Monitoring the operation of a respiratory system

Abstract

A method for detecting faults in a respiratory system is provided, the method comprising the steps of: (a) obtaining a set of measurements of a first parameter of the respiratory system; and (b) setting a fault boundary for the first parameter responsive to the plurality of measurements of the first parameter. The method further comprises at least one updating procedure comprising the steps of: (c) obtaining one or more additional measurements of the first parameter; and (d) updating the fault boundary, wherein the updated fault boundary depends on the updated set of measurements of the first parameter, and the updated set of measurements of the first parameter includes at least one of the additional measurements of the first parameter.

Description

Technical Field

[0001] The present invention relates to the monitoring of the operation of respiratory systems, and more particularly, but not limited thereto, to monitoring the operation of a respiratory system having a gas supplied by a constant flow treatment device such as a gas mixer to identify when a fault or error has occurred.

[0002] Air / oxygen mixers are known to be used in a variety of healthcare applications to provide a reliable and accurate way to supply gas to patients. For example, in a hospital, gases are typically supplied from wall-mounted sources, and these gases need to be mixed in the desired proportions and supplied to the patient at a specific pressure and / or flow rate.

[0003] The ability to supply a mixture of air and oxygen in a safe, easy, and controlled manner is becoming increasingly important. Therefore, it is important to know whether / when there is a fault in the supply of gas from the device to the patient.

[0004] Some of the faults in the system have a significant impact on measurable parameters. This allows the fault boundaries, i.e., the boundaries of the measurable parameters that indicate that there is a fault in the system associated with the device when exceeded, to be set further away from the normal values associated with the measurable parameters, making it possible to detect faults. However, other faults in the system have little impact on the measurable parameters, meaning that the fault boundaries need to be set close to the normal values of the measurable parameters to detect the faults.

[0005] To detect such a failure, it is necessary to make the failure boundary particularly narrow. However, since this system is used throughout its life with various device attachments and interfaces with patients, it is generally impossible to pre-determine the required failure boundary during manufacturing without introducing a large number of false errors. As a result, in an attempt to capture all potential system failures, the failure boundary has to be set particularly wide, and it is necessary to set the upper and lower fault boundaries extremely, but this is currently often ineffective.

[0006] A common solution to this problem is to enable the operator to set the failure boundary when the specified device is attached to the apparatus for operation. This allows the failure boundary to be set narrower, enabling the detection of the more subtle potential failures described above. However, this places a burden on the operator to update the failure boundary, and the operator needs to do both a) recognize the correct boundary for each attachable device and b) implement these boundaries correctly.

[0007] Currently, an improved method for monitoring the operation of an apparatus has been devised, according to which the above-mentioned and / or other drawbacks associated with the prior art are overcome or substantially reduced.

Summary of the Invention

[0008] According to a first aspect of the present invention, a method for detecting a failure in a breathing system is provided. The method includes (a) obtaining a series of measurements of a first parameter of the breathing system; and (b) setting a failure boundary for the first parameter, the failure boundary depending on a plurality of measurements of the first parameter. The method includes at least one update procedure, the update procedure including (c) obtaining one or more additional measurements of the first parameter; (d) updating a fault boundary, the updated fault boundary depending on an updated set of measurements of the first parameter, the updated set of measurements of the first parameter including at least one of the additional measurements of the first parameter.

[0009] The method is advantageous in that it allows for an accurate setting of the fault boundary regardless of the configuration of the respiratory system. The fault boundary of the first parameter depends on the measurements of the first parameter obtained in previous steps of the method and ensures that the fault boundary is appropriate regardless of the equipment or patient interface used with the respiratory system.

[0010] Furthermore, by updating the fault boundary depending on the additional measurements of the first parameter obtained, it is ensured that the fault boundary remains appropriate throughout the use of the system. This is particularly advantageous since, for example, the breathing rate of the patient and any movement of the components of the respiratory system are not constant and vary in particular depending on whether the patient is asleep or during the waking period. Thus, by updating the fault boundary, it becomes possible to take into account the patient's condition and / or any movement of the components of the respiratory system when determining what should be considered a fault and what should not be considered a fault.

[0011] Setting the fault boundary for the first parameter can include setting the fault boundary to be offset from a measurement parameter that depends on a plurality of measurements. After obtaining one or more additional measurements, the measurement parameter may be updated. The updated measurement parameter may depend on at least one of the additional measurements.

[0012] The measurement parameter may be the average value of a plurality of measurement values. Alternatively, the measurement parameter may be the minimum value and / or the maximum value of a series of measurement values. After obtaining a series of measurement values of the first parameter, the method may further include determining the average value of the plurality of measurement values. The step of determining the average value of the plurality of measurement values may include calculating the average value or median of the plurality of measurement values, or any other functionally equivalent calculation of a representative value. When the measurement parameter is updated, the updated measurement parameter may be the average value of a plurality of sets of updated measurement values, or the minimum value and / or the maximum value of a set of updated measurement values.

[0013] The setting of the fault boundary or the updated fault boundary for the first parameter can include setting the fault boundary in comparison with the measurement parameter or the updated measurement parameter, for example, the determined average value, minimum value and / or maximum value of a series of measurement values, the average value of a plurality of sets of updated measurement values, or the minimum value and / or the maximum value of a set of updated measurement values. The setting of the fault boundary can include setting an upper fault boundary and / or a lower fault boundary. The upper fault boundary may be greater than the measurement parameter, or when the upper fault boundary is the updated upper fault boundary, the updated measurement parameter and the lower fault boundary may be less than the measurement parameter, or when the lower fault boundary is the updated lower fault boundary, it may be the updated measurement parameter. For example, the upper fault boundary may be greater than the determined average value or the updated average value, and the lower fault boundary may be less than the determined average value or the updated average value.

[0014] The fault boundary may be offset from the measured parameter by a predetermined amount. Alternatively, the fault boundary may be offset from the measured parameter by an amount that depends on the variance factor of a plurality of measured values. The fault boundary may be offset from the measured value by a fraction or percentage of the determined average value. If the fault boundary is an updated fault boundary, the offset of the updated fault boundary from the updated measured parameter may be a predetermined amount or an amount that depends on the updated variance factor of a plurality of sets of updated measured values.

[0015] The method may further include, after obtaining a series of measured values of a first parameter, determining the variance factor of the plurality of measured values. The variance factor may depend on the variance of the plurality of measured values. The variance factor may be dependent on the variance of a plurality of measured values with respect to the measured parameter, for example, the determined average value.

[0016] The variance factor may include the difference between the highest and lowest measured values among the plurality of measured values. Alternatively, the variance factor may include the maximum difference between any one of the plurality of measured values and the measured parameter (e.g., the determined average value). Alternatively, the variance factor may include an upper variance factor and a lower variance factor, where the upper variance factor is the maximum difference between the measured parameter and any one of the plurality of measured values above the measured parameter, and the lower variance factor is the maximum difference between the measured parameter and any one of the plurality of measured values below the measured parameter. Alternatively, the variance factor may include the statistical variance of the plurality of measured values, such as the statistical deviation.

[0017] The fault boundary may be offset from the measured parameter by a value obtained by multiplying the variance factor by an error factor. The error factor may correspond to an acceptable amount of variance during normal operation of the system.

