SYSTEM FOR FILLING AN ESOPHAGUS BALLOON

Description

[0001] When critically ill patients require prolonged mechanical ventilation, a lung-protective ventilation strategy is necessary. The goal of a lung-protective ventilation strategy is to minimize the effects of mechanical pressure and volume overload on the lungs during ventilation. The adaptation of the ventilation to the individual regional lung function and the patient's ventilation needs must be regularly evaluated, as lung-protective ventilation significantly improves the survival rate of patients with acute respiratory distress syndrome (ARDS).

[0002] It is well established that the respiratory-synchronous collapse and reopening of lung areas ("atelectatic trauma") in ARDS patients is one of the main factors for ventilator-associated lung injury and represents an independent risk factor for increased mortality. Optimally set PEEP is a fundamental requirement for lung-protective ventilation in order to minimize respiratory-cyclic alveolar cycling. At excessively low PEEP values, lung compartments are damaged by atelectatic trauma; at excessively high PEEP and constant driving pressure, overdistension (volutrauma) of predominantly ventral lung areas occurs.

[0003] The extent of mechanical stress on the alveoli, and thus the ventilator-associated lung damage, is not determined by the inspiratory plateau pressure set on the ventilator (ventilation pressure at the end of inspiration), but by the transpulmonary pressure (TPP), defined as the difference between ventilation pressure and pleural pressure.

[0004] Bedside measurement of esophageal pressure (peso) was previously reserved for scientific research. Modern intensive care ventilators and novel balloon catheters now allow this measurement to be performed minimally invasively, providing valuable information about the current ventilation status. Changes in esophageal pressure during a respiratory cycle reflect changes in pleural pressure.

[0005] Chiumello et al. (Am J Respir Crit Care Med 178;346-355) demonstrated in 2008 that, due to the high variability in the ratio of lung elastance to thoracic wall elastance, an inspiratory plateau pressure set on the ventilator resulted in highly variable values ​​for the transpulmonary pressure gradient. In patients with elevated pleural pressure, for example, as a consequence of elevated intra-abdominal pressure, the same inspiratory pressure may be associated with less ventilator-associated lung injury than in patients with low pleural pressure. If the transpulmonary pressure becomes negative, atelectasis develops. A crucial aspect of the effect of PEEP is the maintenance of a positive end-expiratory transpulmonary pressure.

[0006] During mechanical ventilation, the inspiratory plateau pressure (Pplat) and the end-expiratory pressure (PEEP) are used as surrogate parameters for calculating the inspiratory and expiratory alveolar pressure, respectively, and the esophageal pressure (Peso) is used for pleural pressure.

[0007] Esophageal pressure is measured using a commercially available nasally inserted balloon catheter, which also functions as a feeding tube. The pressure probe is connected to the ventilator's pressure transducer. Proper balloon inflation is crucial for ensuring a valid measurement setup and thus reliable esophageal pressure readings. Over- or under-inflating the balloon will result in inaccurate esophageal readings and consequently invalid transpulmonary pressure measurements.

[0008] The correct inflation volume of the esophageal balloon is just as crucial as its correct placement. Since the measured esophageal pressure values ​​depend directly on this, inflation must be individualized for each patient. The standard inflation level suggested by some authors is likely incorrect and leads to inaccurate readings.

[0009] It has been found that the standard volume is not ideal for every patient and that the optimal volume can vary depending on individual patient parameters, patient position, and other factors. Ideally, the filling volume should be chosen so that blood flow to the inner wall of the esophagus is not impaired while still obtaining reliable measurement results.

[0010] Bedside inflation is complex and time-consuming, requiring exceptional practical experience from medical staff. Therefore, a method for determining and maintaining an optimal inflation volume of esophageal balloons is needed.

[0011] The problem is solved by a system according to claim 1.

[0012] The figures show exemplary embodiments of the system 100 according to the invention and of the exemplary method. They show: Fig. 1 the basic structure of a system according to the invention. Fig. 2 an esophageal catheter, whereby Fig. 2A a schematic side view of the catheter shows and Fig. 2B a cross-section along line SS through a section of a catheter tube. Fig. 3 A schematic illustration of an esophageal catheter placed in the esophagus. Fig. 4a graphical representation of an exemplary pressure-volume behavior of an esophageal catheter in vitro Examples of implementation

[0013] The exemplary method and the system 100 according to the invention are described with reference to the following embodiments. Further features and advantages of the present invention will become clear in the following descriptions of embodiments with reference to the figures. The invention is not limited to the embodiments shown. A method as such is not covered by the claims.

[0014] Figure 1 shows the basic structure of a system according to the invention 100.

[0015] System 100 comprises a pressure measuring device 1, at least one pressure source 57, and at least one line 5. The pressure measuring device is configured as a medical catheter 1. The catheter 1 is preferably an esophageal catheter. The at least one line is configured as a pressure line 5.

[0016] The pressure source 57 can be configured and designed to serve as a pressure source and / or a suction source. The pressure source 57 can apply pressure and / or reduce pressure. In some embodiments, the pressure and suction sources can also be configured as separate units. In some embodiments, the pressure source 57 can alternatively or additionally also be configured as a volume source. The pressure source 57 can thus also apply volume and / or extract or reduce volume.

