WO1998001176A1

WO1998001176A1 - Device for preparation of a respiratory gas

Info

Publication number: WO1998001176A1
Application number: PCT/EP1997/003544
Authority: WO
Inventors: Burkhard Lachmann; N. Govinda Rajan
Original assignee: Epazon B.V.
Priority date: 1996-07-04
Filing date: 1997-07-04
Publication date: 1998-01-15
Also published as: DE19626924A1; EP0925085A1; DE19626924C2

Abstract

The invention relates to a device for preparation of a respiratory gas with at least one respiratory gas source (4), a control system (12) for the respiratory gas flow and respiratory gas conveying means (6) for controlled respiratory gas flow. The gas conveying means (6) can be connected to at least one oxygen source (16), the respiratory gas source comprising a fan (4) driven by a motor. The device can also have at least one measuring device (8, 10, 19) to determine at least one parameter of the conveyed gas flow, the at least one measuring device (8, 10, 19) affecting the control system (12). The invention also relates to a process for preparation of a respiratory gas for living creatures (2).

Description

Breathing gas supply device

The invention relates to a device for providing a breathing gas with at least one breathing gas source, a controller for the breathing gas flow and a gas delivery device for the controlled breathing gas flow, the gas delivery device being connectable to at least one oxygen que 1 le.

Such devices are known both for outpatient emergency use and for inpatient clinical use.

In the case of stationary clinical use, a central compressed air or oxygen supply with corresponding connection points in the treatment rooms and hospital rooms usually serves as the respiratory gas source. The devices themselves are usually movable on rollers and have corresponding connection lines with which the devices can be connected to the central breathing gas source.

For the use of such devices for outpatient emergency use, generally simpler devices are used. Common compressed gas cylinders for compressed air and / or oxygen serve as the breathing gas source. The gas contained in the compressed gas cylinders is usually filled under an overpressure of approximately 200 bar.

In order to have at least one breathing gas supply available for transport to a hospital, at least one such gas cylinder with a filling volume of 10 l is required. Due to the bulky dimensions and in particular the high weight of such a filled pressurized gas bottle, such a device for outpatient emergency use is only for use in vehicles or e.g. a helicopter practically possible.

In stationary use, a mixture of compressed air and oxygen is usually used as the breathing gas. Since oxygen is practically always supplied with such a device in outpatient emergency use, two pressurized gas

CONFIRMATION COPY bottles required as a breathing gas source, namely a compressed air bottle and an oxygen bottle, which leads to a further increase in weight. In order to avoid such an increase in weight, it is also known to carry only one oxygen bottle and to mix ambient air with the oxygen from the compressed gas bottle and use it as breathing gas by appropriately designing flow paths via a Venturi nozzle.

Furthermore, the known devices also have a mechanical or electronic control, by means of which the respiratory gas flow can be controlled in accordance with the required ventilation frequency.

A device of the type mentioned at the outset is known, for example, from W087 / 06142. The device disclosed therein includes a monitor for monitoring the breathability of a patient. At the beginning of each inhalation, a volume pulse of oxygen is delivered to the patient. If the patient breathes irregularly or cannot breathe spontaneously at all, the device provides a continuous flow of oxygen.

Another device is known from EP-A-324 275, which comprises a ventilator and a breath synchronization. The device is intended for use when the breath is stopped, wherein a breathing gas can be released from the ventilator to the patient at selected times after the start of inhalation or exhalation. The synchronization device is connected to a monitor for monitoring breathing. The monitor records the body condition, electromyograms, chest movements and the like.

These known systems work satisfactorily as long as the patient is relatively healthy and his lungs are in relatively good condition. However, many patients are in poor condition or have atelectatic lungs, that is, they are not completely filled with air, so the oxygen administered at the start of inhalation has little, if any, effect. If a continuous stream of oxygen is added for an extended period of time, the purpose of the device, namely to save oxygen, is the opposite.

It is therefore the aim of the present invention to improve known devices for providing a breathing gas, in particular with regard to oxygen consumption.