[0018] When the determined dispersion coefficient includes an upper dispersion coefficient and a lower dispersion coefficient, setting the failure boundary can include setting an upper failure boundary offset from the measurement parameter by an amount obtained by multiplying the upper dispersion coefficient by an upper error coefficient, and setting a lower failure boundary offset from the measurement parameter by an amount obtained by multiplying the lower dispersion coefficient by a lower error coefficient. The upper and lower error coefficients may be the same or different. When the failure boundary is an updated failure boundary, the updated failure boundary may be offset from the updated measurement parameter by an amount obtained by multiplying the updated dispersion coefficient by the error coefficient.

[0019] The set of updated measurements can include at least one of the measurements on which the updated failure boundary depends and at least one of the additional measurements. The set of updated measurements can include a plurality of measurements on which the updated failure boundary depends and at least one of the additional measurements. In the set of measurements to be updated, the plurality of measurements on which the updated failure boundary depends may be the most recently acquired measurements among the measurements on which the updated failure boundary depends. The set of updated measurements can include the same number of measurements as the plurality of measurements on which the updated failure boundary depends. The set of updated measurements can include at least one of the additional measurements that replaces the same number of the earliest measurements on which the updated failure boundary depends.

[0020] One or more additional measurements of the first parameter can include a single additional measurement. In this case, the set of updated measurements can include all but one of the plurality of measurements on which the updated failure boundary depends. The set of updated measurements can include all but the earliest measurement among the plurality of measurements on which the updated failure boundary depends. Alternatively, one or more additional measurements of the first parameter can include a series of additional measurements. In this case, in the set of updated measurements, the series of additional measurements can replace the same number of the earliest measurements among the same number of measurements on which the updated failure boundary depends.

[0021] The method can further include the step of updating the measured parameter after obtaining one or more additional measurements of the first parameter, and the updated measured parameter depends on at least one of the additional measurements of the first parameter. For example, the method can further include the step of updating the determined average value, and the updated average value depends on at least one of the additional measurements of the first parameter. Updating the determined average value can include determining the average value of the updated set of measurements of the first parameter. This is generally referred to as maintaining a rolling average of the measurements of the first parameter.

[0022] This can be advantageous in that it allows the moving average of the first parameter to be maintained over the operation of the respiratory system and the fault boundary to be updated according to the current operation.

[0023] The method can further include the step of updating the determined coefficient of variation after obtaining one or more additional measurements of the first parameter, and the updated coefficient of variation can depend on at least one of the additional measurements of the first parameter. Updating the determined coefficient of variation can include determining the coefficient of variation for the updated set of measurements of the first parameter. The updated coefficient of variation can depend on the variance of the updated set of measurements. The updated coefficient of variation can depend on the variance of the updated set of measurements for the updated measured parameter, for example, the updated average value.

[0024] The updated dispersion coefficient can include the difference between the maximum and minimum measured values of the updated set of measured values. Alternatively, the updated dispersion coefficient can include the maximum difference between any one of the updated set of measured values and the updated measurement parameter (e.g., the updated average value). Alternatively, the updated dispersion coefficient can include the updated upper dispersion coefficient and the updated lower dispersion coefficient, where the updated upper dispersion coefficient is the maximum difference between the updated measurement parameter and any one of the updated set of measured values above the updated measurement parameter, and the updated lower dispersion coefficient is the maximum difference between the updated measurement parameter and any one of the updated set of measured values below the determined measurement parameter. Alternatively, the updated dispersion coefficient can include the statistical dispersion of the updated series of measured values, e.g., the statistical deviation.

[0025] By updating the determined dispersion coefficient depending on additional measured values of the obtained first parameter, it is guaranteed that the fault boundary remains appropriate throughout the use of the system. This is particularly advantageous when considering changes in the patient's respiratory rate and the movement of the components of the respiratory system, which depend greatly on whether the patient is asleep or during the waking period. For example, when the patient is asleep, the patient's respiratory rate does not change much and the respiratory system remains relatively stationary, so a lower dispersion coefficient is determined and a narrower boundary can be set, enabling the detection of smaller changes that may indicate an obstruction or a leak. On the other hand, when the patient is in the waking phase or is generally more restless, the respiratory rate changes more and the respiratory system moves more, so a higher dispersion coefficient is determined and a wider boundary is set, making it less likely for false alarms to occur.

[0026] Thus, by updating the fault boundary, it becomes possible to consider the patient's condition when determining what should be considered a fault and what should not be considered a fault.

[0027] Updating the fault boundary for the first parameter can include updating the fault boundary as compared to the updated measurement parameter. For example, updating the fault boundary for the first parameter can include updating the fault boundary as compared to the updated average value. Updating the fault boundary can include updating the fault boundary depending on the updated coefficient of variation. Updating the fault boundary can include updating the upper fault boundary and updating the lower fault boundary.

[0028] The method can further include comparing the measured value of the first parameter with the fault boundary, or if the fault boundary is updated, with the updated fault boundary, and determining that there is a fault in the operation of the respiratory system in response to the measured value being outside the fault boundary or the updated fault boundary. If the fault boundary includes an upper fault boundary and a lower fault boundary, the method can include comparing the measured value of the first parameter with the upper fault boundary, or if the upper fault boundary is updated, with the updated upper fault boundary, and determining a fault in the operation of the respiratory system in response to the measured value exceeding the upper fault boundary or the updated upper fault boundary, and comparing the measured value of the first parameter with the lower fault boundary, or if the lower fault boundary is updated, with the updated lower fault boundary, and determining a fault in the operation of the respiratory system in response to the measured value being less than the lower fault boundary or the updated lower fault boundary. If the fault boundary is updated, it is possible to compare the measured value of the first parameter with the latest updated fault boundary.

[0029] In response to determining a fault in the operation of the respiratory system, the method can further include steps indicating the fault. Additionally or alternatively, the respiratory system can operate to adjust its parameters and / or operating method and / or operating state accordingly.

[0030] The update procedure may be repeated at least once. The failure boundary updated in each subsequent update procedure may be the updated failure boundary from the previous update procedure. The update procedure may be repeated at intervals during the operation of the breathing system. The operation of the breathing system can be considered during the period when gas is supplied to the breathing system and / or during the period when treatment is provided to the patient. The update procedure may be repeated at intervals following an initial calibration process for any one of the breathing system, the device for supplying gas to the breathing system, and the device for performing the method according to the first aspect of the present invention, or any combination thereof.

[0031] The update procedure can be repeated up to turning off the power of the breathing system or the device, changing any accessory that requires resetting the failure boundary, changing any parameter settings, changing the treatment performed by the breathing system or the device, and confirmation by the user of existing failures, or any combination thereof.

[0032] This interval may be a regular interval. The update procedure can be repeated at least 3 times, at least 5 times, at least 10 times, at least 50 times, or at least 100 times. The update procedure can be repeated every 0.01 seconds, every 0.1 seconds, every 1 second, every 2 seconds, every 5 seconds, every 10 seconds, or every 15 seconds. The interval may be less than 0.01 seconds, less than 0.1 seconds, less than 1 second, less than 2 seconds, less than 5 seconds, less than 10 seconds, or less than 15 seconds.

[0033] Steps (a) and / or (b) of the first aspect of the present invention may occur during the operation of the breathing system, that is, during the period when gas is supplied to the breathing system and / or during the period when treatment is provided to the patient. Before step a) of the first aspect of the present invention, the method may include a step of starting the supply of gas to the breathing system. The method may further include a step of continuing the supply of gas to the breathing system while performing steps (a) to (d) of the first aspect of the present invention. Step (a) can start immediately after starting the supply of gas to the breathing system.

