Lung simulator and method for operating the lung simulator
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- IMT ANALYTICS AG
- Filing Date
- 2024-05-28
- Publication Date
- 2026-04-29
Smart Images
Figure CH2024050026_02012025_PF_FP_ABST
Abstract
Description
[0001]Lung simulator and operating method of the lung simulator Technical field The present invention describes a lung simulator with a housing in which electronics, a connection unit and an internal pipe and / or hose system are arranged, from an inlet through a first actuator to an inhalation / exhalation air outlet leading out of the housing, as well as various methods for simulating a human or animal lung and using a radial fan. State of the art Lung simulators are technically differently designed devices that are used for training and for testing ventilation systems and / or anesthesia systems and are sometimes also referred to as test lungs. A distinction is made between mechanical / pneumatic lung simulators and complex / physiological lung simulators. A lung simulator has previously consisted of at least one resistance element, e.g.a tube and an elastic element, such as a balloon. Mathematically, this is represented by the so-called "equation of motion," which is expressed as a function of time: Formula 1: Paw. ( t ) = Raw Crs where Paw ( t ): the airway pressure, Raw: the airway resistance, V'( t ) = d V ( t ) / dt is the gas flow in the airways, Crs: the total respiratory compliance and V( t ): the volume flowing into the lungs. However, two important elements are missing from the above equation: the constant term and the airway pressure generated by the respiratory muscles. The complete equation therefore looks like this: Formula 2: Paw ( t ) = Raw ∙ + V ( t ) ∙ Crs + Pmusc ( t )+ K This constant is of great importance in clinical practice, as it corresponds to the so-called intrinsic PEEP, which can have both therapeutic and traumatic effects. Basically, it depends on the definition of V(t) whether K is already included or not. Mathematically, the constant K is not necessary, as it can be calculated as part of V(t), meaning that the lung volume V(t) does not start at 0 at the beginning of a breath, which is actually the case when there is intrinsic PEEP. In clinical practice, simple test lungs are used, but more complex designs are also used. Lung simulators are often used for basic respiratory physiological studies and are specifically adapted to these needs. The autonomous baby lung simulator is an actual lung simulator in a silicone body, designed in detail to enable a maximum simulation experience.The body itself is not important for lung simulation, but rather the built-in equipment. The system also includes a vital sign monitor that reflects the results of the respiratory treatment. If the mechanical / pneumatic elements are expanded to include gas exchange, non-linear compliance, collapsible and recruitable volumes, dead space, shunts, heart-lung interaction, etc., then P235428WO lung simulators are referred to as complex / physiological lung simulators. Here, lung ventilation controls the physiological response of the system, depending on how the individual parameters are adjusted. The following equation is important for gas exchange: Formula 3: Va′ = (Vt − Vd) ∙ RR where Va′ = V'a is the alveolar ventilation, Vt is the tidal volume, Vd is the anatomical or serial dead space, and RR is the respiratory rate. In combination with the above “Equation of Motion”, the gas exchange equation can be used to calculate the partial pressure of CO2 and O2 in arterial blood.If one also simulates the ineffective gas exchange in collapsed lung tissue, the pathological admixture of venous blood can also be calculated. In summary, one obtains a lung simulator that reacts automatically. If one adds breathing control, one obtains an autonomous system, an autonomous lung simulator. It is important for this type of simulator that the models used are made transparent. The basic test setup of a ventilator or anesthesia device 2 comprises, according to the prior art and Figure 1, a lung simulator 1, a ventilator or anesthesia device 2 being tested, at least one ventilation tube 3, a connector 4 between ventilation tube 3 and test lung 1, a computer unit 5, and a connection 6 between test lung 1 and computer unit 5. Simple mechanical / pneumatic lung simulators 1 are commercially available from the applicant.This involves a container, usually a P235428WO silicone bag, with a variable volume (representing total respiratory compliance (Crs)), which can be closed with a cap of varying size (representing Raw). By clamping a portion of the container, different total respiratory compliances (Crs) can be simulated. However, the simulation options for this type of lung simulator are severely limited and not particularly realistic. Michigan Instruments (https: / / www.michiganinstruments.com / de / lungensimulatoren / ) has described various technically far more complex lung simulators1, in which even more than one volume, bellows, electronically controlled lever mechanisms, and manometers are compactly housed in a single housing. Depending on the model, spontaneous breathing (Pmusc(t)) can also be simulated.Pmusc(t) is simulated by attaching an additional module to test lung 1, which uses a lever mechanism to push a lung lid upward. A disadvantage of this technical solution is that only