This object is achieved according to the invention by a device of the type mentioned at the outset, which is characterized in that the respiratory gas source comprises a motor-driven blower. Due to the design of the device according to the invention, it is no longer necessary to carry large compressed gas cylinders. For the medically necessary oxygen demand in a device according to the invention, a 1-liter bottle is sufficient to supply a patient with about 3 hours. Due to the small, handy 1-liter bottle, it is possible to operate such a device, especially in outpatient use, and in particular, fixed installation in vehicles is no longer necessary. This also enables the use of such a device in other hi-fi vehicles as an ambulance. When using an electric motor, a device according to the invention can be operated practically anywhere where there is a possibility of a power supply. With appropriate equipment with accumulators, it is even possible to design a device according to the invention in such a way that the device manages completely without external power supply for a while. This can e.g. be useful when rescuing injured people from rough terrain.

However, a drive other than an electric motor can also be provided, for example a compressed air drive. This is useful if the device is to be used in places where a compressed air supply is guaranteed for other reasons, but the compressed air does not have the purity required for medical treatment, for example, it contains oil. This could be the case, for example, in large ambulance vehicles or when carrying such a device on overseas flights in commercial aircraft. In order to be able to use the device as a continuous breathing device even when a patient's breathing completely fails, it is expedient if the device, in operation, has a dynamic pressure of more than 400 Pa, in particular of about 600 Pa, in relation to the ambient pressure at one end of the gas delivery device , can deliver.

Another device according to the invention of the type mentioned at the outset can be used for ventilation with positive end-expiratory pressure (PEEP) while still being compact and easy to handle, if the device further comprises a backflow device and a valve device which is used to control the respiratory gas flow is connected, the valve device essentially releasing the cross section of the gas delivery device in the direction of its consumer end in a first operating position and largely closing and / or connecting the cross section of the gas delivery device to the environment in a second operating position, and wherein the valve device in the the first operating position essentially closes the cross section of the backflow device and essentially releases it in the second operating position.

In order to separate the inspiration flow and expiration flow as effectively as possible, it is expedient that the return flow device is connected to the gas delivery device in the vicinity of the consumer end of the gas delivery device.

In order to be able to use the PEEP and CPPV ventilation techniques with the least possible outlay on equipment, it is expedient if the device delivers a dynamic pressure above the ambient pressure at the consumer end of the gas delivery device when the valve device is in the second operating position, especially when the Dynamic pressure above the ambient pressure is set by a pressure regulator 1 in the return flow device, the dynamic pressure expediently being approximately 50-200 Pa.

For minimal oxygen consumption, it is advisable if the device further comprises a metering device for metering an amount of oxygen to be conveyed to the breathing gas and the control influences the metering device.

For optimal coordination of the components and e.g. to compensate for losses due to leaks, e.g. on a breathing mask, it is expedient if the device is characterized by at least one measuring device for determining at least one parameter of the pumped gas, the at least one measuring device influencing the control.

The object is further achieved by a device of the type mentioned at the outset, which is characterized by at least one measuring device for determining at least one parameter of the conveyed gas, the at least one measuring device influencing the control, in particular via the control the metering device for metering the oxygen to be conveyed to the breathing gas is affected.

The inventive design of the device of the type mentioned at the outset now makes it possible to adjust the supply of breathing gas depending on the condition of the patient and his needs, in particular also the addition of oxygen to the breathing gas.

The at least one measuring device expediently comprises a gas flow measuring device and / or a gas pressure measuring device and / or a device for determining a gas concentration, in particular an oxygen concentration, in the conveyed gas.

The object is further achieved by a method for providing a breathing gas for living beings, which is characterized by detecting at least one parameter of the gas conveyed and for measuring a certain amount of oxygen as a function of the at least one detected parameter. This enables an optimization of the oxygen consumption in relation to the medically necessary metering of oxygen. A specific amount of oxygen is preferably metered in after a predetermined value for the at least one parameter has been recorded, in particular at a specific point in time after such a value has been recorded, in particular at a specific point in time after the start of an inhalation phase.

