Method and device for automatic hose reversal detection in a ventilator or anesthesia machine

Abstract

Method for automatic detection of a fluidic connection situation of a ventilator or anesthesia machine (10), wherein the ventilator or anesthesia device (10) comprises a gas delivery unit (30), at least one pressure sensor or flow sensor (44, 46), a control unit (70), an inspiratory fluidic port (16), an expiratory fluidic port (18) and further a fluidic measuring port (28) which is coupled to the at least one pressure sensor or flow sensor (44, 46), wherein the inspiratory fluidic port (16) and the expiratory fluidic port (18) can be connected to a Y-piece (20) as part of a breathing circuit by means of breathing tubes (12, 14) and wherein the fluidic measuring port (28) can also be connected to the Y-piece (20) by means of a sample gas line (26), the procedure comprises the following process steps, which are carried out under the control of the control unit (70): - before determining a comparative measurement (66), a reference situation is established, - during the reference situation, a measured value is recorded as the reference value (62), - Following the recording of the reference value (62), the reference situation is terminated, - Following the termination of the reference situation, the gas delivery unit is activated to establish a pressure build-up in the breathing circuit and the comparative measurement value (66) in the form of a pressure measurement value or flow value is determined by means of the pressure sensor (46) or flow sensor (44). - the reference measurement (66) is compared with a predetermined or predefinable expected value (68) whereby, by means of the comparison, a deviation of the measurement (66) from the reference value (62) in relation to the predetermined or predefinable expected value (68) is monitored. - and depending on the result of the comparison, a warning message is issued, characterized by - that following the pressure build-up in the breathing circuit and the recording of the comparative measurement, a pressure drop is caused in the breathing circuit, - that a further comparative measurement is recorded for the pressure drop, - that a deviation of the further comparative measurement value from the reference value is checked in relation to a further expected value, - and that a further warning message will be issued if the deviation does not correspond to the further expected value, or does not correspond at least substantially. - whereby the evaluation of the comparative measurement value and the further comparative measurement value can be carried out on the basis of an inverse order of the resulting pressure flanks.

Description

[0001] The invention relates to a method for automatically detecting a fluidic connection situation of a ventilator or anesthesia machine, namely for automatically detecting incorrectly connected, swapped breathing tubes. The invention further relates to a ventilator or anesthesia machine, hereinafter sometimes referred to collectively as a medical device or simply as a device, as a apparatus for carrying out the method. A swap of breathing tubes is understood to mean a situation in which the intended connection between an inspiratory fluidic port and an expiratory fluidic port of a medical device, each with a connection to a so-called Y-piece, is not established by means of two breathing tubes, but rather the two ports of the device are connected by means of one breathing tube and the two connections of the Y-piece are connected by means of the other breathing tube.

[0002] In the event that a patient requires ventilation using a designated medical device, it is essential to ensure that the device's ventilation tubing is correctly connected and not reversed, thus guaranteeing safe ventilation. This check is performed by the device operator, typically medical personnel. The check comprises several manual steps and is usually carried out when the device is switched on or during a brief leak test.

[0003] In practice, however, due to the sometimes quite large number of tubes and cables in the patient area, it often happens that breathing tubes are connected incorrectly.

[0004] One object of the present invention is to provide a method and a device implementing the method in which, by means of an automatic tube exchange detection, a possible exchange of the ventilation tubes is reliably detected and, based on such detection, an automatic notification can be sent to the respective user.

[0005] This problem is solved according to the invention by means of a method with the features of claim 1. In the method for the automatic detection of swapped breathing tubes, i.e., for the automatic detection of a corresponding specific fluidic connection situation of a ventilator or anesthesia machine, the device is provided to comprise at least one gas delivery unit, a measuring device, at least one sensor and a control unit, an inspiratory fluidic port, an expiratory fluidic port, and furthermore a fluidic measuring port which is coupled to the at least one sensor. Inside the device, up to the respective inspiratory and expiratory fluidic ports, which function as interfaces, a portion of a breathing circuit is formed which can be completed with at least one breathing tube.The inspiratory and expiratory fluidic ports can be connected to a Y-piece via breathing tubes and are connected to the Y-piece when correctly connected. The fluidic measurement port can be connected to the Y-piece via a sample gas line and is connected to the Y-piece when correctly connected. The sensor can also be located, for example, on the Y-piece itself, and thus upstream of the sample gas line in the direction of airflow. The sample gas line is designed to supply a gas sample, drawn from the breathing circuit at the Y-piece, to a measuring device.

[0006] With regard to the method itself, it is provided that it comprises the process steps mentioned in claim 1, which are carried out under the control of the control unit.

[0007] The portion of the breathing circuit inside the device that can be completed with at least one breathing tube comprises an inspiratory branch and an expiratory branch. Each of these branches leads to a port on the device, i.e., an inspiratory port and an expiratory port. The breathing tubes can be connected to these ports. In the previously described reversal of the breathing tubes, the two ports will be connected to each other via a breathing tube (short circuit). Even with such an incorrect connection of the two ports, the portion of the breathing circuit inside the device will not be completed into a closed breathing circuit. With a correct connection of the breathing tubes, a breathing tube from the inspiratory port and a breathing tube from the expiratory port are connected using a Y-connector.Even with such correct placement of the breathing tubes, the part of the breathing circuit located inside the device is completed to form a closed breathing circuit. Downstream of the Y-connector, another breathing tube leads to the ventilated patient.

