VENTILATION APPARATUS AND VENTILATION METHOD

Abstract

A ventilator (1), for ventilating the lungs of a patient with breathing air, includes a ventilation module (2) for generating a breathing air flow, a determination module (3) for determining a first ventilation parameter as well as a different second ventilation parameter of the ventilator, and a control module (4) for controlling the ventilator as a function of the determined first and/or second ventilation parameter. The control module is configured to reduce the first ventilation parameter automatically over an analysis period including at least one breathing cycle. A classification module (5) is configured to classify a pulmonary status of the lungs of the patient based on a change in the second ventilation parameter, which change was brought about by the automatic reduction of the first ventilation parameter. A process is further provided for ventilating the lungs of a patient with breathing air with a ventilator (1).

Claims

1. A ventilator for ventilating the lungs of a patient with breathing air, the ventilator comprising: a ventilation module configured to generate a breathing air flow; a determination module configured to determine a first ventilation parameter as well as a second ventilation parameter of the ventilator, which said second ventilation parameter is different from the first ventilation parameter; a control module configured to control the ventilator as a function of the determined first ventilation parameter and/or of the determined second ventilation parameter, wherein the control module is configured automatically to reduce the first ventilation parameter over an analysis period comprising at least one breathing cycle; and a classification module configured to classify the pulmonary status of the lungs of the patient on the basis of a change in the second ventilation parameter, which was brought about by the automatic reduction of the first ventilation parameter.

2. A ventilator in accordance with claim 1, wherein the control module is configured to carry out a recruitment maneuver to improve the pulmonary status corresponding to a classification of the pulmonary status of the lungs of the patient, which was carried out by the classification module.

3. A ventilator in accordance with claim 1, wherein the classification module is configured to classify the pulmonary status of the lungs of the patient qualitatively as collapsed, overdistended or normal.

4. A ventilator in accordance with claim 1, wherein the classification module is configured to classify the pulmonary status of the lungs of the patient quantitatively.

5. A ventilator in accordance with claim 4, further comprising an alarm device configured to output an alarm when the quantitatively classified pulmonary status falls below a collapse limit value or exceeds an overdistension limit value.

6. A ventilator in accordance with claim 1, wherein the control module is configured to reduce a ventilation volume and/or a ventilation pressure automatically as a first ventilation parameter.

7. A ventilator in accordance with claim 1, wherein the control module is configured to reduce the first ventilation parameter stepwise over an analysis period comprising a plurality of breathing cycles.

8. A ventilator in accordance with claim 1, further comprising a display device, wherein the display device is configured to display the pulmonary status of the lungs of the patient and/or to display a recruitment maneuver recommended on the basis of the pulmonary status.

9. A ventilator , in accordance with claim 1, wherein the classification module is configured to estimate a linear lung model of the lungs of the patient on the basis of the first ventilation parameter and second ventilation parameter, which were determined prior to the automatic reduction of the first ventilation parameter, wherein the classification module is further configured to classify the pulmonary status of the lungs on the basis of the estimated lung model and on the basis of the second ventilation parameter determined after the automatic reduction of the first ventilation parameter.

10. A ventilator in accordance with claim 1, further comprising an EIT module for determining a pulmonary status of the lungs or at least a part of the lungs of the patient, wherein the classification module is configured to take into account a change in the distension and/or compliance of the lungs, which was brought about after the automatic reduction of the first ventilation parameter and was detected by the EIT module during the classification of the pulmonary status.

11. A ventilator in accordance with claim 1, wherein the control device is configured to reduce the first ventilation parameter automatically by between 20% and 60%.

12. A process for ventilating lungs of a patient with breathing air by means of a ventilator, the process comprising the steps of: generating a breathing air flow by means of a ventilation module of the ventilator; determining a first ventilation parameter and of a second ventilation parameter different from the first ventilation parameter by means of a determination module of the ventilator; automatically reducing the first ventilation parameter over an analysis period comprising at least one breathing cycle by means of a control device of the ventilator; determining a change in the second ventilation parameter, which change was brought about by the automatic reduction of the first ventilation parameter, by means of the determination module; and classifying a pulmonary status of the lungs of the patient on the basis of the change in the second ventilation parameter, which was brought about by the automatic reduction of the first ventilation parameter, by means of a classification module of the ventilator.

