Apparatus and method for determining regional lung compliance

Abstract

The invention relates to an apparatus and a method for determining a measure of the regional extensibility of a lung of a patient (P) in a plurality of different regions of the lung. An airway pressure sensor (3) measures a time-variable pressure (P aw ). The difference between the end-inspiratory transpulmonary pressure and the end-expiratory transpulmonary pressure is determined. An EIT measuring device (17) measures the volume change of a lung region by means of electrical impedance tomography (EIT). The difference between the end-inspiratory volume and the end-expiratory volume of the lung region is determined using the signal of the EIT measuring device (17). As a measure of the regional extensibility of the lung region, the quotient of the volume difference for the region and the pressure difference applied to the lung is calculated.

Description

Technical Field

[0001] The invention relates to a device and a method for determining a measure of the respective regional extensibility of a patient's lung in a plurality of different regions of the lung. Extensibility is also referred to as "compliance". Background Art

[0002] In the following the term "respiratory system" of the patient is used. The respiratory system includes his lungs and his chest cavity.

[0003] If the patient is breathing spontaneously and / or is being artificially ventilated, the following two undesirable situations should be avoided, each of which alone could damage the patient's lungs:

[0004] - The pneumatic pressure applied to the lung is too low and the lung collapses (collapses).

[0005] -The pressure applied is too great and over-expands the lungs.

[0006] A scheme for controlling a ventilator based on the extensibility of the lung is described in Zhanqi Zhao et al., “Positive End-Expiratory Pressure Titration with Electrical Impedance Tomography and Pressure–Volume Curve in Severe AcuteRespiratory Distress Syndrome,” Annals of Intensive Care 9, No. 1 (December 2019) (available at https: / / doi.org / 10.1186 / s13613-019-0484-0, retrieved on June 12, 2020). Other schemes for determining the mechanical / pneumatic properties of a patient's lungs and / or for controlling a ventilator are described in:

[0007] -Ola Stenqvist, Per Persson, and Stefan Lundin, “Can We Estimate Transpulmonary Pressure without an Esophageal Balloon?—Yes,” Annals of Translational Medicine 6, No. 19 (October 2018): 392ff, available at https: / / doi.org / 10.21037 / atm.2018.06.05, retrieved on June 12, 2020,

[0008] -Giacomo Bellani et al., “Plateau and Driving Pressure in the Presence of Spontaneous Breathing,” Intensive Care Medicine 45, No. 1 (January 2019): 97–98, available at https: / / doi.org / 10.1007 / s00134-018-5311-9, retrieved June 12, 2020,

[0009] - Daniel Talmor et al., “Mechanical Ventilation Guided by Esophageal Pressure in Acute Lung Injury,” New England Journal of Medicine 359, No. 20 (November 3, 2008): 2095–2104, available at https: / / doi.org / 10.1056 / NEJMoa0708638, retrieved June 12, 2020,

[0010] -JeremyR.Beitler et al.'s "Effect ofTitratingPositive End-ExpiratoryPressure(PEEP)With an Esophageal Pressure–Guided Strategyvs.anEmpirical High" Strategy on Death and Days Free From Mechanical Ventilation Among Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial,” JAMA, February 18, 2019, available at https: / / doi.org / 10.1001 / jama.2019.0555, retrieved June 12, 2020.

[0011] The extensibility of the lungs varies from lung region to lung region. For example, it is known from DE 10 2005 031 752 B4 to measure different regions of the lungs by means of impedance tomography, preferably by means of a so-called EIT belt placed around the patient's body.

[0012] In "Bedside Estimation of Recruitable Alveolar Collapse and Hyperdistension by Electrical Impedance Tomography," Intensive Care Medicine 35, No. 6 (June 2009): 1132–37 (available at https: / / doi.org / 10.1007 / s00134-009-1447-y, retrieved on June 12, 2020), Eduardo LVCosta et al. proposed analyzing the extensibility or elasticity (compliance) of the patient's respiratory system during the setting of a variable end-expiratory pressure (PEEP). Different values ​​were set on a trial basis, and the compliance of the respiratory system was investigated in which areas and to what extent it was reduced, wherein this reduction was interpreted as an overextension of the lungs. or collapse (Kollap). Summary of the invention

[0013] The object of the present invention is to provide a device and a method which are able to measure the extensibility of the lung better than known devices and methods.

[0014] This object is achieved by having the device and method provided by the present invention. Wherever appropriate, advantageous configurations of the device according to the present invention are also advantageous configurations of the method according to the present invention, and vice versa.

[0015] The present invention relates to an apparatus and a method for automatically determining the measure of the respective regional extensibility of a patient's lung in at least two different regions of the lung. The regional extensibility is the extensibility of the lung in lung regions, wherein each lung region is predetermined and comprises a portion of the lung, but not the entire lung. The lung regions preferably do not intersect with each other, i.e. do not overlap. Each region of the lung for which the regional extensibility is to be determined is defined so that at a point in time, the regional extensibility in the entire lung region is considered to be the same everywhere with sufficient accuracy for the application. For example, due to changes in the patient's state or due to different settings of a ventilator for artificially breathing the patient, the determined regional extensibility of the lung region may change over time. At a point in time, the respectively determined regional extensibility may change from lung region to lung region (von Lungenbereich zu Lungenbereich).

[0016] The device according to the invention comprises an EIT measuring device. The EIT measuring device is capable of measuring a measure of volume changes in a lung region and uses the electrical impedance tomography (EIT) method for this purpose. With the aid of the EIT measuring device, a measure of the individual volume changes (Maβ) of each lung region can be measured.

[0017] The device according to the invention further comprises an airway pressure sensor. The airway pressure sensor is capable of measuring a measure, preferably a pneumatic measure, of a time-variable pressure at or in the patient's airway. The pressure is derived from the patient's own breathing activity and / or the patient's artificial respiration performed by the ventilator. The patient's own breathing activity can be derived from the patient's spontaneous breathing as well as from an externally stimulated own breathing activity.

[0018] The data processing control device of the device according to the invention is capable of receiving and processing the signals of the EIT measuring device and the airway pressure sensor and calculating for at least two different regions of the lung a measure of the regional extensibility of the lung in each region. The control device preferably calculates a respective measure of the regional extensibility for four lung regions arranged in the manner of four quadrants or even for eight lung regions.

[0019] As this measure of the regional extensibility of the lung region, the control device calculates

[0020] - the volume difference for that lung region, and

[0021] The quotient of the pressure differences acting on the patient's lungs.

[0022] As a volume difference of a region of the lung, the control device determines a measure of the difference between the end-inspiratory volume and the end-expiratory volume of this region of the lung. The end-inspiratory volume occurs at the end of an inhalation process of the patient, and the end-expiratory volume occurs at the end of an exhalation process. As is known, the lungs expand during inspiration and contract again during exhalation, so that the end-inspiratory volume is greater than the end-expiratory volume. To determine the two volumes, the control device uses the signal of the EIT measuring device. Of course, the volume difference may differ from lung region to lung region and may also be time-variable.

