Systems and methods for promoting secretion movement using mechanical respirator

Abstract

A mucus removal assistance system (100) comprises:-a ventilator system (10) configured to provide a positive air pressure to a user; -one or more sensors (34) configured to detect a flow rate associated with the respirator; and-a controller configured to vary one or more output parameters associated with the respirator, where the controller has programmable logic or memory (32) and a processing unit (30) configured to perform the steps of:-receiving a target flow bias ratio input, the method comprises the steps of:-measuring a flow rate,-receiving the measured flow rate from the one or more sensors,-determining a flow bias ratio from the measured flow rate,-comparing the measured flow bias ratio to a target bias ratio,-determining whether an increase or decrease in the measured flow bias ratio is required,-determining whether the increase or decrease in the measured flow bias ratio is required,-determining whether the increase or decrease in the measured flow bias ratio is required,-determining whether the increase or decrease in the measured flow bias ratio is required. And-modifying at least one of: a fall time parameter, a rise time parameter, and an inspiration time parameter based on determining whether to increase or decrease the measured flow bias ratio.

Description

Copyright Information

[0001] A portion of the disclosure of this patent document contains copyrighted material. The copyright owner does not object to the facsimile reproduction of either this patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but reserves all copyrights. Technical Field

[0002] The present invention relates to using a mechanical ventilator to facilitate the overall movement of secretions generated in the laryngeal and pulmonary regions in a direction towards the laryngeal and oral regions of a person. Background Art

[0003] Secretions in the human airway can affect perfusion, prevent gas humidification via the membrane, and impede normal air flow during breathing. For patients with diseases, mucus secretion may thicken the walls of small airways and develop into more serious health problems.

[0004] Typically, patients with respiratory insufficiency suffer from respiratory tract infections, are in a state of chronic hypersecretion, or have reached a state of respiratory insufficiency due to muscle weakness (which also impedes the mobilization and elimination of accumulated mucus through effective coughing).

[0005] Therefore, these patients who benefit from mechanical ventilator assistance may suffer from worsening mucus accumulation because the positive pressure applied at the oral or tracheal interface tends to push the secretions in the caudal (wrong) direction for airway clearance.

[0006] It is further recognized that applying mechanical ventilation through an artificial airway usually impedes the patient's ability to extract or swallow the elevated airway secretions.

[0007] Currently, caregivers usually adopt specific adjuvant therapies for mechanically ventilated patients to cause the secretions to move towards the upper airway, such as over-inflation, PEEP-ZEEP maneuvers, chest compression, or by using a Mechanical Insufflation Exsufflation (MI-E) device.

[0008] These devices and maneuvers generate high expiratory flow rates that strip mucus from the walls of the chambers and facilitate its movement from the lungs towards the main bronchi.

[0009] However, these techniques are usually invasive and require the assistance of trained professionals to implement, which may consume human capital or make home care solutions difficult.

[0010] The present disclosure and the embodiments provided below seek to provide a solution for reducing human capital while using current mechanical ventilator devices to provide a mucus clearance system. From the written description provided, these solutions and other advantages will be apparent to those skilled in the art. SUMMARY OF THE INVENTION

[0011] In one embodiment, a method of using a ventilator to assist in mucus clearance includes the steps of: 1) inputting a target flow bias ratio into the ventilator, where the target flow bias ratio is in the exhalation direction; 2) measuring the current flow bias ratio of the ventilator; 3) comparing the target flow bias ratio with the measured current flow bias ratio; and 4) when the measured current flow bias ratio is not within a predetermined range of the target flow bias ratio, modifying at least one of the operating parameters of the ventilator: a) rise time, b) fall time, or c) inspiratory time.

[0012] The above method may further include the steps of: measuring the fall time of the ventilator and determining whether the fall time of the ventilator has reached a predetermined minimum value.

[0013] The above method may further include the steps of: if the measured fall time has not reached the predetermined minimum value, generating a new fall time.

[0014] The above method may further include the steps of: if the measured fall time has reached the predetermined minimum value, generating a new rise time, a new fall time, and a new inspiratory time.

[0015] The above method, wherein the ventilator is configured to maintain a prescribed pressure treatment level.

[0016] A variant of the above method of using the ventilator, wherein the modifying step is configured to: increment the measured flow bias ratio during the respiratory cycle until the flow bias ratio achieves the desired target flow bias ratio. The respiratory cycle is at least 5 breaths, at least 10 breaths, at least 15 breaths, at least 20 breaths, or at least 25 breaths.