[0017] The pressure source 57 is integrated into a ventilator 50. The pressure source 57 can (in examples not covered by the scope of protection) also be an anesthesia machine or be integrated into an anesthesia machine.

[0018] The catheter 1 comprises at least one esophageal balloon 10, which is hereinafter referred to as balloon 10. The catheter 1 also comprises a tube 9 with a wall 8 and a lumen. The at least one pressure line 5 runs at least partially within the lumen and / or the wall 8 of the tube 9. The pressure line 5 is connected to the balloon 10. The pressure line 5 terminates in the balloon 10 of the catheter 1.

[0019] The catheter 1 also includes a pneumatic interface 13. The pneumatic interface 13 is located at one end of the catheter 1. In its operational state, the pneumatic interface 13 is located outside the patient at the distal end of the catheter 1. The catheter 1 can be connected to the ventilator 50 via the pneumatic interface 13. The pneumatic interface 13 may include a switching valve, which may, for example, be configured as a three-way stopcock (not shown).

[0020] To pneumatically connect the ventilator 50 to the catheter 1, the ventilator 50 can have a catheter port 53. The catheter 1 can be pneumatically connected to the ventilator 50 via the pneumatic interface 13 and the catheter port 53.

[0021] Pressure line 5 then runs from the ventilator 50 to the catheter 1. Pressure line 5 begins at the pressure source 57 of the ventilator 50 and ends at the balloon 10 of the catheter 1. Thus, the catheter 1 can be pneumatically connected to the ventilator 50. The balloon 10 of the catheter 1 is pneumatically connected to the ventilator 50 via pressure line 5 and the pneumatic interface 13. The balloon 10 can be inflated via pressure line 5. The balloon 10 can also be deflated via pressure line 5. The balloon 10 can be inflated to a predetermined pressure and / or volume. The balloon 10 can be deflated to a predetermined pressure and / or volume. The pressure and / or volume can be applied completely or in stages. Deflation can be performed actively, whereby pressure and / or volume can be actively released from the balloon 10. The pressure and / or volume can also be released passively.

[0022] A ventilator (50) encompasses all devices that support a user or patient (70) in their natural breathing, and / or take over the ventilation of a user or patient (70), and / or serve as part of respiratory therapy, and / or otherwise influence the breathing of a user or patient (70). This includes, but is not limited to, CPAP and BiLevel devices, anesthesia machines, respiratory therapy devices, clinical, home, or emergency ventilators, high-flow therapy devices, and cough machines.

[0023] The ventilator 50 can have an operating and information system 54. The required pressure and / or flow and / or volume can be set via the operating and information system 54, or the current pressure and / or flow and / or volume can be displayed. This user information can, for example, be visualized graphically or displayed numerically.

[0024] The ventilator 50 comprises at least one pressure source 57 (not shown) and a control unit 58. The pressure source 57 is configured as a pressure and / or suction source. The pressure source 57 can build up and / or reduce pressure. The pressure source 57 can also be configured as a volume source. The pressure source 57 can apply and / or remove a volume.

[0025] The balloon 10 can be filled and emptied using the pressure source 57. The balloon 10 can be filled with a fluid via the pressure line 5. The balloon 10 can be filled to a predetermined pressure and / or volume. The fluid is typically a gas, for example, air and / or oxygen and / or a gas mixture and / or an oxygen-containing gas mixture. The balloon 10 is preferably made of a flexible, gas- and water-impermeable material. For example, the balloon 10 is made of latex.

[0026] In addition to pressure source 57, the ventilator 50 has another pressure source, designed as a breathing gas source 55. The breathing gas source 55 can ensure the ventilation of the patient 70. The breathing gas source 55 can provide a fluid for ventilation. For example, the breathing gas source 55 can provide a gas and / or gas mixture. The breathing gas source 55 can provide breathing gas and / or oxygen and / or an oxygen-containing gas mixture and / or other suitable gases for ventilation. The breathing gas source 55 is designed, for example, as an electric motor with a fan wheel or as a compressed gas connection. For example, the breathing gas source 55 can apply ventilation pressure 22 and / or flow and / or volume. The control unit 58 can specify the ventilation parameters in a controlled manner and / or at least partially assisted or adaptively, taking measurement signals into account.

[0027] The pressure source 57 for inflating and / or deflating the balloon 10 and the breathing gas source 55 for providing the ventilation pressure 22 are two distinct pressure sources that can be controlled independently of each other. In some embodiments not covered by this scope of protection, the pressure source 57 for inflating and / or deflating the balloon 10 and the breathing gas source 55 for providing the ventilation pressure 22 may also be one and the same device.

[0028] The ventilator 50 can also have at least one interface 56 through which data transmission is possible.

[0029] In addition to the pressure measuring device 1, the pressure source 50 and the pressure line 5, the system 100 can contain further elements.

[0030] In particular, the system 100 can be connected to a patient interface 80 via a tubing system 82. A connection can be established via the patient interface 80 from the ventilator 50 to a patient 70 for ventilation purposes.

