Systems and methods for characterizing an inflatable cuff
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- AW TECH APS
- Filing Date
- 2023-06-26
- Publication Date
- 2026-06-30
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a system for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient. The present disclosure further relates to a method for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient.
Background Art
[0002] As is known, patients wearing ventilators, especially those in intensive care, are intubated with an endotracheal tube or a tracheal tube. Many tubes have an inflatable cuff that seals the trachea against air leakage and aspiration of gastric contents, blood, secretions, and other body fluids while allowing the patient to breathe through the tracheal tube.
[0003] A characteristic of such cuffs of inflatable tubes is that they can deteriorate over time, which can cause leakage around the cuff. The presence of such leakage can reduce the efficiency of the ventilator, and bacteria may be aspirated into the lungs, potentially increasing the risk of pneumonia and lengthening the patient's hospital stay.
[0004] Patients with pneumonia have a significantly increased hospital stay, which directly leads to increased mortality and reintubation rates.
[0005] Several techniques are used to monitor and control the cuff pressure over time. For example, the pressure can be maintained above a certain minimum pressure or within a certain pressure range. However, monitoring the pressure of the cuff or maintaining a constant pressure within the cuff does not provide any detailed information about the condition of the cuff, the likelihood of leakage around the cuff, or other problems with the cuff or the patient.
Summary of the Invention
[0006] One object of the present disclosure is to provide a system for characterizing an inflatable cuff disposed around a tracheal tube for providing respiratory support to a patient. Accordingly, a first aspect of the present disclosure relates to a system for characterizing an inflatable cuff disposed around a tracheal tube for providing respiratory support to a patient, The system includes, at least one flow unit, such as a pump, in fluid communication with a cuff conduit connected to the inflatable cuff, the at least one flow unit being adapted to fill the inflatable cuff with gas or liquid, at least one pressure sensor configured to measure the pressure within the inflatable cuff, at least one flow sensor for measuring the flow rate of gas or liquid to and / or from the inflatable cuff, a processing unit for estimating the volume of gas or liquid, or a change in the volume of gas or liquid, within the inflatable cuff based on the measurement of the flow rate of gas or liquid to and / or from the inflatable cuff, configured to extract a pressure-volume relationship between the measured pressure and the estimated volume of gas or liquid or change in volume of gas or liquid within the inflatable cuff, and a processing unit configured to compare the pressure-volume relationship to a previously measured or predetermined reference pressure-volume relationship to characterize the inflatable cuff.
[0007] By extracting the pressure-volume relationship between the measured pressure and the estimated volume of gas or liquid or change in volume of gas or liquid within the inflatable cuff and comparing the pressure-volume relationship to a previously measured or predetermined reference pressure-volume relationship, a change in the pressure-volume relationship over time can be obtained. The pressure-volume relationship may be, for example, a coefficient for converting or converting at least one given volume to a corresponding pressure, or a coefficient for converting or converting at least one given pressure to a corresponding volume. The change in the pressure-volume relationship may be used to non-invasively characterize the inflatable cuff.
[0008] Characterization of an inflatable cuff can provide a measure of elasticity or a measure of the inflatable cuff, but can also provide information about the structure around the inflatable cuff, typically the trachea. The pressure-volume relationship in a given configuration can be represented by a coefficient that converts at least one given volume to the corresponding pressure, or a coefficient that converts at least one given pressure to the corresponding volume. Generally, the higher the coefficient, the higher the pressure required to obtain a given volume. As will be understood by those skilled in the art, it is equivalently possible to use a coefficient having the opposite meaning. Next, a processing unit can be used to interpret changes in the pressure-volume relationship. If the coefficient is below the previously measured coefficient, it means that a lower pressure than the first measurement is required to obtain a given volume. This can indicate a more elastic inflatable cuff. If the change in elasticity exceeds a predetermined limit, the system can categorize that the inflatable cuff has been consumed. The predetermined limit is usually not a limit for all inflatable cuffs in all patients, but in some cases is a limit for a specific inflatable cuff in a specific patient and in some cases at a specific time. If the coefficient is above the previously measured coefficient, it means that a higher pressure than the first measurement is required to obtain a given volume. Since it generally becomes no more difficult for the inflatable cuff to be filled with gas or liquid over time, a change to a higher coefficient can be interpreted as the structure around the inflatable cuff applying an external pressure to the inflatable cuff. Thus, in one embodiment, the system is further configured to identify that the patient's trachea has become stiffer as a result of the increase in the coefficient.