[0008] Due to the operation of the gas delivery unit, a state expected in the breathing circuit results under the given operating conditions, for example, a pressure corresponding to a predetermined or predefinable expected value, or at least substantially corresponding to it. The Y-piece is closed during the test, i.e., during the execution of the procedure, for example, by placing the Y-piece in a so-called parking holder, which then closes the Y-piece.

[0009] Determining a comparative measurement in a time-correlated manner with a predefined operating situation of the gas delivery unit—for example, a situation in which pressure is built up in the breathing circuit, particularly in the inspiratory branch, by means of the gas delivery unit, or a situation in which a predefined gas concentration is built up in the breathing circuit by means of the gas delivery unit—ensures the comparability of the determined comparative measurement with a respective expected value. The control unit controls both the gas delivery unit and the determination of the comparative measurement, so that the determination of the comparative measurement in a time-correlated manner with the respective operating situation of the gas delivery unit is readily possible. The control unit also performs the comparison of the determined comparative measurement with the expected value.Depending on the result of the comparison, the control unit may also issue a warning message, for example, by activating an optical and / or acoustic signal or display element.

[0010] The aforementioned problem is solved, as well as by means of the method described above, by means of a device in the form of a medical device of the type mentioned at the outset, with the features of the parallel independent device claim. For this purpose, the medical device is provided to include, for carrying out the method outlined above and described in further detail below, a gas delivery unit, a measuring device, at least one sensor and a control unit, an inspiratory fluidic port, an expiratory fluidic port, and furthermore a fluidic measuring port which is coupled to the at least one sensor, wherein the inspiratory fluidic port and the expiratory fluidic port can be coupled to a Y-piece by means of breathing tubes, and wherein the fluidic measuring port can be coupled to the Y-piece by means of a sample gas line.The medical device, and specifically its control unit, is designed and configured to carry out the procedure.

[0011] A key advantage of the approach presented here is that any potential reversal of the breathing tubes is automatically detected and recognized during the execution of the procedure or the operation of the medical device. If, with reversed breathing tubes, the inspiratory and expiratory fluidic ports of the device are short-circuited by a breathing tube, neither breathing tube is connected to the Y-connector. The conditions that arise in the breathing circuit due to the predefined operating state of the gas delivery unit therefore do not affect either the Y-connector or the sample gas line connected to the Y-connector (at least in this respect) correctly.A comparative measurement taken by the sensor and measuring device with respect to the sample gas line will therefore not correspond to the value that would result from a correct connection of the breathing tubes to the Y-piece (expected value). The result of the comparison automatically detects the exchange of the breathing tubes by means of the control unit, and a warning message can be issued accordingly. If the sensor is not connected to the Y-piece because the sample gas line is not connected or not connected correctly to the Y-piece, a faulty connection exists. Even with correctly connected breathing tubes to the Y-piece, the conditions that arise in the breathing circuit due to the predefined operating conditions of the gas delivery unit will then have no influence on the comparative measurement determined by the sensor.Here too, comparing the reference measurement with an expected value automatically identifies the faulty connection, and a warning message can be issued on this basis.

[0012] As a result, the detection of fluidic connection problems, such as incorrect connections or a possible reversal of the breathing tubes, no longer depends on personnel performing a manual test to ensure correct tube placement before starting ventilation. The use of the medical device becomes safer, and medical personnel are no longer burdened with manual, time-consuming, and error-prone tests.

[0013] In the applicant's anesthesia machine, known under the brand name ZEUS, the Y-piece is attached to a port with a valve. This allows pressure to be built up in the breathing circuits using the gas delivery unit and subsequently released via the valve. A pressure drop detected at a pressure sensor on the inspiratory or expiratory port indicates that the breathing circuits are correctly connected to the Y-piece. In contrast to the test procedure proposed here and below, a method using an additional valve on the Y-piece or the parking holder is more expensive, because the test procedure proposed here utilizes functional units that a medical device with breathing circuits, particularly an anesthesia machine, already possesses, instead of requiring an additional valve.

[0014] US Patent 8,230,858 B2 discloses a method in which a differential pressure value is measured on an anesthesia machine using a sensor, and a pump in a sample gas line is switched on or off whenever the differential pressure value exceeds or falls below a threshold. This is intended to ensure that the sample gas line pump is only active when ventilation of the patient is actually required, thus reducing wear and tear on the pump due to its on-demand activation.

[0015] From WO 2014 / 06800 A1, a ventilation device is known in which a leakage situation of ventilation tubes is checked by introducing a pressure signal into the ventilation tubes by means of a gas supply unit and in which a pressure value is then measured by means of a sensor of a gas sampling line, which is compared to a reference value to determine whether a leakage situation exists.

[0016] From US 2008 / 0202526 A1, an anesthesia ventilation device is known in which a leakage situation is detected by introducing a gas with a predetermined gas concentration into breathing tubes and then monitoring the introduction of the gas of the predetermined gas concentration via a sensor unit on a gas sampling line.