[0031] The term "patient interface 80" refers to any peripheral device designed for interaction with a living being. In particular, the patient interface 80 is designed for therapeutic and / or diagnostic purposes in conjunction with the ventilator 50. The patient interface 80 can be configured as a breathing mask. This mask can be a full-face mask, i.e., covering both the nose and mouth, or a nasal mask, i.e., a mask covering only the nose. Tracheal tubes or cannulas, as well as nasal prongs or nasal pillow masks, can also be used as patient interfaces 80. The system 100 and method according to the invention are particularly suitable for invasive ventilation in conjunction with tracheal tubes or cannulas. The patient interface 80 and the ventilator 50 are preferably gas-conductingly connected to each other via the at least one tubing system 82. The tubing system 82 is preferably flexible and / or rotatable.The hose system 82 can, for example, be designed as an elastic pipe and / or hose and / or hose system.

[0032] The System 100 can also include a connection (not shown) for invasive blood pressure measurement 86 and / or temperature measurement. Furthermore, at least one external monitor 85 can be integrated into the System 100. Multiple external monitors 85 are also possible (not shown).

[0033] System 100 is configured and designed to determine or ascertain esophageal pressure 20, at least temporarily or intermittently. Esophageal pressure 20 serves as a surrogate parameter for pleural pressure 21. Changes in esophageal pressure 20 during a respiratory cycle reflect changes in pleural pressure 21.

[0034] During mechanical ventilation, the inspiratory plateau pressure (Pplat) and the end-expiratory pressure (PEEP) are used as surrogate parameters for calculating the inspiratory and expiratory alveolar pressure, respectively, while the esophageal pressure (20) is used for pleural pressure. In some embodiments, the system is additionally designed and configured to measure a gastric pressure (24) in order to estimate the gastric pressure increases on the lungs.

[0035] The control unit 58 is, for example, designed to determine the esophageal pressure 20. To determine the esophageal pressure 20, the ventilator 50 has a pressure measurement input 51 and a sensor 52. The pressure measurement input 51 can be, for example, pneumatic, electronic, and / or optical. The sensor can be a pressure sensor 52. The pressure sensor 52 is connected, at least indirectly, to the balloon 10. The esophageal pressure 20, measured via the gas-filled balloon 10 of the catheter 1, can be determined using the pressure sensor 52. The control unit 58 is, for example, configured to identify a change in the esophageal pressure 20 and then to control the ventilator 50 to specify a ventilation parameter.

[0036] If the esophageal pressure exceeds or falls below a threshold value 20, the control unit 58 generates, for example, a control signal for the ventilator 50 to specify an inspiratory or expiratory breathing gas pressure. Alternatively, if the esophageal pressure exceeds or falls below a threshold value 20, the control unit 58 generates, for example, a control signal for the ventilator 50 to terminate the specification of an inspiratory or expiratory breathing gas pressure.

[0037] Fig. 1Figure 1 schematically shows the arrangement of the ventilator 50 in the system 100. The measurement of the esophageal pressure 20, also referred to herein as peso, is based on the use of the esophageal balloon 10. The esophageal pressure 20 serves as a surrogate parameter and reflects the changes in the pleural pressure 21. The pleural pressure 21, also called intrathoracic pressure, is the pressure difference between the pressure prevailing in the pleural space and the external pressure.

[0038] From the measured esophageal pressure 20 and a ventilation pressure 22 specified or measured by the ventilator 50, the transpulmonary pressure 23 can be continuously or intermittently calculated or determined.

[0039] Transpulmonary pressure (TPP) is the pressure required to expand the lungs and chest wall. TPP corresponds to the pressure difference between the alveoli and the esophagus. For example, TPP can be determined during end-inspiratory or end-expiratory occlusion.

[0040] Measuring esophageal pressure 20 thus enables the determination of transpulmonary pressure 23. Continuously or intermittently measured or determined transpulmonary pressures 23 allow for an assessment of the mechanical pressure and volume load during ventilation, enabling lung-protective adjustment of the ventilation regimen. Furthermore, monitoring esophageal pressure 20 aids in identifying and treating the causes of ineffective patient effort.

[0041] Figure 2 shows an esophageal catheter 1, whereby Fig. 2Aa schematic side view of catheter 1 shows and Fig. 2B a cross-section along line SS through a section of tube 9 of catheter 1. Figure 3 shows a schematic illustration of an esophageal catheter 1 placed in the esophagus 95.

[0042] The catheter 1 is designed as an esophageal catheter and includes at least one balloon 10 and the tube 9 as well as at least one line 5.

[0043] Line 5 runs at least partially through the lumen of the tube 9 and / or the tube wall 8. Line 5 is designed as a pressure line 5 and is connected to the balloon 10. The pressure line 5 terminates in the balloon 10 of the catheter 1. In addition to pressure line 5, the catheter 1 may have further lines. These one or more lines are generally not in communication with each other and are arranged as separate lines in the lumen of the tube 9 and / or in its wall 8 (see Figure 1). Fig. 2B ).

[0044] In some embodiments, the catheter 1 can include a feeding tube 6 and a port 4. The feeding tube 6 extends, for example, from the port 4 along the entire length of the catheter 1 and terminates in the esophagus 95 and / or the stomach. Preferably, the feeding tube 6 terminates in the fundus of the stomach. The feeding tube 6 and the port 4 are designed and configured to allow tube feeding. The tube feed can be introduced into the feeding tube 6 via the port 4. The tube feed then enters the patient's body 70 via the feeding tube 6. The feeding tube 6 thus enables the direct delivery of food to the stomach.