[0023] As a pressure difference, the control device determines a measure of the difference between the end-inspiratory transpulmonary pressure and the end-expiratory transpulmonary pressure of the patient's entire respiratory system. The term "transpulmonary pressure" denotes the pressure acting on the lungs from the inside or also from the outside. This transpulmonary pressure is - the pressure acting on the patient's entire respiratory system, and

[0024] - Pressure on the patient's pleural cavity

[0025] difference.

[0026] The pleural cavity surrounds the patient's lungs. The respiratory system includes the patient's lungs and thoracic cavity, and the pleural cavity occurs between the lungs and the thoracic cavity.

[0027] The control device uses the signals of the airway pressure sensors to determine the pressure difference. These signals are a measure of the total pressure acting on the respiratory system and

[0028] - only the patient's own respiratory activity, i.e. spontaneous breathing or external stimulation,

[0029] - only artificial respiration of the patient by means of a ventilator, or

[0030] -The superposition of self-respiration and artificial respiration

[0031] produce.

[0032] The knowledge of how different regions of the patient's lungs are stretchable can be used to better set up the ventilator for artificially ventilating the patient. The ventilator performs a forced breathing sequence based on at least one operating parameter. For example,

[0033] - End Expiratory Pressure (PEEP),

[0034] - End-inspiratory pressure,

[0035] - the desired lung volume (tidal volume), which is the volume of gas delivered to the patient during a mandatory breath from the ventilator, or - the desired volume flow between the ventilator and the patient

[0036] These are operating parameters that can be set on the ventilator.

[0037] In particular, the ventilator should be set in such a way that, during artificial respiration, an overextension of the lungs is avoided on the one hand and collapse of the lungs is excluded on the other hand. The knowledge of how the patient's lungs can be expanded can also be used for a patient monitor and / or for automatic monitoring of the patient. The patient monitor receives and uses the measured values ​​of the device according to the invention and preferably displays the received measured values ​​on a display unit in a form perceptible by humans, in particular visually.

[0038] It is well known that the ductility of a pneumatic system with variable volume is

[0039] - the pressure difference acting on the system (the denominator of the quotient), and

[0040] - the quotient of the volume changes resulting from this pressure difference (numerator of the quotient).

[0041] According to the invention, the pressure difference and the resulting volume change are determined.

[0042] If the patient is supplied with the required breathing air only by artificial respiration, i.e. is completely anesthetized, the current signal value of the sensor for the airway pressure provides a good measure of the pressure currently acting on the lungs and thus the load. However, the patient is often supplied with breathing air only by artificial respiration for as short a time as possible. In addition to or instead of artificial respiration, the patient is kept in a state of anesthesia for as long as possible. ) performs its own breathing activity, i.e. spontaneous breathing and / or stimulated breathing, i.e. breathing with its own respiratory muscles. Artificial respiration thus assists its own breathing activity. In this case, the current signal value of the airway pressure sensor alone is not sufficient to determine the pressure currently acting on the lungs and therefore also the effective pressure difference sufficiently reliably. According to the invention, the end-inspiratory transpulmonary pressure and the end-expiratory transpulmonary pressure are determined more precisely, and the difference between these two transpulmonary pressures is used as the pressure difference.

[0043] The resulting volume change of the entire lung can be determined with the aid of a volume sensor or a volume flow sensor. For example, the current volume flow into or out of the patient's lungs is measured several times in succession and the measured values ​​are integrated.

[0044] However, the extensibility of the lungs can vary significantly from lung region to lung region, so that the global volume change of the lungs is in many cases not sufficient to determine the regional extensibility. Therefore, according to the invention, the individual extensibility of at least two different lung regions, preferably four lung regions arranged as four quadrants, or even eight different lung regions is determined. According to the invention, the signals of an EIT measuring device are used for this purpose. These signals provide for different lung regions a measure of the regional volume change of the lung region caused by breathing / artificial respiration. Preferably, the resulting volume change is determined for each region of the lung or at least for each region of the relevant part of the lung.

[0045] The device according to the invention and the method according to the invention can of course also be used during time intervals in which the patient is supplied with breathing air only by artificial respiration. It is possible, but not necessary due to the invention, to determine the regional ductility in two different modes, namely

[0046] - a mode for artificial respiration only, and

[0047] - A mode for superimposing artificial respiration on one's own breathing activity, i.e., assisted artificial respiration

[0048] Convert between.

[0049] The airway pressure sensor is preferably located outside the patient's body. For example, the sensor components are located in front of the patient's mouth and divert air from the breathing air flow or breathing cycle. The evaluation unit of the sensor is spatially remote from the patient, for example located at or in a ventilator or patient monitor. Due to this configuration, it is not necessary to temporarily introduce the components of the airway pressure sensor into the patient's body and remove them again later. However, airway pressure sensors with a measured value sensor element in the patient's body can also be used for the present invention.

[0050] The pressure in the pleural space cannot be measured directly in humans and in many other biological situations. In one embodiment, the device additionally comprises a pneumatically operated sensor for the pressure in the esophagus. The sensor provides a measure of the pressure in the esophagus of the patient. The measured pressure in the esophagus is a good approximation of the pressure in the pleural space. As already stated, the difference between the airway pressure and the pressure in the pleural space that cannot be measured directly is a measure of the transpulmonary pressure. According to this embodiment, the transpulmonary pressure is used as

[0051] - the airway pressure measured by the airway pressure sensor, and

[0052] - Esophageal pressure measured by esophageal pressure sensor

[0053] For determining the pressure difference, the end-inspiratory transpulmonary pressure is used at least once as the difference between the end-inspiratory airway pressure and the end-inspiratory esophageal pressure, and the end-expiratory transpulmonary pressure is used at least once as the difference between the end-expiratory airway pressure and the end-expiratory esophageal pressure. Preferably, the pressure difference is re-determined at each sampling time point of the two sensors.

[0054] In a preferred implementation, the esophageal pressure sensor comprises a catheter and a measuring balloon, both of which are positioned in the esophagus of the patient. The measuring balloon is in fluid connection with the catheter, and the catheter is in fluid connection with an evaluation unit outside the patient.

[0055] In a preferred configuration, the present invention is used during artificial respiration of a patient by a ventilator, and during assisted or only artificial respiration. The ventilator can be configured as an anesthesia machine and anesthetizes the patient additionally with the aid of at least one anesthetic. Artificial respiration is implemented so that the end-expiratory pressure (PEEP) that the ventilator should cause is set to a specific predetermined value. At the end of the exhalation process, this end-expiratory pressure should exist in the patient's respiratory system. The airway pressure sensor can measure the actual end-expiratory pressure, so that it is possible to adjust the artificial respiration with the actual value of the end-expiratory pressure equal to the predetermined value, and automatic adjustment is also possible. Preferably, at least two, preferably more than two different values ​​of the end-expiratory pressure to be caused are predetermined in this way, and the ventilator is set to the respective values.

