Restless button access hemorrhages

Description

Technical field

[0001] The present disclosure relates to a monitoring device for a dialysis machine for detecting a venous needle disconnection by means of venous pressure monitoring based on a limit value setting. Furthermore, the present disclosure relates to a monitoring method for detecting a venous needle disconnection. Background of the invention

[0002] A venous needle disconnection, also known as access hemorrhage, is estimated to occur at least once a year in every dialysis center worldwide. This type of needle disconnection involves a break in the connection between a venous access device and an infusion line. If left undetected, a venous needle disconnection can lead to the patient's death within minutes. The risk of life-threatening disconnections is increased by a restless patient, a lack of awareness of pressure monitoring on a dialysis machine, and inadequate patient monitoring.

[0003] To monitor venous access, blood pressure at the entry point into a catheter or shunt can be used. This involves measuring venous pressure after the dialyzer and before the final clamp of the dialysis machine. If the pressure rises or falls outside a defined range, the blood pump stops immediately, triggering a patient-safe state.

[0004] In existing systems, lower and upper limits can only be individually adjusted during treatment. Such individual adjustments are cumbersome, as these settings are often located in a deeper menu requiring some machine knowledge, for example: "Submenu Input / Limits / PV / PV / Upper Δ or OV Lower Δ".

[0005] For example, setting asymmetric pressure monitoring as a preset can only be done by a technical service within the Technical Support and Maintenance (TSM) program.

[0006] Another disadvantage is that a gradually decreasing venous pressure is often not recognized by the dialysis machine as a venous needle disconnection. Furthermore, any triggered venous pressure alarm can be cleared by the user simply acknowledging it, whereby restarting the blood pump results in an adjustment of the current venous pressure. State of the art

[0007] The primary purpose of pressure monitoring is to reliably detect various complications that can occur during extracorporeal blood therapy. These complications include faulty vascular access, which can be caused, for example, by the cannula slipping out or becoming suctioned. Pressure changes also occur when the volume of blood pumped by a blood pump changes.

[0008] EP3445419 A1 relates to a blood treatment device comprising a controller, a pump actuator for pumping blood through an extracorporeal blood circuit comprising an arterial line (upstream to a dialysis filter) and a venous line (downstream to a dialysis filter), and a pressure sensor for detecting the pressure in the venous line, wherein the controller has a detection function for detecting a venous needle disconnection, which compares a value determined from the pressure in the venous line with a threshold value to detect a venous needle disconnection, wherein the threshold value with which the detection function compares the value determined from the pressure in the venous line can be variably set and / or is variably set by the controller.

[0009] EP3019212 A1 relates to a method for monitoring an extracorporeal blood treatment device with an extracorporeal blood circuit and, in particular, a venous needle disconnection by means of pressure pulse measurement on the extracorporeal blood circuit. Furthermore, EP3019212 A1 relates to a device for carrying out a monitoring method and a blood treatment device that includes such a monitoring device.

[0010] In the aforementioned known systems, an alarm is triggered if certain fixed limits are exceeded, in order to ensure patient safety continuously and completely. However, during dialysis treatment, dynamic adjustment of the limits is advantageous, as static limits have the disadvantage of triggering false alarms in certain situations, which can negatively impact the dialysis treatment.

[0011] US 2018 / 126062 A1 describes a monitoring system which performs a method for detecting an interruption of a fluid connection between a first fluid-containing system and a second fluid-containing system. Brief description of the Revelation

[0012] The purpose of the present disclosure is to eliminate or at least reduce the aforementioned disadvantages of the prior art and preferably to enable improved handling of restless patients, further preferably to eliminate any existing lack of knowledge about the pressure monitoring of the dialysis machine and thus improve any inadequate monitoring of the patient in order to avoid life-threatening venous needle disconnections as far as possible and to improve the usability of the dialysis machine.

[0013] The above problem is solved by the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

[0014] Accordingly, the aforementioned problem is solved by a monitoring device of an extracorporeal blood treatment machine, preferably a dialysis machine, for detecting a venous needle disconnection by means of venous pressure monitoring based on a limit value setting. According to the disclosure, the monitoring device has a button (icon), hereinafter also referred to as the "Restless Button," which, when activated, is designed and configured to cause the monitoring device to set a lower limit value and an upper limit value depending on a (measured) actual pressure.The monitoring device is designed and configured, after a predetermined time, to increase the lower limit LCL to a new lower limit nLCL if the moving average x has increased by more than a predetermined amount, or to decrease the lower limit LCL to a new lower limit nLCL if the difference between a new moving average x and the lower limit LCL is less than a lower target limit, and to detect an incremental decrease in venous pressure, an incremental decrease being present if the new lower limit nLCL falls by more than a predetermined percentage p% of a previous moving average x.