[0045] In some embodiments, the catheter 1 may include a gastric pressure line 7 and a gastric balloon 15. The gastric pressure line 7 may be connected to the gastric balloon 15. The gastric pressure line 7 terminates in the gastric balloon 15 of the catheter 1. The gastric pressure line 7 and the gastric balloon 15 are, for example, configured and designed to measure the gastric pressure 24. For this purpose, the gastric pressure line 7 may be connected to the ventilator 50 (not shown). The gastric pressure 24 can be measured during the placement of the catheter 1 in order to estimate the gastric pressure increases on the lungs. Optionally and / or additionally, the catheter 1 may have further lines. For example, a line for aspirating gastric contents and / or a line for administering medication (not shown) is conceivable.

[0046] In some advantageous embodiments of the catheter 1, a channel for a guide wire 14 (not shown) may be provided. The guide wire 14 can mechanically stiffen the catheter 1 from the inside. The guide wire 14 facilitates the insertion of the catheter 1 into the patient's body 70.

[0047] The in Fig. 2 The exemplary catheter 1 has a pressure line 5, a feeding line 6 and a gastric pressure line 7 (see Fig. 2B ).

[0048] The pressure line 5 terminates in the balloon 10. The gastric pressure line 7 terminates in the gastric balloon 15. The catheter 1 comprises a catheter end 11. The feeding line 6 terminates at the catheter end 11. The catheter end 11 is positioned in or on the stomach or in the esophagus 95 in an application state. Preferably, the catheter end 11 is positioned in the fundus of the stomach.

[0049] The catheter end 11 can be open. For example, enteral feeding from the feeding tube 6 can be discharged into the esophagus 95 and / or stomach via the open catheter end 11. Preferably, the enteral feeding can be discharged from the feeding tube 6 into the fundus of the stomach via the open catheter end 11.

[0050] It is also conceivable that stomach contents can be absorbed from the stomach and drained from the stomach via tube 9 and / or via a separate line in tube 9 or in the tube wall 8.

[0051] When the catheter 1 is used on the patient, part of the catheter 1 is located inside the patient's body. The catheter 1 is at least partially inserted into the esophagus 95 of the patient 70. The catheter 1 is in a state of use when the catheter end 11 and at least part of the tube 9, as well as the at least one balloon 10, are located in the esophagus 95 and / or in the stomach of the patient. In a state of use, the catheter end 11 is preferably located in the fundus of the stomach, and at least part of the tube 9, as well as the balloon 10, are located in the esophagus 95 of the patient.

[0052] The catheter 1 can include at least one distributor 12. The distributor 12 is located outside the patient's body 70 in an application state. The distributor 12 can represent an interface at which different lines 5, 6, 7 are joined or separated.

[0053] System 100 can have a valve 60 ( Fig. 1 The valve 60 is preferably located outside the body of a patient 70 in the application state of the catheter 1. The valve 60 can preferably be located in or on the ventilator 50. In some embodiments, the valve 60 can also be located in or on the pressure line 5. The valve 60 is configured and designed to direct a defined volume from the pressure source 57 of the ventilator 50 into the balloon 10. The balloon 10 can be inflated via the valve 60. The valve 60 is also configured and designed to direct a defined volume from the balloon 10 into the ventilator 50. The balloon 10 can be deflated via the valve 60.

[0054] Filling and emptying can preferably be carried out via a valve 60. In some embodiments, it is also conceivable that filling and emptying can be carried out via two or more valves 60. Filling and / or emptying takes place via the pressure line 5. Venting takes place via the pressure line 5 from the ventilator 50 to the balloon 10. Emptying takes place via the pressure line 5 from the balloon 10 to the ventilator 50.

[0055] Catheter 1 can include at least one of the following functions: Measurement of esophageal pressure 20, which reflects pleural pressure 21; patient nutrition; suctioning of gastric contents; recording of cardiac pulsation; measurement of gastric pressure 24

[0056] System 100 is designed and configured to determine, set, and maintain a filling volume VB of esophageal balloons 10. System 100 is specifically designed and configured to determine, set, and maintain an optimal filling volume VBopt of esophageal balloons 10. System 100 is furthermore designed and configured to determine a minimum filling volume VBa and / or a maximum filling volume VBe of esophageal balloons 10. According to the invention, a method is provided for determining and setting a filling volume VB of a balloon 10 of a catheter 1, which is placed in the esophagus 95 of a living being, wherein the balloon 10 is filled and / or emptied with a fluid. For this purpose, different balloon volumes VB can be applied and balloon pressures PB can be determined.

[0057] To determine the esophageal pressure 20, the inflation volume VB of the balloon 10 is preferably selected such that the balloon pressure PB corresponds to the esophageal pressure 20. The esophageal pressure 20 provides information about pressure changes in the thoracic cavity between the lungs and the chest wall and can serve as a surrogate parameter for the pleural pressure 21.