[0034] The term "almost immediately" can account for a slight delay between starting the supply of gas to the respiratory system and the start of step (a) of the first aspect of the present invention, thereby allowing the supplied gas to move through most or all of the respiratory system before a series of measurements are taken. In use, the respiratory system may be connected to an apparatus for supplying gas, which can include, for example, a gas bottle or canister, or a fixed gas line within a hospital wall. The supply of gas from the gas supply apparatus to the respiratory system may be controlled by a suitable device such as a gas mixer. The supply of gas from the gas supply apparatus to the respiratory system may be controlled by at least one valve for controlling the gas supply. A suitable device, for example, a gas mixer, may include at least one valve. Thus, starting to supply gas to the respiratory system can include opening at least one valve. For example, the apparatus for supplying gas may already be "on", i.e., the apparatus can readily supply gas, but may be configured such that gas is not supplied to the respiratory system until the valve is opened.

[0035] According to a further aspect of the present invention, there is provided an apparatus configured to carry out the method according to the first aspect of the present invention. The apparatus may be for supplying gas to a respiratory system. The gas may be a respiratory gas.

[0036] The device for supplying gas can include an inlet through which gas is supplied to the device and an outlet through which gas is supplied to a respiratory system to which the device is connected. The respiratory system may comprise a patient supply tube and a patient interface, and the supply tube is arranged to supply gas from the device to the patient interface. The patient interface may comprise a connector configured to connect to the patient supply tube. The patient supply tube may have a first end for connecting to the outlet of the device and a second end for connecting to the patient interface. The patient interface may be configured to supply the gas supplied from the device to the patient via the patient supply tube. The patient interface may be, for example, a respiratory mask.

[0037] The first parameter may depend on a failure in the configuration of the respiratory system, such as a twist in the patient supply tube, an occlusion of the patient supply tube, a breakage or removal of a component of the respiratory system, or a leak within the respiratory system. This can be advantageous in that it enables the detection of the occurrence of these failures to be recognized as a failure in the operation of the respiratory system.

[0038] This method can be further advantageous in that it enables these failures relating to the operation of the respiratory system to be recognized regardless of the type of respiratory system connected to the device for supplying gas.

[0039] The first parameter may be a parameter of the gas supply within the respiratory system. The first parameter may be a parameter of the respiratory system and may be measured by the device. The first parameter may depend on the configuration of the respiratory system. Thus, a change in the first parameter can indicate a change in the configuration of the respiratory system. A change in the first parameter can indicate a malfunction of the respiratory system. The first parameter can be a parameter related to the influence of the respiratory system on the gas supply within the device. The first parameter may be a parameter that is not controlled in the device. That is, the first parameter may not be adjusted or calibrated by the device. The first parameter may be the pressure within the device or the respiratory system. The first parameter may be measured in the device, for example, within the device, at the outlet of the device, or at the inlet of the device. Alternatively, the first parameter may be measured within the respiratory system, for example, within the breathing tube or at the patient interface.

[0040] The first parameter may be any one of flow rate, back pressure within the respiratory system, or patient pressure.

[0041] Backpressure can be defined as the difference between the pressure at any point within the respiratory system and the ambient pressure, i.e., the environmental pressure surrounding the respiratory system. The patient interface of the respiratory system may be exposed to the ambient pressure. During use, the pressure at any point within the respiratory system must be higher than the ambient pressure in order to ensure the flow of gas through the respiratory system and supply gas from the device to the patient interface. The ambient pressure may be the atmospheric pressure. It can be assumed that the atmospheric pressure is fixed, for example, at about 1 atmosphere, about 1 bar, or about 100 kPa. When the atmospheric pressure is considered fixed, the pressure within the device rather than the backpressure within the respiratory system can be measured. Backpressure may occur as a result of gas flowing through the resistance within the respiratory system. That is, backpressure depends on the resistance to the flow of gas through the respiratory system and may thus vary as a function thereof. For this reason, an increase in the resistance to flow can increase the backpressure within the respiratory system. Backpressure may also depend on the flow rate and may thus vary as a function of the flow rate. Similarly, the patient pressure can be defined as the pressure in the vicinity of the patient interface of the respiratory system, for example, at the patient interface.

[0042] The method can further include controlling a second parameter of the respiratory system. Controlling the second parameter of the respiratory system can include controlling the device for supplying gas to the respiratory system. The first parameter may further depend on the second parameter.

[0043] Controlling the second parameter of the respiratory system and the first parameter that depends on the second parameter can provide further advantages over the prior art. Thus, according to a further aspect of the invention, a method of detecting a fault in a respiratory system is provided. The method comprises (a) supplying gas to the respiratory system; (b) obtaining a series of measurements of a first parameter of the respiratory system; (c) A step of setting a fault boundary for a first parameter, the fault boundary depending on a plurality of measurement values of the first parameter, and the step, A second parameter of the breathing system is controlled during the supply of gas to the breathing system, and a first parameter of the breathing system depends on the second parameter and the breathing system such that a change in the first parameter can indicate a fault in the breathing system.

[0044] Controlling a second parameter of the gas supply in the device can include supplying the device with a gas having a predetermined value for the second parameter. Controlling a second parameter of the gas supply in the device can include measuring the value of the second parameter at a first location within the device, for example, at the outlet of the device. Controlling a second parameter of the gas supply in the device can include adjusting and / or calibrating the value of the second parameter of the gas supply at a second location of the device in response to the measured value of the second parameter at the first location. It should be understood that the above positions are referred to as the first position and the second position in order to distinguish these measured values, and do not necessarily indicate positions within the device relative to each other.

[0045] The second parameter can be any parameter that can be controlled in the device. The second parameter can be any parameter of the gas supply that can be set or defined in the device or when supplied to the device. The second parameter may be measurable in the device, for example, at the inlet or outlet of the device. The second parameter may be measurable in the breathing system, for example, in the patient supply tube or the patient interface. The second parameter may be measurable by a sensor. The second parameter may be adjusted and / or calibrated by the device. The second parameter may be a flow rate. This is because the flow rate is typically a parameter controlled by the device for supplying gas. However, it is also possible that the second parameter is the pressure within the device or the breathing system, for example, the pressure at the outlet of the device, the back pressure within the breathing system, or the patient pressure.

[0046] The device can have a second fault detection system for monitoring the operation of the respiratory system. The second fault detection system can signal a fault in response to a change in a second parameter. For example, when the difference between the measured value of the second parameter, or the average value of a plurality of measured values of the second parameter, and a predetermined target value for the second parameter exceeds a fault boundary. Thus, the method according to the invention can be implemented together with another fault detection system of the device itself.

[0047] In use, when the second parameter is flow rate and the first parameter is the back pressure within the respiratory system or the pressure indicating the back pressure within the respiratory system, and there is a change within the respiratory system (e.g., a twist in the patient supply tube), which causes the flow rate to instantaneously decrease, the device typically provides increased power for conveying gas into the respiratory system in order to maintain a constant flow rate. In this arrangement, a change within the respiratory system, such as a twist in the patient supply tube, increases the back pressure within the respiratory system. Thus, the method according to the invention signals a fault when the back pressure within the system is outside at least one boundary, while the second fault detection system of the device does not signal a fault since the flow rate is maintained normally.

[0048] On the other hand, if the device cannot provide sufficient increased power for conveying gas into the respiratory system to maintain a constant flow rate, there may not be an increase in back pressure sufficient for the method according to the invention to signal a fault, so the method according to the invention may not signal a fault. On the other hand, the second fault detection system of the device will signal a fault as a result of the decreased flow rate. The increased power provided by the device may be equal to the increased supply pressure.