[0017] From US 2010 / 0078018 A1, a method for detecting a leakage situation in an anesthesia device is known, in which flow sensors are used.

[0018] A method for automatically calibrating a pressure sensor is known from US 6237592 B1.

[0019] From DE 4111965 A1 a method for calibrating a flow sensor of a breathing system is known, in which opening and closing of the consultation circuit is provided for the calibration or recording of a reference value for a flow measurement.

[0020] US Patent 587361 discloses a method for operating a ventilation device in which the ventilation circuit can be ventilated for calibration purposes.

[0021] Advantageous embodiments of the invention are the subject of the dependent claims. References to the main claim indicate the further development of the subject matter of the main claim by the features of the respective dependent claim and are not to be understood as a waiver of the right to obtain independent, pecuniary protection for the combinations of features in the referenced dependent claims. Furthermore, when interpreting the claims, if a feature is specified in more detail in a dependent claim, it must be assumed that no such limitation exists in the preceding claims.

[0022] A reference situation is established before determining the comparative measurement. During the reference situation, for example, after a predetermined or predefinable time period has elapsed following the initiation of the reference situation, a measurement is recorded and temporarily stored as a reference value for normalization purposes. The reference situation is then terminated. Establishing and terminating the reference situation is performed automatically by the control unit, which activates at least one functional unit within the device accordingly. Following the termination of the reference situation, the gas delivery unit is activated to establish its predefined operating state.Following activation of the gas delivery unit, for example after a predetermined or predefinable time period, the sensor and measuring device determine the comparative measurement value already mentioned in connection with the more general form of the procedure. This comparison, also previously mentioned, is used to monitor any deviation of the comparative measurement value from the reference value in relation to the predetermined or predefinable expected value.

[0023] This has the advantage that, by additionally considering a reference value, the subsequently recorded comparative measurement can be normalized. Normalization is achieved by considering the deviation of the comparative measurement from the reference value in relation to the expected value. In the simplest case, such a deviation is a difference between the comparative measurement and the reference value, thus achieving the aforementioned normalization. Normalization defines, in a sense, a zero or reference point, and relative to this, rising or falling measured values, as well as rising or falling edges in the measured value curve, are particularly easy to identify automatically. By considering this deviation in relation to the expected value, specifying a suitable expected value for use within the procedure becomes easier. Typically, a certain tolerance range around the expected value is also taken into account.By normalizing the comparative measurement value as achieved with this embodiment of the method, the tolerance range can be chosen to be smaller than would be possible without such normalization. This makes the automatic evaluation of the comparative measurement value more reliable.

[0024] In a specific embodiment of the method providing for the standardization of the reference measurement, the device comprises, in addition to the gas delivery unit and the control unit, at least one venting device and the aforementioned pressure sensor. The reference situation is established by venting the breathing circuit through the opening of the venting device. Following venting, a pressure measurement is recorded as a reference value for standardization purposes using the pressure sensor. After recording the reference value, the reference situation is terminated by closing the venting device and ending the venting of the breathing circuit. The opening and closing of the venting device occur automatically under the control of the control unit and based on a corresponding command from the control unit.Following the termination of the reference situation, the predefined operating situation of the gas delivery unit is automatically established. For this purpose, the gas delivery unit is activated by the control unit to build up pressure in the breathing circuit, and pressure is established in the breathing circuit by means of the activated gas delivery unit. After activation of the gas delivery unit, for example, after a predefined or configurable time period has elapsed, a pressure measurement is automatically recorded as a reference value based on the resulting pressure buildup, triggered by the control unit and using the pressure sensor and measuring device. Following the recording of the reference value, the control unit then checks for any deviation of the reference value from the predefined or configurable expected value.At the end of the process, a warning message is issued by the control unit, or at least under the control of the control unit, if the deviation does not correspond to the expected value, or does not correspond to it at least substantially.

[0025] In an additional, specific embodiment of the method for normalizing the measured value, the device comprises, in addition to the gas delivery unit and the control unit, at least one venting device and a sensor in the form of a gas concentration sensor. In this embodiment, the reference situation is established by purging the breathing circuit with a first test gas of a predetermined or predeterminable composition. Subsequently, a gas concentration value is recorded as a reference value for normalization purposes using the gas concentration sensor. The reference situation is then terminated. Establishing and terminating the reference situation, as well as recording the reference value, are carried out by the control unit and under its control, as described above.Following the termination of the reference situation, the control unit activates the gas delivery unit and floods the breathing circuit with a second test gas of a predetermined or predefinable composition. After activation of the gas delivery unit, the control unit, acting on a corresponding signal, records a further gas concentration value as a comparison value using the gas concentration sensor. Following the recording of this comparison value, the control unit then checks for any deviation of the comparison value from the reference value in relation to the predetermined or predefinable expected value. Finally, the control unit, or at least under its control, issues a warning message if the deviation does not correspond to the expected value, or does not correspond to it substantially.