[0017] The fall time in the above method may be decreased to increase the measured flow bias ratio. Alternatively, the fall time may be increased to decrease the measured flow bias ratio.

[0018] In yet another embodiment, a mucus clearance assistance system includes: a ventilator system configured to provide positive air pressure to a user; one or more sensors configured to detect a flow rate associated with the ventilator; and a controller configured to change one or more output parameters associated with the ventilator, wherein the controller has programmable logic or memory and a processing unit configured to perform the following steps: 1) receive a target flow bias ratio input, 2) receive the measured flow rate from the one or more sensors, 3) determine a flow bias ratio based on the measured flow rate, 4) compare the measured flow bias ratio with the target bias ratio, 5) determine whether the measured flow bias ratio needs to be increased or decreased, and 6) modify at least one of the following based on determining whether to increase or decrease the measured flow bias ratio: a decay time parameter, a rise time parameter, and an inspiratory time parameter.

[0019] The above mucus clearance assistance system can be designed such that: the decay time parameter and the rise time parameter are based on their respective pressurization or decompression rates. The controller can also be configured to modify the pressurization rate and the decompression rate of the ventilator.

[0020] The above mucus clearance assistance system can be designed such that: the controller is further configured to determine whether the decay time of the ventilator has reached a predetermined minimum value.

[0021] The above mucus clearance assistance system can be designed such that: if the measured decay time does not reach the predetermined minimum value, the controller can generate a new decay time.

[0022] The above mucus clearance assistance system can be designed such that: the controller is further configured to perform the following steps: if the measured decay time has reached the predetermined minimum value, generate a new rise time, a new decay time, and a new inspiratory time.

[0023] Those skilled in the art will appreciate these and other embodiments upon review of the remainder of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] As shown in the drawings, the foregoing objects, features, and advantages of the present invention, as well as other objects, features, and advantages, will become apparent from the following description of specific embodiments of the present invention, in which like reference numerals refer to like parts throughout the different views. The drawings are not necessarily to scale, but rather emphasis is placed on illustrating the principles of the invention.

[0025] Figure 1 A ventilator system is shown;

[0026] Figure 2Shows the lungs and the inspiratory and expiratory flows entering and leaving the lungs;

[0027] Figure 3 Shows a schematic diagram of the mucus clearance system;

[0028] Figures 4A to 4B Shows various methods for setting a target flow bias, measuring a current flow bias, and determining a modification;

[0029] Figure 5 Shows a schematic diagram that also includes using a bias error as part of the determination to update ventilator operation parameters;

[0030] Figures 6A.1 to Figure 6D.5 Shows various graphs providing examples of changing ventilator operation parameters in various ways based on the measured flow bias and other measured parameters. Detailed Description

[0031] The following are some definitions that assist with this application, including:

[0032] Inspiratory flow refers to the air flow entering and flowing into the lungs. Expiratory flow refers to the air flow leaving the lungs and flowing towards the glottis.

[0033] Rise time is the rate at which pressure ramps up to a specified or determined pressure level. Pressure typically rises during inspiration. The pressure rise time can affect the flow rate, and particularly the inspiratory flow rate, and more particularly the peak inspiratory flow.

[0034] Fall time is the rate at which pressure ramps down to a determined pressure level. Pressure typically decreases during expiration. The pressure fall time can affect the flow rate, and particularly the expiratory flow rate, and more particularly the peak expiratory flow.

[0035] Inspiratory time refers to the length of time the ventilator delivers inspiratory pressure.

[0036] PEEP is positive end-expiratory pressure.

[0037] ZEEP is zero end-expiratory pressure.

[0038] Lung overinflation refers to the lungs being overly filled.

[0039] Specified pressure or pressure dose is the pressure to which the ventilator ramps up during use of the ventilator and is typically specified by a healthcare provider. The pressure unit is typically in the form of cm H20 or centimeters of water column. The specified pressure is typically in the range of 5 - 25 cm H20 and typically does not exceed 30 cm H20.

[0040] Flow bias refers to the difference between two flows when the peak expiratory flow (PEF) and the peak inspiratory flow (PIF) are assigned the same directional sign. For example, if PIF = 30 L / min and PEF = -35 L / min, the flow bias is 5 L / min.