[0049] The first parameter depends on the third parameter and can thus reflect or indicate the third parameter. A change in the first parameter may indicate a change in the third parameter. The third parameter may depend on the configuration of the respiratory system. For example, the third parameter may depend on the failure state described above. The third parameter may be, for example, the back pressure within the respiratory system or the patient pressure. This enables an easy measurement of the first parameter within the device or the respiratory system, and any variation in the first parameter indicates a variation in the third parameter, which is usually more difficult to measure but may be advantageous in indicating a failure within the respiratory system.

[0050] The first parameter may be the pressure within the device. The third parameter may be the back pressure within the respiratory system. When the ambient pressure is fixed, the pressure offset from the ambient pressure indicates the back pressure through the respiratory system and enables the determination of the back pressure within the respiratory system, so the first parameter may be determined by measuring the pressure at a location within the device. Thus, additional processing or calculation may not be required to obtain the back pressure.

[0051] A series of measurements may be taken over a first period. The first period may be at least 10 seconds, at least 20 seconds, at least 30 seconds, at least 45 seconds, at least 1 minute, at least 2 minutes, at least 3 minutes, at least 4 minutes, or at least 5 minutes. Measuring the first parameter during the first period may include measuring the parameter at least every 0.01 seconds, at least every 0.1 seconds, at least every 1 second, at least every 2 seconds, at least every 2 seconds, at least every 5 seconds, at least every 10 seconds, or at least every 15 seconds.

[0052] Measuring the first parameter can include measuring the first parameter using at least one sensor. The at least one sensor may include a plurality of sensors arranged at different positions throughout the device, and each measurement of the first parameter may include obtaining an instantaneous average of the measurements taken by the plurality of sensors.

[0053] The first parameter may depend on any one of, or any combination of, the number or type of components of the respiratory system, the type of device for supplying gas, the operating mode of the device and / or the respiratory system, and the type of treatment provided by the respiratory system. Also, the first parameter may depend on the failure state described above.

[0054] When the device utilizes a plurality of sensors, determining the average of the plurality of measurements can include obtaining an average of the instantaneous averages measured over a first period, i.e., calculating the average value or median of the instantaneous averages measured over the first period. In an exemplary embodiment, the failure boundary may be offset from the determined average value by 5 to 50%, 10 to 30%, or 15 to 25%, for example, by 5%, 10%, 15%, 20%, 25%, or 30%. In a further exemplary embodiment, the failure boundary may be offset from the determined average by one times the determined coefficient of variation, two times the determined coefficient of variation, three times the determined coefficient of variation, or four times the determined coefficient of variation.

[0055] The offset of the fault boundary from the measurement parameter, or if the fault boundary is updated, the offset of the updated fault boundary from the updated measurement parameter, may be compared to a predetermined minimum offset. The predetermined minimum offset can be associated with at least one sensor that measures the first parameter. The predetermined minimum offset can be associated with the measurement accuracy of at least one sensor that measures the first parameter. That is, the predetermined minimum offset may be a selected value related to the measurement accuracy of at least one sensor that measures the first parameter. The selected value may be the minimum difference required between any two measured values for at least one sensor that measures the first parameter to distinguish between two values without error based on its measurement accuracy. If the offset of the fault boundary or the offset of the updated fault boundary is less than the predetermined minimum offset, the offset of the fault boundary or the updated fault boundary may be increased to match the predetermined minimum offset.

[0056] This can be advantageous in ensuring that the boundary is wide enough to prevent a large number of errors from being falsely notified.

[0057] The offset of the lower fault boundary and / or the upper fault boundary from the determined average, or if the lower fault boundary and the upper fault boundary are updated, the offset of the updated lower fault boundary and / or the updated upper fault boundary from the updated average can be compared to a maximum offset. If the offset of the lower fault boundary and / or the upper fault boundary (or if the lower fault boundary and the upper fault boundary are updated, the offset of the updated lower fault boundary and / or the updated upper fault boundary) is greater than the maximum offset, the offset of the lower fault boundary and / or the upper fault boundary (or if the lower fault boundary and the upper fault boundary are updated, the offset of the updated lower fault boundary and / or the updated upper fault boundary) can be decreased to match the maximum offset.

[0058] The upper fault boundary may be a first upper fault boundary, and the lower fault boundary may be a first lower fault boundary. Also, a second upper fault boundary and a lower fault boundary may be implemented. The second upper fault boundary and the lower fault boundary may be conventional wide fault boundaries. The second upper fault boundary may be larger than the first upper fault boundary, and the second lower fault boundary may be smaller than the first lower fault boundary. Alternatively, the second upper fault boundary may be less than or equal to the first upper fault boundary, and the second lower fault boundary may be greater than or equal to the first lower fault boundary. This is possible as a result of the dynamic nature of the first upper fault boundary and the first lower fault boundary and their dependence on additional measured values of the first parameter.

[0059] Comparing a measured value of the first parameter with a fault boundary or an updated fault boundary may include continuously obtaining additional measured values of the first parameter and comparing each measured value with the fault boundary. Further measurements can be made every 0.01 seconds, 0.1 seconds, 1 second, 2 seconds, 5 seconds, 10 seconds, or 15 seconds. Notifying of a fault in the operation of the fault may include emitting an alarm signal. The alarm signal may include any one or any combination of an audio signal, a visual signal, and a vibration.

[0060] When a second upper fault boundary and a lower fault boundary are implemented, different faults in the operation of the device can be determined in response to the first parameter exceeding the second upper fault boundary or being lower than the second lower fault boundary. In this example, different signals may occur in response to the first parameter exceeding the second upper fault boundary or being lower than the second lower fault boundary.

[0061] The method may update the determined average value of the first parameter only if one or more additional measured values of the first parameter are inside the fault boundary. If the average value is an updated average value, the method may update the updated average value only if one or more additional measured values of the first parameter are inside the updated fault boundary from a previous update procedure.

[0062] This method may update the determined average value after each of one or more additional measurements of the first parameter, or after a series of additional measurements of the first parameter. For example, if the first parameter is measured every 0.1 seconds, the average value of the first parameter and the coefficient of variation of the measured values for the determined average value of the first parameter may be updated every 10 measurements, i.e., every 1 second.

[0063] This is advantageous in that at least one boundary associated with the first parameter is dynamically updated with respect to the most recent measured value of the first parameter.

[0064] In response to determining that there is a fault in the operation of the breathing system, the device may pause or shut down so that the operation of the device stops. The method of monitoring the operation of the breathing system may stop. The method of monitoring the operation of the breathing system may resume the step of setting the second parameter when the fault in the operation is resolved. The fault in the operation of the breathing system may be automatically resolved by the device or may be resolved by an operator. Alternatively, the breathing system may continue to operate and the method of monitoring the operation of the breathing system may also continue. In this case, an alarm signal may be continuously generated until the fault in the operation of the breathing system disappears.

[0065] The method of monitoring the operation of the breathing system may also resume the step of setting the second parameter in response to any one of turning off the power of the breathing system or the device, changing any accessory that requires resetting of the fault boundary, changing any parameter setting, changing the treatment performed by the breathing system or the device, or confirmation by the user regarding an existing fault, or any combination thereof.

[0066] The device may be a gas mixer. The gas mixer may form part of an anaesthetic machine or a stand-alone unit arranged to be connected to a gas supply. The gas mixer may comprise an input port for supplying gas from a pressure line. Alternatively, the device may be a continuous positive airway pressure (CPAP) driver, or an infant flow driver.