In an advantageous embodiment of the method, this is characterized in that the metering of a certain amount of oxygen is proportional to a peak value of a respiratory gas flow and / or a respiratory gas pressure in a breathing cycle, in particular that the peak value of the respiratory gas flow and / or the respiratory gas pressure is determined as the peak value of the breathing gas flow and / or breathing gas pressure in a previous breathing cycle, in particular as an average of the peak values of a certain number of previous breathing cycles.

A particularly low oxygen consumption can be achieved if a certain amount of oxygen is added to the breathing gas as a function of a detected value of the oxygen concentration in the exhaled gas, in particular if the duration of the oxygen release of the oxygen source is determined as a function of a detected value the oxygen concentration in the exhaled gas.

The method is advantageously characterized by the use of a device according to the invention.

The breathing gas supply to the patient can be detected on the basis of the parameter of the conveyed gas flow detected by the measuring device. When the lungs are sufficiently opened so that all breathing gas supplied is transported to the alveoli, oxygen is delivered to the patient in an impulse-like manner. Depending on the condition of the patient's lungs, the supply of oxygen can take place shortly after the start of inhalation or with a suitable delay, for example if the lungs are strongly atelectatic or collapsed. The expression "positive gas pressure" is used here for a pressure above a a predetermined basic pressure (atmospheric pressure or positive pressure during ventilation with positive end-expiratory pressure / PEEP) after spontaneous or forced inhalation. In contrast, the start of spontaneous inhalation is recognized by a decrease in gas pressure.

With this special time behavior, oxygen replaces nitrogen and accumulates in the alveoli within 1 or 2 minutes of ventilation.

It does not matter whether the patient breathes spontaneously or not. The supply of oxygen takes place according to the determined parameter. This embodiment of the invention can be used with practically all ventilation and breathing support systems, either by installation in the system or as an external accessory.

When the invention is used in conjunction with a breathing apparatus that supplies a patient with air or other breathing gas during inhalation, the use of a certain time delay for the addition of oxygen from the oxygen source may be advantageous. The time delay can be fixed by a doctor on the device, but is preferably done according to the condition of the lungs. The delay time can e.g. can be determined as the average time to reach a certain percentage of a peak value over a preselected number of breathing cycles or depending on the condition, compliance and the functional residual capacity of the lungs.

The invention will be explained in more detail below with reference to exemplary embodiments shown in the drawings.

Show it:

Figure 1 is a schematic representation of an inventive

Contraption,

Figure 2 is a block diagram of another invention

Formation of the device, Figure 3 is a diagram illustrating the operation of the device in a first mode of operation and

Figure 4 is a diagram illustrating the operation of the device in a second mode.

FIG. 1 shows a device 1 according to the invention for providing a breathing gas which can be connected to a patient 2. Cleaned air is drawn in and conveyed from the environment by a motor-driven blower 4 via a suitable filter 3, the blower 4 serving as a breathing gas source. A conventional compressed gas source can also be used as the breathing gas source.

Via a valve device 5, the volume flow delivered by the blower 4 into a supply line 6 as a gas delivery device or the pressure built up in the gas delivery device 6 can be adjusted. The valve device 5 can assume at least two operating positions. In a first operating position of the valve device 5, this essentially releases the cross section of the gas conveying device 6 in the direction of a consumer end 7. In a second operating position, the valve device 5 completely or partially closes the cross section of the gas delivery device 6 and / or connects the gas delivery device 6 to the surroundings, i.e. the gas delivery device 6 is vented.

The consumer end 7 of the gas delivery device 6 serves to connect the device 1 to the patient 2 and can e.g. be designed as a tube device. A flow meter 8 is expediently integrated into the consumer end 7 as a gas flow measuring device.

In order to be able to use the ventilation method with exhalation against excess pressure (PEEP / CPPV), which is particularly advantageous for ventilation in ate lung and to avoid a lung collapse, a line 9 is expediently connected as a backflow device to the consumer-side end 7 of the gas delivery device 6. In order to be able to adjust the valve device 5 in accordance with the spontaneous or controlled breathing of the patient 2, it is also expedient to integrate a gas pressure measuring device 10 into the consumer-side end 7 of the gas delivery device 6.