[0009] Furthermore, the present disclosure relates to a method for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient, The method includes measuring the pressure within the inflatable cuff in an inflated configuration, and measuring the flow rate of gas into and / or out of the inflatable cuff, and estimating the volume of gas within the inflatable cuff, or the change in volume of gas or liquid, based on the measurement of the flow rate of gas into and / or out of the inflatable cuff. Extract the pressure - volume relationship between the measured pressure and the estimated gas volume or the change in the volume of gas or liquid within the inflatable cuff, and Include the step of comparing the pressure - volume relationship to a previously measured or predetermined reference pressure - volume relationship to characterize the inflatable cuff.
[0010] As will be understood by those skilled in the art, the method of the present disclosure for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient is performed using any embodiment of the system of the present disclosure for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient, and vice versa.
[0011] The method may be implemented as a computer program having instructions that, when executed by a computing device or computing system, cause the computing device or computing system to perform a method for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient. A non - transitory storage medium may include a computer program product having instructions embodied thereon that, when executed by a computing device or system, cause the computing device or system to perform a method for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient.
[0012] The present invention will be described below with reference to the accompanying drawings. The drawings are examples of embodiments and are not limited to the system of the present disclosure for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient. BRIEF DESCRIPTION OF THE DRAWINGS
[0013]
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[0014] The present disclosure relates to a system for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient, The system includes at least one flow unit, such as a pump, in fluid communication with a cuff conduit connected to the inflatable cuff, the at least one flow unit being adapted to fill the inflatable cuff with gas or liquid; at least one pressure sensor configured to measure the pressure within the inflatable cuff; at least one flow sensor for measuring the flow rate of gas or liquid to and / or from the inflatable cuff; a processing unit for estimating the volume of gas or liquid, or the change in the volume of gas or liquid, within the inflatable cuff based on the measurement of the flow rate of gas or liquid to and / or from the inflatable cuff, configured to extract a pressure - volume relationship between a measured pressure and an estimated volume of gas or liquid or a change in volume of gas or liquid within an inflatable cuff; a processing unit configured to compare the pressure - volume relationship to a previously measured or predetermined reference pressure - volume relationship in order to characterize the inflatable cuff.
[0015] By characterizing the inflatable cuff, particularly by analyzing the pressure - volume relationship over time, conclusions can be drawn regarding both the inflatable cuff itself and the structures surrounding the inflatable cuff. Characterizing the inflatable cuff can provide a measure of the elasticity and / or compliance of the inflatable cuff. The system may be part of a ventilator or operate as an independent system.
[0016] The term "tracheal tube" is to be broadly construed to include any tube suitable for maintaining a patient's airway, including but not limited to endotracheal tubes and tracheostomy tubes. Thus, the inflatable cuff may sometimes be referred to as an inflatable endotracheal tube cuff or an inflatable tracheostomy tube cuff.
[0017] Also, the "processing unit" is to be broadly construed to include any means suitable for processing and computing data. The processing unit may be a local device optionally integrated into a ventilator system, or may be provided on a remote device such as a cloud computing device.
[0018] A flow sensor can be used to measure the flow rate of gas or liquid. All types of flow sensors can be used for the flow of gas or liquid to and / or from the inflatable cuff according to the present disclosure. Based on the flow rate of gas or liquid over a period of time, the volume of gas or liquid within the inflatable cuff or the change in volume of gas or liquid can be estimated. The system of the present disclosure is not limited to a specific flow sensor for characterizing the inflatable cuff.