[0026] The advantage of a test procedure based on the recording of at least one gas concentration measurement is that, in addition to the possible detection of swapped breathing tubes, further errors in the gas supply of the medical device in question may also be detectable, for example, if no oxygen is available via a connected oxygen supply line, or if a connected gas cylinder is not filled with oxygen or not filled sufficiently, or if there is an incorrect internal tubing connection of the gas mixer of the medical device.

[0027] The advantage of this method, which involves recording pressure measurements, lies in the fact that reference conditions for a given pressure measurement can be easily and reliably established through venting. Pressure measurements can be recorded using suitable and relatively inexpensive sensors, both as reference values ​​and as comparative measurements taken during the specified operating conditions of the gas delivery unit. The resulting measurements (reference and comparative values) thus provide a good basis for a relatively simple implementation of the test procedure proposed here.

[0028] A combination of the two variants, i.e., a consideration of pressure measurements and gas concentration values, results in a redundant and diverse test procedure, which is therefore particularly safe because even if a sensor fails, for example the sensor for recording the pressure measurements, it is still possible to carry out the test procedure and to detect incorrectly connected breathing tubes.

[0029] In one embodiment of the method, the comparative measurement is recorded at the end of a rising slope in a pressure curve within the breathing circuit, resulting from the pressure build-up. The end of the rising slope defines a specific time for recording the comparative measurement. An expected value can be readily determined for such a comparative measurement. This also applies to the variant of the method based on recording gas concentration values.

[0030] Following the pressure build-up in the breathing circuit and the recording of the reference measurement, a pressure drop is automatically induced in the breathing circuit by the control unit. At the time of this pressure drop, particularly at the end of a resulting downward slope in the pressure curve, another reference measurement is recorded in the breathing circuit. After this measurement, the deviation of this additional reference measurement from the reference value is checked against a further expected value. At the conclusion of this supplemented test procedure, a warning message is issued if the deviation does not correspond to the further expected value, or does not correspond to it substantially.

[0031] This method is particularly advantageous because the consideration of two comparative measurements—the first comparative measurement and the subsequent comparative measurement—results in a particularly robust test procedure. The first comparative measurement, recorded in temporal correlation with the pressure build-up in the breathing circuit, could also be generated by short-circuiting the Y-piece with a breathing tube and compressing it during the pressure build-up, for example, by stepping on the breathing tube. The resulting pressure increase, which reaches the pressure sensor via the sample gas line, does not result from the pressure build-up in the breathing circuit, because the short-circuited Y-piece is not connected to the breathing circuit at all.Even if the breathing circuits are incorrectly connected, in such a special situation—where a user steps on the breathing circuit short-circuiting the Y-piece in temporal correlation with the pressure build-up occurring during the test procedure—the evaluation of the pressure increase detectable by the pressure sensor could lead to a misinterpretation, indicating a correct connection despite the actual faulty connection. Considering two comparative measurements significantly reduces the at least theoretical risk of such a misinterpretation.By also recording a comparative measurement, the further comparative measurement, for the pressure drop, especially at the end of a resulting falling flank, and checking it in relation to a corresponding expected value, a misinterpretation could only occur with a short-circuited Y-piece if, on the one hand, the person stepping on the breathing tube short-circuiting the Y-piece is in suitable temporal correlation with the pressure build-up occurring during the test procedure, and on the other hand, the person taking their foot off the breathing tube is in equally suitable temporal correlation with the pressure drop occurring during the test procedure.Stepping on and removing the foot from the breathing tube in exactly the same temporal correlation as the pressure build-up and pressure drop are generated according to the test procedure, and the comparative measurements are subsequently recorded, is extremely unlikely, resulting in a very safe test procedure.

[0032] In a test procedure that takes into account a pressure drop following a previously generated pressure increase, the pressure drop in the breathing circuit is triggered by activating the venting device. Opening the breathing circuit to the environment by activating the venting device results in a particularly significant and therefore easily evaluable pressure drop. Alternatively, the pressure drop could also be generated by the gas delivery unit, for example, in a gas delivery unit with an impeller by reversing the direction of rotation, or in a gas delivery unit in the form of a piston-cylinder unit by creating a vacuum in the breathing circuit through appropriate piston movement.

[0033] Although the preceding section described the test procedure based on a pressure build-up in the breathing circuit, and—in a particular embodiment—based on a pressure build-up followed by a pressure drop, the gas delivery unit in certain medical devices can also generate a negative pressure in the breathing circuit, at least during a test situation. The evaluation of the comparative measurement and the subsequent comparative measurement can therefore also be performed based on an inverse sequence of the resulting pressure slopes, and such a variant is always considered to be included in the description presented here and should be read accordingly.

[0034] An embodiment of the invention is explained in more detail below with reference to the drawing. Corresponding objects or elements are provided with the same reference numerals in all figures.

[0035] The embodiment or embodiments described herein are not to be understood as limiting the invention. Rather, modifications and alterations are possible within the scope of the present disclosure, in particular variants and combinations which, for example, can be deduced by a person skilled in the art from the solution of the problem by combining or modifying individual features in conjunction with those described in the general or specific description section and contained in the claims and / or the drawing, and which lead to a new subject matter through combinable features.