13. A process in accordance with claim 12, wherein a breathing pressure is used as the first ventilation parameter and a ventilation volume is used as the second ventilation parameter.

14. A process in accordance with claim 12, wherein the classified pulmonary status of the lungs of the patient and/or a recruitment maneuver suitable for improving the pulmonary status of the lungs are displayed by means of a display device of the ventilator, and/or a recruitment maneuver suitable for improving the pulmonary status of the lungs is carried out by means of the control device.

15. A process in accordance with claim 12, wherein the control device is configured to carry out a recruitment maneuver to improve the pulmonary status corresponding to a classification of the pulmonary status of the lungs of the patient, which classification was carried out by the classification module.

16. A process in accordance with claim 12, wherein the classification module is configured to classify the pulmonary status of the lungs of the patient qualitatively as collapsed, overdistended or normal.

17. A process in accordance with claim 12, wherein the classification module is configured to classify the pulmonary status of the lungs of the patient quantitatively.

18. A process in accordance with claim 17, further comprising providing the ventilator with an alarm device configured to output an alarm when the quantitatively classified pulmonary status falls below a collapse limit value or exceeds an overdistension limit value.

19. A process in accordance with claim 12, wherein the control module is configured to reduce a ventilation volume and/or a ventilation pressure automatically as a first ventilation parameter.

20. A process in accordance with claim 12, wherein the control module is configured to reduce the first ventilation parameter stepwise over an analysis period comprising a plurality of breathing cycles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In the drawings:

[0070] FIG. 1 is a schematic view of a preferred embodiment of a ventilator according to the present invention;

[0071] FIG. 2 is a time diagram showing a response of collapsed lungs to a first reduction of the ventilation pressure;

[0072] FIG. 3 is a time diagram showing a response of overextended lungs to the first reduction of the ventilation pressure;

[0073] FIG. 4 is a time diagram showing a response of collapsed lungs to a second reduction of the ventilation pressure;

[0074] FIG. 5 is a time diagram showing a response of overdistended lungs to the second reduction of the ventilation pressure;

[0075] FIG. 6 shows time diagrams of pressures and volumes of collapsed lungs compared to a first linear lung model;

[0076] FIG. 7 shows time diagrams of pressures and volumes of overdistended lungs compared to a second linear lung model; and

[0077] FIG. 8 is a flow chart of a preferred embodiment of the process according to the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0078] Referring to the drawings, elements having the same function and mode of operation are provided with the same reference numbers in FIGS. 1 through 8.

[0079] The preferred embodiment of a ventilator 1 according to the present invention, which is schematically shown in FIG. 1, has a ventilation module 2 for generating a breathing air flow for ventilating the lungs of a patient. The ventilation module 2 is coupled to a patient inhalation interface 10 and to a patient exhalation interface 11 in a fluid-communicating manner. Moreover, the ventilator 1 preferably has an air inlet and/or oxygen inlet and/or an anesthetic gas inlet and/or a breathing air outlet, which are not shown, and which are coupled to the patient inhalation interface 10, to the patient exhalation interface 11 and to the ventilation module 2 in a fluid-communicating manner and can be coupled via a breathing air tube for ventilating the lungs of the patient in a fluid-communicating manner. The patient inhalation interface 10 can be coupled via a breathing air tube, not shown, in order to ventilate the patient via the breathing air tube. The patient exhalation interface 11 can be coupled to the breathing air tube in order to remove breathing air from the patient to the ventilator 1. In addition, the course of the exhalation of the patient can be better controlled hereby, especially by setting or adjusting the PEEP. The patient's lungs can be prevented from collapsing in this manner.