[0058] The balloon pressure PB corresponds to the esophageal pressure 20 when the filling volume VB is set so low that the blood flow of the inner wall of the esophagus 95 is not impaired and is set so high that the balloon wall lies against the esophageal wall 96 in such a way that reliable measurement results can be obtained.

[0059] Accordingly, the balloon 10 of an esophageal catheter 1 has a minimum filling volume VBa and a maximum filling volume VBe. The balloon 10 should be filled with at least the minimum filling volume VBa and at most the maximum filling volume VBe so that the balloon pressure PB corresponds to the esophageal pressure 20 and reliable measurement results can be obtained. The minimum filling volume VBa can be determined using this procedure. Furthermore, the maximum filling volume VBe of the balloon 10 can be determined using this procedure.

[0060] The exemplary procedure serves in particular to determine an optimal filling volume VBopt of balloon 10. The measurement of esophageal pressure 20 is particularly valid when balloon 10 is filled with the optimal filling volume VBopt. The optimal filling volume VBopt lies in a range between the minimum filling volume VBa and the maximum filling volume VBe.

[0061] The following describes an exemplary procedure. The procedure is preferably performed using a catheter 1 placed inside a person. The procedure is performed, for example, under controlled bilevel ventilation. Alternatively or additionally, the procedure can also be performed under spontaneous breathing.

[0062] Catheter 1 is placed in the patient. The balloon 10 of catheter 1 is placed in esophagus 95. The balloon 10 of catheter 1 can be placed anywhere in esophagus 95. Preferably, the balloon 10 is placed in the lower to middle third of the esophagus (see Fig. 3 The balloon 10 is particularly preferably placed in the middle third of the esophagus.

[0063] Initially, the balloon 10 is filled with a standard volume VB0 specified by the manufacturer. The standard volume VB0 of commercially available esophageal balloons 10 is typically between 0.5 ml and 5 ml, depending on the size and length of the balloon 10. For example, the balloon 10 is initially filled with a standard volume VB0 of 3 ml of fluid.

[0064] An initial pressure adjustment is then performed. For this, different balloon volumes VB are applied and the corresponding balloon pressures PB are measured.

[0065] Balloon 10 is first emptied again. Ideally, it should be emptied completely. Complete emptying occurs when no fluid remains in balloon 10. Ideally, the volume after complete emptying is 0 ml.

[0066] At least one breath is allowed to pass before balloon 10 is refilled. Preferably, more than one breath is allowed. For example, three or four breaths are allowed. It is also possible to allow more than four breaths.

[0067] After at least one breath has been taken, balloon 10 is refilled. Refilling is preferably done in stages. Staged filling means that balloon 10 is repeatedly filled with a defined volume. The staged filling is additive; no deflation occurs between stages.

[0068] The gradual filling and / or emptying is carried out using predetermined volume levels Vi. These volume levels Vi can, for example, always have the same value. In some embodiments, the volume levels Vi can also have different values.

[0069] The volume increments Vi for the individual filling stages range from 0.1 ml to 2 ml. Preferably, the balloon 10 is filled in volume increments Vi of 0.2 ml to 0.8 ml. For example, the balloon 10 is filled in volume increments Vi of 0.5 ml.

[0070] After each volume increment Vi, at least one breath is allowed to pass before the balloon 10 is filled with another volume increment Vi. Preferably, more than one breath is allowed to pass. For example, 3 or 4 breaths are allowed to pass. It is also possible to wait for more than 4 breaths, for example, up to 10 breaths or more.

[0071] The balloon is filled until it reaches a final volume VB1. At this final volume, balloon 10 is slightly overfilled. For example, at an esophageal pressure of 20 mbar, balloon 10 is slightly overfilled. For example, balloon 10 is filled in stages until it reaches a final volume VB1 of 10 ml.

[0072] After reaching a balloon pressure PB of, for example, 30 mbar and / or after reaching a final volume VB1 of, for example, 10 ml, the balloon is emptied again.

[0073] The emptying process is carried out in stages. Staged emptying means that a defined volume is repeatedly removed from balloon 10. No refilling takes place between the individual stages of staged emptying. The emptying process is complete. Emptying continues until the volume of balloon 10 ideally returns to 0 ml.

[0074] The gradual emptying is carried out using predetermined volume increments Vi. The volume increments Vi for the gradual emptying range from 0.1 ml to 2 ml. Preferably, the balloon 10 is emptied in volume increments Vi of 0.2 ml to 0.8 ml. For example, the balloon 10 is emptied in volume increments Vi of 0.5 ml. The volume Vi of the emptying increments is preferably equal to the volume Vi of the filling increments. In some embodiments of the method, the volume Vi of the emptying increments can be larger or smaller than the volume Vi of the filling increments.

[0075] After each deflation stage, at least one breath is allowed to pass before the balloon 10 is deflated with a further volume stage Vi. Preferably, more than one breath is allowed to pass. For example, 3 or 4 breaths are allowed. It is also possible to allow more than 4 breaths to pass.

[0076] The number of breaths to be waited for after each deflation stage is preferably equal to the number of breaths to be waited for after each inflation stage. However, it is also possible to wait for more or fewer breaths after each deflation stage than after each inflation stage.