negative values of Pmusc(t) can be simulated, which corresponds to active inspiration. Overall, these compact lung simulators 1 are complex, bulky, and heavy. A smart solution comes from Ingmar Medical and is called the ASL 5000 (https: / / www.ingmarmed.com / product / asl-5000-breathing-). This lung simulator 1 essentially has a volume in the form of a cylinder in which a piston is moved back and forth under motor and software control, generating a changing air volume and simulating some of the functions of a human lung. The computer unit 5 works with internal electronics that measures air pressure using sensors and controls the drive of the piston in the cylinder. The lung simulator 1 measures the pressure in the inlet tube, i.e., between the ventilator connection and the piston. This pressure P235428WO corresponds to Paw(t). Using the "Equation of Motion" / Formula 2, Raw, Crs, and Pmusc(t) can be simulated.A similar solution is disclosed in US20210241657, which comprises a lung simulator as a physical lung model (PLM) for training and teaching, with a lung chamber defined by an expandable and shrinkable piston for increasing and decreasing the volume of the lung chamber (8, 8'). A mechanical stop on the piston ensures different movements and pumped volumes of the piston. Additionally, a lever is attached to block the movement of the stop at a fixed point on the movement path when the lung chamber is enlarged, thereby limiting the expansion of the lung chamber.Although the known solutions show compact and more or less mobile lung simulators 1, these can only achieve a versatile, realistic lung simulation by means of a piston / cylinder structure, using various physical, interchangeable breathing resistances, complicated drive mechanisms, and restriction mechanisms. Description of the invention The object of the present invention is to create a lung simulator that can carry out a multitude of simulation scenarios using simpler mechanical means, cylinder / piston-free, controlled by electronics in a housing, and with a more compact and lightweight design than known from the prior art. In addition, several operating methods of the lung simulator are claimed. The lung simulator is used for different methods to simulate a human or animal lung. P235428WO Variations of feature combinations orMinor adaptations of the invention and various method options can be found in the detailed description, depicted in the figures and included in the dependent patent claims. Brief description of the drawings A preferred embodiment of the lung simulator as well as explanations of various operating modes are described below in the detailed description in conjunction with the attached drawings. Further features, details and advantages of the invention will also emerge from the following description of slightly modified embodiments of the invention, some of which will be clear to the person skilled in the art from the drawings alone. Figure 1 shows a schematic representation of a test setup for a ventilator or anesthesia device according to the prior art with a lung simulator according to the prior art.Figure 2a shows a schematic view of a lung simulator according to the invention in a housing with a radial fan, while Figure 2b shows a schematic view of another lung simulator schematically with two radial fans and Figure 2c shows a schematic view of another lung simulator schematically with two radial fans and two controllable valves. Figures 3a to 7 each show flow diagrams of different feasible operating procedures. P235428WO Description A lung simulator 1 essentially simulates a pressure Paw(t) as a function of volume VP(t), flow V'P(t) and Pmusc(t). The relationship between these parameters is widely recognized and known as the "Equation of Motion". Mathematically speaking, it is an ordinary first-order differential equation that describes the dynamic behavior of a lung: Formula 4:. This equation is also known in the following form (The flow V'P(t) corresponds to the derivative of the volume VP(t)): Formula 5: ^^ ^^ ^^( ^^) = ^^ ′ ^^( ^^) ∙ ^^ ^^ ^^ + ^^ ^^( ^^) ∙ ^^ ^^ ^^ + ^^ ^^ ^^ ^^ ^^( ^^) Basically, the equation can be simplified further: Formula 6: ^^ ^^ ^^( ^^) = ^^ ^^ + ^^ ^^ + ^^ ^^ ^^ ^^ ^^ ^^( ^^) where P Rthe differential pressure = pressure drop or pressure loss of the resistance Raw, PC is the pressure created by the lung compliance Crs. The equation therefore describes the sum of three different pressure values. PR is also known as the resistive pressure component and PC as the capacitive pressure component. As is known from the prior art, a lung simulator 1 / test lung 1 is pneumatically connected to a ventilator 2 or an anesthesia machine by means of at least one ventilation tube 3. An electronics unit X as part of the lung simulator 1 is connected to a computer unit 5 by means of a connection 6 in the form of cables, USB, serial, parallel, CAN or wirelessly via wireless WiFi, BT, cellular, NFC, so that the various operating procedures can be carried out in a controlled manner.The computer unit 5, which can be a PC, laptop, tablet, or smartphone, controls the configuration of the electronics X of the lung simulator 1, as well as the monitoring and evaluation of ventilation. P235428WO The lung simulator 1 comprises a housing G in which the components of the lung simulator 1 are mounted and connected to one another. The electronics X is mounted