[0036] They show: Fig. 1 a medical device with breathing tubes, Fig. 2 a device like in Fig. 1 with incorrectly connected breathing tubes, Fig. 3 a medical device with means for automatic detection of incorrectly connected breathing tubes, Fig. 4. A flowchart for a test procedure performed during automatic detection of incorrectly connected breathing tubes, Fig. 5. a graph of the pressure conditions resulting from the test procedure and Fig. 6 a graph of the resulting pressure conditions for a particular embodiment of the test procedure.

[0037] The representation in Fig. Figure 1 shows, in a highly simplified schematic representation, a ventilator or anesthesia device, referred to here and in the following as medical device 10 or sometimes simply as device 10, with connected breathing tubes 12 and 14. The medical device 10 comprises, in a manner known per se, an inspiratory fluidic port 16 and an expiratory fluidic port 18 (hereinafter sometimes referred to simply as inspiratory port 16 and expiratory port 18, respectively). The breathing tubes 12 and 14 connected to these ports are accordingly referred to as inspiratory breathing tube 12 and expiratory breathing tube 14, respectively, or simply as inspiratory tube 12 and expiratory tube 14.

[0038] The two ventilation tubes 12 and 14 are joined together at a so-called Y-piece 20 in a manner known per se, i.e., connected to the Y-piece 20. Downstream of the Y-piece 20, a tube 22 leads to the patient. The Y-piece 20 can be placed in a parking holder 24, which is shown without further details.

[0039] In addition to the breathing tubes 12, 14, a sample gas line 26 for gas measurement is connected to the Y-piece 20. On the medical device 10, the sample gas line 26 is connected to a fluidic measuring port (sample gas port) 28.

[0040] The representation in Fig. Figure 2 shows, in a similarly simplified schematic form, a medical device 10 as in Fig. 1, however, with incorrectly connected breathing tubes 12, 14, namely, with the breathing tubes 12, 14 connected in reverse. The incorrect, reversed connection is evident in the fact that a first breathing tube 12 is connected to both the inspiratory port 16 and the expiratory port 18 (short circuit), and that the two ports of the Y-piece 20 facing away from the tube 22 leading to the patient are also short-circuited by means of another breathing tube 14. Such a reversed connection of the breathing tubes 12, 14 represents a special (faulty) fluidic connection situation of the device 10 and can certainly occur in practice due to the large number of tubes, i.e., in addition to the breathing tubes 12, 14, other tubes not shown here, and / or cables in the nursing or patient area.

[0041] The representation in Fig. Figure 3 shows, in a schematically simplified manner, a medical device 10 of the type mentioned above, according to an embodiment of the approach proposed here. The medical device 10 is accordingly designed and configured to automatically detect a specific fluidic connection situation in the form of reversed ventilation tubes 12, 14.

[0042] The medical device 10 comprises a gas delivery unit 30, which is generally known per se and therefore shown without specific details, and which functions as a ventilation drive, for example in the form of a piston-cylinder unit. Viewed counterclockwise, the so-called inspiratory branch connects to the gas delivery unit 30, with the inspiratory breathing tube 12 connected to the Y-piece 20. The expiratory breathing tube 14 is also connected to the Y-piece 20, and the expiratory branch connects to this within the device 10. A vent line 32 is connected to the expiratory branch. The vent line 32 allows the expiratory branch to be connected to the ambient air and ambient pressure for venting, and the vent line 32 is normally closed. To close the vent line 32, the following applies: Fig. Figure 3 shows a safety valve functioning as a venting device 34. A pressure sensor 36 is provided on the side of the venting device 34 facing the expiratory branch. The pressure conditions in the expiratory branch can be detected by means of the pressure sensor 36. Proceeding counterclockwise, a so-called PEEP valve 38 is located in the expiratory branch following the venting line 32. This valve, particularly in an embodiment as a proportional valve, ensures the maintenance of the so-called positive end-expiratory pressure (PEEP). Further proceeding counterclockwise, following the PEEP valve 38, a resuscitation bag 40, which is generally optional, is shown as an aid for the manual ventilation of a patient.The PEEP valve 38 can also function as a venting device in conjunction with another valve (not shown), for example, located near the resuscitation bag 40. In general, the term "venting" is intended to encompass any other method of establishing a reference pressure situation, and any device designed to establish a reference pressure situation is considered a venting device, even if it does not establish the reference pressure situation by venting to the environment. The circuit shown (breathing circuit) is closed via an optional absorber 42, which is designed to remove carbon dioxide (CO2) from the exhaled gas flowing through the expiratory branch, by means of a connection to the gas delivery unit 30. In the closed form of the breathing circuit shown, gas can also be drawn in, for example, from the resuscitation bag 40 and delivered into the inspiratory branch using the gas delivery unit 30.

[0043] In the illustrated embodiment, the sample gas line 26 is indirectly coupled to the expiratory branch via a gas measuring device 44, typically referred to as a patient gas analyzer (PGA), for sample gas measurement. Upstream of the gas measuring device 44, a pressure sensor 46 is positioned to determine the pressure conditions in the sample gas line 26.