[0077] After each filling and / or emptying stage, at least one breath is allowed to pass in order to reduce vibration artifacts of the balloon 10.

[0078] The balloon pressure PB can be continuously determined during the inflation and / or deflation of balloon 10. The balloon pressure PB can be determined for each individual volume stage Vi of the inflation and / or deflation process. For example, the balloon pressure PB is determined at least once per breath for each volume stage Vi of the inflation and / or deflation process. Preferably, the balloon pressure PB is determined for all breaths.

[0079] The balloon pressure PB is preferably determined at the end of inspiration (Pmax) and at the end of expiration (Pmin).

[0080] The pressure values ​​Pmin and Pmax can be analyzed to determine the minimum filling volume VBa and the maximum filling volume VBe. Furthermore, the values ​​Pmin and Pmax can be analyzed to determine the optimal filling volume VBopt. The balloon pressure PB can be analyzed as a function of the filling volume VB.

[0081] The measured balloon pressures PB for each volume level Vi of filling and / or emptying can be evaluated individually or averaged. For example, the mean value of Pmax for each volume level Vi and the mean value of Pmin for each volume level Vi can be determined. All or only selected balloon pressures PB can be used for averaging. Alternatively or additionally to the mean value, medians, percentiles, derivatives, frequency distributions, or similar parameters can be determined from the measured balloon pressures PB and used as the basis for further calculations.

[0082] The measured values ​​Pmax and Pmin obtained using the above procedure can be analyzed. Determining a pressure difference ΔPB between Pmax and Pmin is advantageous. This pressure difference ΔPB is also referred to as delta-peso.

[0083] The pressure difference ΔPB is preferably determined for each volume stage Vi of filling and / or emptying. In particular, the pressure differences ΔPB between Pmax and Pmin can be determined for identical filling and / or emptying stages. The change in the pressure differences ΔPB between Pmax and Pmin indicates when the balloon pressure PB corresponds to the esophageal pressure 20.

[0084] The measured values ​​can be analyzed and, for example, displayed graphically. For instance, the balloon pressure PB at the end of expiration Pmin and / or the balloon pressure PB at the end of inspiration Pmax can be analyzed as a function of the inflation volume VB. The measured values ​​can be displayed, for example, in an axis diagram (see Fig. 4 ).

[0085] Figure 4 shows a graphical representation of an example of the pressure (P) - volume (V) behavior of an esophageal catheter 1 in vitro. InIn vitro studies of esophageal catheters 1 show a typical hysteresis with respect to their pressure-volume behavior.

[0086] The X-axis represents the volume V, namely the filling volume VB of balloon 10 in ml. The Y-axis represents the pressure P, namely the balloon pressure PB in mbar.

[0087] Out of Fig. 4 Pressure differences ΔPB between Pmax and Pmin become apparent. These pressure differences ΔPB are also referred to here as Delta-Peso. The Delta-Peso describes the pressure difference between Pmax and Pmin as a function of the fill volume VB.

[0088] Out of Fig. 4 It is evident that the curves of Pmin and Pmax run almost parallel in the range of 2 ml to 5.5 ml fill volume (VB). A plateau forms, i.e., a range in which Pmin and Pmax do not change significantly relative to each other.

[0089] The change in the pressure difference ΔPB between Pmax and Pmin indicates when the balloon pressure PB equals the esophageal pressure 20. The pressure difference ΔPB is the difference between Pmax and Pmin.

[0090] The pressure difference ΔPB can be calculated, for example, as follows: ΔPB = Pmax - Pmin

[0091] The pressure difference ΔPB from one volume stage Vi of the stepwise filling and / or emptying to the next volume stage Vi+1 can, for example, be determined as a percentage value or index value in order to determine a relative pressure difference rΔPB.

[0092] The volume level Vi is the volume of the i-th volume level (filling or emptying level). The volume level Vi+1 is the volume of the following volume level (filling or emptying level). The pressure differences ΔPB of successive volume levels (Vi, Vi+1) are compared to determine a percentage deviation.

[0093] The relative pressure difference rΔPB can be determined, for example, using the following formula: r Δ PB = Δ PB Vi + 1 − Δ PB Vi Δ PB Vi + 1 ∗ 100 %

[0094] Based on the relative pressure difference rΔPB, a limiting region GB can be identified. Within the limiting region GB, the curves of Pmin and Pmax remain almost constant. Within the limiting region GB, Pmin and Pmax of the successive volume steps Vi do not deviate significantly from each other. Furthermore, the curves of Pmin and Pmax are approximately parallel to each other within the limiting region GB. Therefore, within the limiting region GB, the pressure difference ΔPB is approximately constant (see Fig. 4 ).

[0095] The limiting region GB is significantly below 100%, preferably below 50%, and particularly preferably below 25%. In a specific embodiment, the limiting region GB lies in a range from 0 to 10% inclusive (not shown).

[0096] If the relative pressure difference rΔPB is greater than the limit GB, the balloon pressure PB lies outside the esophageal pressure 20 and is not suitable for measuring esophageal pressure 20. If the relative pressure difference rΔPB lies within the limit GB, the balloon pressure PB corresponds to the esophageal pressure 20 and is suitable for measuring esophageal pressure 20.