[0015] In other words, such a preferably pre-configured "restless button" improves patient monitoring, particularly of the inserted access point, during dialysis treatment. Pressing the button triggers a pre-configured venous alarm window and monitoring of incrementally decreasing venous pressure. With incremental pressure monitoring, the dialysis system / monitoring device should detect an incrementally decreasing venous pressure when the button is pressed. According to current technology, an incrementally decreasing venous pressure cannot be detected by existing algorithms if the lower venous limit is adjusted to the current pressure profile after a venous pressure alarm is triggered or the blood flow is readjusted.

[0016] A button is preferably a touch icon on a touchscreen display, which can be activated by touching or pressing it. In other words, a button is a control element in a graphical user interface, alternatively designed as a knob or button.

[0017] Furthermore, it is preferred that the button be located on a screen of the dialysis machine to improve the usability of the monitoring device. Preferably, this button remains visible and operable on the screen regardless of which submenu is currently displayed.

[0018] Preferably, the actual pressure is a moving average in a range of preferably 48 mmHg to 69 mmHg. An evaluation of approximately 20,000 hemodialysis treatments shows an average upper venous pressure window of about 69 mmHg and a lower pressure window of about 48 mmHg. Both average pressure values ​​are significantly higher than the pressure values ​​of 40 mmHg and 25 mmHg proposed in a subsequent aspect, which leads to an increase in the sensitivity of the monitoring and is in accordance with the present disclosure.

[0019] It is advantageous if the lower and upper limits are asymmetrical relative to the actual pressure. In other words, the (automatically triggered / executed upon pressing the button) setting of a lower and upper limit results in an asymmetrical pressure range. This means that the lower and upper venous limits are (automatically) fixed for asymmetrical venous pressure monitoring when the button is pressed.

[0020] Advantageously, a greater difference between the upper limit and the actual pressure is preferable to a greater difference between the lower limit and the actual pressure. Asymmetric pressure monitoring with a narrow lower limit leads to improved sensitivity to venous needle disconnection.

[0021] It is preferred that the lower limit be adjustable to 25 mmHg below the actual pressure and the upper limit to 40 mmHg above the actual pressure. In other words, when the button is pressed, the lower and upper venous limits are fixed at 25 mmHg below and 40 mmHg above the actual pressure, respectively, for asymmetric venous pressure monitoring. Evaluation of the approximately 20,000 hemodialysis treatments in Germany mentioned above showed that 19.9% ​​fell below the lower pressure limit of 25 mmHg below the actual pressure. The upper pressure limit of 40 mmHg prevents false alarms triggered by shunt arm movements that could disrupt the dialysis process.

[0022] It is advantageous if the monitoring device is designed and configured to increase the lower limit LCL to a new limit nLCL after 250 to 350 seconds, preferably 300 seconds, if the moving average has increased by more than a predetermined amount, preferably more than 2.5 mmHg. Waiting for the predetermined time has the advantage of avoiding false alarms, since experience has shown that a patient is restless at the beginning of treatment until they have settled into a comfortable position.

[0023] It is preferred that the monitoring device is designed and configured to reduce the lower limit LCL to a new limit nLCL after a predetermined time, preferably 300 seconds, if the distance between the new moving average and the lower limit is less than a lower target limit.

[0024] Advantageously, the monitoring device is designed and configured to secure the new lower limit nLCL and to check whether an incremental decrease is occurring, with the monitoring device being designed to issue an alarm in the event of an incremental decrease.