[0067] According to a further aspect of the invention, there is provided a computer-readable storage medium including instructions which, when executed by a data processor, cause the data processor to perform the method as defined above.

[0068] According to a further aspect of the invention, there is provided a respiratory apparatus comprising a controller and at least one sensor configured to perform the method as defined above.

[0069] The respiratory apparatus may further comprise at least one indicator configured to notify a fault in the operation of the respiratory system in response to additional measurements outside a fault boundary.

[0070] The respiratory apparatus may be integrated with the respiratory system being monitored. The respiratory apparatus may be integrated with a device for supplying gas to the respiratory system. Alternatively, the respiratory apparatus may be remote from the device and respiratory system being monitored.

[0071] According to a further aspect of the present invention, a breathing apparatus for supplying gas to a breathing system is provided. The breathing apparatus comprises at least one sensor configured to obtain a series of measurements of a first parameter of the breathing system and configured to obtain one or more additional measurements of the first parameter in at least one update procedure, and a controller configured to set a fault boundary of the first parameter, the fault boundary depending on a plurality of measurements of the first parameter and configured to update the fault boundary in at least one update procedure, the updated fault boundary depending on a set of updated measurements of the first parameter, the set of updated measurements of the first parameter including at least one of the additional measurements of the first parameter.

[0072] The controller may comprise a processor. The controller may be configured to compare a measurement of the first parameter with the fault boundary. The controller may be further configured to notify a fault in the operation of the breathing system in response to the measurement being outside the fault boundary. The breathing apparatus may further comprise at least one indicator configured to notify a fault in the operation of the breathing system in response to the measurement being outside at least one boundary.

[0073] The controller may be further configured to determine an average value of a plurality of measurements. The controller may be further configured to determine a coefficient of variation of a plurality of measurements.

[0074] The controller may be configured to control a second parameter of the gas supply in the breathing apparatus. The first parameter may further depend on the second parameter. Controlling the second parameter of the gas supply may include supplying the apparatus with gas having a predetermined value or a user-selectable value for the second parameter.

[0075] The breathing apparatus may further comprise at least one sensor configured to measure a second parameter. This at least one sensor may communicate with a controller of the breathing apparatus in order to adjust and / or calibrate the second parameter. This communication may be effected via the controller.

[0076] The breathing apparatus may further comprise a user interface configured to indicate to the user any one or any combination of a set second parameter value, an average value of a plurality of measured values of the first parameter, a determined coefficient of variation of the plurality of measured values of the first parameter, the last measured value of the first parameter, and a failure boundary.

[0077] The at least one indicator may comprise a speaker for supplying an audio signal in response to the first parameter being outside the failure boundary. The at least one indicator may comprise a light source for providing a visual signal in response to the first parameter being outside the failure boundary. Alternatively, the visual signal may be provided on the user interface. The at least one indicator can comprise a plurality of indicators, i.e. a combination of the aforementioned indicators.

[0078] The breathing apparatus may further comprise an inlet. The inlet may be configured to receive gas from an external gas supply source. The inlet may be configured to connect to or be attached to an external gas supply source. The external gas supply source may be in the form of, for example, a gas bottle or canister, or a gas line fixed to a hospital wall. The breathing apparatus may further comprise an outlet. The outlet may be configured to supply gas to a breathing system. The outlet may be configured to connect to or be attached to the breathing system such that the breathing apparatus is in fluid communication with the breathing system. The breathing system may comprise a patient interface for delivering a gas supply to a patient. The breathing system may comprise a breathing tube arranged to deliver the gas supply from the outlet to the patient interface.

[0079] According to a further aspect of the present invention, there is provided a respirator system comprising a respiratory device as defined above and a respiratory system in fluid communication with the respiratory device. The respiratory system comprises a patient interface configured to supply gas to a patient during use and a breathing tube configured to deliver the supply of gas from the respiratory device to the patient interface.

[0080] According to a further aspect of the present invention, there is provided a respirator system comprising a respiratory system and a respiratory device for supplying gas to the respiratory system. The respiratory device comprises at least one sensor configured to obtain a series of measurements of a first parameter of the respiratory system and, in at least one update procedure, to obtain one or more additional measurements of the first parameter, and a controller configured to set a fault boundary for the first parameter, the fault boundary depending on a plurality of measurements of the first parameter and, in at least one update procedure, to update the fault boundary, the updated fault boundary depending on a set of updated measurements of the first parameter, the set of updated measurements of the first parameter including at least one of the additional measurements of the first parameter. The respiratory system comprises a patient interface configured to supply gas to a patient during use and a breathing tube configured to deliver the supply of gas from the respiratory device to the patient interface.

[0081] The controller can comprise a processor. The controller may be further configured to compare the measurements of the first parameter with the fault boundary. The controller can be further configured to notify a fault in the operation of the respiratory system in response to the measurements being outside the fault boundary. The respiratory device may further comprise at least one indicator configured to notify a fault in the operation of the respiratory system in response to the measurements being outside at least one boundary.

[0082] The controller may be further configured to determine an average value of a plurality of measurement values. The controller may be further configured to determine a coefficient of variation of the plurality of measurement values.

[0083] The controller may be further configured to control a second parameter of the gas supply in the breathing apparatus. The first parameter may further depend on the second parameter.

[0084] The breathing system may further comprise a gas supply source connected to the breathing apparatus such that the gas supply source is in fluid communication with the breathing apparatus. The gas supply source may be in the form of, for example, a gas bottle or a gas canister, or a gas line fixed to the wall of a hospital.

[0085] The patient interface may be, for example, a face mask or a nasal mask.

[0086] Possible embodiments of the present invention are described merely by way of example with reference to the accompanying drawings.

Brief Description of the Drawings

[0087]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0088] FIG. 1 shows how the failure boundary of gas parameters in a constant flow therapy device according to the first embodiment is dynamically updated during the operation of the device to determine whether there is an error in the operation of the device and then to inspect for failures.

[0089] Steps 100 to 120 shown by the dashed boxes in FIG. 1 indicate an initialization process in which the long-term average of the sensor is determined.

[0090] In step 100, it is determined whether the device is in the startup mode. The startup mode is defined as a state where the power of the device has just been turned on, a state where the therapy provided by the device has just been changed, or a state where the parameters of the device have just been changed by the operator. When the device is in the startup mode, the initialization process indicated by the dashed box is executed as a continuous loop for 45 seconds. It should be understood that the exact value of this period is not essential and can be changed within a reasonable range.

[0091] If it is determined in step 100 that the device is in the startup mode, the method proceeds to step 120, where the parameter is measured and the long-term average value of the parameter (i.e., the average value for 45 seconds) is updated.

[0092] The measured parameter is a parameter that varies as a result of another parameter predefined by the user, i.e., as a result of using a different patient interface, or as a result of a change in the therapy provided. The measured parameter is also a parameter that varies as a result of a fault in the breathing system to which the device is connected. In the following embodiments, this measured parameter is exemplified as the pressure in the device. The pressure in the device is known to depend on the back pressure in the breathing system to which the device is connected, and the back pressure in the breathing system is known to depend on any fault in that breathing system. Thus, a change in the pressure in the device indicates a change in the back pressure in the breathing system, and if this is large enough, it may indicate a fault in the breathing system.

[0093] When the long-term average value is updated, the method proceeds to step 130. In step 130, it is determined whether the device is still in the startup mode. If YES, the method returns to the start and continues with the initialization process.

