mixture comprising air and oxygen, wherein the two components are delivered by two ducts;

[0076] FIG. 2 is a schematic view showing a ventilation circuit, in which a patient is supplied with a mixture of air, oxygen and an anesthetic and is anesthetized with a mixture of air, oxygen and an anesthetic;

[0077] FIG. 3 is a schematic view showing the time course of the volume flow and that of the pressure of the gas mixture that is flowing to the patient;

[0078] FIG. 4 is a schematic view showing a purely pneumatic pressure reducer;

[0079] FIG. 5 is a schematic view showing an exemplary dependence of the back pressure on the volume flow;

[0080] FIG. 6 is a schematic view showing an actuated pressure reducer with a control pressure chamber; and

[0081] FIG. 7 is a schematic view showing an actuated pressure reducer without a control pressure chamber.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0082] Referring to the drawings. the present invention is used in the exemplary embodiment to mechanically ventilate a patient Pt. A patient-side coupling unit 9, for example, a breathing mask or a tube or a catheter, is attached at or in the body of the patient Pt.

[0083] A ventilator 100, shown only schematically, performs a sequence of ventilation strokes and delivers a gas mixture to the patient-side coupling unit 9 and hence to the patient Pt during each ventilation stroke. This gas mixture contains a percentage (vol.%) of oxygen, this percentage having been predefined by a user. This percentage of oxygen may be higher than the percentage of oxygen in the breathing air. In order to increase the percentage of oxygen compared to breathing air, a gas mixture of breathing air and pure oxygen is generated in the exemplary embodiment. The gas mixture may additionally contain an anesthetic, so that the patient Pt is sedated or anesthetized.

[0084] FIG. 1 schematically shows a device for generating this gas mixture with a higher percentage of oxygen. The two components of the gas mixture, namely, air and pure oxygen, are provided in two ducts K.1 and K.2, a first duct K.1 providing the air and a second duct K.2 providing the oxygen, and the two ducts K.1 and K.2 being merged at a mixing point 8.

[0085] It is possible that a gas mixer mixes the two gas components to form the gas mixture. Such a gas mixer is described, for example, in DE 102008057180 B3 (corresponding to US 8,356,596 B2 which is incorporated by reference), in DE 102012008108 A1 (corresponding to US 9,346,026 B2 which is incorporated by reference), and in DE 102016001383 A1 (corresponding to US 10,821,256 B2 which is incorporated by reference). A Y-piece is arranged at the mixing point 8 in the simplest case.

[0086] An inhalation duct K.30, for example, a hose for the inhalation and optionally a two-lumen hose with one lumen for the inhalation and one lumen for the exhalation, leads from this mixing point 8 to the patient-side coupling unit 9. This inhalation duct K.30 guides the mixture of air and pure oxygen to the patient-side coupling unit 9.

[0087] A user predefines a desired percentage of oxygen in the gas mixture. For example, the user sets the desired oxygen content manually by means of a rotary knob 30 shown schematically.

[0088] A blower 2 or another delivery unit of the ventilator 100 suctions ambient air through an inlet E of the ventilator 100 and feeds the suctioned air into the first duct K.1. A filter 23 is arranged between the inlet E and the blower 2. In the application according to FIG. 1, the delivery unit 2 acts as the source for the first gas component.

[0089] An inlet of the first duct K.1 in the form of a supply connection element V.1 is connected to a supply outlet of the blower 2. The pressure in the first duct K.1 ideally follows a predefined time course (temporal profile), and it is, for example, constant over time. The pressure in the first duct K.1 is above the maximum ventilation pressure in the exemplary embodiment, i.e., it is above the maximum pressure with which the gas mixture is delivered to the patient-side coupling unit 9 and farther into the lungs of the patient Pt, and it is preferably between 20 mbar and 100 mbar.

[0090] The volume flow, i.e., the flow of gas per unit of time, through the first duct K.1 downstream of the delivery unit 2 and/or the pressure in the first duct K.1 shall follow each a respective predefined time course. FIG. 3 shows an exemplary required time course of the volume flow (Vol′) at the top and an exemplary required time course of the pressure (P) at the bottom. Values over the x axis mean a flow of the gas mixture towards the patient Pt (inhalation) and values under this axis mean a flow away from the patient Pt (exhalation).

