EP3899971A1

EP3899971A1 - Method and device for creating a continuous course and for predicting the fluid balance of a patient

Info

Publication number: EP3899971A1
Application number: EP19832639.9A
Authority: EP
Inventors: Christian Baumgartner; Katharina BERGMOSER
Original assignee: B Braun Melsungen AG
Current assignee: B Braun Melsungen AG
Priority date: 2018-12-20
Filing date: 2019-12-18
Publication date: 2021-10-27
Also published as: DE102018009902A1; CN113383394A; US20220076833A1; WO2020127490A1

Abstract

The invention relates to a method for detecting the fluid balance of a patient, in which a transfer function is created for the patient, by means of which a continuous course of the fluid balance of the patient can be determined for the past and a continuous course of the fluid balance can be predicted for the future. The invention also relates to a device for carrying out the method according to the invention, and to a program product.

Description

Method and device for creating a continuous course and

Predicting a patient's fluid balance

Technical field

The present invention relates to a method and an apparatus for

Creation of a continuous course of the preferably cumulative fluid balance of a patient and / or the preferably cumulative fluid supply to one

Patients in the past and to predict a continuous course of the preferably cumulative fluid balance of the patient and / or the preferably cumulative fluid supply to the patient in the future. Another aspect of the present invention relates to a program product. The term "cumulative" is to be understood below as the "accumulation from all sources and sinks over time".

State of the art

In modern intensive care, patients are usually supplied with large amounts of liquids, for example in the form of medications, nutrient solutions, saline solutions or liquids for extracorporeal blood treatment. In most cases, a patient is supplied with an excess of fluid in the initial phase of his stay in the intensive care unit.

In order to stabilize the patient hemodynamically in the long term, a balance must be found between the total amount of liquids supplied to the patient and the total amount of liquids lost by the patient. This is usually achieved in the context of a fluid balance of the patient by subtracting the total amount of liquids lost by the patient from the total amount of liquids supplied to the patient at a certain point in time to determine a fluid balance of the patient at this point in time and to adapt the liquid supply accordingly. In clinical practice, such a fluid balance is usually collected every 24 hours during the patient's stay in the intensive care unit. The

The treating doctor is therefore only able to use discrete values or individual data points for the fluid balance, on the basis of which the further one is available

Course of treatment (e.g. drug administration, fluid administration etc.) must be decided. In addition, the attending doctor usually only receives a relative fluid balance, which reflects the change in the fluid balance of the patient since the last fluid balance assessment (i.e. e.g. 24 hours beforehand).

The information that the attending physician receives with regard to the fluid balance of a patient and on the basis of which a decision must be made about the further course of treatment often reflects the fluid balance state of the patient only inaccurately and thus offers a suboptimal

Basis for the decision to stop the further course of treatment.

This increases what is associated with a stay in the intensive care unit

Patient risk.

Object of the invention

Because an accurate survey and adjustment of the fluid balance of a patient as well as the coordinated administration of medication are particularly important

seriously ill intensive care patients is an important factor in reducing mortality, the present invention is based on the object, a method and a

To provide a device which provides the treating physician with more precise and detailed information regarding the fluid balance of a patient and thus a more solid basis for the decision about the further course of the patient

Provides treatment to the patient.

Summary of the invention

The above object is achieved by a method according to claim 1, an apparatus according to claim 8 and a program product according to claim 11. The program product can be used to retrofit existing devices, such as blood treatment or fluid balancing systems, in the sense of the invention.

In a method according to the invention for fluid balancing or recording the fluid balance of a patient, in contrast to the prior art, not only individual data points of the fluid balance are ascertained, but a transfer function (also referred to as a transfer function, system function or controlled system) is created for a patient by means of the a (measured or calculated from measured values) preferably continuous course of the fluid balance of the patient can be simulated for the past (afterwards) and a predicted preferably continuous course of the fluid balance (or a predicted one)

Trajectory of the trend of the fluid balance) can be created for the future.

A transfer function used in the context of the invention can be, for example, a discrete-time transfer function P [z] with the general formula shown below:

Y [z] and U [z] are the Z transforms of output and

Input variables bo to b _m and ao to a _n are the coefficients of the transfer function. In addition, n denotes the degree of the transfer function.

The main idea of the invention is that

- from a (measured or provided by a nutritional method) course or trend of a cumulative fluid supply (CFI) and

- from a course or trend of a cumulative fluid balance (CFB), which was / is calculated from the course or trend of the cumulative fluid supply (measured or provided by a nutritional method) by subtracting from all cumulative fluid losses taking place / taking place a transfer function is developed to simulate the course or trend of the cumulative fluid balance. A future progression or trend of the cumulative fluid supply predicted by a nutritional method then finds its way into the transfer function in order to obtain a predicted continuous progression or

Create trend of the patient's cumulative fluid balance for the future ..

