RESPIRATOR FOR APAP RESPIRATION USING OSCILLATORY PRESSURE

Abstract

Disclosed is an autoCPAP respirator which comprises a control unit, a respiration blower and a pressure sensor. The control unit comprises a controller for generating a first control signal, which induces the speed of the blower to generate a pressurized breathing gas flow, a controller for generating a periodically variable control signal, which activates the blower such that the speed of the blower varies in an oscillating manner at a frequency in the range of 1-20 Hz, and a sensor device, which ascertains one or more of instantaneous speed, instantaneous electrical current and instantaneous electrical power of the blower to determine the breathing gas flow and/or breathing gas volume generated by the blower while using characteristic data of the blower stored in a memory.

Claims

1. An autoCPAP respirator, wherein the respirator comprises a control unit, a respiration blower, and a pressure sensor, the control unit comprising a first controller for generating a first control signal, which induces a speed of the blower to generate a pressurized breathing gas flow, a second controller for generating a periodically variable control signal, which activates the blower such that a speed of the blower varies in an oscillating manner at a frequency in a range of 1-20 Hz, and a sensor device, which ascertains at least one of an instantaneous speed of the blower, an instantaneous electrical current of the blower, and an instantaneous electrical power of the blower to determine a breathing gas flow and/or breathing gas volume generated by the blower while using characteristic data of the blower stored in a memory and pressure values provided by the pressure sensor.

2. The autoCPAP respirator of claim 1, wherein both a speed of a motor and also a pressure in a region of a flow volume are metrologically detected and supplied to the control unit, the flow volume being ascertained by the control unit by a computed linkage of measured values for the pressure and the speed.

3. The autoCPAP respirator of claim 1, wherein a motor which is provided with a sensor device for speed detection and a sensor for pressure measurement is arranged in a region of a flow volume, the sensor and the sensor device being connected to the control unit, and the control unit is provided with a computer unit for determining the flow volume and/or the breathing gas flow by way of a computed linkage of measured values for the pressure and the speed.

4. The autoCPAP respirator of claim 1, wherein a characteristic map is metrologically recorded and stored in the respirator before a detection of a flow volume.

5. The autoCPAP respirator of claim 1, wherein the pressure is ascertained at the device outlet.

6. The autoCPAP respirator of claim 1, wherein an ascertained breathing gas flow is adapted at least temporarily in consideration of ascertained or stored values of one or more compensation parameters.

7. The autoCPAP respirator of claim 6, wherein the one or more compensation parameters comprise one or more of ambient pressure, temperature, accessories used, ambient humidity, leakage, present treatment pressure.

8. The autoCPAP respirator of claim 6, wherein at least two compensation parameters are ascertained by sensors or determined by computer or read out or input by a user.

9. The autoCPAP respirator of claim 6, wherein an ascertained breathing gas flow is at least temporarily adapted in consideration of ascertained values of the one or more compensation parameters and while using at least one of a characteristic map, a linear regression equation, multidimensional regression, linearization. quadratic/exponential equations.

10. The autoCPAP respirator of claim 6, wherein a stored device-typical compensation parameter is retrieved and used to adapt an ascertained breathing gas flow at least temporarily.

11. The autoCPAP respirator of claim 1, wherein values provided by the sensor device are corrected based on ambient pressure.

12. The autoCPAP respirator of claim 1, wherein values provided by the sensor device are corrected based on a temperature of a breathing gas at the respiration blower and/or ambient humidity.

13. The autoCPAP respirator of claim 1, wherein values provided by the sensor device are corrected by specific characteristic maps depending on accessory type.

14. The autoCPAP respirator of claim 1, wherein a FOT oscillation is generated using the respiration blower and a 1-20 Hz oscillation is modulated for this purpose to a treatment target pressure and is also regulated by a pressure regulator.

15. The autoCPAP respirator of claim 1, wherein a target pressure is changed in an oscillating manner by the controller to generate an FOT oscillation.

16. The autoCPAP respirator of claim 14, wherein in particular at high frequencies, the pressure regulator estimates a pressure drop via a hose and other accessories on the basis of a calculated breathing gas flow and attempts to compensate for it.

17. The autoCPAP respirator of claim 1, wherein a consistency of airways is ascertained on the basis of a quotient of an amplitude of computed breathing gas flow and pressure.

18. The autoCPAP respirator of claim 1, wherein during apnea classification with FOT, a predefined target pressure value P.sub.set is overlaid with a sinusoidal oscillation at a frequency of 2-10 Hz.

19. An autoCPAP respirator, wherein the respirator comprises a control unit, a respiration blower, and a pressure sensor, the control unit comprising a first controller for generating a first control signal, which induces a speed of the blower to generate a pressurized breathing gas flow, a second controller for generating a periodically variable control signal, which activates the blower such that the speed of the blower varies in an oscillating manner at a frequency in a range of 1-30 Hz, and a sensor device, which ascertains at least one of instantaneous speed of the blower, instantaneous electrical current of the blower, and instantaneous electrical power of the blower to determine a breathing gas flow and/or breathing gas volume generated by the blower while using characteristic data of the blower stored in a memory and pressure values provided by the pressure sensor, the breathing gas flow thus ascertained being adapted at least temporarily in consideration of ascertained values of one or more compensation parameters.