In the line 9, a pressure relief valve 11 can be integrated, via which the line 9 is vented i d when a critical pressure is exceeded. Such a pressure relief valve 11 serves as a safety valve in the event of failure of the valve device 5, in particular in its first operating position.

The signals from measuring devices, such as the flow meter 8 or the gas pressure measuring device 10, are fed to a controller 12, which at least applies a control signal to the valve device 5. An actuator 13, which e.g. can be formed by a stepper motor or an electromagnet. Furthermore, feedback from the actuator 13 about the position of the valve device 5 to the controller 12 can take place. Furthermore, the controller 12 can also influence the fan 4, e.g. to minimize the power consumption of device 1.

The valve device 5 includes both influencing the gas flow in the gas delivery device 6 and in the return flow device 9. Downstream of the valve device 5, a pressure control valve 1 14 is arranged at the end of the return flow device 9, which sets the desired overpressure in the return flow device 9 against that patient 2 should exhale. The pressure which is set via the pressure control valve 14 can expediently be changed directly or via the controller 12 and a corresponding actuator in the pressure control valve 14 in accordance with the medically desired specifications.

In order to ensure, in particular if the device 1 fails, that the patient 2 is not supplied with exhaled breathing gas again when inhaled, valve 15 in the gas delivery device 6 and the backflow device 9 a direction of the gas flow are forced. The check valves 15 can be formed, for example, by conventional flap valves. Furthermore, the connection of an optional oxygen source 16 is indicated in FIG. 1, by means of which the breathing gas can be enriched with oxygen. Details of such an arrangement with an oxygen source 16 are described below.

FIG. 2 shows a device 1 for providing a breathing gas according to a further embodiment of the device according to the invention. A patient 2 connected to the device 1 is also shown to illustrate the mode of operation. The device 1 shown comprises a respiratory gas source, which can either comprise a blower 4, as described above, or can be formed by a conventional breathing apparatus or respirator. The breathing device can e.g. be a stationary hospital device with all known special features, e.g. Volume and pressure control as well as patient monitor. The breathing gas can accordingly be provided in a conventional manner via a central compressed gas supply or pressure cylinders.

The device 1 shown further comprises a flow meter 8, a pressure measuring device 10, a controller 12 and an oxygen source 16. The controller 12 is connected to a control valve 17 as a metering device for measuring an amount of oxygen to be conveyed. The control valve 17 is integrated in a gas line 18 which connects the oxygen source 16 with a gas delivery device 6 designed as a tube system. Furthermore, a measuring device 19 for the oxygen concentration is arranged in the consumer end 7 of the tube system 6.

The breathing aid 4 is connected to the patient 2 via a tube device 6. The tube device 6 comprises a tube for inhalation and can also be connected to another tube 9 for exhalation. The use of an additional tube 9 for exhaling depends essentially on the Type of respiratory device 4 used. In portable devices for accident medicine and domestic use, only one tube is usually used for inhalation. The patient exhales directly into the environment through a valve. The flow meter 8 and the pressure measuring device 10 are arranged in the tube system 6 in order to determine the gas volume flow to the patient 2 and the airway pressure in the patient 2. The measured values are transmitted to the controller 12, which controls the breathing apparatus 4 in accordance with the measured values.

The controller 12 also controls the control valve 7 for adding oxygen from the oxygen source 16 to the patient 2 via a gas line 18 and the tube system 6.

FIG. 3 shows a diagram in which the volume flow and the pressure are shown over two breathing cycles. The diagram shows how the device works volume-controlled.

First, a first inhalation volume flow 20A is supplied to the patient. The volume flow 20A is constant. After a brief pause, a first exhalation 20B takes place, which in turn is followed by a second inhalation stream 20C and another exhalation 20D.

As can be seen from the pressure diagram, the pressure P in the airways 22A increases as the patient is supplied with breathing gas. During the pause in delivery, pressure begins to drop and continues to decrease during exhalation 22B. The pressure drops to atmospheric pressure or an elevated pressure level if ventilation with positive end-expiratory pressure (PEEP) takes place. However, ventilation with negative end-expiratory pressure (NEEP) can also be used. Accordingly, the process is repeated during the second inhalation 22C and the second exhalation 22D.