[0019] Figure 1 shows a schematic view of an embodiment of the general concept of intubation of patient P by tracheal tube 2 and inflatable cuff 3. A system 1 is disclosed for characterizing an inflatable cuff 3 disposed around tracheal tube 3 to provide respiratory support to patient P. As described above, system 1 is connectable or integrated with a ventilator for artificial respiration of patient P. Tracheal tube 2 has a side wall portion 2c and extends between a first end portion 2a and a second end portion 2b. Tracheal tube 2 is preferably made of PVC or the like, but may be made of any suitable material. Tracheal tube 2 has an associated inflatable cuff 3. The inflatable cuff 3 may be configured to seal the trachea of patient P to isolate the second end portion 2b from the external environment. The inflatable cuff 3 may be an annular element externally fitted to the side wall portion 2c of tracheal tube 2. The inflatable cuff 3 divides tracheal tube 2 into a first portion 4a and a second portion 4b. When positioned within the trachea, the inflatable cuff 3 also divides the patient's trachea into an isolation zone Z1 and a non-sterile zone Z2.
[0020] The inflatable cuff 3 may have a substantially annular shape (doughnut shape). As will be appreciated by those skilled in the art, the inflatable cuff 3 may have any other suitable shape. Preferably, the inflatable cuff 3 is disposed in fluid communication with at least flow unit 5 via conduit 6. The inflatable cuff 3 may have a chamber joined by an outer membrane portion. The outer membrane portion may be made of, for example, PVC having a thickness of less than 100 microns, or polyurethane having a thickness of less than 50 microns.
[0021] Flow unit 5 may also be connected to tracheal tube 2. This may be a different flow unit than that used for inflatable cuff 3. It may be configured to generate positive pressure and pause pressure and may be connected to tracheal tube 2 through at least one connecting mouth 13, 14. At least one connecting mouth has an inlet mouth 13 and an outlet mouth 14, both of which may be in fluid communication with tracheal tube 2 through a 2-input 1-output connector 15.
[0022] FIG. 2 shows a schematic diagram of a further embodiment of the system 1 of the present disclosure for characterizing an inflatable cuff 3 disposed around the tracheal tube 2. In FIG. 3, the processing unit or control unit 9 controls the flow unit 5. The processing unit 9 may also estimate the volume of gas or liquid in the inflatable cuff, or the change in volume of gas or fluid, based on the measurement of the flow rate of gas or liquid to and / or from the inflatable cuff 3 based on the flow sensor 12. The flow sensor 12 may be disposed at any suitable location. The pressure sensor 11 is configured to measure the pressure within the inflatable cuff 3. The pressure sensor 11 may be disposed at any suitable location. The system 1 of the example figure has a vent conduit 7 that can be used in parallel flow. The system 1 of FIG. 2 further includes a fork 8 disposed along the conduit 6.
[0023] According to aspects of the present disclosure, the system and / or method includes the step of inflating, or deflating, or both in combination, the aforementioned inflatable cuff, controlled by either flow or pressure, to estimate the characteristics of an endotracheal tube cuff or tracheal tube cuff within an intubated patient.
[0024] Preferably, the step of continuously causing inflation, or deflation, or both in combination, of the aforementioned inflatable cuff controlled by either flow or pressure includes the step of periodically and continuously causing either an overpressure within the inflatable cuff to be followed by a standard pressure setting within the inflatable cuff, or a pressurization within the inflatable cuff to be followed by a standard pressure setting within the inflatable cuff, or a combination of both, to measure the pressure / volume correlation within the inflatable cuff.
[0025] The flow unit may be switchable between an inflation configuration for inflating and / or continuing to inflate the inflatable cuff, a deflation configuration for deflating and / or continuing to deflate the inflatable cuff, or a combination of inflation / deflation configurations.