[0056] In a refinement of this embodiment, the control device automatically predetermines a first desired value and at least one second desired value for the end-expiratory pressure. The artificial respiration is carried out with the control objective that the actual value of the end-expiratory pressure is first equal to the first predetermined value and then equal to the second predetermined value or a second predetermined value, wherein the two values ​​differ from one another. It is possible to predetermine more than two values ​​for the end-expiratory pressure and to set the artificial respiration successively to each of these at least three values.

[0057] The regional extensibility of a region of the lung determined according to the invention depends on the set value of the end-expiratory pressure.According to this configuration, for each of at least two values ​​of the end-expiratory pressure and for a plurality of regions, a respective regional extensibility of the lung is determined according to the invention.

[0058] In one application of this configuration, a fluid connection is used between the ventilator and the patient in order to automatically determine the nominal operating value of the end-expiratory pressure that the ventilator should cause during artificial ventilation. The respective regional extensibility of the lungs caused at different values ​​of the end-expiratory pressure is determined. An accumulation is suitably performed on these caused regional extensibilities. The required operating value of the end-expiratory pressure is preferably calculated based on a measure of the extensibility of the lungs. This measure of the extensibility of the lungs is calculated by accumulation on the regional extensibility of the lung regions calculated according to the invention.

[0059] In one implementation, that value of the expiratory pressure that results in the highest regional ductility for the lung region is determined for each of the multiple lung regions. This optimal value generally varies from lung region to lung region. For each lung region considered and for multiple values ​​of the end-expiratory pressure, a relative ductility or stiffness or elasticity of the lung region is calculated. The optimal value for the lung region is automatically determined based on the determined relative ductility. For the optimal value that results in the greatest regional ductility, this relative value is 100%. This is then accumulated over the lung regions whose regional ductility is determined.

[0060] The configuration just described, in which the artificial respiration is successively set to different values ​​of the end-expiratory pressure, can be combined with the above configuration in which the transpulmonary pressure is determined as the difference between the airway pressure and the esophageal pressure.

[0061] In a different configuration, the necessity of equipping the patient with a pneumatic sensor for the pressure in the esophagus is avoided. This alternative configuration can also be applied if the patient is artificially ventilated and the achieved end-expiratory pressure is set successively to at least two different values. Each value of the end-expiratory pressure leads to a respective end-expiratory lung volume, i.e. the lung volume at the end of the exhalation process. The difference between the two end-expiratory lung volumes is calculated. In addition, the difference between the two values ​​of the end-expiratory pressure is calculated. The quotient of the volume difference and the pressure difference provides a measure of the difference between the end-inspiratory transpulmonary pressure and the end-expiratory transpulmonary pressure.

[0062] The airway pressure sensor and the control device can be components of a ventilator or anesthesia machine. A fluid connection, optionally a breathing circuit, is established between the patient and the ventilator or anesthesia machine at least temporarily. The EIT measuring device is in data connection with the ventilator or anesthesia machine.

[0063] The invention further relates to a system that can artificially ventilate a patient. The system comprises a ventilator that can be designed as an anesthesia machine and a device according to the invention. The ventilator can artificially ventilate the patient and preferably perform a forced breathing sequence during artificial ventilation. For this artificial ventilation, the ventilator uses the regional extensibility of the patient's lungs determined according to the invention. Preferred configurations of the device according to the invention are also preferred configurations of the system.

[0064] The ventilator preferably generates a value of at least one operating parameter of the ventilator according to the regional ductility. The operating parameter is, for example:

[0065] - tidal volume, i.e. the volume of breathing air delivered to the patient's body during one mandatory breath,

[0066] - Maximum volume flow per minute,

[0067] - the maximum artificial respiration pressure during one mandatory breath,

[0068] -The pressure at the end of inspiration and before the subsequent exhalation, often called the plateau pressure,

[0069] - End-expiratory pressure (PEEP), which is the pressure in the lungs at the end of a mandatory breath,

[0070] - Ramp time, i.e. the time that elapses during a mandatory breath until the artificial respiration pressure has reached its maximum value,

[0071] - the duration of the inspiratory phase, i.e. the phase during which the breathing air flows to the patient,

[0072] - the duration of the exhalation phase, ie the duration of the phase in which the breathing air flows away from the patient, or - the frequency with which mandatory breaths are administered.

[0073] Preferably, a predetermined calculation criterion is used to calculate the value of the operating parameter as a function of the regional extensibility. The calculation criterion is predetermined so that a region of the lung is neither overextended nor collapsed due to too low a pressure. In one embodiment, the ventilator outputs the calculated value and the user can confirm the value or overwrite it with another value. In another embodiment, the ventilator uses the automatically calculated value. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The present invention is described below based on embodiments. In this case,

[0075] Figure 1 A patient and a ventilator performing artificial respiration on the patient are shown;

[0076] Figure 2 A schematic representation of a sensor on a display unit of a ventilator is shown;

[0077] Figure 3 showing the time course of multiple vital parameters of the patient;

[0078] Figure 4 Output showing three values ​​of transpulmonary pressure;

[0079] Figure 5 An exemplary EIT measurement device is shown;

[0080] Figure 6 Shows the maneuver to gradually reduce the end-expiratory pressure and the regional extensibility of the lungs, respectively. DETAILED DESCRIPTION

[0081] In this embodiment, the present invention is implemented by means of an apparatus, the apparatus comprising

[0082] -Ventilator,

[0083] -EIT measurement equipment,

[0084] - other sensors, and

[0085] - A higher-level data processing control device. The higher-level control device receives the signals of the EIT measuring device and other sensors and controls the respirator as a function of these signals, in particular the actuators of the respirator that perform forced breathing.

[0086] Figure 1 A patient P is schematically shown, on whom artificial respiration is being performed. The esophagus Sp, stomach Ma and diaphragm Zw of the patient P are shown. In addition,

[0087] - Ventilator 9,

[0088] - a flexible measuring conduit 14,

[0089] - a connection piece 11 in the mouth of the patient P,

[0090] -EIT band 7,

[0091] - a plurality of exemplary sensors, and

[0092] - Superior control devices 16, these are described below.

[0093] A fluid connection (not shown) connects the patient P to the ventilator 9 . A gas or a gas mixture can flow from the ventilator 9 to the patient P via this fluid connection. Optionally, a breathing circuit is established between the patient P and the ventilator 9 , ie the breathing air exhaled by the patient P flows back to the ventilator 9 .

[0094] The different sensors measure different vital parameters of the patient P. The pneumatic sensor 3 comprises a measured value sensor element 3.1 which comprises an opening which is arranged near the mouth of the patient P and which taps off air from the fluid connection between the patient P and the ventilator 9. The tapped off air is conveyed via a hose to a pressure sensor 3.2 which measures the airway pressure P aw (Pressure in airway)). In one embodiment, the measured value sensor element 3.1 is arranged in or at the Y-piece close to the connecting piece 11. Optionally, a sensor 15 at the ventilator 9 measures a measurement of the volume Vol' per time unit of the flow of breathing air from the ventilator 9 to the patient P or from the patient P back to the ventilator 9. By evaluating the measured values ​​of the sensor 3 and / or the sensor 15, the ventilator 9 is able to determine when the inhalation process (inspiration) of the patient P begins and when the inhalation process ends, as well as when the exhalation process (exhalation) begins and when the exhalation process ends.