in the housing G, serves as the measuring and control electronics, and is connected to a connection unit C, a screen D, and, via appropriate cabling, to other internal components and a power supply. The electronics X serves as a controller, which reads in measured values, controls at least one actuator R, and controls the screen D including the user interface. The electronics X preferably has a microprocessor for carrying out the method, and a memory for storing the configuration, lookup tables (LUTs), and the program code.On screen D with a graphical user interface (GUI), preferably in the form of a touchscreen, values are displayed and can be manually configured, for example setpoints for lung simulation, e.g. (Crs, Raw, Pmusc(t), RL, b, ...). The display or monitoring of ventilation and the lung simulation procedure can be shown on screen D. Possible data interfaces are USB, serial, CAN, WiFi, BT, NFC, which are housed in the connection unit C. Of course, the electronics X is connected to an on / off switch and optionally mechanical control elements such as potentiometers can be used for configuration. The ventilation tube 3 of a ventilator 2 / anesthesia machine 2 and thus an air flow are led through an inlet E into the housing G and then into a pipe and / or hose system.Various pressure sensors and / or flow measuring devices are arranged along the internal pipe and / or hose system, each of which can directly or indirectly measure or determine prevailing air pressures and flow rates at different locations. The air flow is passed on via at least one first actuator R, which is designed here as a P235428WO radial blower R, and is then led out of the internal pipe and / or hose system via an inhalation / exhalation air outlet A, optionally also out of the housing G. An additional hose (not shown) and / or a humidifier can be connected to the inhalation / exhalation air outlet A outside the housing G, depending on the desired lung simulation program. According to the invention, the pressure Paw(t) is generated here by a radial blower R, also called a blower R, as the at least one first actuator R.The radial blower R has a rotor R2 with radially extending rotor blades, mounted in a blower housing R1 with a radial outlet R3, wherein the radial blower R is driven by a blower motor R5. Due to the rotation of the rotor R2, air is sucked in axially and centrally through an intake nozzle R4, the internal pipe and / or hose system, and the inhalation / exhalation air outlet A. The air is then deflected by 90 degrees by centrifugal force and pumped through the radial outlet R3. Brushless blower motors R5 with a particularly long service life are used in such radial blowers R, which ensure the generation of the air flow through the radial outlet R3, with volume flows of up to several hundred liters per minute being possible. The use of such known radial blowers R as the first actuator R of a lung simulator 1 is not known from the prior art.The radial blower R is connected to the electronics X, which can be controlled and regulated depending on the desired simulation program and the specific pressure and / or flow values. P235428WO Since the speed of the rotor R2 in the radial blower R is also adjustable, various simulation scenarios can be run. The control of the radial blower R and thus the setting of Paw is specified using the equation of motion. This requires at least one pressure and / or flow measurement before or after the radial blower R, it is important that it is in series with the radial blower R in order to be able to measure the variable V'P(t) and determine VP(t) by integration. Within the housing G, a flow measuring sensor and / or a differential pressure measuring sensor is arranged within the piping system, in series with at least one radial blower R, R'.For the control, either the flow measurement or the differential pressure measurement must be carried out, or both, so that the electronics X and the desired control of the at least one radial fan R, R' can be coordinated with the desired simulation. With such a lung simulator 1, the operating method as described in Figures 3a, 3b, 4a and 4b can be carried out, whereby only a first actuator R as the radial fan R is necessary. The lung simulator 1 according to the invention can, as can be seen in Figure 2a, contain a second actuator V in the form of a valve V between the inlet E and the outlet A. The valve V is operated by a valve motor M, controlled by the electronics X and can be used for additional simulation methods. In a further modification, the lung simulator 1 can have an additional third actuator R', again designed as a radial fan R'.The intake port R4 of the first radial fan R is coupled to the axial intake port R4' of the third actuator R', i.e., the second radial fan R'. Alternatively, the radial outlets R3 and R3' of the radial fans R, R' can also be coupled to one another. The second radial fan R' is also connected and controlled by the electronics X. Alternatively, the valve V could be omitted, and the lung simulator 1 comprises only one radial fan R or two radial fans R, R'. In a further modification, the lung simulator 1' has, in addition to the first actuator R and third actuator R', a radial fan R, R', with the second actuator V as a valve, a second valve V'.This second valve' is connected downstream of the first actuator R in the pipe and / or hose system