[0026] According to the systems and methods of the present disclosure, the flow unit can have its first inflation configuration, contraction configuration, or a combination of both periodically and continuously switched either manually or automatically.
[0027] The control module, which may include a processing unit, can be configured to control signals to the flow unit to activate or deactivate inflation or contraction, which may include opening and closing valves.
[0028] In one embodiment, the system is configured to determine the degradation of an inflatable cuff based on the characterization of the inflatable cuff. The degradation of the inflatable cuff may be seen when the inflatable cuff loses its resilience, i.e., its ability to withstand rubbing without tearing. The degradation may also be seen as a more elastic inflatable cuff. The processing unit is configured to calculate or extract a measure of the elasticity of the inflatable cuff based on the pressure-volume relationship.
[0029] The pressure-volume relationship can describe the relationship between one or more given volumes and one or more corresponding pressures. The pressure-volume relationship describes the relationship between one or more given pressures and one or more corresponding volumes. This can be illustrated, for example, by FIG. 7, which shows the volumes and pressures of two inflatable cuffs (or the same inflatable cuff at different times) A and B. The pressure-volume relationship can be represented by a pressure-volume curve that includes measurements of a plurality of pressure levels and a plurality of volumes extracted from a plurality of measurements of the gas flow rate into and / or out of the inflatable cuff. On the first axis, such as the Y-axis of this curve, pressure is given, and on the second axis, such as the X-axis, volume is given. The pressure-volume relationship can be represented by a coefficient or formula that converts at least one given volume to the corresponding pressure or at least one given pressure to the corresponding volume. If it is a single pressure and volume, it can be a single coefficient. If there are several measurements, this relationship can be expressed as a formula. A higher coefficient may indicate that a higher pressure is required to obtain a given volume, a lower coefficient may indicate that a lower pressure is required to obtain a given volume, or a higher coefficient may indicate that a smaller volume is required to obtain a given pressure, and a lower coefficient may indicate that a larger volume is required to obtain a given pressure. In the example of FIG. 7, the inflatable cuff in scenario A requires a higher pressure to obtain a given volume compared to scenario B. Scenarios A and B can be for the same inflatable cuff. If B occurs later than A, B can be considered to be more elastic. As in the example of FIG. 7, when pressure is given on the Y-axis and volume is given on the X-axis, the steeper the curve, the lower the elasticity of the inflatable cuff and / or the higher the coefficient, and the flatter the curve, the higher the elasticity of the inflatable cuff and / or the lower the coefficient. In one embodiment, the processing unit is configured to categorize that the inflatable cuff has been consumed based on the change in the pressure-volume relationship over time. If the coefficient is below the previously measured coefficient, the processing unit can be configured to categorize that the inflatable cuff has been consumed.In some cases, for the coefficient to categorize that the inflatable cuff is worn out, the coefficient needs to exceed a predetermined limit that is lower than the previously measured coefficient.
[0030] The processing unit may additionally or alternatively be configured to identify a change in the structure around the cuff as a change in the pressure-volume relationship. Accordingly, the system may be configured to characterize the structure around the inflatable cuff based on the characterization of the inflatable cuff. The processing unit may be configured to identify that the patient's trachea becomes rigid as a result of the increase in the aforementioned coefficient and / or may be configured to identify that the patient's trachea becomes soft as a result of the decrease in the coefficient. In the example of FIG. 7, if scenario B represents the first measurement and scenario A represents the subsequent second measurement, the higher the coefficient of A, the harder the patient's trachea can be shown.
[0031] To characterize the inflatable cuff, the system may be configured to collect the necessary measurements. In one embodiment, the system may be configured to gradually fill the inflatable cuff with gas or gradually empty the inflatable cuff, and the pressure sensor and the flow sensor measure the pressure inside the inflatable cuff and the flow rate of gas to and / or from the inflatable cuff continuously or at discrete time points to generate a pressure-volume curve.
[0032] FIGS. 3A-C show an example of a process for extracting the pressure-volume relationship between the measured pressure and the estimated volume of gas or liquid inside the inflatable cuff.