[0095] The measuring catheter 14 is placed into the esophagus Sp of the patient P. The measuring catheter 14 starts in the connection 11. The probe 10 (preferably comprising a measuring balloon) in the esophagus Sp measures the time-variable pneumatic pressure P in the esophagus Sp. es The probe 10 is in fluid connection with the connection piece 11 via a measuring conduit 14 or is a component of the measuring conduit 14. In one embodiment, the probe 10 is positioned at the transition between the esophagus Sp and the stomach Ma and comprises a measuring balloon, optionally two measuring balloons. The measuring balloon or balloons of the probe 10 are located in the lower region of the esophagus Sp and are regulated according to the pressure P in the esophagus Sp. es Another optional measuring balloon is located behind the stomach inlet in the stomach Ma and is deformed according to the stomach pressure P in the stomach Ma. ga It is also possible to place an additional stomach probe 13 in the form of a measuring balloon in the stomach Ma, see Figure 2 In both cases, the gastric pressure P in the stomach Ma can be measured ga The measurement of.

[0096] Furthermore, a plurality of measuring electrodes are preferably fastened to the chest of the patient P. Figure 1By way of example, a pair of measuring electrodes 5.1.1, 5.1.2 close to the heart and a pair of measuring electrodes 5.2.1, 5.2.2 close to the diaphragm are shown. In addition, a measuring electrode for grounding, not shown, is fixed to the chest of the patient P. With the aid of these optional measuring electrodes 5.1.1, ..., 5.2.2, the grounding electrode, an electrocardiogram (EKG) and / or an electromyogram (EMG) of the patient P is generated. Optionally, during artificial respiration, the EKG and / or EMG are output in a form perceptible to humans. The measuring electrodes 5.1.1 to 5.2.2 are not necessarily required for the method described subsequently.

[0097] Furthermore, a belt 7 for electrical impedance tomography (EIT) is placed around the body of the patient P, as will be described further below. This EIT belt 7 belongs to an EIT measuring device which in this embodiment comprises a sensor for measuring the airway pressure P aw Other sensors (not shown).

[0098] The patient P is artificially ventilated at least temporarily by the ventilator 9. A fluid connection, optionally a breathing circuit, is established between the patient P and the ventilator 9. The ventilator 9 performs forced respiration and thereby delivers breathing air to the mouthpiece 3 and to the lungs of the patient P via the fluid connection. Optionally, the breathing air is provided with at least one anesthetic agent, so that the patient P is at least temporarily anesthetized.

[0099] On the display unit 12 which is data-connected to the respirator 9

[0100] - a schematic representation showing the lungs Lu and the esophagus Sp of a patient P,

[0101] - schematically shows the respective locations at which the vital parameters of the patient P are measured, and

[0102] - Display of the current values ​​of various vital parameters of the patient P and of other parameters when the patient P is being artificially ventilated. Figure 2 The exemplary diagram illustrates the representation of the values ​​of different time-variable vital parameters on the display unit 12. In this case,

[0103] -P aw (airway pressure) means the measurement of airway pressure,

[0104] -P es (pressure in esophagus, esophageal pressure) means the measure of the pressure in the esophagus Sp,

[0105] -P ga(Gastric pressure) means the measurement of gastric pressure in the stomach Ma,

[0106] -P tp (transpulmonary pressure) means the measure of transpulmonary pressure, which is further explained below,

[0107] -EIP means the end-inspiratory pressure at the airway of the patient P, that is, the pressure P at the end of the inspiration process and before the next exhalation process aw The current value of the end-inspiratory pressure, which is often also called the plateau pressure P plat ,

[0108] - PEEP (positive end-expiratory pressure) means the end-expiratory pressure at the airway, ie the pressure P at the end of the exhalation process and before the next inhalation process of the patient P aw The current value of

[0109] -ΔPaw means the difference between the current values ​​of the end-inspiratory pressure EIP and the end-expiratory pressure PEEP at the airway, i.e. ΔPaw=EIP-PEEP, where this difference is also called driving pressure,

[0110] - EIPes (end-inspiratory esophageal pressure) means the end-inspiratory pressure in the esophagus Sp, ie the pressure P at the end of the inspiration process and before the next expiration process of the patient P es The current value of

[0111] - EEPes (end-exspiratory esophageal pressure) means the end-expiratory pressure in the esophagus Sp, ie the pressure P at the end of the exhalation process and before the next inhalation process of the patient P es The current value of

[0112] -ΔPes means the difference between the current values ​​of the end-inspiratory pressure EIPes and the end-expiratory pressure EEPes in the esophagus Sp, that is, ΔPes=EIPes-EEPes,

[0113] - EIPtp (end-inspiratory transpulmonary pressure) means the end-inspiratory transpulmonary pressure, i.e. the transpulmonary pressure P at the end of the inspiration process and before the next exhalation process of the patient P tp The current value of

[0114] - EEPtp (end-expiratory transpulmonary pressure) means the current value of the end-expiratory transpulmonary pressure, which is the pressure P at the end of an exhalation process and before the next inhalation process of the patient P tp ,

[0115] -ΔPtp (transpulmonary driving pressure) means the difference between the current values ​​of the end-inspiratory transpulmonary pressure EIPtp and the end-expiratory transpulmonary pressure EEPtp, i.e. ΔPtp=EIPtp-EEPtp,

[0116] - EEPga (end-expiratory gastric pressure, not shown) means the current value of the expiratory gastric pressure, which is the gastric pressure P at the end of the expiratory process and before the next inspiratory process of the patient P ga ,

[0117] -P di The transdiaphragmatic pressure (also not shown) is the gastric pressure P at the end of the exhalation process. ga The difference between the current value of the pressure EEPes in the esophagus Sp and the current value of the pressure at the diaphragm Zw, that is, P di =P ga -EEPes.

[0118] Pneumatic sensor 3 measures airway pressure P aw In one embodiment, the pneumatic sensor is arranged in a Y-shaped piece before the connection piece 11. The probe 10 in the esophagus Sp measures the pressure P in the esophagus Sp. es For example, the deformation or volume change of a balloon belonging to the probe 10 is measured and used as the pressure P in the esophagus Sp. es Another measuring balloon of the probe 10 or an additional stomach probe 13 enables the pressure P in the stomach Ma to be measured. ga For example, the deformation or volume change of a measuring balloon belonging to the probe 10 is measured and used as the pressure P in the esophagus Sp. es The deformation or volume change of another measuring balloon of the probe 10 or the deformation or volume change of the separate stomach probe 13 provides a measurement of the stomach pressure P ga The remaining signals are derived from the measurements of these sensors, as described further below.

[0119] Figure 2Furthermore, a schematic representation of the lungs Lu, stomach Ma and esophagus Sp of the patient P and the positions of the pneumatic sensor 3 and probes 10 and 13 are shown.