[0025] It is preferred that the monitoring device is designed and configured to verify that the previously set lower limit LCL does not deviate by more than a predetermined percentage p% from the moving average of the last predetermined time, preferably 300 seconds. It is preferred that the percentage p% be between 1% and 30%. In other words: Inkrementell _ ALM = LCL < nLCL * 1 + p

[0026] In other words, the newly set venous lower limit nLCL must not be below the calculated moving average of the previously set venous lower limit LCL, which is calculated as follows: PV Δ = ∑ T = 1 300 PVmin T + PVmin t ∗ 1 T + t ∗ p%

[0027] This monitoring is intended to protect the patient from, for example, undetected bleeding into the tissue by detecting a drop in pressure. Furthermore, the alarm is handled as follows: The button, i.e., the automatic setting of an asymmetric pressure window and the algorithm for monitoring an incrementally decreasing venous pressure, does not replace the implemented algorithm for monitoring the venous shunt pressure until the button has been pressed by a user.

[0028] It is advantageous if the monitoring device is designed and configured to issue an alarm when a lower limit is undershot and when an upper limit is exceeded, whereby at least the alarm when the lower limit is undershot must be acknowledged by means of a PIN entry.

[0029] Preferably, the monitoring device is designed and configured to issue a different alarm after a predetermined number of alarms, preferably two or more, each requiring PIN entry. In other words, when the button is pressed, an incrementally decreasing venous pressure is detected such that after two or three venous pressure alarms have been acknowledged, a "red alarm" is triggered, and the blood pump remains stopped. This "red alarm" displays detailed instructions on a screen of the dialysis machine on how to control venous access and can only be deactivated using a PIN code. It is preferred that the PIN code is exclusively in the possession of the head nurse.

[0030] In other words, for example, when a first alarm occurs, the blood pump stops. Once this first alarm is acknowledged without PIN entry, the blood pump restarts. If a second, or preferably third, alarm occurs, the blood pump stops again, and the alarm can only be acknowledged by entering a PIN. Should the second or third acknowledgment result in a "red alarm," the blood pump remains stopped.

[0031] It is preferred that, when the venous (shunt) pressure drops below the lower limit, the user receives instructions to check the shunt arm, and the triggered alarm can only be acknowledged by entering a PIN. In other words, to emphasize the criticality of the venous pressure alarm and to recommend that the user check the shunt arm, the alarm can only be acknowledged with a PIN code. Triggering the alarm shuts off the blood supply to that side, stopping the blood pump and preventing patient blood from leaking into the surrounding area or tissue.

[0032] It is preferred that the alarm can be acknowledged / must be acknowledged without a PIN entry if the upper limit is exceeded, and that the alarm can be acknowledged / must be acknowledged with a PIN entry if the lower limit is not reached.

[0033] Alternatively, it is preferred that the alarm can be acknowledged / must be acknowledged with a PIN entry both when the upper limit is exceeded and when the lower limit is not reached.

[0034] It is advantageous if an alarm is triggered when the upper venous pressure limit is exceeded, which stops the blood pump. No PIN entry is required to acknowledge this alarm. Exceeding the upper venous pressure is due to patient movement, particularly kinking of the venous catheter. The alarm should nevertheless provide detailed instructions on how to check the venous catheter and venous access.

[0035] Furthermore, the present disclosure relates to an extracorporeal blood treatment machine, preferably a dialysis machine, which is characterized by a monitoring device according to one of the preceding aspects.

[0036] Furthermore, the present disclosure relates to a monitoring method for detecting a venous needle disconnection with venous pressure monitoring based on a limit setting, comprising the following steps: Pressing the button to set a lower venous limit LCL and an upper venous limit based on a current pressure, detecting a drop below the lower venous limit LCL after a predetermined time, decreasing the lower limit LCL to a new lower limit nLCL if the moving average x has increased by more than a predetermined amount, or increasing the lower limit LCL to a new lower limit nLCL if the difference between a new moving average x and the lower limit LCL is less than a lower target limit, saving the new lower limit nLCL, and checking for an incremental decrease, whereby an incremental decrease occurs if the new lower limit nLCL falls by more than a predetermined percentage p% of a previous moving average x.

[0037] Optionally, an alarm can be triggered if the condition is present.

[0038] According to the invention, an incremental decrease occurs when the new lower limit falls below the previous moving average by more than a predetermined percentage p%.