[0033] In Scenario A, the inflatable cuff first expands from a first pressure P_0 or a first volume V_0 to a second pressure P_1 or a second volume V_1 within a second time interval Δt1. Preferably, both the pressure and the volume are measured continuously or at discrete time points. Next, the second pressure P_1 or the second volume V_1 decreases to a third pressure P_2 or a third volume V_2 within second and third time intervals Δt2 and Δt3. Next, the third pressure P_2 or the third volume V_2 increases to return to the first pressure P_0 or the first volume V_0 within a fourth time interval Δt4.
[0034] In Scenario B, the inflatable cuff first expands from a first pressure P_0 or a first volume V_0 to a second pressure P_1 or a second volume V_1 within a second time interval Δt1. Next, the second pressure P_1 or the second volume V_1 decreases to the first pressure P_0 or the first volume V_0 within a second time interval Δt2.
[0035] In Scenario C, the inflatable cuff first contracts from a first pressure P_0 or a first volume V_0 to a third pressure P_2 or a third volume V_2 within a third time interval Δt3. Next, the third pressure P_2 or the third volume V_2 increases to the first pressure P_0 or the first volume V_0 within a fourth time interval Δt4.
[0036] Preferably, the time interval is at least 0.01 seconds.
[0037] Preferably, the second pressure is at least 1 cmH2O higher than the first pressure. Preferably, the third pressure is at least 1 cmH2O lower than the first pressure.
[0038] Preferably, the second volume is at least 0.1 mL larger than the first volume. Preferably, the third volume is at least 0.1 mL smaller than the first volume.
[0039] Figures 5A - C show an example of a sequence for expanding and contracting an inflatable cuff to establish a pressure - volume relationship. The inflatable cuff starts in the initial state shown in Figure 5A. Thereafter, the pressure increases to the second state shown in Figure 5B. Next, the pressure decreases to the third state shown in Figure 5C.
[0040] Figures 6A - C show an example of a sequence for contracting and expanding an inflatable cuff to establish a pressure - volume relationship. The inflatable cuff starts in the initial state shown in Figure 6A. Thereafter, the pressure decreases to the second state shown in Figure 6B. Next, the pressure increases to the third state shown in Figure 6C.
[0041] Advantageously, in this way, as shown in Figure 4, it is possible to characterize the endotracheal tube within the intubated patient by correlating the measured pressure and the volume that can be expanded. Figures 4A - C show an example of the pressure - volume relationship between the measured pressure within the inflatable cuff and the estimated volume of gas or liquid. Figure 4A can be regarded as the initial pressure - volume relationship between the pressure and volume of the gas or liquid within the inflatable cuff. Next, Figures 4B and C can be subsequent measurements of the pressure - volume relationship between the pressure and volume of the gas or liquid within the inflatable cuff. In this regard, in Figure 4B, it may represent a stiffer trachea, while in Figure 4C, it may represent a more elastic inflatable cuff.
[0042] Since the inflation volume of the inflatable cuff is determined according to the type of patient, it is proportional to the size of the trachea and correlates with the target pressure generated within the inflatable cuff. However, the pressure inside the inflatable cuff may be determined independently of the volume. Implicitly, to prevent ischemia, the pressure P_0 within the inflatable cuff is preferably between 20 - 30 cmH2O.
[0043] Furthermore, the present disclosure relates to a method for characterizing an inflatable cuff arranged around an endotracheal tube to provide respiratory support to a patient, This method comprises measuring the pressure within the inflatable cuff in an inflated configuration, and Measuring the flow rate of gas to and / or from the inflatable cuff, estimating the volume of gas within the inflatable cuff based on the measurement of the flow rate of gas to and / or from the inflatable cuff, extracting the pressure-volume relationship between the measured pressure and the estimated volume of gas within the inflatable cuff, including the step of comparing the pressure-volume relationship to a previously measured or predetermined reference pressure-volume relationship to characterize the inflatable cuff.