[0120] Figure 3 By way of example, a diagram is shown with the time course of the following vital parameters:

[0121] - at the top left a current tidal image ("tidal image") Tb, which is the current distribution of the breathing air in the lungs Lu of the patient P, and also the current distribution in a horizontal cross section in which the EIT belt 7 extends, and an illustration of the EIT belt 7 around the chest or stomach Ma of the patient P,

[0122] - In the diagram in the top row, the global change in resistance (impedance), which is measured by means of the EIT belt 7 and is related to the tidal volume (tidal rate VT); and the airway pressure P measured by the pneumatic sensor of the EIT measuring device aw The time-varying process,

[0123] - (second row from the top) airway pressure P measured by means of pneumatic sensor 3 aw ,

[0124] - Pressure P in the esophagus Sp es ,

[0125] - Transpulmonary pressure P tp , which is preferably calculated as the difference P aw -P es ,

[0126] - Gastric pressure P in stomach Ma ga .

[0127] Furthermore, the measurement location (lower left) and the current values ​​of a number of vital parameters (right column) are shown. Figure 3 The representation is output on the display unit 12.

[0128] Different operating parameters can be set at the ventilator 9 during artificial respiration of the patient P, for example: the end-inspiratory pressure EIP at the airway caused by forced respiration,

[0129] - rated value of PEEP,

[0130] -Rated value of platform pressure,

[0131] - Airway pressure P aw the lower and / or upper limits of

[0132] - the tidal volume VT, i.e. the resulting increase in lung volume, achieved by the forced breath, or

[0133] - The start, duration, amplitude and / or frequency of mandatory breaths, for example depending on the patient's P own respiratory activity.

[0134] The ventilator 9 preferably carries out a control operation in which the volume or pressure in the fluid connection is predetermined and used as a control variable for the control circuit (here: breathing cycle). The control variable can be variable in time.

[0135] If the patient P breathes spontaneously and / or is artificially respired, the lungs of the patient P expand and contract again. Each forced breath of the ventilator 9 feeds air into the lungs and causes an expansion of the lungs. Exhalation causes air to flow out of the lungs. This expansion and contraction of the lungs can be compared in a simplified manner to the process of inflating a bicycle inner tube and then expelling air from the inner tube again. In the case of severely damaged or diseased lungs, exhalation can lead to collapse of the lungs.

[0136] Two situations that are critical for patient P must be avoided because each of these situations may damage his lungs:

[0137] - Lung collapse due to too little pressure (the lung collapses).

[0138] -Overexpansion of the lungs due to excessive pressure.

[0139] In particular in the case of damaged lungs, both situations may occur simultaneously, ie in different regions of the lung which are damaged to different degrees and / or in different ways.

[0140] The lungs and chest wall of patient P together constitute a malleable respiratory system.

[0141] If the patient P is fully anesthetized and does not perform spontaneous breathing, the pressure acting on the respiratory system of the patient P is applied only by the ventilator 9. The pressure P measured by the sensor 10 near the mouth of the patient P is aw In the case of complete anesthesia (the patient does not perform any own respiratory activity at all), it is a good measure of the pressure acting on the respiratory system. However, the following situation should be taken into account, that is, the patient P is not completely anesthetized, but at least temporarily breathes spontaneously during artificial respiration or his own respiratory activity is stimulated and artificial respiration is superimposed on the patient P's own respiratory activity (spontaneous respiration and / or stimulated own respiratory activity). In many cases, it is not possible to measure the pressure alone by the measured pressure P aw Not adequately considering your own breathing activity.

[0142] The forced breathing of the ventilator 9 and the breathing activity itself help to stretch the respiratory system. The total pressure generated by the ventilator 9 causes not only the lungs to stretch but also the chest cavity to stretch. The outer layer of the lungs, called the pleura, slides along the inside of the chest cavity during breathing. A thin pleural cavity is located between the lungs and the chest cavity. This pleural cavity is filled with liquid and the two adjacent surfaces of the lungs and the chest cavity are glued together by capillary forces.

[0143] A good measure of the pneumatic pressure acting on the lungs during artificial respiration and thus of the transpulmonary pressure is the difference between the total pressure exerted on the respiratory system of the patient P and the pressure in the pleural cavity. The pressure at the airway, preferably the airway pressure P measured by the sensor 3 aw is used as a measure of the total pressure applied. The pressure in the pleural cavity occurs between the outside of the lungs (lung membrane) and the inside of the thoracic cavity (chest wall) (pleura). This pressure difference quantitatively takes into account both the artificial respiration caused by the ventilator 9 and the own respiratory activity of the patient P. By taking into account this difference, the pressure acting on the lungs is separated from the pressure acting on the thoracic cavity in the total pressure acting on the respiratory system and the pressure acting on the lungs is thus determined in isolation.

[0144] The pleural cavity is a closed system. It is therefore not possible to measure the pleural pressure directly. A good approximation of the pleural pressure is the pressure P measured by the probe 10 in the esophagus Sp of the patient P. es - The prerequisite is that the probe 10 is correctly positioned in the esophagus Sp.

[0145] In order to avoid collapse and / or too strong stretching of the lungs of the patient P, a measure of the mechanical stretchability or elasticity of the lungs is measured. This stretchability is also called the compliance of the lungs. The stretchability is the quotient of the induced change ΔVol (increase or decrease) of the lung volume Vol and the change ΔP in the pressure exerted on the lungs that causes this volume change, i.e. compliance=ΔVol / ΔP.

[0146] In this embodiment, the transpulmonary pressure P tp The change in ΔVol / ΔP is used as the pressure difference acting on the lungs and causing the volume change. tp Used as a measure of the extensibility (elasticity) of the lungs.

[0147] Transpulmonary pressure tp It is a measure of the mechanical load to which the lungs are subjected due to expansion and contraction during breathing. tp It is preferably a reference value, for example the ambient air pressure, and can therefore assume negative values. The end-inspiratory transpulmonary pressure EIPtp is a measure of the maximum lung extension that occurs during breathing and during artificial respiration, which must not become too large. The end-expiratory transpulmonary pressure EEPtp is a measure of the minimum extension and can indicate the risk of lung collapse, especially in the case of negative values ​​of the extension relative to the ambient pressure.

[0148] In one configuration, the current values ​​of these three parameters are displayed on the display unit 12 . Figure 4 The current values ​​of the three parameters Ptp, EIPtp and EEPtp and the value ΔP are shown as examples. tp How is it displayed on the display unit 12? In addition, Figure 4 The transpulmonary pressure P tp time change process.

[0149] Transpulmonary pressure tp cannot be measured directly. In one configuration, the transpulmonary pressure P tp is calculated as the pressure P at the airway aw and the pressure P in the esophagus Sp es The difference is

[0150] P tp =P aw -P es .

[0151] Applicable accordingly Figures 2 to 4 The parameters shown are:

[0152] EIOtp = EIP - EIPes and

[0153] EEP tp =PEEP-EEP es .