[0041] The flow bias ratio refers to the absolute value of the ratio PEF / PIF.

[0042] The target flow bias refers to the specified difference or ratio of PEF relative to PIF used to facilitate airway clearance.

[0043] The measured flow bias refers to the measured or observed flow bias.

[0044] The measured flow bias ratio refers to the measured or observed flow bias ratio.

[0045] The term "significant" as used throughout this application, whether it is a significant decrease, significant improvement, significant deterioration, or other change, is intended to convey a statistical or mathematical deviation from the mean or expected mean. Such a statistical deviation typically means at least one standard deviation or greater, and a situation less than a standard deviation will not be considered significant. Using the standard deviation is not always robust, so other forms of deviation, such as the median absolute deviation, can be used. In summary, those skilled in the statistical art will understand the situations where a value has a'mathematical or statistical' significant change.

[0046] Figure 1 A basic ventilator system 10 is shown, which supplies pressurized air through a tube 12 into an airway adapter 14 (such as a face mask) to a user / patient 16. In some cases, a face mask is not used, and in these cases, the tube is directly inserted into the trachea, such as a tracheostomy.

[0047] Figure 2 The lungs 20 are shown, including the trachea 22 and the bronchi 24 of the lungs. The inspiratory flow path 26 travels into the trachea 22 and into the bronchi 24, while the expiratory flow path 28 travels from or out of the lungs 20 and the bronchi 24, into the trachea 22 and out of the trachea.

[0048] It should be understood that the volume of air inhaled or taken in by the user / patient should generally be equal to the volume of air exhaled or expelled by the user / patient. If it is not equal, the user / patient will have problems. Therefore, when the user / patient uses a ventilator machine, these ventilator machines are designed to maintain an equal volume of air entering and leaving the lungs.

[0049] As is well known, in a second-order pneumatic system (a second-order pneumatic system is a system in which the dynamics within the system are determined only by pressure, flow rate, and the first derivatives of pressure and flow rate), the peak flow rate is determined by the rate of change of the driving pressure. The rate of change of the driving pressure is programmed in a mechanical ventilator setting through the "rise time" and "fall rate" settings. The "rise time" affects the peak inspiratory flow rate because this rise time determines the rate of pressurization at the start of inspiration. The "fall time" affects the peak expiratory flow rate because this fall time determines the rate of depressurization at the start of expiration.

[0050] Using a leaf blower as an analogy, a more powerful leaf blower has a greater flow rate and is more likely to lift fallen leaves from the ground for collection for disposal. In the present invention, the higher peak expiratory flow rate caused by a rapid decompression of the airway is more likely to lift secretions from the airway wall to accumulate the secretions near the glottis, where the secretions can be removed.

[0051] In mechanical ventilation therapy, it is typically the case that during assisted inspiration, when air is forced into the lungs, the leaf blower is pointed in the wrong direction and it is more difficult for the patient to control the upward movement of secretions by natural means or by coughing. Thus, in accordance with this analogy, it should be understood that by controlling or varying the "rise time" and "fall time", an overall effect of pointing the leaf blower in the correct direction can occur, which is determined by the target bias flow ratio or difference.

[0052] As pointed out in the background art, prior manual techniques (such as expiratory rib cage compression (ERCC)) or monitored techniques (such as overinflation, which sometimes includes temporarily setting the peak inspiratory pressure to 40 cm H2O) were only designed to be used in monitored situations. This is because each of these techniques requires additional tools that require medical professionals to implement and / or require medical professionals to monitor because these techniques are inherently extreme and not intended for frequent use. In contrast, the methods and systems discussed herein help to eliminate some additional medical professional monitoring and / or implementation because these methods and systems can be implemented within the prescribed pressure limits that the user / patient is within for a longer period of time. For example, overinflation (using a pressure of 40 cm H2O) far exceeds the normal prescribed range of 5 - 25 cm H2O used for continuous use of a ventilator. Thus, by automatically modifying the rise time, fall time, and inspiratory time parameters without changing the prescribed pressure, the methods and systems described herein can achieve the desired flow bias difference or ratio over a longer period of time and avoid additional medical professional time or techniques implemented by medical professionals. In some cases, the consistency of the methods and systems described herein becomes more effective, less costly, requires less medical professional labor intensity for clearing mucus from the user / patient, and can be adapted to utilize existing ventilators on the market.