This means that the course of the CFI for the past is preferably only determined using the approximation method. The course of the CFB for the past is determined by using the CFI, which is preferably approximated by means of an approximation method, as the input for the transfer function. The output sequence then contains the approximated CFB. The CFI is predicted by extrapolating the CFI, which is preferably approximated with the aid of the approximation method, or the prediction of a target CFI can also be carried out by integrating the transfer function into a control loop and setting a target CFB.

The CFB is predicted by using the CFI, which is preferably approximated and extrapolated via the approximation method, as the input for the transfer function. The output sequence then contains the approximated, predicted CFB. , or the CFB can also be predicted by integrating the transfer function into a control loop and defining a target CFB. The exit of the

The control loop then contains the actually expected target CFB, which, if the control loop manages to find a suitable target CFI curve, corresponds to the target CFB.

In other words, the transfer function is used in combination with the

Approximation method as a mathematical model, by means of the data acquired, for example with regard to the fluid supply to the patient and that of the patient

Patients lost fluid, both a continuous course or trend of the fluid balance and / or the fluid supply of the patient for the past simulated as well as a continuous course or trend of the fluid balance and / or the

Fluid supply to the patient can be predicted for the future. A cumulative fluid balance is preferably represented by means of the transfer function, which, in contrast to the relative fluid balance known from the prior art, which only shows the difference to the last data point of the fluid balance, shows the overall course of the fluid balance for the patient since the start of the recording (e.g. since the patient was admitted to the intensive care unit).

The preferably cumulative fluid balance is determined by subtracting the

Total amount of fluids lost by the patient out of the total amount of

Fluid delivery to the patient is calculated. The total amount of liquids lost by the patient (fluid losses) is preferably subtracted from the total amount of fluid / liquid supply to the patient.

Medications, nutrient solutions, saline solutions etc. and other liquids that are administered to the patient in any way, such as, for example, via gastric tubes, intrapulmonary, intranasal etc., are included in the total amount of fluid / liquid supply to the patient.

When determining the total amount lost by the patient

Liquids are all liquids lost by the patient, e.g. the amount of urine excreted by the patient, insensitive losses, but also the

for example, lost through wound drainage or pulmonary suction

Liquids included.

As an alternative or in addition to the cumulative fluid balance, an approximation method can also be used to map a cumulative fluid supply which reproduces the overall course of the fluid supply to the patient since the start of the recording (for example since the patient was admitted to the intensive care unit).

In addition to the fluid supply and the fluid balance, other data relating to the patient can also be taken into account. For example, effects or

Side effects of various medications administered to the patient on the fluid balance or fluid balance of the patient are included. As well Physiological data of the patient, blood values of the patient or also information regarding the age, gender, any previous illnesses of the patient, planned course of treatment including planned operations etc. can be taken into account, for example when embedding the transfer function in a control loop.

According to one aspect of the invention, a method according to the invention comprises the steps:

Collecting and / or determining data relating to a patient's cumulative fluid delivery (CFI) and the patient's cumulative fluid balance (CFB);

Creation of a transfer function for this patient on the basis of the acquired and / or determined data relating to the cumulative fluid supply and the cumulative fluid balance, the cumulative fluid supply and / or the cumulative fluid supply and / or using the transfer function in combination with an approximation method from the data relating to the cumulative fluid supply or the cumulative fluid balance of the patient can be determined or simulated, and

Calculate using the transfer function in combination with the

Approximation method of a predicted continuous course or trend of the cumulative fluid supply and / or the cumulative fluid balance of the patient for the future.

For example, in a case where the course of the cumulative

Fluid delivery to a patient is to be mapped using an approximation method, the method comprising the following steps:

Collecting data related to cumulative fluid delivery to a patient;

Applying an approximation method for this patient based on the collected data regarding the cumulative fluid supply, using the

Approximation method from the recorded data relating to the cumulative fluid supply, the cumulative fluid supply of the patient can be determined, and

Calculate a continuous course or trend of the cumulative

Fluid supply of the patient for the past as well as a predicted one

continuous course or trends of the cumulative fluid supply of the patient for the future. For example, in a case in which the course of the cumulative fluid balance to a patient is to be mapped using the transfer function, the method can include the following steps:

Collecting data regarding a patient's cumulative fluid delivery and cumulative fluid balance;

Creation of a transfer function for this patient on the basis of the recorded data relating to the cumulative fluid supply and the cumulative fluid balance, wherein the cumulative fluid balance of the patient can be determined using the transfer function in combination with an approximation method from the data relating to the cumulative fluid supply and the cumulative fluid balance ( To obtain the CFB curve, either the raw CFI data can be used as input for the transfer function or the approximated CFI calculated using the approximation method.Using the approximated CFI results in a CFB trajectory and no unsmoothed CFB curve), and

Calculate using the transfer function in combination with a

Approximation method of a continuous course or trend of the cumulative fluid balance of the patient for the past as well as a predicted one

continuous course or trends of the cumulative fluid balance of the patient for the future.

In addition, from the course of the cumulative fluid supply by means of a

Transfer function in combination with an approximation method of the course of the cumulative fluid balance can be determined. In such a case, a

The method according to the invention comprises the steps:

Collecting data relating to the cumulative fluid balance and the cumulative fluid supply to a patient;

Creating a transfer function for this patient on the basis of the recorded data relating to the cumulative fluid supply and the cumulative fluid balance, wherein the cumulative fluid balance of the patient can be determined using the transfer function in combination with the approximation method from the data relating to the cumulative fluid supply, and

Calculate using the transfer function in combination with the

Approximation method of a continuous course or trend of the cumulative Fluid balance of the patient for the past as well as a predicted continuous course or trends of the cumulative fluid balance of the patient for the future.

For example, the determined continuous courses of the cumulative fluid supply and / or the cumulative fluid balance for each patient for the past and future can be displayed together or separately on a display device.

The continuous courses of the cumulative fluid supply and / or the cumulative fluid balance for each patient for the past and future displayed in this way can thus be made available to a treating doctor when deciding on the further course of treatment. The patient therefore not only receives individual data points, but also a continuous course of the cumulative fluid supply and / or the cumulative fluid balance for each patient during their entire stay in the intensive care unit, as well as a prediction of the further development of the course of the cumulative fluid supply and / or the cumulative fluid balance for this patient. This improves the

Basis for the decision of the treating doctor when determining the further course of treatment and thus increases patient safety.

According to a further aspect of the invention, a method according to the invention further comprises the steps:

Setting a target value or a target course of the cumulative

Fluid balance of the patient; and

Calculating a course of the cumulative fluid supply to the patient, by means of which an actual value or an actual course of the cumulative fluid balance of the patient can be brought to the set target value or target course of the cumulative fluid balance.

The patient is then informed on the basis of the calculated course of the cumulative fluid supply to the patient, by means of which the actual value or actual course of the cumulative fluid balance for the patient is adjusted to the setpoint value or setpoint. The course of the cumulative fluid balance can be brought, supplied with fluid until the actual value or actual course of the cumulative fluid balance for the patient corresponds to the set value or target course of the cumulative fluid balance. The setpoint value or setpoint curve can correspond to a desired positive or negative gradient of the curve in a specific time interval.

This aspect of the invention offers the advantage that the cumulative fluid delivery is half based on the transfer function intended for a patient

can be regulated automatically or also fully automatically in such a way that an actual value or actual profile of the cumulative fluid balance for the patient is set to the set target value or target profile of the cumulative fluid balance. The recourse to the continuous course of the predicted by means of the transfer function

cumulative fluid balance allows a more precise adjustment of the cumulative fluid supply than this with the individual known from the prior art

Data points of the fluid balance is possible.

The cumulative fluid supply to the patient can also be regulated using the transfer function for this patient. In this case, the procedure includes the steps:

Setting a target value or target course of the cumulative fluid supply to the patient; and

Calculating a course of the cumulative fluid supply to the patient, by means of which an actual value or actual course of the cumulative fluid supply for the patient can be brought to the set value or set course of the cumulative fluid supply.

The patient is then brought on the basis of the calculated course of the cumulative fluid supply to the patient, by means of which the actual value or actual course of the cumulative fluid supply for the patient is brought to the set value or set course of the cumulative fluid supply can, fluid supplied until the actual value or actual course of the cumulative fluid supply for the patient corresponds to the set value or set course of the cumulative fluid supply. The target value or The desired course can correspond to a desired (positive) gradient of the course in a specific time interval.

According to another aspect of the invention, an invention comprises

A step of determining a turning point using a method

Approximation method in the history of the cumulative fluid balance and / or the cumulative fluid supply based on the history of the cumulative fluid balance and / or the cumulative fluid supply for the past and the predicted

continuous course of the cumulative fluid balance and / or the cumulative fluid supply for the future.