[0154] To determine the transpulmonary pressure P tp The alternative does not require the pressure in the esophagus Sp and therefore does not require the probe 10. Such a method is described in EP2397074B1. In the case of this alternative, the difference ΔPtp between the end-inspiratory transpulmonary pressure EIPtp and the end-expiratory transpulmonary pressure EEPtp is determined. The ventilator 9 performs artificial respiration so that two different values ​​of the end-expiratory pressure PEEP, peep1 and peep2, are generated in sequence, of which peep2 is the larger value. Each value results in a value eelv1, eelv2 of the end-expiratory lung volume EELV, respectively. The pressure change peep2-peep1 causes a volume change eelv2-eelv1. The difference ΔPtp sought is calculated, for example, according to the calculation criterion

[0155] ΔPtp=(eelv2-eelv1) / (peep2-peep1)

[0156] to calculate.

[0157] The elasticity (compliance) of the respiratory system, including the lungs and thorax, is represented below by C resp The ductility of the lung is represented by C lung and the extensibility of the chest wall is represented by C cwThe reciprocal 1 / C is also called the elasticity (Elastance) E. Applicable to:

[0158] 1 / C resp =1 / C Lung +1 / C cw and E resp =E Lung +EC cw .

[0159] It is well known that the scalability of a system is

[0160] - the volume change caused, and

[0161] -The quotient of the pressures that cause this volume change.

[0162] During inspiration, the respiratory system of the patient P is stretched by the applied pressure and is retracted during expiration. The tidal volume VT can be used as the volume difference ΔVol. The average stretchability of the respiratory system can be described approximately with the aid of the following lung mechanics model equation:

[0163] C resp =VT / ΔP aw ,

[0164] C Lung =VT / ΔP tp ,

[0165] C Cw =VT / ΔP es .

[0166] In one configuration, in addition to the airway pressure P aw In addition, the sensor 3 in front of the patient P's mouth also measures the volume flow Vol', that is, the amount of gas moved per time unit, into and out of the airway of the patient P. In another embodiment, an optional flow sensor 15 at the ventilator 9 measures this volume flow Vol'. From this volume flow Vol', the volume change and in particular the tidal volume VT, that is, the volume that the lungs accommodate during a single inhalation process, can be derived. The lungs increase this volume.

[0167] It is possible to use the volume flow Vol' and the transpulmonary pressure P tp The ductility of the lung is derived. This provides an average ductility. However, the ductility of the lung generally varies from region to region of the lung. Individual regions of the lung may be significantly less ductile than other regions. Therefore, this global approach will generally not lead to satisfactory results. In order to measure the local ductility of the lung, i.e. the ductility in a specific region, an EIT measuring device with an EIT belt 7 is used in this embodiment.

[0168] The basic idea of ​​such a measuring device is as follows: a sequence of at least four, for example 16 electrodes is placed on the skin of a patient P. An alternating current (feed current) with a current intensity that is predetermined or known by measurement is fed between two electrodes of the sequence. These two electrodes are also referred to as a stimulation electrode pair. The voltage resulting from the feeding is measured on the remaining electrodes. The impedance Z of the tissue between the two electrodes of the stimulation electrode pair is derived according to Ohm's law as the quotient of the measured value of the voltage at the remaining electrodes and the known feeding current intensity. The muscles and blood in the body of the patient P can conduct the fed-in measurement current better than the lung tissue because the muscles and blood have more unconstrained ions. Which two electrodes are used as the stimulation electrode pair is automatically changed over time at a high frequency, wherein each electrode belongs to the stimulation electrode pair in a respective part of the measurement time interval.

[0169] The higher the air content in a region of the lung, the greater the impedance measured in this region. Usually, during inspiration (generated by natural breathing activity and / or artificial respiration), the air content in a region and thus the impedance increases, and during exhalation decreases again. The regional difference between the impedance at the end of inspiration and the impedance at the end of exhalation is related to the regional change of the air content in the lung. A linear relationship can be used as such a correlation, which is determined in advance, for example, during calibration. The EIT measurement method thus provides an image of the regional change of the air content in the lungs in the body.

[0170] Figure 5 An EIT measuring device 17 as described, for example, in DE 102005031752 B4 is shown by way of example. EIT stands for electrical impedance tomography. An EIT belt 7 belonging to the EIT measuring device 17 is placed around the body of a patient P. The EIT belt 7 comprises a plurality of measuring electrodes 1, in the example shown 16 measuring electrodes 1.

[0171] Each measuring electrode 1 is connected to a switch or multiplexer 60 via a cable 2. The switch or multiplexer 60 applies an AC signal to two measuring electrodes 1, which are then used as a stimulation electrode pair. The selection of the stimulation electrode pair is carried out around the body of the patient P. The remaining 14 measuring electrodes 1 are used as measuring electrodes. The voltage signal of the measuring electrode 1 is fed to the control and evaluation unit 20 via the switch or multiplexer 60, the differential amplifier 62 and the analog-to-digital converter 64. The control and evaluation unit 20 generates an image of the regional distribution of the air content in the lungs from the voltage signal. In order to generate this image, the control and evaluation unit 20 uses a suitable method for image reconstruction. The generated image can be called an electrical impedance tomography (Elektroimpedanztomographie) image (EIT image).

[0172] The two respectively activated measuring electrodes 1 are supplied with alternating current by an alternating current source 22. The control and evaluation unit 20 is connected to the alternating current source 22 via a digital-to-analog converter 21 and controls it. The alternating current of the alternating current source 22 is galvanically isolated from the changeover switch or multiplexer 60 by means of an isolating transformer or converter 40.

[0173] For example, the measuring electrode 4 is fixed at the right leg of the patient P, and the measuring electrode 4 measures the common mode signal at the body of the patient P relative to the ground. The signal of the measuring electrode 4 is fed to the control and evaluation unit 20 via the measuring amplifier 6 and the analog-to-digital converter 8. The control and evaluation unit 20 is connected to the compensating AC power supply 30 via the digital-to-analog converter 29. The control and evaluation unit 20 controls the compensating AC power supply 30 according to the phase and amplitude, so that the symmetry of the primary AC power supply 22 at the secondary side of the isolation transformer 40 is detuned (verstimmt), and the common mode signal at the body of the patient P is minimized. For this regulation, the control and evaluation unit 20 uses the common mode signal, which is measured by the measuring electrode 4 and then amplified.

[0174] By means of such an EIT measuring device 17 , the regional changes in impedance and thus the regional changes in the air reserve in the lungs of the patient P are determined. Regional ductility (compliance) C is sought Lung [Reg], where the regional elasticity relates to a region Reg of the lung of the patient P. The calculation of the respective elasticity should be carried out for a plurality of lung regions or even for each region. The region or each region Reg is selected such that the elasticity in this region can be considered to be the same for the entire region at a point in time. The regional elasticity of the respiratory system of the patient P is denoted by C resp[Reg] represents. The regional extensibility of a lung region can change over time. In one embodiment, each pixel (pixel) of the generated EIT image of the lung is a region Reg. Larger regions are also possible, i.e. regions with multiple pixels of the EIT image. As already stated, the extensibility depends on the pressure change and the resulting volume change. The resulting volume change is therefore determined by the EIT measuring device 17 as just described.