[0053] Figure 3 Shows a schematic diagram of a mucus clearance system 100 including a ventilator system 10, the ventilator system including a processing unit 30 configured to: receive input parameters (such as a target flow bias parameter) via a user / patient input interface 36, implement algorithms, protocols, and direct and analyze sensor data captured by a sensor 34, call data and place the data in a memory 32, and direct communications over a network 40 to a remote server / cloud 50, the remote server / cloud also including processing circuitry and storage means. Directed communications 42 can be made to and from a communication network, and the communication network can make directed communications 44 to and from the remote server / cloud 50. Cloud computing is generally understood in the art to mean providing computing services—including servers, storage, databases, networking, software, analytics, and intelligence—over the Internet (“the cloud”) to provide faster innovation, flexible resources, and economies of scale.

[0054] Figures 4A to 4B Shows various methods of setting a target flow bias, measuring a current flow bias, and determining (and making) the required modifications until the measured flow bias (ratio or difference) is within a predetermined range of the target flow bias (ratio or difference).

[0055] Reference Figure 4A In flowchart 400A of, a user (such as a medical professional) sets a target flow bias or difference to be achieved by the operation of a ventilator. An example target range for the flow bias ratio can be 1.1. Other target flow bias ratios can be 1.05, 1.06, 1.07, 1.08, 1.09, 1.11, 1.12, 1.13, 1.14, and 1.15. The target flow difference can be at least 17 L / min, and alternative differences can be at least 16 L / min, at least 18 L / min, and at least 19 L / min. Once the target flow bias is entered, the next step is to start measuring the flow to determine the current flow bias. This can be done using one or more sensors associated with the ventilator. Flow and pressure are common measurements that most ventilators are configured to make. Measuring pressure is typically used to estimate leaks in a given ventilator system, which provides a more accurate estimate of the actual flow being measured.

[0056] These measurements can be used to determine the PEF and PIF, which can then be used to determine the ratio PEF / PIF or the difference PEF - PIF. Once the measured flow bias is determined, the next step is to determine whether the measured flow bias is within a predetermined range of the target flow bias. The predetermined range can be an actual number, or it can be determined statistically whether the predetermined range is not significant based on the input target flow bias number. As shown by the decision step, for example, if the target flow bias ratio is 1.1 and the measured flow bias ratio is 1.0998, then this is likely to be within the predetermined range, and thus there is no need to modify the current operating parameters of the ventilator. Therefore, the measurements will continue until the difference between the target flow bias and the measured flow bias exceeds the predetermined range.

[0057] When it is determined that the measured value exceeds the predetermined range, depending on whether the ratio or difference is above or below the target, the next step will be to modify at least one of the following parameters: 1) rise time, 2) fall time, or 3) inspiratory time. In some cases, it may be necessary to adjust more than one of the above parameters. Once the (multiple) parameters are adjusted, the next step is to allow one or more cycles and start measuring the flow bias using the updated parameters. These steps are repeated until the optimal parameters are achieved. It should be noted that the breathing of the user / patient may change during the day or night, as different stages of sleep or wakefulness may change the breathing pattern. Therefore, the parameters can be automatically updated continuously throughout the day based on the user / patient's biological cycle.

[0058] Reference Figure 4B In the flowchart 400B, the user (such as a medical professional) again sets the target flow bias ratio or the target bias flow difference to be achieved by the operation of the ventilator. The first few steps are similar to the first few steps of flowchart 400A; however, once it is determined that the measured target flow bias exceeds the predetermined range, there is an intermediate step of determining whether the current fall time is at the minimum threshold. If not, the method recommends updating the new rise time. If the current fall time is at the minimum threshold, the method can recommend the new rise time, fall time, and inspiratory time. After each recommendation, the method can include implementing these new recommendations and starting a new cycle of measuring the flow bias and comparing it with the target flow bias.

[0059] Figure 5Shows a schematic diagram that also includes using a bias error as part of the determination to update ventilator operation parameters. Here, the target flow bias is set to a ratio of 1.1, and the target flow bias is compared with the measured flow bias ratio. Kp indicates a proportional gain controller that helps modify the speed or rate of ventilator pressurization and decompression. As described above, the rate of ventilator pressurization affects the speed of the flow rate during the down time or up time, which ultimately determines the PEF and PIF used to calculate the flow bias ratio. If the flow bias ratio is appropriately optimized, this flow bias ratio can help the user / patient clear mucus from the lungs, trachea, and other areas without the need for additional therapy or at least reduce the number of additional treatments to manage mucus accumulation in the user / patient's body. Some of the equations shown can be used to determine the bias error. Similar to flowchart 400B, the current down time can be measured and used to determine if it is at a minimum threshold. If not, a new down time is recommended, and if so, the current down time can be used to initiate the bias error equation to determine a new up time, a new down time, a new inspiratory time, and / or even a new pressure support.