[0094] When the 45-second initialization process is executed, in step 130, it is determined that the device is no longer in the startup mode, and the method simultaneously proceeds to step 140 and step 150. In step 140 and step 150, an upper fault boundary and a lower fault boundary are defined. These are defined as values that are 20% higher than the long-term average pressure and 20% lower than the long-term average pressure, respectively. It should be understood that the exact values of these percentages are not essential and can be varied within a reasonable range.

[0095] In step 160, the offset of the lower fault boundary from the long-term average value defined in step 150 is compared with a predetermined minimum offset. The predetermined minimum offset is associated with the measurement accuracy of the sensor that measures pressure in the device. That is, the predetermined minimum offset is equal to the minimum difference between any two measurement values of the sensor necessary for the sensor to reliably distinguish between two values based on its measurement accuracy. If the offset of the lower fault boundary is lower than the predetermined minimum offset assigned to the sensor, in step 170, the lower fault boundary is adjusted. This ensures that the upper and lower fault boundaries do not become too narrow for the long-term average value, especially when the precision or accuracy of the sensor is relatively low, so that a large number of measurement values are not erroneously determined as error measurement values.

[0096] If it is determined that the offset of the lower fault boundary from the long-term average value is lower than the predetermined minimum offset, both the offset of the lower fault boundary and the offset of the upper fault boundary are increased to the predetermined minimum offset. As an example, if the long-term average value in step 120 is 3, with a 20% fault boundary, the upper boundary is 3.6 and the lower boundary is 2.4. The offset of the fault boundary, 0.6, is compared with the predetermined minimum offset assigned to the sensor. If the predetermined minimum offset assigned to the sensor is 2 (i.e., the sensor has an accuracy of ±2), the offset of the lower fault boundary and the offset of the upper fault boundary are increased to 2. As a result, the lower fault boundary becomes 1 (i.e., 3 - 2) and the upper fault boundary becomes 5 (i.e., 3 + 2). In other examples, it will be understood that only one of the fault boundaries may be offset in response to the offset of the lower fault boundary from the long-term average value being lower than the predetermined minimum offset.

[0097] If the offset of the lower fault boundary is higher than the predetermined minimum offset assigned to the sensor, the method then proceeds to step 180.

[0098] The maximum offset may also be defined in a similar manner so that the fault boundaries do not become too wide with respect to the long-term average value.

[0099] In step 180, the sensor acquires a pressure measurement value. This measurement value is compared with the defined fault boundaries in step 190. If it is determined that the measured pressure is outside those fault boundaries, an adaptive alarm fault occurs in step 200, and an alarm signal is generated to inform the operator that there is a fault in the operation of the device. The alarm signal is a combination of a visual signal and an acoustic signal that warns the operator that there is a fault in the configuration of the device. If it is determined that the measured pressure is inside those fault boundaries, no adaptive alarm fault occurs in step 210. This means the end of the algorithm. In either case, the algorithm ends at this point (220) and restarts at step 100.

[0100] Since the device is no longer in the startup mode, in step 100, the method proceeds to step 110. In step 110, if it is determined that there was an adaptive alarm fault in the previous method loop, the pressure measured during the previous method loop is not used to update the long-term average value of the pressure. Instead, the method proceeds directly to step 130 to determine again whether there is still a fault in the operation of the device or whether the fault has been resolved.

[0101] If it is determined that there was no adaptive alarm fault in the previous method loop, the pressure measured during the previous method loop is used in step 120 to update the long-term average value of the pressure. Next, the method proceeds to step 130, and in steps 140 and 150, the upper and lower limits are updated based on the updated long-term average value of the pressure, and the pressure is measured and monitored again in steps 180 to 210.

[0102] Steps 100 to 220 are repeated as a continuous loop until the power of the device is turned off, any attached equipment that requires a reset of the method is replaced, the parameters implemented in the treatment are changed, the change of the treatment performed by the device is initiated, or the user interrupts by checking an existing alarm failure signal. That is, in response to any of these events, it is necessary to repeat the initialization process once again for 45 seconds.

[0103] FIG. 2 shows a method in which the failure boundary of the gas parameters in the constant flow rate treatment device according to the second embodiment is dynamically updated during the operation of the device to determine whether there is an error in the operation of the device and then to check for failures. It should be noted that the long-term average value of the sensor and the average deviation of the sensor are first determined by the initialization process described in connection with FIG. 3 below.

[0104] Although shown differently, for the sake of simplicity of explanation, since this method is actually a continuous loop, it will be described here as starting from step 340.

[0105] In step 340, an average reading value is obtained from a plurality of sensors that measure the same parameters. In step 350, in order to determine the short-term deviation of the sensor, it is calculated how much the average reading value obtained in step 340 deviates from the long-term average value of the sensor. Next, it is determined whether the average reading value obtained in step 340 is outside the failure boundary set to three times the average deviation from the long-term average value of the sensor. That is, it is determined whether the average reading value obtained in step 340 is greater than the first failure boundary or less than the second failure boundary.

[0106] Similar to the method described in connection with FIG. 1, the method of this embodiment also uses the same correction method when it is determined that the failure boundary caused by three times the average deviation from the long-term average value is too narrow. For the sake of brevity, the description will not be repeated here.

[0107] If the average reading value obtained in step 340 is within the failure boundary, the method proceeds to step 360 and the test is passed. That is, it is determined that there is no failure in the operation. If the average reading value obtained in step 340 is outside the failure boundary, the method proceeds to step 370 and the test fails. That is, it is determined that there is a failure in the operation.

[0108] In either case, the method returns to step 300 and performs another iteration of the method. In step 300, it is currently determined whether there is a failure in the operation notified by the alarm. If there is a failure, the method proceeds to step 340 and the update of the long-term average value of the sensor and the average deviation of the sensor is skipped. This is performed so that the long-term average value of the sensor and the average deviation of the sensor used to determine whether a failure has occurred are not distorted by the addition of sensor values that themselves lead to an error alarm signal.

[0109] If there is no current alarm signal, the method proceeds to step 310. In step 310, it is determined whether one second has elapsed since the long-term average value of the sensor and the average deviation of the sensor were updated. Thereby, without using the processing power to update the long-term average value of the sensor and the average deviation of the sensor every time a reading is taken, the reading values of multiple sensors can be obtained every second. If one second has not elapsed, the method re-executes steps 340 to 370 as described above. In an alternative embodiment, it will be understood that the long-term average value of the sensor and the average deviation of the sensor may be updated every time a sensor reading is taken.

[0110] When one second has elapsed since the long-term average value of the sensor and the average deviation of the sensor were updated, this method proceeds to step 320, where the long-term average value of the sensor is updated. Here, the average value of the short-term average readings obtained during the one second since the long-term average value was last updated is added to the long-term average value of the sensor. The long-term average value of the sensor includes 32 readings consisting of the previous 32 short-term average values, and the latest value replaces the oldest of these 32 readings.

[0111] Next, this method proceeds to step 330, where the average of the short-term deviations calculated during the one second since the average deviation was last updated is added to the average deviation of the sensor. The average deviation of the sensor includes 64 readings consisting of the previous 64 average short-term deviations, and the latest value replaces the oldest of these 64 readings.

[0112] Steps 300 to 370 are repeated as a continuous loop until the device is turned off, any accessories that require a reset of the method are replaced, the parameters implemented in the treatment are changed, the start of a change in the treatment performed by the device is initiated, or the user interrupts by checking an existing alarm fault signal. That is, in response to any of these events, it is necessary to repeat the initialization process shown in FIG. 3 for another 45 seconds.