[0044] The method may include gradually filling the inflatable cuff with gas and / or gradually emptying the inflatable cuff with gas, and measuring the pressure within the inflatable cuff and the flow rate of gas to and / or from the inflatable cuff continuously or at discrete points in time to generate a pressure-volume curve.
[0045] Details 1. A system for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient, at least one flow unit, such as a pump, in fluid communication with a cuff conduit coupled to the inflatable cuff, the at least one flow unit being adapted to fill the inflatable cuff with gas or liquid, at least one pressure sensor configured to measure the pressure within the inflatable cuff, at least one flow sensor for measuring the flow rate of gas or liquid to and / or from the inflatable cuff, a processing unit for estimating the volume of gas or liquid, or the change in volume of gas or liquid, within the inflatable cuff based on the measurement of the flow rate of gas or liquid to and / or from the inflatable cuff, configured to extract a pressure-volume relationship between the measured pressure and the estimated volume of the gas or liquid or a change in the volume of the gas or liquid within the inflatable cuff; the processing unit configured to compare the pressure-volume relationship to a previously measured or predetermined reference pressure-volume relationship to characterize the inflatable cuff; the system comprising the same.
[0046] 2. The system for characterizing an inflatable cuff according to clause 1, configured to determine degradation of the inflatable cuff based on the characterization of the inflatable cuff.
[0047] 3. The system for characterizing an inflatable cuff according to any one of the preceding clauses, further configured to characterize a structure surrounding the inflatable cuff based on the characterization of the inflatable cuff.
[0048] 4. The system for characterizing an inflatable cuff according to any one of the preceding clauses, wherein the pressure-volume relationship describes a relationship between one or more given volumes and one or more corresponding pressures, or the pressure-volume relationship describes a relationship between one or more given pressures and one or more corresponding volumes.
[0049] 5. The system for characterizing an inflatable cuff according to any one of the preceding clauses, wherein the pressure-volume relationship is represented by a coefficient that converts at least one given volume to a corresponding pressure or at least one given pressure to a corresponding volume.
[0050] 6. It is shown that the higher the coefficient, the higher the pressure required to obtain the given volume, and the lower the coefficient, the lower the pressure required to obtain the given volume, or the higher the coefficient, the smaller the volume required to obtain the given pressure, and the lower the coefficient, the larger the volume required to obtain the given pressure. A system for characterizing the inflatable cuff according to clause 5.
[0051] 7. The processing unit is configured to categorize that the inflatable cuff has been consumed based on the change in the pressure-volume relationship over time. A system for characterizing the inflatable cuff according to any one of clauses 4 to 6.
[0052] 8. When the coefficient is lower than the previously measured coefficient, the processing unit is configured to categorize that the inflatable cuff has been consumed. A system for characterizing the inflatable cuff according to clause 7.
[0053] 9. The pressure-volume relationship is represented by a pressure-volume curve including a plurality of pressure levels and a plurality of volume measurements extracted from a plurality of measurements of the gas flow rate to and / or from the inflatable cuff. A system for characterizing the inflatable cuff according to any one of the preceding clauses.
[0054] 10. The pressure is provided on a first axis such as the Y-axis of the curve, and the volume is provided on a second axis such as the X-axis. A system for characterizing the inflatable cuff according to clause 9.
[0055] 11. The steeper the curve, the lower the elasticity of the inflatable cuff and / or the higher the coefficient, and the flatter the curve, the higher the elasticity of the inflatable cuff and / or the lower the coefficient. A system for characterizing the inflatable cuff according to any one of clauses 9 to 10.
[0056] 12. The at least one flow unit is configured to gradually fill the inflatable cuff with gas or to gradually empty the inflatable cuff, and the pressure sensor and the flow sensor measure the pressure in the inflatable cuff and the flow rate of the gas to and / or from the inflatable cuff continuously or at discrete points in time to generate a pressure-volume curve, a system for characterizing an inflatable cuff according to any one of the preceding clauses.