[0044] In one embodiment, the method for automatically detecting a possible exchange of the breathing tubes 12, 14 is based on a pressure measurement in the sample gas line 26 using the pressure sensor 46. During the procedure, the Y-piece 20 is closed downstream of the connection of the sample gas line 26 with a plug or the like and is located, for example, in a parking holder 24. The method (test procedure) is schematically simplified in the illustration in Fig. 4 in the form of a flowchart 50 to illustrate individual process steps 52-58 encompassed by the procedure. In the representation in Fig. Figure 5 additionally shows a graph 60 relating to the conditions that arise during the individual procedural steps 52-58 within the framework of the test procedure.

[0045] In the first step of the test procedure, the entire breathing circuit is initially depressurized by means of the venting device 34. For this purpose, the venting device 34, in this case the safety valve, is actuated for a predetermined or predefinable period of time so that the venting device 34 opens to the environment. Simultaneously or in conjunction with this, the intake of sample gas through the sample gas line 26 is stopped by means of the gas measuring device 44. The venting can be monitored and checked by means of the pressure sensor 36 associated with the venting line 32.

[0046] The in Fig. Graph 60 shown in Figure 5 is a graph of the pressure conditions sensed by the pressure sensor 46. The pressure sensor 46 is located downstream of the sample gas line 26, which is connected to the Y-piece 20. An incorrect connection of the sample gas line 26 to the Y-piece 20 is not normally expected, because the sample gas line 26 has a different, and in particular smaller, cross-section compared to the breathing tubes 12, 14, so that the sample gas line 26 can only be connected to the Y-piece 20 as intended. During venting, the pressure in the breathing circuit gradually approaches the ambient pressure. In the illustration in Figure 5, the pressure in the breathing circuit gradually approaches the ambient pressure. Fig. Figure 5 illustrates this with an example of a falling curve in graph 60.

[0047] In a second step 54 of the test procedure, an instantaneous pressure measurement is recorded as a reference value 62 using the pressure sensor 46. This is shown in the diagram. Fig. Reference value 62 is shown as a point on graph 60 in a time interval belonging to the second process step 54. After the reference value 62 has been recorded, the venting device 34 is closed.

[0048] In a third step 56 of the test procedure, the gas delivery unit 30, for example the piston-cylinder unit shown, is started to maintain a predefined operating condition. Due to the resulting pressure build-up in the breathing circuit, a positive pressure edge 64 of, for example, 20 hPa is generated. The pressure edge 64 and a resulting pressure measurement at the end of the pressure edge 64 can be detected by the pressure sensor 46. The pressure measurement at the end of the pressure edge 64 is recorded as a reference measurement 66 and temporarily stored. At the conclusion of the third step 56 of the test procedure, the reference measurement 66 is compared with the previously recorded reference value 62.If the change in pressure conditions detected by the pressure sensor 46, here the pressure increase (i.e., the difference between the comparative measurement 66 and the reference value 62), corresponds to a predefined or predefinable expected value 68 according to the pressure increase applied by the gas delivery unit 30, less a predefined or predefinable tolerance, it can be ruled out that the breathing tubes 12 and 14 were mixed up when connected to the Y-piece 20. If, on the other hand, the detected change in pressure conditions does not correspond to the expected value 68 less the tolerance, a warning message is issued in a fourth step 58 of the test procedure, for example, by activating an optical and / or acoustic signal or indicator element not shown. Optionally, a corresponding display can also be triggered in the fourth step 58 if the test procedure has reliably determined that no mix-up has occurred.

[0049] The representation in Fig. Figure 6 shows a resulting graph 60 of the pressure conditions in a particular embodiment of the test procedure. During the first, second, and third procedure steps 52, 54, 56, the sequence of this particular embodiment of the test procedure corresponds to the sequence already described. Following the third procedure step 56 and the pressure build-up in the breathing circuit caused therein, a pressure drop in the breathing circuit is generated in an additional procedure step 57. The pressure drop can occur, for example, by automatically controlling the venting device 34 accordingly. Due to the pressure drop, a falling edge results, and in connection with the pressure drop, particularly at the end of the falling edge or after a predetermined or predeterminable time interval has elapsed after the triggering of the pressure drop, a further comparative measurement 67 is recorded as a pressure measurement.The additional comparative measurement 67 can be evaluated analogously to the evaluation of the comparative measurement 66. Following the recording of the additional comparative measurement 67, a deviation of the additional comparative measurement 67 from the reference value 62 is checked in relation to a further expected value 69. If the deviation does not correspond to the further expected value 69, or does not correspond at least substantially to it, a warning message is issued.

