DE102005031808B4 - Device for pressure control in ventilators - Google Patents

Abstract

Device for pressure control in ventilators, which has a control unit and at least one sensor for a ventilation parameter and which is coupled to a respiratory gas supply which is adjustable to at least two different pressure levels, the control unit determining the time position of inspiration phases (14) and expiration phases (15). evaluates and prescribes a pressure reduction within the inspiratory phase before the beginning of the expiration phase, characterized in that the pressure control takes place using a sensor with which a vertex of the flow profile (13) during the inspiration phase (14) is detected, wherein following the metrological detection of such a vertex of the beginning of the lead time (17) is started and the pressure reduction is performed.

Description

The invention relates to a method for pressure control in ventilators, in which the pressure is adjustable to at least two different pressure levels as a function of at least one ventilation parameters detected by measurement technology.

The invention further relates to a device for pressure control in ventilators, which has a control unit and at least one sensor for a ventilation parameters and which is coupled to a breathing gas supply which is adjustable to at least two different pressure levels.

An application in medical devices takes place in connection with respiratory air supplies, which are used in the context of a CPAP therapy (Continious-Positive-Airway-Pressure). Also, applications for so-called bilevel, APAP and home ventilation are possible. Also, such breathing air supplies are used in the hospital in the intensive care ventilation. To avoid dehydration of the respiratory tract, it proves to be particularly useful for longer periods of ventilation to carry out a humidification of the air. Such humidification of the breathing air can also be realized in other applications.

But there may also be various applications outside the field of medical technology. For example, ventilators for divers or firefighters may have the problem of kinking or compressing used ventilator hoses. The same problem may also arise in the industrial sector for activities which require the use of respiratory equipment to protect the person concerned from the action of environmental gases and where the persons concerned are not free to perform their intended tasks in order to be self-sufficient Respiratory equipment to be able to act. Finally, there are conceivable applications in the field of ventilators used by astronauts or pilots.

State of the art

The hitherto known methods and devices are not yet sufficiently suitable for providing the greatest possible ease of use, which in particular, in spite of the respiration pressure predetermined by the respirator, as far as possible approximates the transition from inspiration phases and expiration phases to a normal breathing process. As a disturbing it is perceived by a user of the ventilator, in particular, if at the beginning of the expiratory phase, a relatively high ventilation pressure is present, which counteracts exhalation.

task

Object of the present invention is therefore to improve a method of the aforementioned type such that an increased ease of use is achieved.

This object is achieved in that the pressure during an inspiratory phase is reduced before a start of the expiratory phase.

Another object of the present invention is to construct a device of the initially mentioned kind for achieving an improved user comfort.

This object is achieved in that the control unit evaluates the timing of inspiration phases and expiratory phases and prescribes a pressure drop within the inspiratory phase before the beginning of the expiratory phase.

By lowering the pressure even before one end of the inspiratory process, a reduced pressure exerted against the exhalation process is provided, and nevertheless the reduced residual pressure ensures that there is internal pressure support for the flow paths for the respiratory gas. This achieves a high degree of functionality with at the same time pleasant conditions of use.

A pressure curve which is perceived as particularly pleasant is achieved by carrying out the pressure reduction after exceeding a flow maximum.

Another control variant is that the pressure reduction is carried out after a predetermined flow reduction.

A secure pressure reduction to a beginning of the expiratory phase can be achieved in that the pressure reduction with a minimum time interval to an already detected or based on the waveform of a the flow-related parameter predicted phase change is performed.

A secured pressure reduction can be achieved in that the pressure reduction is carried out with a temporally maximum distance to an already detected or predicted on the basis of the signal waveform of a parameter associated with the flow phase change.

A further increase of the user comfort can take place in that the pressure reduction is continued after a phase change.

To carry out an optimization of the pressure control is proposed that the pressure reduction is carried out according to a predetermined lowering profile.

A particularly simple embodiment is that the pressure reduction is carried out according to a substantially linear ramp.

It also contributes to a simple device control that the pressure reduction is carried out substantially passively by idling the conveyor.

A great opportunity for optimization is provided by the fact that the pressure reduction is actively carried out using at least one control element.

Another variant is that the pressure reduction is active in a first lowering phase and then carried out passively.

In addition, it is also thought that the pressure reduction is carried out passively and then actively in a first lowering phase.

A collapse of the flow paths can be prevented, that after the implementation of the pressure reduction, the pressure for a predeterminable range is maintained at a substantially constant lower pressure level.

It also proves to be advantageous to avoid obstructions that a pressure increase is set before one end of the expiratory phase.