[0097] Thus, the minimum filling volume VBa and the maximum filling volume VBe can be derived from a stepwise filling and emptying of the balloon 10.

[0098] The minimum filling volume VBa is reached when, after a volume step Vi, the relative pressure difference rΔPB is within the limit range GB for the first time. Therefore, the minimum filling volume VBa is reached when it does not fall below the minimum value of the limit range GB.

[0099] The minimum fill volume VBa is therefore located at the beginning, from which Pmax and Pmin run almost parallel. The relative pressure difference rΔPB at the minimum fill volume VBa is defined by the upper end of the limit range GB. In a specific embodiment, the relative pressure difference rΔPB at the minimum fill volume VBa can be 10%.

[0100] The maximum filling volume VBe occurs at the volume level Vi where the relative pressure difference rΔPB is last within the limit range GB. Therefore, the maximum filling volume VBe is present when it does not exceed the minimum value of the limit range GB.

[0101] The maximum filling volume VBe is therefore located at the end where Pmax and Pmin run almost parallel and remain constant for the last time. The relative pressure difference rΔPB at the maximum filling volume VBa is likewise defined by the upper end of the limit range GB. In a specific embodiment, the relative pressure difference rΔPB at the maximum filling volume VBe can be 10%.

[0102] The relative pressure difference rΔPB for filling volumes exceeding the maximum filling volume VBe is outside the limit range GB.

[0103] Fill volumes that are smaller than the minimum fill volume VBa and / or larger than the maximum fill volume VBe are not suitable for measuring esophageal pressure 20.

[0104] Fill volumes that are larger than the minimum fill volume VBa and / or smaller than the maximum fill volume VBe are suitable for measuring esophageal pressure 20.

[0105] The optimal filling volume VBopt lies in the range between the minimum filling volume VBa and the maximum filling volume VBe. In some embodiments, the optimal filling volume VBopt can also be equal to the minimum filling volume VBa or equal to the maximum filling volume VBe.

[0106] In a preferred embodiment, the optimal filling volume VBopt is larger than the minimum filling volume VBa and smaller than the maximum filling volume VBe.

[0107] When balloon 10 is filled with the optimal volume VBopt, it exhibits an optimal fit to the esophagus 95. The esophageal wall 96 is not negatively affected by balloon 10 filled with the optimal volume VBopt. Furthermore, balloon 10 provides reliable, valid, and reproducible measurements when filled with the optimal volume VBopt. The pressure changes in balloon 10 optimally reflect the esophageal pressure 20 and thus the pleural pressure 21. The pleural pressure 21, in turn, reflects the pressure in the lungs.

[0108] In some embodiments, the optimal filling volume VBopt is more than 10% higher than the minimum filling volume VBa and less than 80% lower than the maximum filling volume VBe. Preferably, the optimal filling volume VBopt is more than 20% higher than the minimum filling volume VBa and less than 50% lower than the maximum filling volume VBe. In a specific embodiment, the optimal filling volume VBopt is 30% higher than the minimum filling volume VBa and 70% lower than the maximum filling volume VBe.

[0109] The optimal filling volume VBopt can be calculated, for example, using the following formula: VBopt = VBa + VBe − VBa 3

[0110] Out of Fig. 4 It becomes apparent that the minimum filling volume VBa in this specific embodiment is, for example, approximately 2 ml and the maximum filling volume VBe is, for example, approximately 5.5 ml. Between the minimum filling volume VBa and the maximum filling volume VBe, Pmin and Pmax lie in an almost constant range.

[0111] With a minimum filling volume VBa of, for example, 2 ml and a maximum filling volume VBe of, for example, 5.5 ml, the optimal filling volume VBopt is therefore approximately 3.17 ml.

[0112] If the optimal filling volume VBopt and the initially set standard volume VB0 are not the same, and the initial pressure adjustment is no longer performed, the balloon pressure PB can be corrected. Balloon 10 can then be set with the determined optimal filling volume VBopt.

[0113] Alternatively and additionally, a pressure correction of the optimal filling volume VBopt can be performed. This pressure correction adjusts the optimal filling volume VBopt while taking esophageal compliance Ces into account.

[0114] Esophageal compliance Ces is the elastic volume distensibility of the esophagus 95. Because the esophageal wall 96 has distensibility, the balloon pressure PB increases when the balloon 10 is enlarged and decreases when the balloon 10 is reduced. In vivo Thus, instead of a plateau, a linearly increasing pressure profile can develop, caused by esophageal compliance Ces (not shown). The esophageal compliance Ces of esophagus 95 is in vivo not uniform and can vary depending on the section of the esophagus 95. For the method according to the invention, esophageal compliance Ces can be assumed to be constant by way of example.

[0115] In some embodiments, esophageal compliance Ces is reassessed at regular intervals. It may be provided that esophageal compliance Ces is additionally or alternatively reassessed at least when it is determined that the filling volume VB of the balloon 10 lies outside the limit GB, or when the limit GB changes such that the filling volume VB lies outside the limit GB at least once.