20. An autoCPAP respirator, wherein the respirator comprises a control unit, a respiration blower and a pressure sensor, the control unit comprising a first controller for generating a first control signal, which induces a speed of the blower to generate a pressurized breathing gas flow, a second controller for generating a periodically variable control signal, which activates the blower such that the speed of the blower varies in an oscillating manner at a frequency in a range of 1-30 Hz, and a sensor device, which ascertains at least an instantaneous speed of the blower to determine the breathing gas flow generated by the blower while using characteristic data of the blower stored in a memory and pressure values provided by the pressure sensor, the breathing gas flow thus ascertained being adapted at least temporarily in consideration of one or more compensation parameters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the following drawings:

[0041] FIG. 1 shows a basic structure of a respiration device according to the invention;

[0042] FIG. 2 is a schematic block diagram to explain a part of an internal construction of the device of FIG. 1;

[0043] FIG. 3 is a characteristic map which shows the dependence of the flow volume on the respective pressure for an exemplary respiration system;

[0044] FIG. 4: shows a measured curve of the flow volume and a curve computed by a control unit of a respiratory system according to the invention;

[0045] FIG. 5a shows an example of pressure and flow oscillation in the event of obstructed airways;

[0046] FIG. 5b shows an example of pressure and flow oscillation in the event of open airways.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0047] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description in combination with the drawings making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

[0048] FIG. 1 shows the basic structure of a device for respiration (1). A breathing gas pump is arranged in a device interior in the region of a device housing having an operating panel (10) and display (11). A connecting hose is connected via a coupling (14). An additional pressure measuring hose can extend along the connecting hose, which is connectable via a pressure inlet nozzle to the device housing. The device housing has at least one interface (12, 13) to enable a data transmission.

[0049] An operating element (15) is arranged in the region of the device housing, to be able to manually predefine a dynamic mode of the respirator. The operating element (15) can be arranged in the region of the operating panel or can be embodied as an external or separate operating element.

[0050] To avoid drying out of the airways, it has proven to be advantageous in particular during longer respiration phases to carry out humidification of the breathing air. Such humidification of the breathing air can also be implemented in other applications. A breathing air humidifier is laterally adapted for the humidification.

[0051] It is possible that the control device is suitable and designed for the purpose of monitoring a flow signal and/or a pressure signal and evaluating them on the basis of at least one algorithm, to classify an event. The flow signal and/or the pressure signal are provided in this case by at least one sensor element associated with the control device. The sensor element is provided in this case for detecting at least one flow property and/or at least one pressure property of the air flow for the respiration. The evaluation of flow signals and/or pressure signals enables a reliable recognition and classification of events of the respiration.

[0052] The control device is particularly preferably also suitable and designed to register at least one respiration parameter on the basis of the flow signal and/or the pressure signal, for example, the breathing frequency, the breath volume, the respiratory minute volume, the inspiration flow and/or the inspiration pressure and/or the airway resistance.

[0053] The control device can additionally be suitable and designed for the purpose of applying an oscillating control signal to the flow generator. The flow generator thereupon generates a breathing gas flow having a modulated pressure oscillation, which is preferably in the range of 1-20 Hz, particularly preferably 2-10 Hz, or also about 4 Hz, and causes a pressure stroke of 0.1-1 cm H.sub.2O, preferably about 0.4 cm H.sub.2O. This pressure stroke also induces an oscillating flow.

[0054] The control device can be suitable and designed to output a corresponding notification to a user in the event of registered breathing events. For example, the notification can be visually and/or acoustically indicated by means of a display device. The notification can also be output, for example, by means of an interface to at least one external data processing device. Such a notification is particularly advantageous, because the respiration treatment can be adapted accordingly in awareness of the events. On the other hand, if the notification does not occur, a corresponding success of the respiration treatment can be established.

[0055] The respirator can be adapted dynamically and in particular depending on the breathing phase of the user. For example, a breathing phase change can be recognized on the basis of the control device, so that a higher or lower pressure can be provided depending on the breathing phase. For example, the respirator can be designed as a CPAP or APAP device. The respirator 1 can also be designed as a bilevel device. For example, the respirator 1 reacts to determined breathing events, for example, snoring, breath flattening, and/or obstructive pressure peaks, with corresponding settings of the respiration parameters.

[0056] Using the respirator 1 shown here, events which occur in the breathing or during the respiration are recognized and classified. For this purpose, the sensor means detects one or more respiration parameters such as pressure and/or flow and/or ODS signal and supplies corresponding signals to the control device 7. The control device 7 analyzes the signals by means of suitable algorithms, so that characteristic signal curves can be recognized and classified as an event. In this case, for example, a parameter extraction can be used with reference to levels and amplitude values, time intervals, envelope curves, zero crossings, and slopes. In the case of an analysis with regard to time features, for example, periodicities and frequencies are used during a parameter extraction. An obstructive apnea (OA) is recognized if a greatly reduced flow volume is recognized and/or an ODS increase occurs for at least two breaths.