The turning point can be determined either from the raw data for CFI or CFB for the past (this is done here for the CFI to get the CFI approximation) or from the predicted data for the CFI (data are generated either by approximation and extrapolation or when setting of a target CFB course in the control loop) or the predicted data for the CFB (data are generated either by using the transfer function on the CFI smoothed and extrapolated using the approximation method or via the control loop output).

The inflection point indicates the point in the course of the cumulative fluid balance and / or the cumulative fluid supply at which the patient is off the ebb phase

(Acute phase) of the shock with reduced metabolism in the flow phase

(Secondary phase) of the shock passes.

For example, a method according to the invention can include a step of

Determining an inflection point in the cumulative fluid supply history based on the continuous cumulative fluid supply history for the

Past as well as on the basis of the continuous course of the cumulative fluid supply for the future predicted by means of approximation methods or in combination with the transfer function. Alternatively or additionally, a method according to the invention can include a step of determining an inflection point in the course of the cumulative fluid balance on the basis of the course of the cumulative fluid balance or on the basis of the continuous course of the cumulative fluid balance for the past and the one calculated using the transfer function in combination with the approximation method predicted continuous progression of the cumulative fluid balance for the future.

Here, the turning point of the cumulative fluid balance and / or the cumulative fluid supply can be determined by means of an approximation method, in which a number of potential turning points in the course of the cumulative fluid balance and / or the cumulative fluid supply of the patient corresponds to the actual one

Inflection point closest potential inflection point is selected.

For a certain time interval, for example the duration of the patient's stay in the intensive care unit, for example, each point in time can be examined as a potential turning point. Within the entire determined time interval, the determined values can also be examined as potential turning points at defined subordinate time intervals. For example, an hour may occur during the patient's stay in the intensive care unit

Investigation to determine the turning point or to investigate a

potential turning point. Other defined subordinate time intervals can be set as desired.

When examining a potential turning point in a particular

Time interval, for example from tO to t1, becomes the potential turning point

preferably defined such that the time interval from t0 to t1 is divided into two sections by the potential turning point. Then, for example, using linear interpolation and linear regression (both sections are approximated using linear regressions. Line 1 describes the trajectory from tO to

(Potential) turning point, line 2 describes the trajectory from the (potential) turning point to t1. An extrapolation takes place only when the CF I trajectory is predicted from time t1 to t2 (time of prediction). Finds between tO and t1 no extrapolation instead, since all data is available. An interpolation may be necessary if data points are missing in the previous course of CFI) the course of the cumulative fluid balance and / or the cumulative fluid supply between the time tO and the potential turning point in the first section of the

Time interval from tO to t1 and between the potential inflection point and the

Time t1 determined in the second section of the time interval from tO to t1. The two straight lines intersect at the potential turning point, which in the first section and in the second section of the time interval from tO to t1 reflect the course of the cumulative fluid balance and / or the cumulative fluid supply.

Instead of a linear interpolation or a linear regression, any other function, e.g. a non-linear function, can be used for interpolation or regression. In addition, the approximate determination of the turning point can be carried out for any number of passes or with any number of iterations.

To determine the quality of the approximate determination of the turning point, i.e. In order to determine how close an investigated potential turning point comes to the actual turning point, the statistical deviation between the course approximated by means of preferably linear regression through the two straight lines and the actual course is determined. The root mean squared error (RSME) is preferably used for this. For each potential turning point, the calculated RSME is compared to the lowest RSME of another

potential turning point from one of the previous rounds of the

Approximation compared.

If the currently calculated RSME value is lower, i.e. if the currently examined potential inflection point is closer to the actual inflection point, the currently investigated potential inflection point is currently the best (i.e. the

actual turning point, next turning point) is saved. Otherwise the currently examined potential inflection point is discarded and the other potential inflection point with the lower RSME value from one of the previous passes of the approximation process are stored as the closest turning point to the actual turning point.

The next turning point determined can also be displayed to a treating doctor, for example by means of a display device, as to what the

Information basis based on one decision about the other

Treatment course must be taken, further improved.

The slope of the straight line through the potential inflection point, which simulates the course of the cumulative fluid supply to the patient in the second section of the time interval from tO to t1, is used, for example, in a linear extrapolation for the prediction of the cumulative fluid supply to the patient in a second Time interval from t1 to t2 (prediction interval) used.

In combination with the transfer function, on the basis of the slope of the straight line which simulates the course of the cumulative fluid supply to the patient in the second section of the time interval from tO to t1, the course of the cumulative fluid balance for the patient in the second time interval from t1 to t2 can be predicted.