between the inlet E and the exhaled air outlet A, in parallel to the second radial fan R', which has the largest possible cross-section, whereby a valve V' identical to the first valve V is usually used. The valve V' is provided with a valve motor M, which is also controllable by the electronics X, so that the second valve V' is open when the second radial fan R' is switched off and the second valve V' is closed when the second radial fan R' is switched on. This allows lower airway resistances to be simulated, since the resistance of the second radial fan R' is bridged by the second valve V'. The diagram of the possible process sequence with two radial fans R, R' and two valves V, V' is shown in Figure 6b.The simplest operating procedure of the lung simulator 1 is shown in the diagram in Figure 3a and is as follows: 1.) Determination of a Crs 2.) V'P(t) is determined, measured by a flow measurement or differential pressure measurement 3.) Determination of VP(t), ideally by temporal integration of V'P(t) 4.) Determination of a target variable Palv_soll (voltage, speed, current, pressure) for the first actuator R based on P235428WO of VP(t), Crs, ideally by calculating a capacitive component VP(t) * Crs 5.) Repeat steps 2 ... 4 as often as desired, but at least once. At least one radial fan R is used as the actuator R. This simple process could be implemented purely discretely, i.e. without a microprocessor in the electronics E. However, a processor is preferred because it can be produced more cost-effectively. With this system, arbitrarily high tidal volumes can be simulated, since the air is not “stored” anywhere.This solution also enables an extremely compact design (e.g. less than 10 cm x 10 cm x 10 cm). This also makes a mobile application conceivable. The test lung 1 can also be used purely as a flow measuring device if the actuator R is switched off or as a pressure / flow source if the actuator R is controlled accordingly. Accordingly, the test lung 1 can also be used for other purposes and is therefore multifunctional. This would be a particular advantage for testing ventilators or in engineering, as these additional functions could offer significant added value. The separate flow measurement is also an advantage, as it can be adjusted and calibrated independently according to a standard procedure. This means that no separate measuring device is required to verify ventilation. The test lung 1 is therefore a measuring device and simulator in one.The method can be adapted so that not only VP(t) and Crs are used for the Palv_soll, but also Raw and V'P(t). For this, Raw must also be determined. Generally, the differential pressure PR, which results from the airway resistance, is added to the Palv_soll. A distinction is usually made between linear airway resistance PR = V'P(t) * Raw and quadratic / parabolic airway resistance PR = V'P(t). 2* Raw. This process is shown in the diagram in Figure 3b and is as follows: 1.) Determination of Crs and Raw 2.) V'P(t) is determined, ideally measured by a flow measurement (differential pressure method is also possible) 3.) Determination of VP(t), ideally by time integration of V'P(t) 4.) Determination of a setpoint value Palv_soll (voltage, speed, current, pressure) for the first actuator R based on V'P(t), VP(t), Crs, Raw, ideally by adding a capacitive component VP(t) * Crs and a resistive component V'P(t) 2* Raw. 5.) Repeat steps 2 … 4 as often as desired, at least once. Not only compliance but also airway resistance can be simulated, leading to a more accurate simulation, schematically shown in Figure 3b as option 1. Optionally, the pressure of the radial fan R is not only controlled but also regulated with a closed-loop controller. For this, a pressure value Palv_mess is required, ideally measured with a pressure sensor, as indicated in Figure 2. Estimation via flow and / or radial fan speed is also conceivable. The pressure value Palv_mess can represent either Paw or Palv, ideally Palv. This procedure is shown in the diagram in Figure 4b and is as follows: 1.) Determination of a Crs, Raw 2.) V'P(t) is determined, ideally measured by a flow measurement (differential pressure method also conceivable) P235428WO 3.) Determination of VP(t), ideally by time integration of V'P(t) 4.) Determination of a target value Palv_soll (voltage, speed, current, pressure) for the first actuator R based on V'P(t), VP(t), Crs, Raw, ideally by adding a capacitive component VP(t) * Crs and a resistive component V'P(t). 2* Raw. 5.) Repeat steps 2 … 4 as often as you like, but at least once 6.) Determine a pressure value Palv_mess 7.) Control from Paw_mess to Palv_soll using the first actuator R as a closed loop 8.) Repeat steps 6 … 7 as often as you like, but at least once More accurate simulation of the equation of motion, because the at least one radial fan R is not only controlled but also regulated. The controller can either be part of the at least one radial fan R or part of the electronics X. The use of a "variable resistor" as a second actuator, designed here as valve V, for the simulation of Raw improves the process. Additional sub-options: • A differential pressure sensor to determine Praw_mess, which can measure either the differential pressure across valve V or the differential pressure across the valve + flow measurement. Advantageous over valve + flow measurement, as this also compensates for the influence of the flow measurement.