In a patient with acute respiratory failure (ARDS), closed breathing cycles do not have uniform time constants, ie different characteristics of flow resistance and compliance. If oxygen applied immediately after inhalation, vital parts of the lungs may not yet be effectively ventilated. In order to improve the addition of oxygen to the lungs using a minimum of oxygen, the addition of oxygen is delayed until the lungs are opened sufficiently, as indicated by the pressure curve in 22A in Figure 3. When a certain pressure P is reached in relation to the maximum pressure, oxygen is added, as shown by the black bars 24 and 26.

Figure 4 shows essentially the same for a pressure controlled mode. A first inhalation 32A and a second inhalation 32C take place at a predetermined pressure level. A first and second exhalation 32B and 32C occurs at a positive end expiratory pressure (PEEP). The pressure pulse 32A causes an inhalation flow 30A to the patient. The inhalation stream 30A is large at the beginning of the inhalation and then decreases until the exhalation 30B begins. A second inhalation 30C and exhalation 30D follow accordingly.

In this operating mode, oxygen is only added when the gas flow reaches a predetermined percentage Φ of the maximum gas flow, which is indicated by the black bars 34 and 36 in FIG. 4.

The measured maximum values in one breathing cycle or the calculated mean values of several previous breathing cycles can be used as a reference axima. When the gas flow or pressure reaches the percentage preset by a physician of the reference maximum, oxygen is added. A combination of volume flow and pressure can also be used.

Instead of using certain volume flow or pressure values, a certain time delay can also be entered by the doctor or calculated by the controller 12. As can be seen from FIGS. 3 and 4, the oxygen is added after a certain time delay. The size of this time delay is determined by the state of the Lung and corresponds to a time behavior that ensures the best efficiency when adding oxygen. Based on the measurements of the lungs, a doctor can set a certain time delay after the start of inhalation for the addition of oxygen. Alternatively, the controller 12 can be programmed to calculate the time delay based on the measurements of the volume flow and the pressure. For example, the controller can calculate an average value for the time delay over a number of breathing cycles, as shown in FIGS. 3 and 4, and then use the calculated time delay. For relatively healthy patients, the time delay can also be set to a fixed value without adapting to the individual lung constitution, for example for devices used in accident medicine.

The same mode of operation can be used for other modes of operation of a breathing apparatus or a respirator, e.g. in breathing support. Furthermore, manually operated ventilators can also be equipped accordingly by medical personnel.

Another possible control variable is the duration of the oxygen addition. This is controlled so that it is long enough to deliver oxygen to the corresponding parts of the lungs, i.e. Airways and alveoli, but not so long that oxygen is exhaled again unused. This can be done by measuring the oxygen concentration in the exhaled air, e.g. with the measuring device for the oxygen concentration 19 in Figure 1, or by the oxygen concentration of the blood (not shown).

Correspondingly sophisticated breathing aids or respirators can be equipped accordingly, but other arrangements are possible.

Claims

claims

1. Device for providing a breathing gas with at least one breathing gas source (4), a controller (12) for the breathing gas flow and a gas delivery device (6) for the controlled breathing gas flow, the gas delivery device

(6) can be connected to at least one oxygen source 1 le (16), characterized in that the respiratory gas source is a motor-driven blower

(4).

2. Device according to claim 1, characterized in that the device in operation at a consumer end

(7) the gas delivery device (6) can deliver a back pressure of more than 400 Pa compared to the ambient pressure.

3. Device according to claim 2, characterized in that the dynamic pressure is about 600 Pa.

4. Device according to the preamble of claim 1 or one of the preceding claims, characterized in that the device further comprises a backflow device (9) and a valve device (5) which is connected to the controller (12) for the respiratory gas flow, the Valve device (5) in a first operating position essentially releases the cross section of the gas delivery device (6) in the direction of its consumer end (7) and in a second operating position the cross section of the gas delivery device (6) mainly closes and / or with the Connects the surroundings and the valve device (5) essentially closes the cross section of the backflow device (9) in the first operating position and essentially releases it in the second operating position.