[0050] The test procedure is carried out automatically by means of a control unit 70 included in the medical device 10 ( Fig. 3) controlled and monitored. The test procedure is automatically triggered whenever the device 10 is switched on and / or before a patient is connected by the user. The control unit 70 comprises, for example, a processing unit in the form of a microprocessor, as well as a memory in which a control program 72 with an implementation of the test procedure is loaded. For the execution of the test procedure, the control unit 70 is connected, in a manner known per se, to the functional units of the device 10 used within the framework of the test procedure, i.e., at least the gas supply unit 30, the venting device 34, and the pressure sensor 46. For the sake of clarity in the presentation in Fig. 3. The corresponding line connections are not shown. During the execution of the individual process steps 52-58 of the test procedure and / or during the transition from one process step 52-58 to the next, the control unit 70 monitors predefined or predefinable time intervals based on the control program 72. For example, after the venting device 34 is activated, a time interval is monitored during which the breathing circuit is vented, or after which sufficient venting of the breathing circuit can be expected. Instead of monitoring such time intervals, predefined conditions can also be monitored. During the venting of the breathing circuit, sufficient venting can be recognized, for example, by a measured value from the pressure sensor 36.Similarly, a measurement can be recorded at the end of a rising edge 64 or at the end of a falling edge of a measurement curve by using the control unit 70 to wait for the elapse of a predefined or predefinable time interval following an action that triggered the rising edge 64 or the falling edge. Alternatively, the control unit 70 can also monitor the measurement curve itself, so that the recording of the respective measurement is not time-dependent, but occurs based on the detected end of the respective edge.

[0051] Instead of considering pressure measurements and a resulting reference value 62 and comparative measurement 66, as well as, if applicable, a further comparative measurement 67, the described procedure can also be carried out based on flow measurements. In place of the previously mentioned pressure measurements, corresponding flow measurements are used: Many measuring devices 44 functioning as PGAs already include a sensor for recording flow measurements, and accordingly, the measuring device 44 itself is considered a flow sensor here. With such a sensor, control is possible that aims for a constant flow through the measuring device 44. The sensor in question, like the pressure sensor 46, can be used within the test procedure to determine the respective measured values.If, as previously described, the intake of sample gas through the sample gas line 26 is stopped by means of the measuring device 44 in connection with the execution of the test procedure, a flow detectable by the flow sensor is the result of any venting of the breathing circuit and / or activation of the gas delivery unit 30 that may have occurred during the test procedure. The available flow measurements can thus be used, as previously described using the pressure measurements, to detect swapped breathing tubes 12, 14. Therefore, if the pressure of the gas delivery unit 30 generates a pressure at the Y-piece 20 and the sample gas line 26 is connected to the measuring device 44 and the flow sensor, a flow through the measuring device 44 and the flow sensor occurs.If, on the other hand, a flow rate cannot be measured, this is an indication that the sample gas line 26 is not connected or that the detectable error case of a swap of the breathing tubes 12,14 is present.

[0052] The acquisition and evaluation of flow measurements can be performed in parallel and / or in addition to the acquisition and evaluation of pressure measurements. A resulting combined test procedure is redundant and diverse, which is particularly reliable because even if a sensor fails, for example the pressure sensor 46 for recording the pressure measurements, the test procedure can still be executed and a faulty connection of a breathing tube 12, 14 can still be detected.

[0053] By means of an optional gas mixer 74, not yet considered, the test can also be carried out based on gas concentration measurements, again under the control of the control unit 70. For this purpose, if the establishment of a reference situation is planned at the beginning of the test procedure, the breathing circuit is first purged with a gas of a known gas concentration (for example, approximately 21% oxygen in the ambient air) using the gas mixer 74 or via ambient air as part of a first procedure step 52. To record the reference value 62, a pump encompassed by the gas measuring device 44 is started, so that the sample gas used to purge the breathing circuit is drawn into the sample gas line 26 and to the sensor 46, which functions here as a gas concentration sensor. Using the sensor 46, a gas concentration measurement can then be recorded as the reference value 62 in a second procedure step 54.Subsequently, in a third process step 56, a test gas or a defined quantity of a test gas (for example, 100% oxygen) is metered into the breathing circuit by means of the gas mixer 74 for a defined period of time. At the end of a resulting rising edge 64 in the concentration profile of the gas under consideration, for example, oxygen, or after a predetermined or predefinable period of time has elapsed, a gas concentration measurement is recorded by the sensor 46 as a reference measurement 66. The evaluation of the resulting reference measurement 66, or of the reference measurement 66 and the reference value 62, is carried out analogously to the evaluation already described and based on pressure measurements. This is shown in the illustration in [reference number]. Fig.As shown in Figure 6, a falling edge in the respective gas concentration can be generated after the metering of a sample gas, for example, by opening the breathing circuit using the venting device 34, thus allowing ambient air to enter the breathing circuit instead of the sample gas. In contrast to the evaluation based on pressure measurements, an evaluation based on gas concentration measurements requires that during the test procedure, at least before and during the recording of the reference value 62, before and during the recording of the comparative measurement 66, and optionally also before and during the recording of the further comparative measurement 67, the pump included in the measuring device 44, or another pumping unit effective for conveying gas through the sample gas line 26 to the sensor 46, is running and causes a corresponding delivery of gas from the breathing circuit to the sensor 46.