An optimum time for the end of the pressure reduction is defined by the pressure increase being carried out as a function of an evaluation of the flow profile and / or the course of a signal associated with the flow.

Further optimization of the operation can take place in that the pressure increase is carried out in accordance with a predefinable increase profile.

Also with regard to the pressure increase, it contributes to a simple device control that the pressure increase is carried out substantially linearly.

A typical field of application is opened up by setting a higher first pressure level at a pressure level of about 10 mbar.

To achieve a comfortable user comfort, it usually proves sufficient that a second lower pressure level at a pressure level of about 7 to 8 mbar is given.

The device implementation is supported by the fact that at least one flow parameter is detected by measurement technology via a sensor.

Further adaptation to different application requirements can be made by adaptively changing an upper pressure level.

In addition, it is also thought that a lower pressure level is adaptively changed.

Further reduction of the risk of collapse of the flow paths or obstructions may be achieved by providing a third elevated pressure level at a pressure level of about 11 to 14 mbar.

It is envisaged that at least two pressure levels, which may be in a range of 2 to 80 mbar, can be predetermined. Additional pressure levels may optionally be set in the range of preferably +/- 5 mbar around the lower and / or upper preset levels.

list of figures

• 1 eine perspektivische Darstellung eines Beatmungsgerätes gemäß einem Ausführungsbeispiel,
• 2 einen typischen Flowverlauf bei der Durchführung eines Beatmungsvorganges,
• 3 einen zu 2 korrespondierenden Druckverlauf bei einer Drucksteuerung innerhalb einer Exspirationsphase proportional zum Flow,
• 4 eine zum Flowverlauf in 2 korrespondierende Drucksteuerung mit linearer Druckabsenkung in der Exspirationsphase,
• 5 eine Darstellung eines weiteren Flowverlaufes ähnlich zu 2,
• 6 eine zum Flowverlauf in 5 korrespondierende Drucksteuerung mit einem Beginn der Druckabsenkung bereits vor einem Ende der Inspirationsphase,
• 7 eine weitere Darstellung zueinander korrespondierender Druck- und Flowverläufe bei proportionaler Druckabsenkung,
• 8 eine zueinander korrespondierende Darstellung von Druck- und Flowverläufen bei einem Auftreten von Druckspitzen,
• 9 eine weitere zueinander korrespondierende Darstellung von Druck- und Flowverläufen bei Mundexspirationen,
• 10 eine weitere Darstellung zueinander korrespondierender Druck- und Flowverläufe,
• 11 eine Darstellung eines Atemgasschlauches mit elastisch expandierbarem Ausgleichselement in einem Grundzustand,
• 12 das Ausgleichselement gemäß 11 nach einer teilweisen Expansion,
• 13 das Ausgleichselement gemäß 11 und 12 nach einer vollständigen Expansion,
• 14 eine Darstellung einer Beatmungsmaske mit einem flexiblen Bauteil,
• 15 eine weitere Ausführungsform zur Beatmungsmaske gemäß 14,
• 16 eine nochmals abgewandelte Ausführungsform zur Darstellung in 14 und
• 17 eine Darstellung eines Flowverlaufes und eines Druckverlaufes mit im wesentlichen flowproportionaler Druckabsenkung zu einem Exspirationsbeginn und einer Druckanhebung zu einem Beginn der Inspirationsphase.

In the drawings, embodiments of the invention are shown. Show it:

• 1 a perspective view of a ventilator according to an embodiment,
• 2 a typical flow during the execution of a ventilation process,
• 3 one too 2 corresponding pressure profile in a pressure control within an expiratory phase proportional to the flow,
• 4 one to the flow in 2 corresponding pressure control with linear pressure reduction in the expiration phase,
• 5 a representation of another flow course similar to 2 .
• 6 one to the flow in 5 corresponding pressure control with a beginning of Pressure reduction already before one end of the inspiration phase,
• 7 a further representation of corresponding pressure and flow profiles with proportional pressure reduction,
• 8th a representation of pressure and flow curves corresponding to one another when pressure peaks occur,
• 9 a further corresponding representation of pressure and flow patterns in mouth exhalations,
• 10 a further representation of corresponding pressure and flow progressions,
• 11 a representation of a breathing gas hose with elastically expandable compensation element in a ground state,
• 12 the compensation element according to 11 after a partial expansion,
• 13 the compensation element according to 11 and 12 after a full expansion,
• 14 a representation of a respiratory mask with a flexible component,
• 15 a further embodiment of the respiratory mask according to 14 .
• 16 a further modified embodiment for illustration in 14 and
• 17 an illustration of a flow profile and a pressure curve with substantially flow-proportional pressure reduction to a beginning of expiration and a pressure increase to a beginning of the inspiration phase.