[0080] In the preferred embodiment of the present invention that is shown in FIG. 1, a determination module 3 is coupled to the patient inhalation interface 10 and to the patient exhalation interface 11 such that air pressures as well as air volume flows in the patient inhalation interface 10 as well as in the patient exhalation interface 11 can be determined by means of the determination device 3. In addition, provisions may be made according to the present invention for the determination device 3 to have additional sensors, for example, a temperature sensor, a humidity sensor or the like in order to determine additional parameters of the air flows within and outside the ventilator. The determination device 3 is thus configured to determine the first ventilation parameter, especially a ventilation volume, and the second ventilation parameter, especially a ventilation pressure.

[0081] The ventilator 1 has a control module 4 for controlling the ventilator 1 as a function of the first ventilation parameter determined by the determination module 3 and/or of the determined second ventilation parameter. The control module 4 is thus configured to control the ventilation module 2, especially automatically to reduce the first ventilation parameter over an analysis period comprising at least one breathing cycle. Further, the ventilator 1 has a classification module 5, which is configured to classify a pulmonary status of the lungs of the patient on the basis of a change in the second ventilation parameter, which change is brought about by the automatic reduction of the first ventilation parameter. The ventilator 1 has an optional alarm device 6 in this preferred embodiment. The alarm device 6 is configured to output an alarm, especially an optical and/or acoustic alarm, when the quantitatively classified pulmonary status falls below a collapse limit value or exceeds an overdistension limit value.

[0082] Moreover, the ventilator 1 has an EIT module 8 for determining a pulmonary status of the lungs or at least of a part of the lungs of the patient. The ventilation module 2, the determination module 3, the control module 4, the classification module 5, the alarm device 6 and the EIT module 8 are arranged within a housing 9 of the ventilator 1. Provisions may be made for one or more of these components, for example, the alarm device 6 or an ET module 8, to be arranged completely or at least partially outside the housing 9. The ventilator 1 preferably has an electrode interface, not shown, for coupling patient electrodes to the EIT module.

[0083] Furthermore, the ventilator 1 has a display device 7 for displaying ventilation parameters. The display device 7 is preferably configured to display actuation information for the improved actuation of the ventilator 1. Provisions may be made according to the present invention for the display device 7 to be configured as a touchscreen. The alarm device 6 may also be integrated at least partly in the display device 7, so that the display device is configured for displaying and/or acoustically outputting alarms. The display device 7 is arranged in this exemplary embodiment outside the housing 9 and is held at same adjustably, for example, rotatably about a vertical axis and/or pivotably about a horizontal axis. Provisions may also be made for the display device 7 to be arranged completely or at least partially within the housing 9, for example, behind a window. Provisions may likewise be made according to the present invention for the display device 7 to be configured such that it is detachable from the housing 9.

[0084] A response of collapsed lungs to a first ventilation pressure reduction is shown schematically in a diagram in a schematic time diagram in FIG. 2. The first four breathing cycles take place with non-adapted ventilation parameters. The ventilation pressure dP is reduced by the fifth breathing cycle by reducing P.sub.insp.set at constant PEEP.sub.set. This brings about a reduction of the ventilation volume. The quotient of the ventilation volume (V.sub.T) and ventilation pressure (dP) (V.sub.T/dP) drops in this case. The classification module 5 can recognize from this that a collapse of the lungs is present.

[0085] FIG. 3 schematically shows in a time diagram a response of overdistended lungs to the first ventilation pressure reduction. The first four breathing cycles take place with non-adapted ventilation parameters. The ventilation pressure is reduced by the fifth breathing cycle by reducing P.sub.insp.set at constant PEEP.sub.set. This brings about a reduction of the ventilation volume. The quotient of the ventilation volume (V.sub.T) and the ventilation pressure (dP) (V.sub.T/dP) increases in this case. The classification module 5 can recognize from this that an overdistension of the lungs is present.