• Alternatively or in addition, a second pressure measurement Paw_mess can be used to mathematically determine the pressure value Praw_mess: Praw_mess = Paw_mess – Palv_mess. • To monitor Paw and increase the accuracy of Praw_mess, it is advantageous if Paw_mess is measured with a P235428WO pressure sensor and Praw_mess is measured with a differential pressure sensor. The procedure now changes in that the simulation of the airway resistance Raw is carried out by the valve V and the simulation of Crs is carried out by the radial fan R. This procedure is shown in the diagram in Figure 5b and is as follows: 1.) Determination of a Crs, Raw 2.) V'P(t) is determined, ideally measured by a flow measurement (differential pressure method is also conceivable) 3.) Determination of VP(t), ideally by time integration of V'(t) 4.) Determination of a target value Palv_soll (voltage, speed, current, pressure) for the first actuator R based on VP(t), Crs ideally by a capacitive component VP(t) * Crs 5.) Determination of a target value Pr_soll (voltage, speed, current, pressure, opening) for the second actuator V / the valve V based on V'P(t), Raw ideally by a resistive component V'P(t). 2* Raw. 6.) Repeat steps 2 … 5 as often as required, but at least once 7.) Determine a pressure value Palv_mess 8.) Control from Palv_mess to Palv_soll using the first actuator R as a closed loop 9.) Repeat steps 7 … 8 as often as required, but at least once 10.) Determine the differential pressure Pr_mess (via measurement or calculation) 11.) Control from Pr (or Pr_soll => are identical) to Pr_mess using the second actuator V 12.) Repeat steps 10 … 11 as often as required, but at least once P235428WO The closed-loop control of Pr_mess (steps 10 to 12) is not absolutely necessary if the second actuator V is controlled instead of regulated. For example, using a mathematical function or a lookup table (LUT). This means that Pr_soll is fed directly to the second actuator V. By adding a valve V as a second actuator V, the simulation of Pr can be done much faster and more accurately.The reason for this is that a change in flow immediately generates a change in the differential pressure Pr. This would require the first actuator R, i.e. the radial fan R without a valve V, to be able to immediately increase the pressure. This is not possible with a radial fan R according to the current state of the art. However, if a valve V with a variable cross-section is used, a change in the differential pressure also immediately occurs when the flow changes. By moving the valve V, different values of Raw and / or different characteristics (linear, quadratic) of Raw can be simulated. Additional sensors (measuring the differential pressure) increase the accuracy and enable the use of inexpensive valves V. Measuring Paw makes it possible to either omit the differential pressure sensor or to monitor Paw. In principle, it is also possible to simulate Pmusc(t) with this system. For this purpose, a Pmusc(t) is determined in the process (between steps 1 and 6).Either by reading a memory unit or by reading a digital or analog input. Pmusc(t) is then calculated together with Crs and VP(t) to obtain Palv_soll. This procedure is as follows: 1.) Determination of a Crs, Raw 2.) V'P(t) is determined, ideally measured by a flow measurement (differential pressure method is also conceivable) P235428WO 3.) Determination of VP(t), ideally by time integration of V'P(t) 4.) Determination of the muscular lung pressure Pmusc(t) 5.) Determination of a target variable Palv_soll (voltage, speed, current, pressure) for the radial fan R based on VP(t), Crs,Pmusc(t), ideally by adding Pmusc(t) with a capacitive component VP(t) * Crs 6.) Determination of a target variable Pr_soll (voltage, speed, current, pressure, opening) for the valve V as the second actuator V based on V'P(t), Raw, ideally by a resistive component V'P(t). 2* Raw. 7.) Repeat steps 2 … 6 as often as required, but at least once 8.) Determine a pressure value Palv_mess 9.) Control from Palv_mess to Palv_soll using radial fan R as a closed loop 10.) Repeat steps 8 … 9 as often as required, but at least once 11.) Determine the differential pressure Pr_mess (via measurement or calculation) 12.) Control from Pr (or Pr_soll => are identical) to Pr_mess using a second actuator V 13.) Repeat steps 11 … 12 as often as required, but at least once By simulating Pmusc(t) a realistic simulation of the inhalation and exhalation efforts can be realized. If the first actuator R has the limitation of generating negative pressure values, which is the case with the radial fan R, a third actuator R' can be used as another radial fan R', which can generate a negative pressure by installing this second radial fan R' in the opposite direction, as indicated in Figure 2b.Both axial intake ports R4, R4' are preferably connected to each other P235428WO and the sides with intake ports R4, R4' face each other accordingly, resulting in the most compact design possible. Alternatively, the outlet ports R3, R3' can be connected to each other, which can lead to a more compact design depending on the form factor of the radial blower used. The procedure changes little, assuming that the controller for Palv controls two actuators R, R', the first radial blower R and the third actuator or the second radial blower R'. Negative pressure values for Palv or Paw can also