1 shows the basic structure of a device for ventilation. In the area of a device housing ( 1 ) with control panel ( 2 ) as well as display ( 3 ) is arranged in a device interior, a breathing gas pump. Via a coupling ( 4 ) a connection hose ( 5 ) connected. Along the connecting tube ( 5 ), an additional pressure measuring hose ( 6 ), which via a pressure input port ( 7 ) with the device housing ( 1 ) is connectable. To enable data transmission, the device housing ( 1 ) an interface ( 8th ) on. A humidifier can be adapted.

In the area of the device housing ( 1 ) facing away from the expansion of the connecting tube ( 5 ) is an exhalation element ( 9 ) arranged. Also, an exhalation valve can be used.

1 also shows a ventilation mask ( 10 ) trained patient interface, which is realized as a nasal mask. A fixation in the region of a head of a patient can be achieved via a hood ( 11 ) respectively. In the area of their connection hose ( 5 ) facing the patient interface ( 10 ) a coupling element ( 12 ) on.

2 shows a typical flow ( 13 ) during the execution of inspiration phases ( 14 ) and expiratory phases ( 15 ).

3 shows a flow path ( 13 ) in 2 corresponding pressure curve ( 16 ), during which the pressure during the expiratory phase ( 15 ) substantially in proportion to the flow profile ( 13 ) is lowered. During the inspiration phase ( 14 ), the pressure typically has a value of about 10 mbar and is during the expiratory phase ( 15 ) lowered by a maximum of about 3 bar.

4 also shows a flow history ( 13 ) in 2 corresponding pressure curve ( 16 ), beginning with the expiratory phase ( 15 ) the pressure is first lowered substantially linearly. This can be done, for example, in a simple manner by switching off the operating energy of the respiratory gas delivery device used, for example a fan. With the beginning of the inspiration phase ( 14 ), the pressure is raised again, also in the embodiment according to 4 essentially with a linear increase.

5 again shows a flow history ( 13 ) similar to in 2 , each again subdivided into phases of inspiration ( 14 ) as well as expiratory phases ( 15 ).

6 shows a flow path ( 13 ) in 5 corresponding pressure curve ( 16 ), in which a pressure reduction already at the beginning of a lead time ( 17 ) before an expiration ( 18 ) is started.

According to the embodiment 6 is the pressure in the inspiratory phase ( 14 ) at the beginning of the lead time ( 17 ) initially lowered substantially linearly from an initial level of about 10 mbar. The pressure drop is determined after the beginning of the exhalation ( 18 ) first and then from a switching time ( 19 ) started a pressure increase. According to the embodiment 6 the pressure increase is also substantially linear. Already before an inspirational start ( 20 ), the pressure at the end of an expiratory pressure rise again substantially reaches its initial level and remains at this initial level for the remainder of the expiratory phase (FIG. 15 ) as well as within the following inspirational phase ( 14 ) until the next lead time ( 17 ).

The pressure reduction during the lead time ( 17 ) and within the first part of the expiratory phase ( 15 ) until reaching a Base pressure ( 22 ) can be done in different ways. For example, it is possible to idle a drive motor of an air conveyor or a blower by completely or partially switching off energy.

The pressure increase in the expiratory phase ( 15 ) after reaching the switching time ( 19 ) is preferably carried out in the form of a slow ramp, since a user of the ventilation device a sudden switching to a higher pressure is perceived as unpleasant. The ramp steepness and the times relevant to the pressure reduction and the pressure increase can be adapted automatically as a function of a respiratory rate of the user. In addition, it is also possible to evaluate characteristic time courses in the respiratory curve of the user and to make an adjustment of the switching times thereto. For example, the average durations between the inspiratory and expiratory peak flows and the phase changes can be evaluated.

By suitable choice of the lead time ( 17 ) as well as the inspiratory pressure reduction ( 21 ), a mean pressure profile can be achieved, which according to an embodiment within the expiratory phase ( 15 ) to a higher average pressure than during the inspiratory phase ( 14 ) leads. This proves to be particularly advantageous for avoiding obstructions of the breathing gas flow paths.

The special pressure control makes it possible to reach an end of the expiratory phase during periods in which there is typically an increased risk of obstruction ( 15 ) and at the beginning of the inspiration phase ( 14 ) to provide sufficient pressure to counteract such obstructions. During the remaining time of the ventilation cycle, the lowest possible pressure level or the lowest possible mean ventilation pressure is specified.