[0116] There is a relationship between the change in the filling volume ΔVB and the change in the balloon pressure ΔPB due to esophageal compliance Ces. The displacement of the esophageal wall 95 by the balloon 10 can be represented by the following formula: ΔVB = Ces * ΔPB

[0117] For the volume range that is suitable for measuring esophageal pressure 20, esophageal compliance Ces is assumed to be constant.

[0118] To determine esophageal compliance (Ces), the minimum inflation volume (VBa) and the maximum inflation volume (VBe) are used, as well as the end-of-expiration pressures (Pmin). PBEa is the balloon pressure at the end of expiration at the minimum inflation volume (VBa). PBEe is the balloon pressure at the end of expiration at the maximum inflation volume (VBe).

[0119] Esophageal compliance (Ces) can be calculated, for example, using the following formula: Ces = VBe − VBa PBEe − PBEa

[0120] A more accurate calculation is achieved by performing a linear regression over the volume range between the minimum fill volume VBa and the maximum fill volume VBe. According to the formula ΔVB = Ces * ΔPB, the pressure correction can be applied as follows.

[0121] In the event that the optimal filling volume VBopt is larger than the standard volume VB0, the following may apply: Δ PB = Ces VBopt − VB 0

[0122] In the event that the optimal filling volume VBopt is smaller than the standard volume VB0, the following may apply: Δ PB = Ces VB 0 − VBopt

[0123] Using the method according to the invention, the optimal filling volume VBopt and a corrected optimal filling volume VBoptkorr can be determined. Thus, the balloon 10 can be filled with the optimal filling volume VBopt. Preferably, the balloon 10 can be filled with the corrected optimal filling volume VBoptkorr, which takes esophageal compliance Ces into account.

[0124] Alternatively or additionally, the ratio between applied filling volume VB and balloon pressure PB can be monitored to detect and compensate for any possible leakage.

[0125] Although the present invention has been described in detail with reference to the exemplary embodiments, it is obvious to those skilled in the art that the invention is not limited to these embodiments. Rather, modifications are possible in such a way that individual features are omitted or different combinations of the described individual features can be implemented, provided that the scope of protection of the accompanying claim is not exceeded. The present disclosure includes all combinations of the presented individual features. Reference symbol list

[0126] 1 catheter 4 Connection 5 Pressure line 6 Nutritional pathway 7 Gastric pressure line 8 hose wall 9 Hose 10 balloon 11 Catheter end 12 Distribution 13 Pneumatic interface 14 guide wire 15 Gastric balloon 20 Esophageal pressure (peso) 21 Pleural pressure (intrathoracic pressure) 22 Ventilation pressure (PAW) 23 Transpulmonary pressure (TPP) 24 Gastric pressure 50 ventilator 51 Pressure measurement input 52 Pressure sensor 53 Catheter connection 54 Operating and information system 55 Source of breathing gas 56 interface 57 Pressure source 58 control unit 60 valve 70 patient 80 Patient interface 82 Hose system 85 External monitor 86 Connection to invasive blood pressure measurement 95 esophagus 96 esophageal wall 100 system Ces Esophageal compliance GB Border area P Pressure PB Balloon print Pmax Balloon print at the end of the inspiration Pmin Balloon pressure at the end of exhalation ΔPB Pressure difference between Pmax and Pmin / Delta-Peso rΔPB relative pressure difference S cutting plane V volume VB Filling volume VB0 Standard volume VB1 Final volume Vi Volume level (filling level / emptying level) VBa Minimum filling volume VBe Maximum filling volume VBopt Optimal filling volume VBoptkorr Corrected optimal filling volume ΔVB Volume difference

Claims

1. A system (100) for ascertaining and adjusting a filling volume (VB) of a balloon (10) of a catheter (1) which is placed in the esophagus of a living being, comprising - the catheter (1) - at least one pressure source (57) having a control unit (58) - at least one line (5) via which the catheter (1) and the pressure source (57) are pneumatically interconnected - at least one sensor means which is designed as a pressure sensor (52) wherein the system (100) is configured and designed to carry out a method for ascertaining and adjusting a filling volume (VB) of a balloon (10) of a catheter (1) which is placed in the esophagus (95) of a living being, wherein the balloon (10) is filled with a fluid and / or emptied, comprising the following method steps - filling and / or emptying the balloon (10) stepwise with at least two volume levels (Vi) by means of the control unit (58) - determining, by means of the control unit (58), a pressure difference (ΔPB) between a pressure at the end of an expiration (Pmin) and a pressure at the end of an inspiration (Pmax) for at least two volume levels (Vi) - determining, by means of the control unit (58), a relative pressure difference (rΔPB) between (Pmin) and (Pmax) - setting, by means of the control unit (58), a limit range (GB) based on the relative pressure difference (rΔPB) - ascertaining, by means of the control unit (58), an optimum filling volume (VBopt) taking into account the limit range (GB), characterized in that the pressure source (57) and the control unit (58) are integrated in a ventilator (50), wherein the ventilator (50) has, in addition to the pressure source (57), a further pressure source which is designed as a breathing gas source (55) that ensures ventilation of a patient, wherein the pressure source (57) is designed to fill and / or empty the balloon (10) and the breathing gas source (55) is designed to provide a ventilation pressure (22) and both pressure sources (55, 57) are different pressure sources which can be actuated independently of one another.