[0091] A signal-processing control device 3 carries out a control, wherein the actual volume flow is the controlled variable. The predefined time course of the volume flow is the command variable, cf. FIG. 1 and FIG. 2. The control device 3 actuates a proportional valve 4.1 and changes thereby the volume flow through the first duct K.1 downstream of the proportional valve 4.1 to the mixing point 8.

[0092] A pneumatic resistance 5.1, for example, a narrowing, is arranged in the first duct K.1. A volume flow sensor 6.1 measures the difference ΔP between the pressure upstream and the pressure downstream of the pneumatic resistance 5.1 and derives an indicator of the actual volume flow through the first duct K.1 from the pressure difference. In addition, a pressure sensor 7,1 measures the actual pressure in the first duct K.1 at a measuring point 28.1 downstream of the pneumatic resistance 5.1. The control device 3 receives a signal each from the two sensors 6.1 and 7.1.

[0093] The second duct K.2 receives pure oxygen (O2) from a supply line 21, which is in connection with a supply port 20. This supply port 20 is arranged in the example shown stationarily in a wall W and belongs to a stationary supply system of a hospital infrastructure. It is also possible that the second duct K.2 receives pure oxygen from at least one pressurized cylinder. The supply port 20 provides the pure oxygen with a pressure that is between 2 bar and 8 bar. An optional nonreturn valve 26 in the supply line 21 prevents pure oxygen from being pressed back into the supply port 20 and then into the hospital infrastructure.

[0094] A pneumatic pressure reducer 1 comprises a front pressure inlet V.3 and a back pressure outlet V.2. The front pressure inlet V.3 is connected to the supply line 21, and the back pressure outlet V.2 is connected to the second duct K.2. The pressure reducer 1 reduces the pressure from the supply port 20 with the aim of having the pressure at the back pressure outlet V.2 of the pressure reducer 1 follow the pressure, which is variable over time, at a referable point 11, 28.1, which will be described below. As a result, the pressure at the back pressure outlet V.2 follows the pressure at the supply connection element V.1 and hence the pressure at the supply outlet of the blower 2. How this goal is achieved will be described in more detail below.

[0095] A pneumatic resistance 5.2, a volume flow sensor 6.2, a pressure sensor 7.2 and a proportional valve 4.2 are arranged in the second duct K.2. These components operate like the corresponding components in the first duct K.1. The pressure sensor 7.2 measures at a measuring point 28.2 an indicator of the pressure in the second duct K.2. The control device 3 controls in the exemplary embodiment the proportional valve 4.2 with the control gain of having the actual volume flow through the second duct K.2 to follow a predefined time course.

[0096] FIG. 2 shows another application of the present invention, in which the patient Pt is not only ventilated mechanically, but is additionally also sedated or anesthetized. Identical reference numbers have the same meanings as in FIG. 1.

[0097] The embodiment according to FIG. 2 has the following additional components: [0098] an anesthetic evaporator 27, which generates gaseous anesthetic, [0099] an exhalation fluid connection with a first section 31 and with a second section 32, and [0100] an absorber 25 for CO2 and anesthetic.

[0101] The gaseous anesthetic, which is generated by the anesthetic evaporator 27, is fed into the gas mixture, which is guided through the inhalation duct K.30 to the patient-side coupling unit 9 and is inhaled by the patient Pt. The anesthetic is fed in the example shown into the first duct K.1 and it flows into this to the mixing point 8. It is also possible that it is fed into the second duct K.2 or into the inhalation duct K.30.

[0102] The air exhaled by the patient Pt often still contains anesthetic. This anesthetic shall not escape into the surrounding area. A closed ventilation circuit is therefore formed. The exhalation fluid connection 31, 32 leads from the patient-side coupling unit 9 back to the blower 2. The blower 2 maintains a flow of gas through this closed ventilation circuit. The first section 31 leads from the patient-side coupling unit to the CO2 absorber 25. This CO2 absorber 25 absorbs carbon dioxide and optionally also anesthetic from the exhaled air. The second section 32 guides the exhaled air, from which the carbon dioxide and optionally the anesthetic had been absorbed, to the filter 23 and from there to the blower 2.