[0057] 13. The processing unit is configured to calculate or extract a measure of the elasticity of the inflatable cuff based on the pressure-volume relationship, a system for characterizing an inflatable cuff according to any one of the preceding clauses.
[0058] 14. The processing unit is further configured to identify a change in the structure around the cuff as a change in the pressure-volume relationship, a system for characterizing an inflatable cuff according to any one of the preceding clauses.
[0059] 15. The processing unit is further configured to identify that the trachea of the patient becomes harder and / or the inner diameter of the trachea becomes smaller as a result of an increase in the coefficient, and / or the processing unit is further configured to identify that the trachea of the patient becomes softer and / or the inner diameter of the trachea becomes larger based on a change over time in the pressure-volume relationship, a system for characterizing an inflatable cuff according to any one of clauses 5 to 6.
[0060] 16. The processing unit is further configured to identify that the trachea of the patient becomes harder and / or the inner diameter of the trachea becomes smaller as a result of an increase in the coefficient, and / or the processing unit is further configured to identify that the trachea of the patient becomes softer and / or the inner diameter of the trachea becomes larger as a result of a decrease in the coefficient, a system for characterizing an inflatable cuff according to any one of clauses 5 to 6.
[0061] 17. A system for characterizing the inflatable cuff according to any one of the preceding clauses, wherein the inflatable cuff is an inflatable endotracheal tube cuff or an inflatable tracheostomy tube cuff.
[0062] 18. A method for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient, comprising: measuring the pressure within the inflatable cuff in the inflated configuration; measuring the flow rate of gas to and / or from the inflatable cuff; estimating a change in volume of the gas, or volume of the gas or liquid, within the inflatable cuff based on the measured flow rate of gas to and / or from the inflatable cuff; extracting a pressure-volume relationship between the measured pressure and the estimated gas volume within the inflatable cuff; comparing the pressure-volume relationship to a previously measured or predetermined reference pressure-volume relationship to characterize the inflatable cuff. The method as described above.
[0063] 19. Gradually filling the inflatable cuff with gas and / or gradually emptying the inflatable cuff, measuring the pressure within the inflatable cuff and the flow rate of gas to and / or from the inflatable cuff continuously or at discrete time points to generate a pressure-volume curve. The method for characterizing an inflatable cuff disposed around a tracheal tube to provide respiratory support to a patient as described in clause 18, comprising the steps as described above.
[0064] 20. The method according to any one of clauses 18 to 19, executed on a system for characterizing an inflatable endotracheal tube cuff according to any one of clauses 1 to 17.
[0065] A computer program having instructions which, when executed by a computing device or a computing system, cause the computing device or the computing system to execute a method for characterizing an inflatable cuff disposed around a tracheal tube for providing to a patient the respiratory support according to any one of clauses 18 to 20.
Claims
1. A system for characterizing an inflatable cuff placed around a tracheal tube to provide respiratory support to a patient, A flow unit, such as a pump, which is in fluid communication with a cuff conduit connected to the inflatable cuff, and which is adapted to fill the inflatable cuff with gas or liquid, At least one pressure sensor configured to measure the pressure inside the inflatable cuff, At least one flow sensor for measuring the flow rate of gas or liquid to and / or from the inflatable cuff, A processing unit for estimating the volume of gas or liquid in the inflatable cuff, or the change in the volume of gas or liquid, based on the measurement of the flow rate of the gas or liquid to and / or from the inflatable cuff, Within the inflatable cuff, the pressure-volume relationship between the measured pressure and the estimated volume of the gas or liquid, or the change in the volume of the gas or liquid, is extracted. To characterize the inflatable cuff, the processing unit is configured to compare the pressure-volume relationship with a previously measured or predetermined reference pressure-volume relationship, The system including the above.
2. The system for characterizing an inflatable cuff according to claim 1, wherein the system is configured to determine the deterioration of the inflatable cuff based on the characterization of the inflatable cuff.