[0113] In step 370, it is determined that there is a malfunction in the operation, and an alarm signal is generated. The alarm signal is a combination of a visual signal and an acoustic signal that alerts the operator that there is a malfunction in the configuration of the device.

[0114] FIG. 3 shows an initialization process in which the long-term average value of the sensor and the average deviation of the sensor are determined before the continuous method of FIG. 2 is implemented.

[0115] In step 400, the operator defines a second parameter (in this case, the flow rate through the device) via the user interface associated with the device. In step 410, measurements of a first parameter (in this case, the pressure in the device) are obtained at 1-second intervals over 45 seconds by a pressure sensor disposed within the device. The average value of the resulting pressure readings is calculated and set as the reference level of the pressure through the respiratory system. The reference level is the long-term average value of the sensor referred to in step 320.

[0116] Simultaneously, in step 420, a deviation of the pressure measurements obtained over those 45 seconds is determined relative to the average pressure calculated in step 410. The deviation of the measurements obtained over those 45 seconds may be the average value of the deviations of each reading obtained over the same 45 seconds (i.e., the average deviation of all readings compared to the average reference level determined in step 410), or it may be the maximum deviation from the reference level experienced over 45 seconds.

[0117] In step 430, a failure boundary is defined as a function of the pressure deviation determined in step 420. Two failure boundaries are defined: a first failure boundary greater than the average pressure calculated in step 410 and a second failure boundary lower than the average pressure calculated in step 410. An example of the calculation for defining the boundaries of the error parameter is shown in more detail below.

[0118] In an alternative embodiment, it is contemplated that an alternative parameter may be set in step 400 and measured in steps 410, 420, and 340. In one example, the pressure may be set in step 400 and the flow rate may be measured in steps 410, 420, and 340.

[0119] In an alternative embodiment, a failure related to the configuration of the device may be resolved by the device itself, in which case the warning signal may be an internal signal transmitted from the device's processor to the device's controller.

[0120] In an alternative embodiment, in step 430, only one failure boundary may be set. In this case, the failure boundary may be greater than or less than the average pressure determined in step 410.

[0121] In an alternative embodiment, in response to determining that there is a failure in the operation of the device in step 370, the operation of the device can be stopped until the operator repairs the failure.

[0122] In an alternative embodiment, the deviation recorded as a reference in step 330 may be the maximum deviation from the long-term average value of the sensor.

[0123] Examples of steps 410 to 430 of FIG. 4 are shown in FIGS. 4, 5 and 6. In these examples, the values are given in arbitrary units for simplicity.

[0124] According to the first example shown in FIG. 4, in step 410, the pressure is measured at 1-second intervals for 45 seconds, and the average pressure is determined to be 20. Therefore, the long-term average value of the pressure is set to 20. The average deviation from the long-term average value of the pressure measurements for these 45 seconds is 2.4.

[0125] In this example, the failure boundary is set as an offset three times the average deviation from the long-term average value. Therefore, the upper boundary is set to 27.2, which is +7.2 from the long-term average value, and the lower boundary is set to 12.8, which is -7.2 from the long-term average value.

[0126] In the second and third examples shown in FIGS. 5 and 6, instead of using the average deviation from the long-term average value of the pressure measurements to calculate the upper and lower boundaries, the maximum deviation is used. Although not shown in FIGS. 5 or 6, this may require the upper and lower boundaries to be offset by a smaller multiple of the calculated deviation.

[0127] In Figure 5, at step 410, the pressure is measured for 45 seconds, and the average pressure is determined to be 20. Accordingly, the long-term average value of the sensor is set to 20. The pressure measurement values vary between 18 and 23 during those 45 seconds. Accordingly, the maximum deviation from the long-term average value of the pressure measurement values is recorded as 3.

[0128] The fault boundary in this example is set as an offset three times the maximum deviation from the long-term average value. Accordingly, the upper boundary is set to 29, which is +9 from the long-term average value, and the lower boundary is set to 11, which is -9 from the long-term average value.

[0129] In Figure 6, at step 410, the pressure is measured for 45 seconds, and the average pressure is determined to be 20. Accordingly, the long-term average value of the pressure is set to 20. The pressure measurement values vary between 18 and 23 during those 45 seconds. In this example, the maximum deviation from the long-term average value of the pressure measurement values is recorded as 2 in the minus direction and 3 in the plus direction.

[0130] The fault boundary in this example is set as an offset three times the maximum deviation in that particular direction from the long-term average value. Accordingly, the upper boundary is set to 29, which is +9 (3×3) from the long-term average, and the lower boundary is set to 14, which is -6 (3×2) from the long-term average.

Claims

Claim 1 A breathing apparatus for supplying gas to a breathing system, at least one sensor configured to obtain a series of measurement values of a first parameter of the breathing system and, in at least one update procedure, configured to obtain one or more additional measurement values of the first parameter; a controller configured to set a failure boundary for the first parameter and, in at least one update procedure, configured to update the failure boundary, wherein the failure boundary is set to be offset from a measured parameter that is a representative value of a plurality of measurement values of the first parameter, and the updated failure boundary is set to be offset from an updated measured parameter using the updated set of measurement values of the first parameter, the updated set of measurement values of the first parameter includes at least one of the additional measurement values of the first parameter, the failure boundary is set to be offset from the measured parameter by an amount that varies according to a plurality of measurement values of the first parameter, and the updated failure boundary is set to be offset from the updated measured parameter by an amount that varies according to the updated set of measurement values of the first parameter; a controller; A breathing apparatus comprising the same. Claim 2 The breathing apparatus according to claim 1, wherein the offset of the failure boundary from the measured parameter is an amount that depends on a coefficient of variation of the plurality of measurement values. Claim 3 The controller is configured to update the measured parameter after the step of obtaining one or more additional measurement values of the first parameter, the updated measured parameter depends on the at least one or more additional measurement values of the first parameter. The breathing apparatus according to claim 1 or claim 2. Claim 4 The breathing apparatus according to claim 3, wherein the controller is configured to set the updated failure boundary to be offset from the updated measured parameter. Claim 5 The offset of the failure boundary from the measured parameter is an amount that depends on a coefficient of variation of the plurality of measurement values, the controller is configured to update the coefficient of variation after the step of obtaining one or more additional measurement values of the first parameter. The updated dispersion coefficient depends on the updated set of measured values of the first parameter, and the offset of the updated failure boundary from the updated measured parameter is an amount that depends on the updated dispersion coefficient. The breathing apparatus according to claim 4.

6. The breathing apparatus according to claim 5, wherein the updated dispersion coefficient depends on at least one of the additional measured values of the first parameter.

7. The measured parameter is an average value of the plurality of measured values, and / or The breathing apparatus according to any one of claims 1 to 6, wherein the updated measured parameter is an average value of a plurality of the updated set of measured values.

8. The breathing apparatus according to any one of claims 1 to 7, wherein the updated set of measured values includes at least one of the measured values on which the updated failure boundary depends and at least one of the additional measured values.

9. The breathing apparatus according to any one of claims 1 to 8, wherein the updated set of measured values includes a plurality of the measured values on which the updated failure boundary depends and at least one of the additional measured values.

10. The breathing apparatus according to claim 9, wherein, in the updated set of measured values, the plurality of measured values on which the updated failure boundary depends are a plurality of measured values selected in a new order from the measured values on which the updated failure boundary depends.

11. The breathing apparatus according to any one of claims 1 to 10, wherein the updated set of measured values includes the same number of measured values as the plurality of measured values on which the updated failure boundary depends.