[0057] An obstructive hypopnea (OH) is shown, for example, by way of a reduced flow volume for two successive inspirations or by obstructive flattening (a typical flattening of the breathing curve) of the flow signal.

[0058] Obstructive snoring (OS) is recognized by cumulative snoring over at least two consecutive inspirations accompanied by obstructions or flattening.

[0059] Obstructive flattening (OF) is recognized by cumulative flattening over at least three inspirations, and at least one increase of the inspirational ODS signal.

[0060] An obstructive event (OE) is recognized by a significant cumulative inspirational increase of the ODS signal.

[0061] Snoring (S) is recognized by cumulative snoring (at least 3 cumulative inspirations) without inspirational ODS increase.

[0062] Nonspecific flattening (NF) is recognized by cumulative flattening (at least 3 inspirations).

[0063] A central apnea (CA) is recognized via a strongly reduced flow volume for 10 seconds without ODS increase or flattening.

[0064] A central hypopnea (CH) is recognized by a reduced flow volume (2 consecutive inspirations) without ODS increase.

[0065] A leak in the region of the patient interface or a mouth and mask leak is recognized in that the target pressure cannot be reached and/or the leak flow is greater than 0.6 l/sec.

[0066] The recognized events can then be stored in the storage device and used for a respiration statistic. One advantage of the event recognition is that an adaptation of the respiration can be performed on the basis of the classified events, for example, an automatic pressure increase in the event of an obstructive apnea. In addition, a diagnosis of determined respiratory disturbances can be performed to a certain extent.

[0067] A special advantage of the respirator 1 shown here is the control device 7, which further analyzes the recognized events and also registers Cheyne-Stokes breathing on the basis of a characteristic occurrence of the events. Such an event analysis is sketched by way of example in FIG. 2.

[0068] FIG. 2 shows a schematic block diagram to explain a part of an internal construction of the device corresponding to FIG. 1. A pump device (13), which is designed as a blower, is provided for conveying the flow volume of breathing gas. The pump device (13) is driven by a motor (14). A sensor (15), which is connected to a control unit (16), is used to detect a speed of the motor (14). A sensor (18) for detecting a pressure is arranged in the region of a line (17), which is fed by the pump device (13), for the flow volume. The sensor (18) is also connected to the controller (16).

[0069] A computer unit (19) is implemented in the region of the control unit (16), which performs a computed linkage of the measured values for the pressure and the speed and computes a present volume flow therefrom. If the control unit (16) is designed as a digital computer, for example a microprocessor, it is possible to implement the computer unit (19) as part of the sequence programming of the control unit (16). In the case of an analog design of the control unit (16), the intention is also to implement the computer unit (19) via components having linear or nonlinear electrical behavior.

[0070] FIG. 3 illustrates a characteristic map, which reflects the dependence of the flow volume on the respective pressure for a respiration system selected by way of example. It can be seen in particular that different characteristic curve profiles result at different speeds of the motor (14). The respective characteristic curves consist of approximately parabolic subregions, which are connected in the surroundings of the pressure axis by approximately linear curves.

[0071] FIG. 4 compares a measured curve (20) of the flow volume and a curve (21) computed by the control unit (16). The flow volume is indicated in this case in l/sec. It can be seen that there is a very extensive correspondence.

[0072] FIG. 5a and FIG. 5b show experimentally obtained pressure and flow oscillation curves for obstructed and open airways respectively. The treatment pressure in both cases was 4 hPa (without leakage).

[0073] For an implementation of the method according to the invention and in a construction of the device according to the invention, the characteristic map is determined metrologically according to FIG. 3. For different motor speeds, the respective characteristic curve is determined in this case for the entirety of motor (14), pump device (13), line (17), and sensor (18). For the individual characteristic curves K for each speed, the pressure P results in this case as a function of the volume flow F according to the equation

P.sub.k(F)=a.sub.k2*F.sup.2+a.sub.k1*F+a.sub.k0

[0074] The above equation represents an approximation of the actual curve, but it has been shown that this approximation has a good correspondence to the actual characteristic curve profile. Each of the secondary coefficients a.sub.ki with i=0 to 2 is dependent on the respective speed. The above equation may therefore also be represented in the form

P(F)=a.sub.2(n)*F.sup.2+a.sub.1(n)*F+a.sub.0(n).

[0075] It has been shown that the secondary coefficients a.sub.ki can also be determined in a good approximation from the respective speed using a quadratic equation. A corresponding equation approach reads

a.sub.i=b.sub.i2*n.sup.2+b.sub.i1*n+b.sub.i0.

[0076] The primary coefficients b.sub.ik represent here the mechanical and electrical properties of the overall system and can be determined metrologically. In consideration of the quadratic approaches for the dependence between the pressure and the volume flow and the secondary coefficients a.sub.ik of the primary coefficients b.sub.ik, a total of nine coefficients b.sub.ik are to be determined metrologically. The simple equation structure enables the secondary coefficients a.sub.k(n) to be recalculated from the known primary coefficients b.sub.i before each value for the volume flow to be recalculated. The actual value for the volume flow is then ascertained via the inverse function of the equation listed first.