3. A system for characterizing an inflatable cuff according to claim 1, wherein the system is further configured to characterize a structure surrounding the inflatable cuff based on the characterization of the inflatable cuff.
4. A system for characterizing an inflatable cuff according to claim 1, wherein the pressure-volume relationship describes a relationship between one or more given volumes and one or more corresponding pressures, or the pressure-volume relationship describes a relationship between one or more given pressures and one or more corresponding volumes.
5. A system for characterizing the inflatable cuff according to claim 1, wherein the pressure-volume relationship is represented by a coefficient that converts at least one given volume to a corresponding pressure, or at least one given pressure to a corresponding volume.
6. A system for characterizing an inflatable cuff according to claim 5, wherein a higher coefficient indicates that a higher pressure is required to obtain the given volume, a lower coefficient indicates that a lower pressure is required to obtain the given volume, or a higher coefficient indicates that a smaller volume is required to obtain the given pressure, and a lower coefficient indicates that a larger volume is required to obtain the given pressure.
7. A system for characterizing an inflatable cuff according to claim 5, wherein the processing unit is configured to categorize the inflatable cuff as worn based on a change in the pressure-volume relationship over time, preferably, if the coefficient is less than a previously measured coefficient, the processing unit is configured to categorize the inflatable cuff as worn.
8. A system for characterizing an inflatable cuff according to claim 1, wherein the pressure-volume relationship is represented by a pressure-volume curve including a plurality of pressure levels and a plurality of volume measurements extracted from a plurality of measurements of gas flow rates into and / or from the inflatable cuff.
9. A system for characterizing an inflatable cuff according to claim 1, wherein the at least one flow unit is configured to gradually fill the inflatable cuff with gas or to gradually empty the inflatable cuff, and the pressure sensor and the flow sensor measure the pressure in the inflatable cuff and the flow rate of the gas into and / or from the inflatable cuff at continuous or discrete time points to generate a pressure-volume curve.
10. The system for characterizing the inflatable cuff according to claim 1, wherein the processing unit is configured to calculate or extract a measure of the elasticity of the inflatable cuff based on the pressure-volume relationship.
11. A system for characterizing the inflatable cuff according to claim 3, wherein the processing unit is further configured to identify changes in the structure surrounding the cuff as changes in the pressure-volume relationship.
12. A system for characterizing the inflatable cuff according to claim 5, wherein the processing unit is further configured to identify that the patient's trachea hardens and / or the inner diameter of the trachea decreases as a result of an increase in the coefficient, and / or the processing unit is further configured to identify that the patient's trachea softens and / or the inner diameter of the trachea increases based on a change in the pressure-volume relationship over time.
13. A system for characterizing an inflatable cuff according to claim 5, wherein the processing unit is further configured to identify that as a result of an increase in the coefficient, the patient's trachea becomes stiffer and / or the inner diameter of the trachea becomes smaller, and / or the processing unit is further configured to identify that as a result of a decrease in the coefficient, the patient's trachea becomes softer and / or the inner diameter of the trachea becomes larger.
14. A method for characterizing an inflatable cuff placed around a tracheal tube to provide respiratory support to a patient, Measuring the pressure inside the inflatable cuff in an inflatable configuration, Measuring the flow rate of gas to and / or from the inflatable cuff, Estimating the volume of the gas in the inflatable cuff, or the change in the volume of the gas or liquid, based on the measurement of the flow rate of the gas to and / or from the inflatable cuff, Extracting the pressure-volume relationship between the measured pressure and the estimated gas volume within the inflatable cuff, To characterize the inflatable cuff, the pressure-volume relationship is compared with a previously measured or predetermined reference pressure-volume relationship, The method, which includes the step of...
15. A computer program having instructions, the instructions, when executed by a computing device or computing system, cause the computing device or computing system to perform a method for characterizing an inflatable cuff positioned around a tracheal tube to provide the respiratory support described in claim 14 to a patient.