[0039] In summary, the present disclosure offers the advantage of improved sensitivity to venous needle disconnection and the ability to detect incrementally decreasing venous pressure. Furthermore, the disclosure facilitates the management of agitated patients, for example, those suffering from dementia, blindness, unconsciousness, etc. Another advantage is the now straightforward operation and adjustment of optimal shunt monitoring. This leads to greater safety for night and home dialysis patients and reduces the number of life-threatening venous needle disconnections. Brief description of the characters

[0040] Fig. 1This is a representation to illustrate an evaluation for determining a moving average of venous pressure. Fig. 2 This is a representation to illustrate an incremental decline according to the state of the art. Fig. 3 This is a representation to illustrate an incremental decline according to the present disclosure. Fig. 4 is a flowchart illustrating the procedural steps according to the monitoring procedure as described in the present disclosure. Figures 5 to 7 Each image is a representation illustrating the display of a dialysis machine. Fig. 8 shows an exemplary dialysis machine with an integrated display according to the Figures 5 to 7 . Description of the exemplary implementations

[0041] The following are examples of embodiments of the present disclosure based on the accompanying figures.

[0042] Fig. 1This is a representation to illustrate an evaluation for determining a moving average of venous pressure. Fig. 1 The graph shows the number of treatments (multiplied by a factor of 10⁴) on the x-axis and the venous pressure in mmHg on the y-axis. Empty points represent the upper limit of the venous pressure, and solid points represent the lower limit of the venous pressure (hereinafter also referred to as PV). These points allow for the calculation of a moving average (x) for the upper limit and a moving average (x) for the lower limit.

[0043] Based on the diagram, an evaluation of approximately 20,000 hemodialysis treatments was performed, and the starting values ​​of approximately 69 mmHg as the moving average x for the upper limit and approximately 48 mmHg as the moving average x for the lower limit were determined. These average pressure values ​​are significantly higher than the pressure values ​​of 40 mmHg and 25 mmHg used in the present disclosure for setting the asymmetric venous pressure window. This results in an increase in the sensitivity of the monitoring.

[0044] Fig. 2 This is a representation illustrating an incremental decline according to the state of the art. The graphic of Fig. 2 as well as the graphic of the Fig. 3 The x-axis represents time in seconds within a time range of 6000 seconds to 7800 seconds, and the y-axis represents venous pressure in mmHg.

[0045] In the graphic of Fig. 2In accordance with the state of the art, a venous pressure curve is shown, represented by a continuous line labeled "venous_pressure_current". A first upper limit (hereinafter also referred to as "venous_max_current") is shown at 250 mmHg and a first lower limit (hereinafter also referred to as "venous_min_current") at 200 mmHg. After approximately 300 seconds, an alarm is triggered due to a drop in the current venous pressure, prompting a check of the access and the adjustment of the limits to the new pressure value. After another 300 seconds, the lower limit is adjusted again, in this case increased, and the upper limit is decreased. At second 7200, the pressure values ​​exceed the upper limit, requiring only an adjustment of the upper limit. After the pressure curve triggers another alarm due to a pressure drop, the limits are adjusted downwards according to the current pressure.

[0046] The pressure curve shows an incremental, hidden decrease in pressure. This incremental venous pressure decrease cannot be detected by current algorithms because a lower limit is adjusted to the current pressure curve after a venous pressure alarm is triggered or blood flow is readjusted. The type of previous alarm(s) is not taken into account.

[0047] In the graphic of Fig. 3 , which corresponds to the diagram in Fig. 2 very similar is a venous pressure curve (according to Fig. 2The graph is shown with a continuous line labeled "venous_pressure_current". An initial upper limit (hereinafter also referred to as "venous_max_current") is marked at 260 mmHg, and an initial lower limit (hereinafter also referred to as "venous_min_current") at 200 mmHg. After approximately 300 seconds, an alarm is triggered due to a drop in the current venous pressure, prompting a check of the access and adjustment of the limits to the updated pressure value. After another 300 seconds, the lower limit is adjusted again, this time increasing it, and the upper limit decreasing it. At second 7200, the pressure exceeds the upper limit, requiring only an adjustment of the upper limit. Shortly before second 7400, another alarm is triggered due to a pressure drop, at which point the limits are adjusted downwards according to the current pressure.The lower limit was adjusted again between second 7600 and second 7700.

[0048] In Fig. 3 Therefore, the upper and lower limits according to the print window are shown as the starting values. Furthermore, it shows Fig. 3 the limit value adjustments provided for according to the invention, the procedure being described later Fig. 4 will be described in more detail.