12. The breathing apparatus according to any one of claims 1 to 11, wherein the updated set of measured values includes at least one of the additional measured values, and at least one of the additional measured values replaces the same number of measured values among the earliest measured values on which the updated failure boundary depends.

13. The breathing apparatus according to any one of claims 1 to 12, wherein the step of setting the failure boundary includes setting an upper failure boundary and a lower failure boundary.

14. The breathing apparatus according to any one of claims 1 to 13, wherein the step of updating the failure boundary includes updating the upper failure boundary and updating the lower failure boundary.

15. The controller is configured to compare the offset of the fault boundary from the measurement parameter or the offset of the updated fault boundary from the updated measurement parameter with a predetermined minimum offset. The predetermined minimum offset is a selected value associated with the measurement accuracy of at least one sensor that acquires a measured value of the first parameter, and the selected value is the minimum difference between any two measured values determined by the at least one sensor that measures the first parameter based on the measurement accuracy of the at least one sensor. The respiratory device according to claim 1 or claim 2.

16. The controller of the respiratory device according to claim 15 is configured to increase the offset of the fault boundary from the measurement parameter or the offset of the updated fault boundary from the updated measurement parameter to the predetermined minimum offset when the offset of the fault boundary from the measurement parameter is less than the predetermined minimum offset or when the offset of the updated fault boundary from the updated measurement parameter is less than the predetermined minimum offset.

17. The controller compares the measured value of the first parameter with the fault boundary or the updated fault boundary after the fault boundary is updated. The respiratory device according to any one of claims 1 to 16, wherein the controller is configured to determine a fault in the operation of the respiratory system in response to the measured value being outside the fault boundary or the updated fault boundary.

18. The controller of the respiratory device according to claim 17 is configured to indicate the fault to the user in response to the step of determining a fault in the operation of the respiratory system.

19. The sensor and / or the controller are configured to repeat the update procedure at least once. The respiratory device according to any one of claims 1 to 18, wherein the fault boundary updated in each subsequent update procedure is the updated fault boundary from the previous update procedure.

20. The sensor and / or the controller are configured to repeat the update procedure at intervals during operation of the respiratory system, including at least the period during which gas is supplied to the respiratory system and / or the period during which treatment is provided to the patient, according to claim 19 of the respiratory device.

21. The respiratory device according to claim 20, wherein at least one of the intervals is less than 10 seconds.

22. The controller is configured to restart a process of setting a failure margin of the first parameter in response to a signal indicating a failure in the operation of the respiratory system, turning off the power of the respiratory device, changing any accessory device, changing a parameter setting, or changing a treatment performed by the respiratory system, according to any one of claims 1 to 21 of the respiratory device.

23. The at least one sensor is configured to obtain a series of measurements of the first parameter of the respiratory system during operation of the respiratory system, and / or the controller is configured to set a failure margin of the first parameter during operation of the respiratory system, according to any one of claims 1 to 22 of the respiratory device.

24. The respiratory device according to any one of claims 1 to 23 is configured to start supplying gas to the respiratory system before the at least one sensor makes a series of measurements of the first parameter of the respiratory system.

25. A respirator system, a respiratory device according to claims 1 to 24, and a respiratory system in fluid communication with the respiratory device, comprising: the respiratory system is a patient interface configured to supply gas to a patient during use, and a breathing tube configured to deliver the supply of the gas from the respiratory device to the patient interface. A respirator system.

26. A respirator system comprising a respiratory system and a respiratory device for supplying gas to the respiratory system, wherein the respiratory device is at least one sensor configured to obtain a series of measurements of a first parameter of the respiratory system and configured to obtain one or more additional measurements of the first parameter in at least one update procedure. A controller configured to set a fault boundary for the first parameter and to update the fault boundary in at least one update procedure, wherein the fault boundary is set to be offset from a measured parameter that is a representative value of a plurality of measured values of the first parameter, and the updated fault boundary is set to be offset from an updated measured parameter that is updated using the set of updated measured values of the first parameter, the set of updated measured values of the first parameter includes at least one of the additional measured values of the first parameter, the fault boundary is set to be offset from the measured parameter by an amount that varies according to a plurality of measured values of the first parameter, and the updated fault boundary is set to be offset from the updated measured parameter by an amount that varies according to the set of updated measured values of the first parameter, comprising a controller, The respiratory system is, A patient interface configured to supply gas to a patient during use, A breathing tube configured to deliver the supply of the gas from the breathing apparatus to the patient interface, comprising, A respirator system.

27. A method for detecting a fault in a respiratory system, comprising: (a) obtaining a series of measured values of a first parameter of the respiratory system; and (b) setting a fault boundary for the first parameter, The method includes at least one update procedure, the update procedure comprising: (c) obtaining one or more additional measured values of the first parameter, (d) A step of updating the failure boundary, wherein the failure boundary is set to be offset from a measured parameter that is a representative value of a plurality of measured values of the first parameter, and the updated failure boundary is set to be offset from an updated measured parameter updated using the set of updated measured values of the first parameter, the set of updated measured values of the first parameter includes at least one of the additional measured values of the first parameter, the failure boundary is set to be offset from the measured parameter by an amount that varies according to a plurality of measured values of the first parameter, and the updated failure boundary is set to be offset from the updated measured parameter by an amount that varies according to the set of updated measured values of the first parameter, the step, including Method. **Claim 28** An apparatus for detecting a failure of a respiratory system, A sensor for obtaining a measured value of a first parameter, A controller configured to execute the method according to claim 27, An apparatus comprising. **Claim 29** The apparatus according to claim 28, wherein the apparatus is an apparatus for supplying gas to the respiratory system. **Claim 30** The apparatus according to claim 29, wherein the apparatus is a gas mixer. **Claim 31** The apparatus according to any one of claims 28 to 30, wherein the at least one sensor includes a plurality of sensors arranged at different positions of the whole apparatus. **Claim 32** A computer-readable storage medium, When executed by a data processor, including instructions for causing the data processor to execute the method according to claim 27, A computer-readable storage medium. **Claim 33** Further comprising a gas supply source configured to supply gas to the respiratory system, The second parameter of the respiratory system is controlled during the supply of gas to the respiratory system, and the first parameter of the respiratory system depends on the second parameter and the respiratory system such that a change in the first parameter can indicate a failure in the respiratory system. The respiratory device according to claim 1. **Claim 34** The respiratory device according to claim 33, further comprising at least one sensor configured to measure the second parameter. **Claim 35** The respiratory device according to claim 33 or claim 34, wherein the second parameter is a flow rate or a pressure in the respiratory device or the respiratory system.

36. The respiratory device according to any one of claims 33 to 35, wherein the first parameter depends on any failure in the configuration of the respiratory system.

37. The respiratory device according to any one of claims 33 to 35, wherein the first parameter is a parameter related to the influence of the respiratory system on the gas supply in the respiratory device.

38. The respiratory device according to any one of claims 33 to 37, wherein the first parameter is a parameter not controlled in the respiratory device.

39. The respiratory device according to any one of claims 33 to 38, wherein the first parameter is any one of a flow rate, a back pressure in the respiratory system, or a patient pressure.

40. The respiratory device according to any one of claims 33 to 35, wherein the first parameter is a pressure in the respiratory device or the respiratory system.

41. The method further includes a step of supplying gas to the respiratory system, wherein the second parameter of the respiratory system is controlled during the supply of gas to the respiratory system, and the first parameter of the respiratory system depends on the second parameter and the respiration such that a change in the first parameter can indicate a failure in the respiratory system. The method according to claim 27.

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