[0103] The absorber 25 acts in this embodiment as the source for the first gas component (air), which enters into the first duct K.1.

[0104] As was already described, a gas mixture is delivered from the mixing point 8 to the patient-side coupling unit 9. The actual volume flow of this gas mixture downstream of the mixing point 8 shall follow a predefined time course. In addition, a required percentage of oxygen is predefined, preferably as vol.%. This oxygen content may be constant over time or variable over time. The predefined time course of the volume flow to the patient-side coupling unit 9, the required percentage of oxygen in the gas mixture as well as the known percentage of oxygen in the air result in a desired time course of the volume flow through the first duct K.1 and in a desired time course of the volume flow through the second duct K.2. The control device 3 or a higher-level control device calculates these two desired time courses for the two ducts K.1 and K.2, and the control device 3 actuates the two proportional valves 4.1 and 4.2 as a function of these two desired time courses. The control device 3 consequently carries out two controls of the volume flow, namely, one in the first duct K.1 and one in the second duct K.2. The same control algorithm can be used in many cases to actuate the two proportional valves 4.1 and 4.2. This is possible especially because the same pressure is present at the supply outlet of the blower 2 and at the back pressure outlet V.2 of the pressure reducer 1. This is brought about by the pneumatic or electronic control (open-loop control) or control (closed-loop control) described below.

[0105] FIG. 1 and FIG. 4 illustrate a pneumatic control of the pressure reducer 1. A pneumatic control line 10 leads from a branch point 11 in the first duct K.1 to a control pressure inlet V.4 of the pressure reducer 1. This control pressure inlet V.4 is needed for the pneumatic control, but not for the electronic control or control described below. The pneumatic control line 10 is preferably configured as a flexible hose, but it may also be a rigid tube. The branch point 11 is arranged downstream of the blower 2 and upstream of the proportional valve 4.1; it also begins upstream of the pneumatic resistance 5.1 in the embodiment shown, and this branch point 11 acts as the reference point in one embodiment.

[0106] Thanks to the pneumatic control line 10, the same pressure is always present at the control pressure inlet V.4 of the pressure reducer 1, aside from inevitable time delays and leaks, as in the first duct K.1, and there in the section between the blower 2 and the proportional valve 4.1 and especially as at the reference point (branch point 11). This pressure in the first duct K.1, which is variable over time, acts as a control pressure and hence as a master and the pressure in the inlet of the second duct K.2 follows this control pressure, which is variable over time, as a slave.

[0107] FIG. 4 shows an exemplary embodiment of a pneumatically operating pressure reducer 1. The front pressure inlet V.3 of the pressure reducer 1 is connected to the supply line 21. The control pressure inlet V.4 is connected to the pneumatic control line 10. The second duct K.2 is connected to the pneumatic control line 10. The second duct K.2 begins in the back pressure outlet V.2 of the pressure reducer 1.

[0108] A rigid housing 19 encloses the interior of the pressure reducer 1. Three chambers, namely [0109] a front pressure chamber Ka.1, which is in a fluid connection with the supply line 21 via the front pressure inlet V.3, [0110] a back pressure chamber Ka.2, which is in a fluid connection with the second duct K.2 via the back pressure outlet V.2, as well as [0111] a control pressure chamber Ka.3, which is in a fluid connection with the pneumatic control line 10 via the control pressure inlet V.4, are formed in this interior.

[0112] A partition wall 15 in the pressure reducer 1 separates the back pressure chamber Ka.2 from the front pressure chamber Ka.1. The partition wall 15 is preferably rigid. An opening 29 is preferably formed in the partition wall 15. A spring-loaded closure 13 is movable linearly relative to the partition wall 15 in two opposite directions (vertically upwards and downwards in FIG. 3) and can release or close this opening 29.

[0113] A movable wall 12 is fastened on the inside to the housing of the pressure reducer 1 and it separates the control pressure chamber Ka.2 from the back pressure chamber Ka.3. The movable wall 12 has the shape of a flexible membrane in the exemplary embodiment. The membrane 12 comprises in one embodiment a fixed plate arranged in a centered manner. The movable wall 12 may also have the form of a rigid plate, which is displaceable vertically in both directions relative to the housing 19. The movable wall 12 preferably separates the two chambers Ka.2 and Ka.3 from one another in a fluid tight manner, aside from inevitable leaks.