be simulated. This means that strong inspiratory efforts (negative Pmusc(t)) on the part of the patient can be simulated. This makes the lung simulator 1 more versatile. In principle, it is possible to simulate negative values for Pmusc(t) with just one radial blower R, but only within a limited range.From the equation Formula 7: ^^ ^^ ^^( ^^) = ^^. ^^ + ^^ ^^+ ^^ ^^ ^^ ^^ ^^( ^^) it can be seen that the minimum value for Pmusc(t) corresponds to the negative value of Pc, so that Pc + Pmusc(t) = 0. Accordingly, with a radial fan R, Pmusc(t) cannot be smaller than the negative value of Pc, since the radial fan R would have to generate a negative pressure. If a second radial fan R' is installed as a third actuator, a Pmusc(t) can also be simulated, which leads to Pc + Pmusc(t) < 0. In this case, the first actuator R stops completely, i.e. comes to a standstill, and the third actuator R' starts to rotate and generates a corresponding negative pressure. Leaks between the mask and the patient occur particularly during non-invasive ventilation (e.g. with masks). Compensating for these leaks is a major challenge for manufacturers of P235428WO ventilators. In order to test the ventilators, it makes sense to also simulate leakage. For this purpose, the method according to the invention can be supplemented as follows.Essentially, leakage occurs "before" the patient. This can be modeled by subtracting the leakage flow V'L(t) from the measured flow V'(t) (or adding it, depending on the definition of the sign of V'L(t)). Formula 8: ^^ ^^ ^^. ( ^^ ) = [ ^^ ′( ^^ ) − ^^′ ^^( ^^)] ∙ ^^ ^^ ^^ + [ ^^ ( ^^ ) − ^^ ^^( ^^)] ∙ ^^ ^^ ^^ + ^^ ^^ ^^ ^^ ^^ ( ^^ ) where VL(t) is defined by the leakage volume. This step is not necessary in the method, since first V'P(t) = V'(t) – V'L(t) is calculated and then V'P(t) is used both for the calculation of PR = V'P(t)*Raw and for the integration of VP(t). Thus, we obtain the equation: Formula 9: ^^ ^^ ^^( ^^) = ^^′ ^^( ^^) ∙ ^^ ^^ ^^ + ^^ ^^( ^^) ∙ ^^ ^^ ^^ + ^^ ^^ ^^ ^^ ^^( ^^) where Formula 10: ^^ ′ ^^ ( ^^ ) = ^^ ′( ^^ ) − ^^ ′ ^^ ( ^^ ) Formula 11: ^^ ^^ ( ^^) = ∫ ^^′ ^^( ^^) And V'P(t) corresponds to the patient flow and VP(t) to the patient volume. The leakage flow VL'(t) is ideally determined by a leakage model, such as: Formula 12: ^^ ′ ^^( ^^) = ^^ ^^ ^^( ^^) ^^∙ ^^ ^^ where b typically ranges from 1 / 2…1. A lookup table (LUT) or a polynomial is also conceivable for determining the leakage flow as a function of pressure. The pressure can be either an estimated pressure (PC + PR) or a measured pressure (Paw). This procedure is as follows: 1.) Determination of a Crs, Raw P235428WO 2.) V'(t) is determined, ideally measured by a flow measurement (a differential pressure method is also conceivable) 3.) Determination of the pressure PL(t), ideally by measuring Paw_mess. 4.) Determination of V'L(t), ideally as a mathematical function / lookup table (LUT) of the pressure PL(t) 5.) V'P(t) is determined, ideally by subtracting V'(t) - V'L(t) 6.) Determination of VP(t), ideally by time integration of V'P(t) 7.) Determination of the muscular lung pressure Pmusc(t) 8.) Determination of a target value Palv_soll (voltage, speed, current, pressure) for the first actuator R based on VP(t), Crs,Pmusc(t) ideally by adding Pmusc(t) with a capacitive component VP(t) * Crs 9.) Determination of a target value Pr_soll (voltage, speed, current, pressure, opening) for the valve V based on V'P(t), Raw ideally by a resistive component V'P(t). 2* Raw. 10.) Repeat steps 2 … 9 as often as required, but at least once 11.) Determine a pressure value Palv_mess 12.) Control from Palv_mess to Palv_soll using the first actuator R as a closed loop. 13.) Repeat steps 11 … 12 as often as required, but at least once 14.) Determine the differential pressure Pr_mess (via measurement or calculation) 15.) Control from Pr (or Pr_soll => are identical) to Pr_mess using valve V 16.) Repeat steps 14 … 15 as often as required, but at least once P235428WO If the leak flow can also be simulated, the lung simulator 1 can be used more versatilely and no additional external device is needed to simulate the leak flow. The lung simulator 1' according to Figure 2b can be expanded in such a way that a hose or general volume is connected to the inhalation / exhalation air outlet A, after the third actuator R'. This can also be done by the user without having to install it in the housing G or.the lung simulator 1' is integrated. The inhaled air then corresponds to the exhaled air. This is especially true if the oxygen content of the inhaled air is higher than 21%. The lung simulator 1' according to Figure 2b can be expanded by connecting a humidifier to the inhalation / exhalation air outlet A, after the third actuator R'. In the simplest case, this is a heating plate with a water tank. This enables the simulation of moist and / or saturated exhaled air. Here, too, the humidifier does not have to be integrated into the housing G. Humid exhaled air corresponds to reality. This enables a more realistic simulation. The lung simulator 1 or 1' can be expanded by metering CO2 between inlet E and inhalation / exhalation air outlet A. This can be achieved with a CO2 source, for example, by connecting a CO2 gas cylinder or a corresponding hose line between E and A.The method can either always deliver a fixed concentration or simulate different values depending on the simulation