[0054] In conclusion, some essential aspects of the description presented here can be briefly summarized as follows: A method and a corresponding device for detecting incorrectly connected or swapped ventilation tubes 12, 14 of a medical device 10 are described, in which a measured value is determined as a comparative measured value 66 by means of a sensor 46 in temporal correlation with a given operating situation of a gas delivery unit 30 of the device 10 and this is compared with a given or predefinable expected value 68, whereby a warning message is issued if necessary depending on the result of the comparison. REFERENCE MARK LIST 10 medical devices 12 (inspiratory) breathing tube 14 (expiratory) breathing tube 16 inspiratory ports 18 expiratory port 20 Y-pieces 22 Hose (to patient) 24 parking spaces 26 Sample gas line 28 Sample gas transport 30 Gas delivery unit 32 Vent line 34 Venting device 36 Pressure sensor 38 PEEP valve 40 resuscitation bags 42 absorbers 44 measuring device / gas measuring device 46 Sensor / Pressure sensor 48 (free) 50 Flowchart 52-58 Procedure step 60 Graph 62 Reference value 64 rising flank 66 comparative measurement 67 (further) comparative measurement 68 Expected value 69 (further) expected value 70 Control unit 72 Control program 74 gas mixers

Claims

[1] Method for automatic detection of a fluidic connection situation of a ventilator or anesthesia machine (10), wherein the ventilator or anesthesia device (10) comprises a gas delivery unit (30), at least one pressure sensor or flow sensor (44, 46), a control unit (70), an inspiratory fluidic port (16), an expiratory fluidic port (18) and further a fluidic measuring port (28) which is coupled to the at least one pressure sensor or flow sensor (44, 46), wherein the inspiratory fluidic port (16) and the expiratory fluidic port (18) can be connected to a Y-piece (20) as part of a breathing circuit by means of breathing tubes (12, 14) and wherein the fluidic measuring port (28) can also be connected to the Y-piece (20) by means of a sample gas line (26), the procedure comprises the following process steps, which are carried out under the control of the control unit (70): - before determining a comparative measurement (66), a reference situation is established, - during the reference situation, a measured value is recorded as the reference value (62), - Following the recording of the reference value (62), the reference situation is terminated, - Following the termination of the reference situation, the gas delivery unit is activated to establish a pressure build-up in the breathing circuit and the comparative measurement value (66) in the form of a pressure measurement value or flow value is determined by means of the pressure sensor (46) or flow sensor (44). - the reference measurement (66) is compared with a predetermined or predefinable expected value (68) whereby, by means of the comparison, a deviation of the measurement (66) from the reference value (62) in relation to the predetermined or predefinable expected value (68) is monitored. - and depending on the result of the comparison, a warning message is issued, characterized by , - that following the pressure build-up in the breathing circuit and the recording of the comparative measurement, a pressure drop is caused in the breathing circuit, - that a further comparative measurement is recorded for the pressure drop, - that a deviation of the further comparative measurement value from the reference value is checked in relation to a further expected value, - and that a further warning message will be issued if the deviation does not correspond to the further expected value, or does not correspond at least substantially. - whereby the evaluation of the comparative measurement value and the further comparative measurement value can be carried out on the basis of an inverse order of the resulting pressure flanks. [2] Method according to claim 1, wherein the device (10) comprises, in addition to the gas delivery unit (30) and the control unit (70), at least a venting device (34) and the pressure sensor or the flow sensor (44,46), wherein the reference situation is established by venting the breathing circuit by opening the venting device (34), wherein a pressure measurement or flow value is recorded as a reference value (62) by means of the pressure sensor or flow sensor (44, 46), wherein following the recording of the reference value (62) the reference situation is terminated by terminating the venting of the breathing circuit by closing the venting device (34). [3] Method according to claim 2 wherein the comparative measurement value (66) is recorded at the end of a rising flank (64) of a pressure profile in the breathing circuit resulting from the pressure build-up. [4] Method according to claim 2, wherein the pressure drop in the breathing circuit is triggered by means of a control of the venting device (34). [5] Ventilator or anesthesia machine (10), comprising a gas delivery unit (30), at least one pressure sensor or flow sensor (44, 46), a control unit (70), an inspiratory fluidic port (16), an expiratory fluidic port (18) and further a fluidic measuring port (28) which is coupled to the at least one pressure sensor or flow sensor (44, 46), wherein the inspiratory fluidic port (16) and the expiratory fluidic port (18) can be connected to a Y-piece (20) by means of breathing tubes (12, 14) and wherein the fluidic measuring port (28) can be connected to the Y-piece (20) by means of a sample gas line (26), wherein the control unit (70) is configured to - to establish a reference situation of the device before determining a comparative measurement (66), - to record a measurement as a reference value (62) during the reference situation, - following the recording of the reference value (62), to end the reference situation, - following the termination of the reference situation to establish a pressure build-up in the breathing circuit by means of the gas delivery unit, to activate it and to determine the comparative measurement value (66) in the form of a pressure measurement value or flow measurement value by means of the pressure sensor or flow sensor (44, 46), - to compare the reference measurement (66) with a predetermined or predeterminable expected value (68) wherein, by means of the comparison, a deviation of the measurement (66) from the reference value (62) in relation to the predetermined or predeterminable expected value (68) is monitored , - and issue a warning message depending on the result of the comparison, characterized by , that the control unit (70) is further configured to, - to cause a pressure drop in the breathing circuit following the pressure build-up in the breathing circuit and the recording of the comparative measurement, - to record another comparative measurement value for the pressure drop, - to check for a deviation of the further comparative measurement value from the reference value in relation to a further expected value, - and to issue a further warning message if the deviation does not correspond to the further expected value, or does not correspond at least substantially.

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