[0086] FIG. 4 schematically shows in a time diagram a response of collapsed lungs to a second ventilation pressure reduction. The first four breathing cycles take place with non-adapted ventilation parameters. The ventilation pressure is reduced by the fifth breathing cycle by raising PEEP.sub.set at constant P.sub.insp.set. This brings about a reduction of the ventilation volume. The quotient of the ventilation volume (V.sub.1) and the ventilation pressure (dP) (V.sub.T/dP) increases in this case. The classification module 5 can recognize from this that a collapse of the lungs is present.

[0087] FIG. 5 schematically shows in a time diagram a response of overdistended lungs to the second ventilation pressure reduction. The first four breathing cycles take place with non-adapted ventilation parameters. The ventilation pressure is reduced by the fifth breathing cycle by raising PEEP.sub.set at constant P.sub.insp.set. This brings about a reduction of the ventilation volume. The quotient of the ventilation volume (V.sub.1) and ventilation pressure (dP) (V.sub.T/dP) drops. The classification module 5 can recognize from this that an overdistension of the lungs is present.

[0088] FIG. 6 schematically shows time diagrams of pressures and volumes of collapsed lungs (collapse) compared to a first linear lung model. The first linear lung model is estimated on the basis of the measured value curves of all breathing cycles. In the presence of an overdistension of the lungs, the compliance of the linear lung model is higher than the actual compliance at the time at which the plateau pressure is reached. Calculated ventilation volumes are thus higher than measured ventilation volumes. In addition, a rise time of the measured ventilation volume is shorter and a fall time is longer compared to the linear lung model, in which the rise time and the fall time are of equal length.

[0089] In the presence of a collapse of the lungs, the compliance of the linear lung model is lower than the actual compliance at the time at which the plateau pressure is reached. Calculated ventilation volumes are thus lower than measured ventilation volumes. Moreover, the rise time of the measured ventilation volume is longer and the fall time is shorter in the presence of a collapse of the lungs compared to the linear lung model.

[0090] FIG. 7 schematically shows time diagrams of pressures and volumes of overdistended lungs (overdistension) compared to a second linear lung model. The second linear lung model is estimated separately for inhalation and exhalation only for the regions in which the value of the ventilation volume flow (q) exceeds a certain limit value. The linear lung model thus has an inspiratory lung model and an expiratory lung model.

[0091] The time constant, the rise time and the fall time of the inspiratory lung model are lower in the presence of an overdistension than those of the expiratory lung model.

[0092] The time constants, the rise time and the fall time of the inspiratory lung model are higher than those of the expiratory lung model in the presence of a collapse.

[0093] FIG. 8 schematically shows a preferred embodiment of the process according to the present invention in a flow chart. In a first process step 100, the breathing air flow for ventilating the patient is generated by means of the ventilation module 2 of the ventilator 1. The ventilation module 2 is controlled here by the control module 4. In a second process step 200, the first ventilation parameter and the second ventilation parameter are determined by means of the determination module 3 of the ventilator 1. The determination is preferably carried out continuously or repeatedly in order to guarantee a defined ventilation of the patient. In a third process step 300, the control device 4 of the ventilator 1 reduces the first ventilation parameter automatically over an analysis period comprising at least one breathing cycle. Either the P.sub.insp.set is reduced here at constant PEEP.sub.set or PEEP.sub.set is raised at constant P.sub.insp.set. In a fourth process step 400, the determination module 3 determines the change in the second ventilation parameter, which was brought about by the automatic reduction of the first ventilation parameter. In a fifth process step 500, the classification module 5 of the ventilator 1 classifies the pulmonary status of the lungs of the patient on the basis of the change in the second ventilation parameter, which change was brought about by the automatic reduction of the first ventilation parameter. Preferred classification categories are “overdistended,” “normal” and “collapsed.” In a sixth process step 600, the classified pulmonary status of the lungs of the patient and/or a recruitment maneuver suitable for improving the pulmonary status of the lungs are displayed by means of the display device 7 of the ventilator 1. As an alternative or in addition, a recruitment maneuver suitable for improving the pulmonary status of the lungs is carried out by means of the control device 4 in a seventh process step 700. The process is preferably carried out iteratively in order to attain successively a normal pulmonary status.

[0094] 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.