[0175] The following lung mechanics model equations are used in this example:

[0176] C resp [Reg]=ΔZ[Reg] / ΔP aw ,

[0177] C Lung [Reg]=ΔZ[Reg] / ΔP tp ,

[0178] C CW [Reg]=ΔZ[Reg] / ΔP es .

[0179] In this case, ΔZ[Reg] denotes the change in the resistance (impedance) in the region Reg, ie the change relative to a predefined reference value. This regional change in impedance is thus determined by the EIT measuring device as just described.

[0180] In order to determine the regional extension of the lung Reg c Lung [Reg], measurements are performed under different settings of the ventilator 9. In one embodiment, the ventilator 9 performs the manipulation automatically. It is possible that a time-variable dominant variable for the manipulation is predefined by a person who monitors the manipulation. In the case of this manipulation, the end-expiratory pressure PEEP is first set to a relatively high value, for example, to a value as large as possible, wherein the respiratory system of the patient P is safely not damaged. The respiratory system of the patient P is thereby opened. The end-expiratory pressure PEEP is then set step by step, i.e. incrementally, to a smaller value than before. Even at the smallest value, the risk of lung collapse is sufficiently low. The determination process is performed separately at each set value of the end-expiratory pressure PEEP. For example, the end-expiratory pressure PEEP is set to 11 values ​​25 cmH2O, 23 cmH2O, ..., 5 cmH2O in sequence.

[0181] On the contrary, it is of course possible to start with a smaller value first and then gradually increase the value. In this alternative, however, the respiratory system of the patient P is not opened at the beginning of the manipulation.

[0182] Each determination process for a set value of the end-expiratory pressure PEEP includes the following steps, which are automatically carried out by the control device 16:

[0183] - Repeated measurement of airway pressure P aw and the pressure P in the esophagus Sp es The sampling frequency is preferably so large that the two pressures P are measured in the time interval between the end of an inhalation process and the beginning of a subsequent exhalation process and in the time interval between the end of an exhalation process and the beginning of a subsequent inhalation process. aw and P es The measurements during these two time intervals are usually more reliable than during other time intervals, because during these two time intervals only relatively little, ideally no, air flows into or out of the lungs of the patient P, so that the two pressures during these two time intervals remain almost constant.

[0184] - In one configuration, according to the calculation criterion P tp =P aw -P es , that is, the transpulmonary pressure is derived using the measured values ​​of sensors 3 and 10. According to this calculation criterion, the values ​​of the end-inspiratory transpulmonary pressure EIPtp and the end-expiratory transpulmonary pressure EEPtp are derived.

[0185] As a measure of the pressure causing this volume change of the lungs, the difference ΔPtp=EIPtp-EEPtp is derived. Another representation of this derivation is the following calculation criterion: ΔPtp=(EIP-EIPes)-(PEEP-EEPes).

[0186] In another embodiment, the difference ΔPtp is calculated according to the calculation criterion ΔPtp=(eelv2-eelv1) / (peep2-peep1). In this case, peep1 is the current value of PEEP and peep2 is the previous value of PEEP.

[0187] Furthermore, the regional change ΔZ[Reg] of the resistance is derived, for which purpose the measured values ​​of the EIT measuring device 17 are used.

[0188] -According to calculation criteria C Lung [Reg]=ΔZ[Reg] / ΔP tp Derivation of the regional extensibility C of the lung in the region Reg Lung [Reg].

[0189] Figure 6Two exemplary regions RegA and RegB of the lungs of a patient P are illustrated above. Usually, the patient P lies on his back during artificial respiration, and the patient P's own weight acts on the patient P's body due to gravity, wherein the body expands perpendicularly to gravity. Region RegA is closer to the heart, and region RegB is closer to the back of the patient P. In the case of a lying patient P, the body's own weight acts significantly more strongly on region RegB than on region RegA. These two exemplary regions RegA, RegB are visible in the EIT image EB of the lungs.

[0190] Figure 6 The graph is shown below. The respectively set values ​​of the end-expiratory pressure PEEP in cm H2O are shown on the x-axis and the regional elasticity C is shown on the y-axis. Lung [Reg], the regional ductility is thus derived as just written. Two curves C are shown Lung [RegA] and C Lung [RegB].

[0191] It can be seen that the regional ductility C Lung [RegA], C Lung [RegB] takes the maximum value C as a function of the set PEEP Lung，max [RegA], C Lurg，max [RegB]. This maximum value usually varies from lung region to lung region. An important reason for this is that the body weight of the patient P acts on these regions with different strengths. Other influencing factors may be regional inflammation, inactive surfactant or edema. max [Reg] denotes the value of the end-expiratory pressure PEEP, i.e., the regional extensibility C for the region Reg at the value Lung [Reg] takes the maximum value. Usually the maximum value varies from region to region.

[0192] In one configuration, for each region Reg of the lung and for each set value of the end-expiratory pressure PEEP, for example, according to the formula

[0193] S Lung，rel [Reg](peep)=

[0194] {C Lung，max [Reg]-C Lung，max [Reg](peep)} / C Lung，max [Reg]*100%={1-E Lung，max [Reg] / E Lung，max [Reg](peep)}*100%

[0195] Calculate the relative stiffness S about the maximum value respectivelyLung，rel The value of [Reg].

[0196] C Lung，max [Reg](peep) is regional compliance, and E Lung，max [Reg](peep) is the regional elasticity when the PEEP value is peep.

[0197] The smaller the regional ductility, the greater the relative stiffness.

[0198] In one configuration of artificial respiration, lung collapse of the patient P should first be prevented. In this application, according to the calculation criteria:

[0199] If peep>=peep max [Reg], then K Lung，rel [Reg](peep)=S Lung，rel [Reg](peep), and

[0200] If peep<peep max [Reg], then K Lung，rel [Reg](peep)=0

[0201] To calculate the regional collapse value K Lung，rel [Reg]. According to the calculation criteria

[0202] K Lung，rel (peep)=Σ{K Lung，rel [Reg](peep)*C Lung，max [Reg]} / ΣC Lung，max [Reg]

[0203] Calculate the cumulative collapse value K Lung，rel (peep). In this case, the sum is taken over all lung regions Reg. This cumulative collapse value depends on the value of the end-expiratory pressure PEEP. The ventilator 9 is set to the pressure PEEP that results in the maximum cumulative collapse value K Lung，rel The value of (peep) is peep.

[0204] In another embodiment, an overextension of the lungs should be prevented.

[0205] If peep<peep max [Reg], then and

[0206] If peep>=peep max [Reg], then To calculate the regional over-extension value. According to the calculation criteria

[0207]

[0208] To calculate the cumulative overstretch value Here again the sum is taken over all considered lung regions. The ventilator 9 is again set to result in the maximum cumulative overextension value The value of .

[0209] These two configurations can be combined with one another.