[0114] The just described construction of the pressure reducer 1 causes the second gas component, here oxygen, to be contained in the front pressure chamber Ka.1 and in the back pressure chamber Ka.2, and the first gas component, here air, to be contained in the control pressure chamber Ka.3. The movable wall 12 prevents these two gas components from mixing with one another in the pressure reducer 1. In a state in which the closure 13 releases the opening 29, the two chambers Ka.1 and Ka.2 are in a fluid connection with one another, and a pressure equalization can take place. With the opening 29 closed, the partition wall 15 interrupts this fluid connection and prevents a pressure equalization.

[0115] A lever 14 is rotatable about an axis of rotation and it lies at the top on the movable wall 12, optionally at the top on the fixed plate of the membrane. The closure 13 lies at the top on the lever 4. As can be seen in FIG. 4, a short lever arm is formed between the axis of rotation DA and the contact point of the closure 13 as well as a long lever arm is formed between the axis of rotation DA and the contact point of the lever 14 on the movable wall 12. As a result, the movable wall 12 is in a functional connection with the closure 13 and can apply a strong force to the closure 13.

[0116] The same pressure prevails in the front pressure chamber Ka.1 as in the supply line 21, i.e., a front pressure that is preferably between 2 bar and 8 bar and is therefore several times higher than the pressure in the two ducts K.1 and K.2. The same pressure prevails in the control pressure chamber Ka.3 as in the pneumatic control line 10 and consequently ideally also the same pressure prevails there as in the first duct K.1 and there in the section between the blower 2 and the proportional valve 4.1. The same pressure with which the second duct K.2 provides pure oxygen is generated in the back pressure chamber Ka.2.

[0117] Thanks to the movable wall 12, the same pressure always becomes established in the two chambers Ka.2 and Ka.3 in case of a variable control pressure (pressure in the first duct K.1) as well. After a change in the control pressure, i.e., in the pressure in the control pressure chamber Ka.3, there is, as a rule, a transient phase before the pressures become equal again. Depending on the position of the movable wall 12, the closure 13 therefore opens or closes the opening 29 in the partition wall 15 and thus makes possible or prevents the flow of pure oxygen from the supply line 21 through the pressure reducer 1 into the second duct K.2. In case of a sufficiently high pressure in the back pressure chamber Ka.2, the movable wall 12 brings about closing of the opening 29 by the closure 13 by means of the functional connection (lever 14).

[0118] The blower 2 ideally generates a constant pressure, doing so independently from the volume flow. This constant pressure is therefore likewise present ideally at the outlet of the pressure reducer 1. The generated pressure decreases in practice with increasing volume flow. FIG. 5 shows this situation as an example, the volume flow Vol′ in [L/min] being plotted on the x axis and the generated back pressure P in [mbar] on the y axis. The designation “back pressure” relates to the outlet of the blower 2. The time course P.2(50) shows the time course of the actual pressure P, which is generated by the blower 2, depending on the volume flow Vol′ in a situation in which the blower 2 shall generate a pressure of 50 mbar. The time course P.2(30) shows the actual pressure at a desired pressure of 30 mbar. The time course P.1 shows the actual pressure at the back pressure outlet V.2 of the pressure reducer 1. It can be seen that despite the dependence on the volume flow, the pressure at the outlet of the pressure reducer 1 is closely correlated with the control pressure (back pressure of the blower 2).

[0119] FIG. 6 and FIG. 7 show two alternative embodiments of the pressure reducer 1. Identical reference numbers have the same meanings as in FIG. 1 and in FIG. 4. The measuring point 28.1, at which the pressure sensor 7.1 measures the pressure, is used as the reference point.

[0120] The two alternative embodiments eliminate the need for a pneumatic control line 10 from the first duct K.1 to the pressure reducer 1 as well as for a pneumatic control pressure inlet V.4. Identical reference numbers have the same meanings as in FIG. 4. In the two alternative embodiments, the pressure reducer 1 has only one inlet, namely, the front pressure inlet V.3, which connects, in turn, the front chamber Ka.1 to the supply line 21.