parameters, based on physiological processes. This allows the CO2 output of the lungs to be simulated. This enables a more realistic simulation. The lung simulator 1 or the electronics X can be expanded in such a way that an FiO2 P235428WO sensor and an interface for the SpO2 sensor, designed as an "artificial finger", are connected to the electronics X between inlet E and inhalation / exhalation air outlet A. This allows the simulation of pulse oximetry. This allows ventilators with so-called closed-loop oxygen algorithms to be tested, whereby the ventilator automatically adjusts ventilation based on oxygen saturation. The values for the artificial finger can be calculated using a state-of-the-art model, such as the model from Kitware.This means that the lung simulator 1 can be used for other applications. The device 1 can be supplemented with data interfaces. Parameters, measurement data and target values can be entered, received and changed via this interface. The lung simulator 1 can be controlled remotely and thus helps to automate test sequences. Or it allows the lung simulator 1 to be controlled via additional software, which runs on a PC, for example. A closed loop is defined as a closed loop, the concept of a feedback loop in a system. A closed control loop is a system in which the output of the system is used to control and adjust the input in order to achieve the desired behavior or results. It is a feedback loop in which information or signals continuously circulate and control the operation of the system.P235428WO List of reference symbols 1 Lung simulator / test lung A Inhalation / exhalation air outlet C Connection unit D Screen E Inlet G Housing M Valve motorR Radial fan / first actuator / third actuatorR1 Fan housing R2 Rotor R3 Radial outlet (radial) R4 Intake port (axial) R5 Fan motor V Valve / second actuator X Electronics Paw ( t ): airway pressure Raw: airway resistance V'( t ) = d V ( t ) / dt gas flow in the airways Crs : total respiratory compliance V( t ): volume flowing into the lungs Va' = V'a alveolar ventilation Vt tidal volume, Vd anatomical or serial dead space RR respiratory rate PR differential pressure due to airway resistance Raw P. C Pressure through the lung compliance Crs 2 Ventilator (or anesthesia machine being tested) 3 Ventilation tube 4 Connector 5 Computer unit 6 Connection P235428WO
Claims
1. Lung simulator (1) with a housing (G) in which electronics (X), a connection unit (C) and an internal pipe and / or hose system are arranged from an inlet (E) through a first actuator to an inhalation / exhalation air outlet (A), characterized in that in the course of the pipe and / or hose system between the inlet (E) several pressure measuring sensors and / or at least one flow measuring device are arranged serially before or after the first actuator, which is designed as a radial fan (R) with a fan housing (R1) in which there is a rotor (R2) with several rotor blades, so that air sucked in by means of a fan motor (R5) through an axial intake nozzle (R4) can be pumped through a radially projecting radial outlet (R3),wherein the radial fan (R) and the plurality of pressure measuring sensors and / or flow measuring devices are electrically connected to the electronics (X) and can be controlled thereby and used for different lung simulations.
2. Lung simulator (1) according to claim 1, wherein in the course of the pipe and / or hose system, a valve (V) with a valve motor (M) as a second actuator (V) and / or a third actuator (R') designed as a radial fan (R') are arranged serially before or after the first actuator and are electrically connected to the electronics (X).
3. Lung simulator (1) according to claim 2, wherein the second radial fan (R') is configured as a third actuator (R') inversely to the radial fan (R), by connecting the first axial P235428WO, Intake port (R4) and the second intake port (R4') of the second radial fan (R') are attached facing each other or the radial outlets (R3, R3') of the two radial fans (R, R') are connected to each other.
4. Lung simulator (1) according to one of the preceding claims, wherein a hose or a volume is connected to the inhalation / exhalation air outlet (A), outside and / or inside the housing (G).
5. Lung simulator (1) according to one of the preceding claims, wherein a humidifier is connected to the inhalation / exhalation air outlet (A), outside and / or inside the housing (G), for simulating moist and / or saturated exhaled air.
6. Lung simulator (1) according to one of the preceding claims, wherein a CO2 source is arranged between the inlet (E) and the inhalation / exhalation air outlet (A) to simulate adjustable CO2-containing exhalation air. 7.Lung simulator (1) according to one of the preceding claims, wherein an FiO2 sensor is inserted between the inlet (E) and the inhalation / exhalation air outlet (A) and is connected to the electronics (X) via an interface.
8. Lung simulator (1) according to one of the preceding claims, wherein data interfaces are provided for receiving and transmitting input parameters and measurement data and thus for remotely controlling the lung simulator (1). P235428WO.
9. Lung simulator (1) according to one of claims 2 to 8, wherein a second valve (V') with a second valve motor (M') is arranged downstream of the first radial fan (R) and parallel to the second radial fan (R') in the course of the pipe and / or hose system.