[0049] Fig. 4 This is a flowchart illustrating the procedural steps according to the monitoring procedure as described in this disclosure. Fig. 4 In the first step (S1), the Restless button is pressed, and a moving average value x is determined based on the current venous pressure according to step S2. After pressing the button according to S1, an asymmetric venous pressure window with an upper and a lower limit LCL is automatically set based on the moving average value x.

[0050] In the OR logic R1, when an alarm is triggered, it is determined / checked whether a predetermined time, preferably 300 seconds, has elapsed since the last setting of the asymmetric print window.

[0051] If a predetermined time has elapsed since the last setting of the upper and lower limits LCL according to R1, i.e., the predetermined time Δt > 300 seconds (R1: yes), the current venous pressure (actual pressure) is recorded in the OR logic R2, and it is checked whether the moving average x has increased by more than 2.5 mmHg. If the moving average has increased by more than 2.5 mmHg (R1: yes, increased), the previous lower limit LCL is increased accordingly according to step S3, and a new lower limit nLCL is defined as a target limit.

[0052] In the event that R2 determines that the difference between the current averaged actual value and the previous lower limit is less than a target limit, the lower limit will be reduced accordingly according to step S4 and a new lower limit nLCL will be provided as a target limit.

[0053] In the event that neither step S3 nor step S4 is fulfilled in R2, the blood pump is readjusted according to step S5 (R2: no) according to the current actual pressure.

[0054] In the event that a predetermined time has not elapsed since the last setting of the upper and lower limits LCL according to R1, the lower and upper limits LCL according to step S6 (R1: no) are retained unchanged.

[0055] If a change to the lower limit is necessary following step S3 or step S4, the new lower limit nLCL is saved in step S7. In a subsequent OR logic operation R3, it is checked whether the last set lower limit LCL deviates by no more than a predetermined percentage p% from the moving average x of the last predetermined time, preferably the last 300 seconds. If the previous lower limit LCL is less than the sum of the new lower limit nLCL and the predetermined percentage p% of the moving average x (R3: yes), step S8 indicates an incremental decrease in venous pressure, the device displays a venous needle disconnection alarm, and the blood pump stops. The device restarts the monitoring procedure. If R3 is not true, the monitoring procedure proceeds to step S9 (R3: no), and the new venous lower limit nLCL is set.

[0056] Figures 5 to 7 Each of these is a representation illustrating a display 2 of a dialysis machine.

[0057] This shows Fig. 5 The initial display on screen 2 includes a button 1 (also called the "Restless Button"). Button 1 is located in a field labeled "restless patient." This field also displays the venous pressure curve. Furthermore, all of the patient's vital parameters are shown on screen 2 along with the initial display.

[0058] Fig. 6 After an alarm is triggered due to a venous needle disconnection, the system displays a detailed description of how to resolve the alarm, including possible causes. The following points are examples of causes for an alarm due to a lower threshold being breached: (1) Decannulation of the venipuncture cannula (2) Bleeding in the tissue (3) Tube rupture in the venous tubing system (4) Disconnection of tubing connections (5) Blood clot formation in the dialyzer

[0059] Suggested solutions are shown on the display as follows: (1) Decannulation of the venipuncture cannula: Check the venous puncture site to ensure the needle is still in the shunt and that no blood is present outside the bloodstream. (2) Tissue bleeding: Check for bleeding into the tissue around the puncture site (look for bruising). (3) Venous tubing rupture: Check the entire venous tubing system from the bladder separator to the puncture site for tears. (4) Tubing connections disconnected: Check the tubing connection from the tubing system to the cannula and also the venous pressure transducer. (5) Blood clot formation in the dialyzer: Check the dialyzer for blood clots and flush it with saline solution if necessary.

[0060] Furthermore, below the detailed description there is a button to unlock the alarm.

[0061] Fig. 7After an alarm is triggered due to a rise in venous pressure, the system displays a detailed description of how to resolve the alarm, including possible causes. The following points are examples of causes for an alarm due to exceeding an upper limit: (1) Venous tube twisted or kinked (2) Filter screen of the bladder catcher clogged (3) Blood clot in the area of ​​the fistula

[0062] Suggested solutions are shown on the display as follows: (1) Check the venous blood tubing system for twists or kinks. (2) Check the filter screen in the venous bladder trap for blockages. Replace the blood tubing system if necessary. (3) Check for possible venous shunt stenosis. Consult a vascular surgeon if necessary.