[0121] The embodiment according to FIG. 6 will be described first. The pressure acts likewise from one side on the movable wall 12 in the back pressure chamber Ka.2, and the force of a spring 16 acts from the other side in the control pressure chamber Ka.3. The spring 16 is connected on the one side to the movable wall 12 and on the other side to a mechanical connection element 18 and it seeks to expand. An actuated control pressure actuator 17, for example, a pump or a piston-and-cylinder unit, is supported at the housing 19 of the pressure reducer 1 and acts from one side on the connection element 18. The control pressure actuator 17 is capable of increasing and decreasing the distance between the connection element 18 and the lower wall of the housing 19 and thereby also the force of the spring 16. The closer the connection element 18 is to the movable wall 12, the stronger is the spring force of the spring 16.

[0122] The control device 3 receives a respective signal each from the two pressure sensors 7.1 and 7.2, cf. FIG. 1, and controls the control pressure actuator 17 such that the pressure in the control pressure chamber Ka.3 and hence the pressure in the second duct K.2 follows the pressure in the first duct K.1 downstream of the blower 2.

[0123] The pressure reducer 1 according to FIG. 7 comprises no back pressure chamber and no movable wall. The control pressure actuator 17 is located in the back pressure chamber Ka.2 and is mechanically connected to the closure 13 via the connection element 18. The pressure control pressure actuator 17 is capable of directly moving the closure 13 in two opposite, vertical directions and is thereby able to move the closure 13 optionally into a released position or into a closed position.

[0124] The embodiments according to FIG. 4 and according to FIG. 6 or FIG. 7 of the pressure reducer 1 may be combined with one another. According to this combination, the pressure reducer 1 consequently has both the control pressure inlet V.4 and the spring 16, the control pressure actuator 17 and the connection element 18. The supply device is preferably configured in this combination as it is shown in FIG. 1. The actuated control pressure actuator 17 and the spring 16 can compensate differences between the pressure in the back pressure chamber Ka.2 and the pressure in the first duct K.1 to a certain extent.