10. A method for simulating a human or animal lung using a lung simulator (1) according to one of claims 1 to 9, characterized by the steps: - determining a total respiratory compliance (Crs) - V'P(t) is determined, measured by a flow measurement or differential pressure measurement - determining VP(t), in particular by temporal integration of V'P(t) - determining a target value Palv_soll (voltage, speed, current, or pressure) for the radial fan (R) based on VP(t), Crs, in particular by calculating a capacitive component VP(t) * Crs and - repeating the preceding steps. 11.Method for simulating a human or animal lung according to claim 10, wherein in the first step the airway resistance (Raw) and / or in the second step a muscular pressure Pmusc(t) is determined and in the fourth step a resistive and / or muscular component is taken into account, in particular by adding a resistive component V'P(t). 2 *Raw with a capacitive component VP(t)*Crs with a muscular component Pmusc(t).
12. A method for simulating a human or animal lung according to claim 10 or 11, wherein after each run of the steps according to claim 10 or 11: P235428WO - Determination of a pressure value Palv_mess and - Control of Paw_mess to Palv_soll by means of a radial fan (R) as a closed loop, whereby the control of the radial fan (R) to Palv_soll is carried out by a controller as part of the radial fan (R) or the electronics (X). 13.Method for simulating a human or animal lung using a lung simulator (1) with a valve (V) as a second actuator, characterized by the steps: a) Determination of a Crs, Raw b) V'P(t) is determined, in particular by a flow measurement or differential pressure determination c) Determination of VP(t) by temporal integration of V'(t) d) Determination of a target value Palv_soll (voltage, speed, current or pressure) for the first actuator (R) on the basis of VP(t), Crs, ideally by a capacitive component VP(t) * Crs e) Determination of a target value Pr_soll (voltage, speed, current, pressure or opening) for the second actuator (V) / the valve (V) on the basis of V'P(t), Raw, in particular by a resistive component V'P(t). 2* Raw and repetition of steps b) to e) at least once after each run f) Determination of a pressure value Palv_mess g) Control of Palv_mess to Palv_soll using the first actuator (R) as a closed loop and at least one repetition of steps f) and g) and h) Determination of the differential pressure Pr_mess via measurement or calculation i) Control of Pr or Pr_soll to Pr_mess using the second actuator (V) and at least one repetition of steps h) and i). P235428WO 14. The method according to claim 13, wherein between steps a) and d) a muscular lung pressure Pmusc(t) is determined, so that in step d) a target value Palv_soll (voltage, speed, current or pressure) for the radial fan R is determined on the basis of VP(t), Crs, Pmusc(t), in particular by adding Pmusc(t) to a capacitive component VP(t) * Crs.
15. The method according to claim 10 or 13, characterized by the steps: a) determining a Crs, Raw b) V'(t) is determined, ideally measured by a flow measurement (a differential pressure method is also conceivable) c) determining the pressure PL(t), ideally by measuring Paw_mess.d) Determination of V'L(t), ideally as a mathematical function / lookup table (LUT) of the pressure PL(t) e) V'P(t) is determined, ideally by subtracting V'(t) - V'L(t) f) Determination of VP(t), ideally by time integration of V'P(t) g) Determination of the muscular lung pressure Pmusc(t) h) Determination of a target value Palv_soll (voltage, speed, current, pressure) for the first actuator (R) based on VP(t), Crs,Pmusc(t) ideally by adding Pmusc(t) with a capacitive component VP(t) * Crs i) Determination of a target value Pr_soll (voltage, speed, current, pressure, opening) for the valve (V) based on V'P(t), Raw ideally by a resistive component V'P(t). 2 * Raw and at least one repetition of steps b) to i), followed by j) determination of a pressure value Palv_mess P235428WO k) Control of Palv_mess to Palv_soll by means of the first actuator (R) as a closed loop and at least one repetition of steps j) and k), l) Determination of the differential pressure Pr_mess by means of measurement or calculation, m) Control of Pr or Pr_soll to Pr_mess by means of a valve (V) and at least one repetition of steps l) and m).
16. Method according to one of the preceding claims 10 to 15, wherein a lung simulator (1) with a third actuator (R') in the form of a second radial fan (R') is used for the optimized simulation of spontaneous breathing of small and negative values of Pmusc(t). 17.Use of a radial fan (R), designed with a fan housing (R1) in which a rotor (R2) with a plurality of rotor blades is located, for simulating the function of a human or animal lung, as a measuring device or pressure / flow source, wherein air sucked in by means of a fan motor (R5) through an axial intake nozzle (R4) can be pumped through a radially projecting radial outlet (R3), wherein the radial fan (R) is electrically connected to an electronic system (X) within an internal pipe and / or hose system of a lung simulator (1) together with a plurality of pressure measuring sensors and / or flow measuring devices between an inlet (E) and an inhalation / exhalation air outlet (A) of the internal pipe and / or hose system.
18. Use according to claim 17, wherein additionally in the course of the pipe and / or hose system a valve (V) with valve motor (M) as second actuator (V) and / or P235428WO. a third actuator (R') configured as a radial fan (R') is arranged and electrically connected to the electronics (X). P235428WO