[0063] Furthermore, below the detailed description there is a button to unlock the alarm.

[0064] Fig. 8 shows an exemplary dialysis machine 3 with an integrated display 2 according to the Figures 5 to 7 . Reference sign

[0065] 1 Button 2 Display 3 Dialysis machine LCL lower limit nLCL new lower limit PV venous pressure X moving average %p predetermined percentage

Claims

1. A monitoring device of an extracorporeal blood treatment machine, preferably a dialysis machine for detecting a venous needle disconnection via venous pressure monitoring based on a threshold value setting, comprising a button (1), preferably arranged on a screen (2) of the dialysis machine, which is provided and configured, upon actuation, to cause the monitoring device to set a lower threshold value (LCL) and an upper threshold value depending on an ACTUAL pressure, characterized in that the monitoring device is provided and configured to increase the lower threshold value (LCL) to a new lower threshold value (nLCL) after a predetermined time has elapsed if the floating average value (x) of the ACTUAL pressure has increased by more than a predetermined amount, or to reduce the lower threshold value (LCL) to a new lower threshold value (nLCL) if a difference between a new floating average value (x) of the ACTUAL pressure and the lower threshold value (LCL) is smaller than a lower target threshold value, and to detect an incremental decrease in the venous pressure, wherein an incremental decrease is present if the new lower threshold value (nLCL) falls by more than a predetermined percentage (p%) of a previous floating average value (x).

2. The monitoring device according to claim 1, characterized in that the ACTUAL pressure is a floating average value (x) in a range of preferably 48 mmHg to 69 mmHg.

3. The monitoring device according to claim 2, characterized in that the lower threshold value (LCL) and the upper threshold value are asymmetrical to the ACTUAL pressure and / or a difference between the upper threshold value and the ACTUAL pressure is greater than a difference between the lower threshold value (LCL) and the ACTUAL pressure.

4. The monitoring device according to one of the claims 1 to 3, characterized in that the lower threshold value (LCL) is settable 25 mmHg below the ACTUAL pressure and the upper threshold value is settable 40 mmHg above the ACTUAL pressure.

5. The monitoring device according to one of claims 1 to 4, characterized in that the monitoring device is provided and configured to increase the lower threshold value (LCL) to the new lower threshold value (nLCL) after 300 seconds have elapsed, if the floating average value (x) has increased by more than the predetermined amount, preferably more than 2.5 mmHg, or to decrease the lower threshold value (LCL) to the new lower threshold value (nLCL) if a distance between the new floating average value (x) and the lower threshold value (LCL) is less than the lower target threshold value.

6. The monitoring device according to claim 5, characterized in that the monitoring device is provided and configured to save the new lower threshold value (nLCL) and to check whether an incremental decrease is present, wherein in case of an incremental decrease the monitoring device is provided to output an alarm.

7. The monitoring device according to claim 6, characterized in that the monitoring device is provided and configured to output an alarm when a lower threshold value (LCL) is undershot and when an upper threshold value is exceeded, wherein at least the alarm when the value falls below the lower threshold value (LCL) is to be acknowledged via a PIN entry.

8. The monitoring device according to claim 7, characterized in that the monitoring device is provided and configured to issue an alarm different from the first alarm for a predetermined number of alarms to be acknowledged with a PIN input, preferably two alarms, further preferably three alarms.

9. An extracorporeal blood treatment machine, preferably dialysis machine, which is characterized by a monitoring device according to one of the preceding claims.

10. A monitoring method for detecting a venous needle disconnection with venous pressure monitoring based on a threshold value setting, comprising the following steps: - actuating the button to set a lower venous threshold value (LCL) and an upper venous threshold value based on an ACTUAL pressure, - detecting a drop below the lower venous threshold value (LCL), - after a predetermined period of time has elapsed, decreasing the lower threshold value (LCL) to a new lower threshold value (nLCL) if the floating average value (x) has increased by more than a predetermined amount, or increasing the lower threshold value (LCL) to a new lower threshold value (nLCL), if the difference between a new floating average value (x) and the lower threshold value (LCL) is less than a lower target threshold value, - saving the new lower threshold value (nLCL), and - checking if an incremental decrease is present, wherein an incremental decrease is present if the new lower threshold value (nLCL) falls more than a predetermined percentage (p%) from a previous floating average value (x).