[0125] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

TABLE-US-00001 List of Reference Characters 1 Pneumatic pressure reducer between the supply line 21 and the second duct K.2; it comprises the back pressure outlet V.2, the front pressure inlet V.3 and the optional control pressure inlet V.4 2 Blower of the ventilator 100; it comprises the inlet E; it is connected via a supply outlet to the first duct K.1,acts as the first source in one embodiment 3 Signal-processing control device; it receives signals from the sensors 6.1, 6.2, 7.1, 7.2 and actuates the proportional valves 4.1 and 4.2 and in one embodiment the control pressure actuator 17 4.1 Proportional valve in the first duct K.1; it is capable of changing the volume flow through the first duct K.1; it is actuated by the control device 3 4.2 Proportional valve in the second duct K.2; it is capable of changing the volume flow through the second duct K.2; it is actuated by the control device 3 5.1 Pneumatic resistance in the first duct K.1 5.2 Pneumatic resistance in the second duct K.2 6.1 Volume flow sensor; it measures the pressure difference ΔP upstream and downstream of the pneumatic resistance 5.1 and diverts the volume flow through the first duct K.1 6.2 Volume flow sensor; it measures the pressure difference ΔP upstream and downstream of the pneumatic resistance 5.2 and diverts the volume flow through the second duct K.2 7.1 Pressure sensor; it measures at the measuring point 28.1 an indicator of the pressure in the first duct K.1 7.2 Pressure sensor; it measures at the measuring point 28.2 an indicator of the pressure in the second duct K.2 8 Mixing point, at which the two ducts K.1 and K.2 open and at which the inhalation duct K.30 begins 9 Patient-side coupling unit, connected to the mixing point 8 via the inhalation duct K.30 10 Pneumatic control line; it leads from the branch point 11 to the control pressure chamber Ka.3 in the pressure reducer 12; it belongs to the pressure-reducing control device 11 Branch point in the first duct K.1, in which the control line 10 begins; it acts as the reference point in one embodiment 12 Movable wall in the form of a membrane in the pressure reducer 1; it separates the chambers Ka.2 and Ka.3 from one another in a fluid-tight manner 13 Closure, which optionally closes or opens the connection in the partition wall 15 between the two chambers Ka.1 and Ka.2; it is in a functional connection with the movable wall 12 via the lever 14 14 Lever; it establishes a mechanical functional connection between the movable wall 12 and the closure 13; it is rotatable about the axis of rotation DA 15 Rigid partition wall in the pressure reducer 1, which wall separates the two chambers Ka.1 and Ka.2 from one another; it has an opening 29, which can be closed by the closure 13 16 Spring; it is connected to the movable wall 12 and to the connection element 18; it belongs to the pressure reducer actuator 17 Control pressure actuator, which moves the connection element 18 and thus changes the force of the spring 16; it is actuated by the control device 3; it belongs to the pressure reducer actuator 18 Mechanical connection element between the control pressure actuator 17 and the spring 16 19 Rigid housing of the pressure reducer 1; it encloses the three chambers Ka.1, Ka.2, Ka.3 20 Supply port in the wall W for pure oxygen; it acts as the second source 21 Supply line; it leads from the supply port 20 to the front pressure inlet V.3; it connects the supply port 20 to the front pressure chamber Ka.1 in the pressure reducer 1 23 Filter behind the inlet E 25 CO2 absorber; it acts as the first source in one embodiment 26 Nonreturn valve in the supply line 21 27 Anesthetic evaporator; it generates gaseous anesthetic and feeds same into the first duct K.1 28.1 Measuring point in the first duct K.1,at which the pressure sensor 7.1 measures the pressure in the first duct K.1; it acts as the reference point in one embodiment 28.2 Measuring point in the second duct K.2, at which the pressure sensor 7.2 measures the pressure in the second duct K.2 29 Opening in the partition wall 15; it is optionally released or closed by the closure 13 30 Rotary knob, which a user can rotate in order to predefine the desired percentage of oxygen in the gas mixture, which is delivered to the patient-side coupling unit 9 31 First section of the exhalation fluid connection; it guides the exhaled air from the patient-side coupling unit 9 to the CO2 absorber 25 32 Second section of the exhalation fluid connection; it guides the exhaled air freed from CO2 from the CO2 absorber 25 to the blower 2 100 Ventilator; it generates a gas mixture from breathing air and pure oxygen; it ventilates the patient Pt mechanically; it comprises the supply device according to the present invention DA Axis of rotation, about which the lever 14 can be rotated E Inlet for ambient air K.1 First duct; it provides breathing air; it is in a fluid connection with the blower; it opens into the mixing point 8 K.2 Second duct; it provides pure oxygen; it is in a fluid connection with the back pressure chamber Ka.2 in the pressure reducer 1; it opens into the mixing point 8 K.30 Inhalation duct; it guides the gas mixture from the mixing point 8 to the patient-side coupling unit 9 Ka.1 Front pressure chamber in the pressure reducer 1, connected vis the front pressure inlet V.3 to the supply line 21 Ka.2 Back pressure chamber in the pressure reducer 1, connected via the back pressure outlet V.2 to the second duct K.2 Ka.3 Control pressure chamber in the pressure reducer 1, connected in one embodiment via the control pressure inlet V.4 to the control line 10; it contains in another embodiment the spring 16 and the connection element 18 P Pressure, especially in the inhalation duct K.30 P.1 Time course of the pressure at the back pressure outlet V.2 P.2 Time course of the pressure at the supply connection element V.1 P.2(30) Time course at a desired pressure of 30 mbar P.2(50) Time course at a desired pressure of 50 mbar Pt Patient; the patient is ventilated mechanically (artificially) by the ventilator 100; the patient carries the patient-side coupling unit 9 V.1 Supply connection element of the first duct K.1, connected to a supply outlet of the blower 2 V.2 Back pressure outlet of the pressure reducer 1, connected to the second duct K.2 V.3 Front pressure inlet of the pressure reducer 1, connected to the supply line 21 V.4 Optional control pressure inlet of the pressure reducer 1, connected to the control line 10 W Wall; it has the supply port 20 for pure oxygen