In terms of device technology, the pressure control takes place using a sensor with which, for example, a vertex of the flow profile (FIG. 13 ) during the inspiratory phase ( 14 ) is detected. Following the metrological detection of such a vertex, the beginning of the lead time ( 17 ) started and the pressure reduction can be performed. Regardless of the metrological detection of such a vertex of the flow path ( 13 ), the beginning of the lead time ( 17 ) as a function of a maximum distance or a minimum distance to the beginning of the expiration ( 18 ) or at the start of inspiration. This would mean that even without detection of a vertex of the flow path ( 13 ) upon reaching a minimum time interval from the beginning of the expiration ( 18 ) the pressure reduction is started and that at a very early reaching the vertex of the flow path ( 13 ) the beginning of the lead time ( 17 ) until a maximum time is reached at the beginning of the expiration ( 18 ) is delayed.

The sensory acquisition of the flow profile ( 13 ) can be done directly or indirectly via a measurement signal related to the flow. It is also thought to recognize the breathing phases by means of non-flow signals. For example, pressure or temperature.

Alternatively to the in 6 illustrated linear ramped pressure reduction and the also linear and ramp-shaped pressure increase, it is also possible to realize the pressure reduction and / or the pressure increase according to predetermined linear or non-linear control profiles.

This may be in the form of a pure control or in the form of direct pressure sensing or sensing of a pressure related signal.

The pressure control can be realized in different ways device technology. For example, it is possible to control or regulate the conveying speed of the motor of the breathing gas conveyor. It is also possible to realize a pressure control by breathing gas deflection, for example by using a valve.

As a signal related to the flow, for example, the engine speed can be evaluated, for example in combination with the pressure or the motor current. Another measuring variant for detecting the flow is the realization of a differential pressure measurement.

The residence time of the pressure within the expiratory phase ( 15 ) to the minimum pressure between the times ( 22 and 19 ) can be chosen to be different depending on the application. In extreme cases, the corresponding residence time can be selected to be zero, but it is also possible to provide the beginning and / or end of the residence time at fixed times, to derive from a respiratory rate of the user, a derivative of the times from a mean expiration time, a mean time between the beginning of exhalation and an expiratory peak flow, an expiratory peak flow detection, a derivative of the flow, or a combination of one or more of the above criteria.

The same criteria for setting the residence time at the minimum pressure in the expiratory phase ( 15 ) apply mutatis mutandis to the residence time at the maximum pressure level, starting from the end of the expiratory pressure increase ( 21 ) until the beginning of the lead time ( 17 ). Likewise, the criteria listed above can be used individually or in an optional combination to specify the shape of the pressure rise profile and / or the pressure drop profile.

According to a further embodiment, it is also contemplated, at least temporarily after the end of the expiratory pressure increase and before the start of the lead time ( 17 ) provide an additional level of pressure to even better balance airflow path obstructions during inspiration and / or to affect inspiratory volume. In a therapeutic application, this can be done especially in the presence of central hypopneas.

The higher pressure level and the lower pressure level and optionally also the above-described additional pressure level can be manually predefinable, for example. It is also intended to specify only one of the pressure values and to derive the other pressure automatically from this predetermined pressure level. The default value may be, for example, the upper pressure, the lower pressure or a medium pressure. The other pressure values are then determined on the basis of this base value by reading from a table or via computational functional relationships.

According to a further embodiment, it is contemplated that for setting the difference between the higher pressure level and the lowered pressure level and / or criteria of the respective time periods and the slopes of the pressure reduction and the pressure increase predefined parameter sets can be manually selected to a respective optimal setting criterion set.

In a combination of out-of-phase pressure reduction with an APAP procedure, if obstructions or snoring sounds are detected, either the higher pressure level, the lower pressure level, or only the lower or upper pressure level are raised.

Also, in a combination of out-of-phase pressure control with an APAP method, in the event of obstructions or an occurrence of snore sounds detected from the flow or using modulated test signals, disable the respective activated device control mode and permanently set the pressure to the upper one to keep raised pressure level.

Another embodiment of such a combination of methods is to change the times of the pressure reduction and the pressure increase such that the proportion of the higher pressure per respiratory cycle is extended.

Another embodiment relates to respiratory rate regulation. At a high measured respiratory rate, there is a change in the durations for the duration of the raised pressure level and the lowered pressure level and, in addition, a change in the decay rates so as to cause a lower spontaneous breathing rate. In particular, this is thought to extend the residence time at the upper pressure level and to slow down the pressure increase within the expiratory phase.

Even with a respiratory rate regulation, it is possible to deactivate the respectively selected operating mode at high respiratory rates and to remain constant at the lower pressure level in this case.

When an apnea occurs or during a longer breathing pause, it is possible to constantly activate the higher pressure level.