[0210] Reference numerals list

[0211]

[0212]

Claims

1. A method for automatically determining the respective regional extensibility (C) of a lung of a patient (P) in a plurality of different predetermined regions (RegA, RegB) of the lung. Lung [RegA], C Lung [RegB]), wherein the device comprises: - an EIT measuring device (17) for measuring a measure of volume changes of a lung region (RegA, RegB), - a pneumatic airway pressure sensor (3), - a pneumatic esophageal pressure sensor (10), and - data processing control equipment (16), wherein the EIT measuring device (17) is configured to measure a measure of the respective volume change of each lung region (RegA, RegB) by means of electrical impedance tomography (EIT), The airway pressure sensor (3) is configured to measure a time-variable pressure (P aw ), wherein the pneumatic esophageal pressure sensor is configured to measure a time-variable pressure (P es ), and The control device (16) is configured to - determining, for each region (RegA, RegB) of the lung, respectively, a measure of the difference between the end-inspiratory volume and the end-expiratory volume of this region (RegA, RegB) of the lung, using the signal of the EIT measuring device (17), and determining, using the signal of the airway pressure sensor (3), a measure of the difference (ΔPtp) between the end-inspiratory transpulmonary pressure (EIPtp) applied to the lung and the end-expiratory transpulmonary pressure (EEPtp) applied to the lung, and - Regional extensibility (C Lung [RegA], C Lung [RegB]), calculating the quotient of the volume difference for the regions (RegA, RegB) and the pressure difference (ΔPtp) exerted on the lung, and wherein the control device (16) is configured for - determining the end-inspiratory transpulmonary pressure (EIPtp) as the difference between the end-inspiratory airway pressure (EIP) and the end-inspiratory esophageal pressure (EIPes), and - The end-expiratory transpulmonary pressure (EEPtp) is determined as the difference between the end-expiratory airway pressure (PEEP) and the end-expiratory esophageal pressure (EEPes).

2. The device according to claim 1, characterized in that The device is at least temporarily in data connection with a ventilator (9) which is configured to perform artificial respiration on the patient (P), The ventilator (9) is configured to perform artificial respiration on the patient (P) so that the end-expiratory pressure (PEEP) at the airway of the patient (P) assumes a predetermined value (peep), and The control device (16) is configured to control the ventilator (9) so that the controlled ventilator (9) performs artificial respiration so that the end-expiratory pressure (PEEP) first takes a predetermined first value (peep1) and then takes at least one predetermined second value (peep2), which is different from the first value (peep1).

3. The device according to claim 2, characterized in that The control device (16) is configured to For each predetermined region (RegA, RegB) of the lung and for the first value (peep1) and the second value (peep2) or at least one second value (peep2) of the end-expiratory pressure (PEEP) assumed during artificial ventilation, the regional extensibility of the lung in the lung region (RegA, RegB) resulting in the values ​​(peep1, peep2) is determined.

4. The device according to claim 3, characterized in that The control device (16) is configured to calculate a required operating value of an end-expiratory pressure (PEEP) at the airway, wherein the control device (16) is configured to When calculating the required operating values, calculating the required operating value based on a measure of the extensibility of the lung, and For at least two values ​​of the end-expiratory pressure (PEEP) the regional extensibility (C Lung [RegA], C Lung [RegB]) to calculate a measure of lung extensibility.

5. The device according to any one of claims 2 to 4, characterized in that The device is configured to - determining a measure of the respective end-expiratory lung volume at a first value (peep1) and at a second value (peep2) of said end-expiratory pressure (PEEP), and - as a measure of the difference between the end-inspiratory transpulmonary pressure (EIPtp) and the end-expiratory transpulmonary pressure (EEPtp), the difference between the two measured end-expiratory lung volumes is calculated, and The quotient of the difference between two set values ​​(peep1, peep2) of the end-expiratory pressure (PEEP).

6. A system for artificially respirating a patient (P), wherein the system comprises - ventilator (9), and - a device according to any one of the preceding claims 1 to 5, The ventilator (9) is configured to adjust the patient's (P) lungs according to the determined regional extensibility (C Lung [RegA], C Lung [RegB]) performs artificial respiration on the patient (P).

7. The system according to claim 6, characterized in that The control device (16) is configured to control the ventilator (9) so that the controlled ventilator (9) performs artificial respiration so that the end-expiratory pressure (PEEP) first assumes a predetermined first value (peep1) and then assumes at least one predetermined second value (peep2), which is different from the first value (peep1). The control device (16) is configured to For each predetermined region (RegA, RegB) of the lung and for the first value (peep1) and the second value (peep2) or at least one second value (peep2) of the end-expiratory pressure (PEEP) assumed during artificial ventilation, the regional extensibility of the lung in the lung region (RegA, RegB) resulting in the values ​​(peep1, peep2) is determined.

8. A method for automatically determining the respective regional extensibility (C) of a lung of a patient (P) in a plurality of different predetermined regions (RegA, RegB) of the lung. Lung [RegA], C Lung [RegB]), wherein the method is carried out using a device comprising - an EIT measuring device (17) for measuring a measure of volume changes of a lung region (RegA, RegB), - a pneumatic esophageal pressure sensor (10), and - a pneumatic airway pressure sensor (3), wherein the pneumatic esophageal pressure sensor measures the time-variable pressure (P es ), The airway pressure sensor (3) measures the time-variable pressure (P) at the airway of the patient (P). aw ), A measure of the difference (ΔPtp) between the end-inspiratory transpulmonary pressure (EIPtp) and the end-expiratory transpulmonary pressure (EEPtp) is determined and for each lung region (RegA, RegB) whose extensibility should be determined, steps are performed such that the EIT measuring device (17) measures a measure of volume changes of the lung regions (RegA, RegB) by means of electrical impedance tomography (EIT), - determining a measure for the difference between the end-inspiratory volume and the end-expiratory volume of the lung region using the signal of the EIT measuring device (17), - as the regional extensibility of the lung region (C Lung [RegA], C Lung [RegB]), calculating the quotient of the volume difference for said region and the pressure difference (ΔPtp) exerted on said lung, - determining the end-inspiratory transpulmonary pressure (EIPtp) as the difference between the end-inspiratory airway pressure (EIP) and the end-inspiratory esophageal pressure (EIPes), and - The end-expiratory transpulmonary pressure (EEPtp) is determined as the difference between the end-expiratory airway pressure (PEEP) and the end-expiratory esophageal pressure (EEPes).

9. A computer program product which can be executed on a control device (16) and which, if the control device (16) receives - a signal of an EIT measuring device (17) for measuring a measure of volume changes in a region (RegA, RegB) of the lung of a patient (P), - for measuring the time-variable pressure (P) at the airway of the patient (P) aw ) of the pneumatic airway pressure sensor (3), and - for measuring a time-variable pressure (P) in the esophagus (Sp) of said patient (P) es ) is a signal of a pneumatic esophageal pressure sensor (10) measured by When executed on the control device (16), this causes the control device (16) to carry out the method according to claim 8.

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