[0060] To further illustrate the effects of the above systems and methods, Figures 6A.1 to Figure 6D.5 various graphs are provided to show examples of changing ventilator operation parameters in various ways based on the measured flow bias and other measured parameters.

[0061] For example, in Figures 6A.1 to Figure 6A.5 , here, the measured initial flow bias ratio is 1.0199, and the desired target flow bias ratio is 1.1. Therefore, the controller reduces the down time operation parameter of the ventilator to increase the measured flow bias ratio. In Figure 6A.1, it can be easily shown that after approximately 10 breaths occur in the cycle, the down time is reduced from an initial 0.1 second to 0.07 second. By comparing the graph of the measured starting flow waveform (Figure 6A.2) and starting pressure waveform (Figure 6A.3) on the left with the final flow waveform (Figure 6A.4) and final pressure waveform ( Figure 6A.5 ) graph on the right, the effect of this change is shown. As shown in Figure 6A.4, the resulting end ratio or new measured ratio is 1.0996.

[0062] In another example, in Figures 6B.1 to Figure 6B.5In this case, the initially measured flow bias ratio is 1.2847. The desired target flow bias ratio is 1.1, so the controller increases the decay time to reduce the initially measured flow bias ratio. In FIG. 6B.1, it can be easily shown that after approximately 10 breaths occur in the cycle, the decay time increases from an initial 0.1 second to 0.13 seconds, and after approximately 25 breaths, the decay time rises to 0.14 seconds. By comparing the measured starting flow waveform (FIG. 6B.2) and starting pressure waveform (FIG. 6B.3) graphs on the left with the final flow waveform (FIG. 6B.4) and final pressure waveform ( Figure 6B.5 ) graphs on the right, the effect of this change is shown again. As shown in FIG. 6B.4, the resulting end ratio or new measured ratio is 1.1006.

[0063] In yet another example, in Figures 6C.1 to Figure 6C.5 In this case, the initially measured flow bias is approximately 1.2. The desired target flow bias ratio is 1.1, so the controller increases the decay time to reduce the initially measured flow bias ratio. In FIG. 6C.1, it can be easily shown that after approximately 10 breaths occur in the cycle, the decay time increases from an initial 0.1 second to approximately 0.12 seconds, and after approximately 25 breaths, the decay time rises to 0.13. By comparing the measured starting flow waveform (FIG. 6C.2) and starting pressure waveform (FIG. 6C.3) graphs on the left with the final flow waveform (FIG. 6C.4) and final pressure waveform ( Figure 6C.5 ) graphs on the right, the effect of this change is shown again. As shown in FIG. 6C.4, the resulting end ratio or new measured ratio is approximately 1.1.

[0064] In yet another example, in Figures 6D.1 to Figure 6D.5 In this case, the initially measured flow bias ratio is approximately 0.6. The desired target flow bias ratio is 1.1, so the controller makes the decay time a minimum and increases the rise time to increase the measured flow bias ratio. In FIG. 6D.1, it can be easily shown that after approximately 10 breaths, the decay time decreases from an initial 0.1 second to a predetermined minimum decay time, and as Figure 5 the algorithm in Figure 5 subsequently adjusts the rise time, pressure support (PS), and inspiratory time (Tinsp). Between 10 and 15 breaths in the cycle, the rise time increases from 0.2 seconds to 1.6 seconds. According to Figure 5 the relationship in Figure 6D.5)The comparison with the curve graph once again shows the effect of this change. As shown in Figure 6D.4, the resulting end ratio or new measured ratio is 1.1. Here, the effective pressure support also remains unchanged while the inspiratory time increases. This can be seen because the maximum delivery pressures of the starting waveform graph and the final waveform graph are the same.