The 7 to 10 illustrate mutually corresponding pressure and flow progressions each with textually explained in the drawings boundary conditions. The fluid dynamic relationships are further illustrated by these diagrams.

11 shows according to an alternative embodiment, a connecting tube ( 5 ), the sections of a balloon-like expanding material ( 23 ) consists. The expandable material ( 23 ), for example, the connection hose ( 5 ) form themselves and / or represent a separate element on or in the hose. According to the embodiment in 11 extends the expandable material ( 23 ) along a segment of the longitudinal extent of the connecting tube ( 5 ). In the limiting case, it is also intended to use the entire connecting hose ( 5 ) of the expandable material ( 23 ) train. The constructive realization and dimensioning of the expandable material ( 23 ) is performed such that at a given pressurization a defined volume of gas is absorbed by the expansion.

As material for the expandable material ( 23 For example, plastic can be used. In particular, the use of silicone and / or latex is intended. According to a further embodiment, a flexible component is used, which is equipped with a pressure relief valve. The pressure relief valve can be realized replaceable. In particular, it is intended to provide a plurality of pressure relief valves with different characteristics. For example, it is possible to use pressure relief valves which open staggered from a pressure of 4, 5, 6, ..., 48, 49 and 50 mbar. A typical opening range for the pressure relief valves is in a pressure range of 4 mbar to 50 mbar. It is also thought to make the pressure relief valve adjustable, so that the opening pressure can be predetermined.

According to the embodiment in FIG 12 an expansion of the expandable material ( 23 ) by a comparison with FIG. 11 higher pressurization. Due to the inherent elasticity of the expandable material ( 23 ) the expansion decreases with decreasing pressure and the expansion process reverses. Typically, the expandable material is tuned to a working pressure range, for example a pressure range of 10 mbar.

A typical dimensioning is such that the expandable material at a base pressure at 10 mbar the in 11 illustrated unexpanded state occupies. When exhaling a user of the ventilation device is a short-term pressure increase, the expandable material ( 23 ) deflects from the rest position. It is here first in 12 shown intermediate positioning and then at a maximum expiratory pressure in 13 shown final positioning taken.

Using the expandable material ( 23 In particular, it is possible to perform an expansion proportional to the pressure increase. At one end of the exhalation process, the pressure decreases again and the expandable material ( 23 ) returns to the 11 shown starting position back.

According to a further embodiment, it is contemplated that the expandable material ( 23 ) is successively expanded with increasing pressure and contracted with decreasing pressure. It is thereby provided for the user of the respiratory device, a lesser back pressure against which the exhalation must occur.

By using the expandable material ( 23 ), a slightly increased pressure is provided to the user during inspiration since the intrinsic elasticity of the expandable material ( 23 ) returns this with decreasing back pressure in the starting position. Thus, during inspiration, adequate pressure is immediately provided which reduces the risk of contraction of the flow paths.

In a preferred embodiment, the upper pressure level is in a range of 4 to 18 mbar, the pressure reduction to the lower pressure level is about 3 mbar. With additional realization of a further pressure increase relative to the first pressure level, this additional increase is about 1 to 4 mbar.

14 to 16 show embodiments in which an expandable material ( 23 ) or a differently designed flexible element in the region of the patient interface ( 10 ), for example a respiratory mask. A patient interface designed as a ventilation mask typically consists of a mask base body ( 24 ) and a flexible contour element ( 25 ). The mask body ( 24 ) and the flexible contour element ( 25 ) are in the range of an edge ( 26 ) preferably joined together in a form-fitting manner.

The expandable material ( 23 ) is preferably in the region of the mask body ( 24 ) arranged. 14 shows a ground state, 15 a part expansion and 16 the maximum expanded state.

17 shows an embodiment in which, in addition to a pressure drop within the expiratory phase, a pressure increase is provided within the inspiratory phase. The pressure increase takes place shortly after a change from the expiratory phase into the inspiration phase. Typically, the pressure reduction and / or the pressure increase is performed at least in sections proportional to the flow.

Claims (1)

Device for pressure control in ventilators, which has a control unit and at least one sensor for a ventilation parameter and which is coupled to a respiratory gas supply which is adjustable to at least two different pressure levels, the control unit determining the time position of inspiration phases (14) and expiration phases (15). evaluates and prescribes a pressure reduction within the inspiratory phase before the beginning of the expiration phase, characterized in that the pressure control takes place using a sensor with which a vertex of the flow profile (13) during the inspiration phase (14) is detected, wherein following the metrological detection of such Vertex the beginning of the lead time (17) is started and the pressure reduction is performed.

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