5. Apparatus according to claim 4, characterized in that the backflow device (9) in the vicinity of the consumer end (7) of the gas delivery device (6) is connected to this.

6. Device according to one of claims 4 or 5, characterized in that the device in operation at the consumer end (7) of the gas delivery device (6) provides a dynamic pressure above the ambient pressure when the vent leinrichtung (5) in the second operating position located.

7. Apparatus according to claim 6, characterized in that the dynamic pressure above the ambient pressure is set by a pressure control valve (14) in the return flow device (9) when the valve device (5) is in the second operating position.

8. Apparatus according to claim 6 or 7, characterized in that the dynamic pressure above the ambient pressure is about 50-200 Pa when the valve device (5) is in the second operating position.

9. Device according to one of the preceding claims, characterized in that the device further comprises a metering device (17) for metering an amount of oxygen to be conveyed to the breathing gas and the controller (12) influences the metering device (17).

10. Device according to one of the preceding claims, characterized by at least one measuring device (8, 10, 19) for determining at least one parameter of the conveyed gas flow, the at least one measuring device (8, 10, 19) influencing the controller (12).

11. Device for providing a breathing gas with at least one breathing gas source (4), a controller (12) for the breathing gas flow and a gas delivery device (6) for the controlled breathing gas flow, the gas delivery device (6) being connectable to at least one oxygen source (16) characterized by at least one measuring device (8, 10, 19) for determining at least one parameter of the gas flow being conveyed, the at least one measuring device (8, 10, 19) influencing the control (12).

12. Device according to one of claims 9 to 11, characterized by at least one measuring device (8, 10, 19) for determining at least one parameter of the gas flow conveyed, the at least one measuring device (8, 10, 19) the controller (12) for Influencing the metering device (17) for metering the oxygen to be conveyed to the breathing gas.

13. Device according to one of claims 10 to 12, characterized in that the at least one measuring device comprises a gas flow measuring device (8).

14. Device according to one of claims 10 to 13, characterized in that the at least one measuring device comprises a gas pressure measuring device (10).

15. Device according to one of claims 10 to 14, characterized in that the at least one measuring device comprises a device (19) for determining a gas concentration in the gas stream.

16. Device according to one of claims 10 to 15, characterized in that the at least one measuring device comprises a device (19) for determining the oxygen concentration in the gas stream.

17. A method for providing a breathing gas for living beings (2) characterized by

Detecting at least one parameter of the conveyed gas flow and metering a certain amount of oxygen as a function of the at least one detected parameter.

18. The method according to any one of the preceding claims, characterized in that the metering of a certain amount of oxygen is carried out after detecting a predetermined value for the at least one parameter.

19. The method according to any one of the preceding claims, characterized in that the metering of a certain amount of oxygen is carried out at a certain time after detecting a predetermined value for the at least one parameter.

20. The method according to any one of the preceding claims, characterized in that the metering of a certain amount of oxygen is carried out at a certain time after detecting the beginning of an inhalation phase.

21. The method according to any one of the preceding claims, characterized in that the metering of a certain amount of oxygen is proportional to a peak value of a breathing gas flow and / or a breathing gas pressure in one breathing cycle.

22. The method according to claim 21, characterized in that the peak value of the breathing gas flow and / or breathing gas pressure is determined as the peak value of the breathing gas flow and / or breathing gas pressure in a previous breathing cycle.

23. The method according to claim 21 or 22, characterized in that the peak value of the breathing gas flow and / or breathing gas pressure is determined as the mean value of the peak values of the breathing gas flow and / or breathing gas pressure of a certain number of previous breathing cycles.

24. The method according to any one of the preceding claims, characterized in that the metering of a certain amount of oxygen to the breathing gas is carried out as a function of a detected value of the oxygen concentration in the exhaled gas.

25. The method according to any one of the preceding claims, characterized in that the duration of the oxygen release of the oxygen source (16) is determined as a function of a detected value of the oxygen concentration in the exhaled gas.

26. The method according to any one of the preceding claims, characterized by the use of a device according to one of claims 1 to 16.