[0065] As described above, by focusing on the initial position of the measured flow bias relative to the target flow bias, the methods and systems described herein can adjust one or more ventilator operating parameters within a specified pressure to achieve operation near the target flow bias ratio or difference. When the flow bias ratio or difference is appropriately set, this can help move mucus out of the lungs and tracheal region. These methods and systems can be implemented to automatically adjust the operating parameters of the ventilator when necessary, thereby allowing a constant and consistent flow bias ratio to be applied to the user, which continuously moves mucus out of the lungs and tracheal region.

[0066] Although the principles of the present invention have been described herein, those skilled in the art should understand that this description is only an example and not a limitation on the scope of the present invention. Other embodiments are envisioned within the scope of the present invention in addition to the exemplary embodiments shown and described herein. Modifications and substitutions made by those of ordinary skill in the art are considered to be within the scope of the present invention.

Claims

1. A method of using a ventilator to assist in mucus clearance, the method comprising the following steps: Inputting a target flow bias ratio into the ventilator, wherein the target flow bias ratio is in the exhalation direction; Measuring the current flow bias ratio of the ventilator; Comparing the target flow bias ratio with the measured current flow bias ratio; and When the measured current flow bias ratio is not within a predetermined range of the target flow bias ratio, modifying at least one of the operating parameters of the ventilator: rise time, fall time, and inspiratory time.

2. The method of using a ventilator to assist in clearing mucus as claimed in claim 1, further comprising the following steps: Measuring the fall time of the ventilator and determining whether the fall time of the ventilator has reached a predetermined minimum value.

3. The method of using a ventilator to assist in clearing mucus according to claim 2, further comprising the following steps: If the measured fall time has not reached the predetermined minimum value, generating a new fall time.

4. The method of using a ventilator to assist in clearing mucus as claimed in claim 2, further comprising the following steps: If the measured fall time has reached the predetermined minimum value, generating a new rise time, a new fall time, and a new inspiratory time.

5. The method of using a ventilator to assist in clearing mucus as claimed in claim 3, wherein, The ventilator is configured to maintain a prescribed pressure treatment level.

6. The method of using a ventilator to assist in clearing mucus as claimed in claim 1, wherein, The ventilator is configured to maintain a prescribed pressure treatment level.

7. The method of using a ventilator to assist in clearing mucus as claimed in claim 1, wherein, The modifying step is configured to: increment the measured flow bias ratio within a respiratory cycle until the flow bias ratio achieves the desired target flow bias ratio.

8. The method of using a ventilator to assist in clearing mucus as claimed in claim 7, wherein, The respiratory cycle is at least 5 breaths, at least 10 breaths, at least 15 breaths, at least 20 breaths, or at least 25 breaths.

9. The method for using a ventilator to assist in clearing mucus as claimed in claim 1, wherein, Decreasing the fall time so as to increase the measured flow bias ratio.

10. The method of using a ventilator to assist in clearing mucus as claimed in claim 1, wherein, Increasing the fall time so as to decrease the measured flow bias ratio.

11. A mucus clearance assistance system, comprising: A ventilator system configured to provide positive air pressure to a user; One or more sensors configured to detect a flow rate associated with the ventilator; And A controller configured to change one or more output parameters associated with the ventilator, wherein the controller has programmable logic or memory and a processing unit configured to perform the following steps: Receiving a target flow bias ratio input; Receiving the measured flow rate from the one or more sensors, determining a flow bias ratio based on the measured flow rate, comparing the measured flow bias ratio with the target bias ratio, determining whether it is necessary to increase or decrease the measured flow bias ratio; and Modifying at least one of the following based on determining whether to increase or decrease the measured flow bias ratio: fall time parameter, rise time parameter, and inspiratory time parameter.

12. The mucus clearance assistance system according to claim 11, wherein, The fall time parameter and the rise time parameter are based on their respective pressurization or depressurization rates.

13. The mucus clearance assistance system according to claim 12, wherein, The controller is configured to modify the pressurization rate and the depressurization rate of the ventilator.

14. The mucus clearance assistance system according to claim 11, wherein, The controller is further configured to determine whether the fall time of the ventilator has reached a predetermined minimum value.

15. The mucus clearance assistance system according to claim 14, wherein, If the measured fall time has not reached the predetermined minimum value, the controller is capable of generating a new fall time.

16. The mucus clearance assistance system according to claim 14, wherein, The controller is further configured to perform the following steps: if the measured fall time has reached the predetermined minimum value, generate a new rise time, a new fall time, and a new inspiration time.

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