According to one aspect of the invention, the transfer function for the patient is performed periodically at predetermined time intervals, for example every hour

Based on newly collected data regarding the preferably cumulative fluid balance and fluid supply updated or adjusted. The adjustment can be made, for example, during the patient's entire stay in the intensive care unit. This can ensure that the transfer function reflects the cumulative fluid balance of the patient or the cumulative fluid supply to the patient as precisely as possible for the duration of the patient's total stay in the intensive care unit.

According to a further aspect of the invention, the

Transfer function for the patient based on patient cohort specific information in which a particular patient cohort is linked to a specific transfer function to be used for this patient cohort.

Here, the patient cohort-specific information is preferably generated by common features of the transfer functions created in the past for a specific patient cohort, such as e.g. Poles, zeros, stability, impulse response, step response etc., especially by means of statistical

Methods, artificial intelligence, neural networks, machine learning or logistic regression are identified or extracted and the characteristics identified in this way are determined when creating the transfer function for one of these

Patients belonging to the patient cohort are used as a basis.

A certain patient cohort refers to a group of patients who share certain characteristics. These features can be, for example, age, gender, treatment or surgery to be carried out, any previous illnesses, length of stay in the intensive care unit, laboratory parameters, etc. Patient cohorts can be formed based on any common characteristics.

With the creation of the transfer function for the patient on the basis of patient cohort-specific information, it is therefore not necessary to individually create a specific transfer function for a specific patient from the data of the cumulative fluid supply and the cumulative fluid balance determined for this patient, but instead it can refer to the common one Characteristics of the transfer functions created in the past for a specific patient cohort as

Empirical values can be used.

The creation of such a transfer function for a patient on the basis of patient cohort-specific information can

Reduce computational effort since no individual transfer function has to be created. Alternatively or additionally, a transfer function for the patient on the basis of patient cohort-specific information can also serve to check the plausibility of an individually created transfer function for this patient by comparing the individually created transfer function with one based on

Patient cohort-specific information created transfer function is compared. Such a comparison increases the accuracy of the transfer function and thus further increases patient safety.

A method according to the invention can be used for only a single patient, but it can also be used for a plurality of patients. If the method is used for a plurality of patients, a transfer function can be created individually for each of the patients in the plurality of patients. Alternatively or additionally, patient cohorts can also be formed from the plurality of patients and on the basis of

cohort-specific information as described above, transfer functions are formed.

The data streams of the data collected for the patients of the plurality of patients (e.g. regarding the fluid balance or fluid supply) can thus be for everyone

Patients are processed separately or can also be merged so that data pools are formed.

Another aspect of the invention relates to a device which is designed to carry out a method according to the invention in accordance with one of the above aspects.

The device is preferably a device for extracorporeal blood treatment, a drug administration system

Fluid management system or an infusion pump or another device which is directly or indirectly related to the fluid balance or the fluid balance and thus the fluid balance of the patient. Such a device preferably has an element or means for collecting the data relating to the preferably cumulative fluid supply to the patient and / or to the preferably cumulative fluid balance of the patient.

Furthermore, such a device preferably has one

Display device, for example a monitor / display, by means of which the information ascertained (courses, prediction values, turning points) is transmitted to one

treating doctor can be made available.

Another aspect of the invention relates to a program product which causes an apparatus to carry out a method according to the invention in accordance with one of the above aspects.

With such a program product, existing devices, e.g. a device for extracorporeal blood treatment

Drug delivery system, a fluid management system, a

Infusion pump or another device, which is directly or indirectly related to the fluid balance or the fluid balance and thus the fluid balance of the patient, to be retrofitted. Such a program product can, for example, be stored on a storage medium.

In the following, an embodiment of the present is exemplified

Invention described with reference to the figures.

Brief description of the figures

The figures 1 a to 1 e show an example of the different steps of a

Method according to an embodiment of the invention.

The figures 2a to 2e show the various steps of an example

Approximation method to determine the trajectory of the cumulative Hydration while determining a turning point in the course of cumulative fluid delivery to a patient.

Description of the embodiments

The figures 1 a to 1 e show an example of the different steps of a

Method according to an embodiment of the invention, in which the

the inventive method is applied to a patient.

As shown in Fig. 1 a, initially for a first time interval of tO

(Origin) to t1 data on the cumulative fluid supply CFI to the patient and the cumulative fluid balance CFB of the patient. The time interval from tO to t1 can be defined as desired and for example a few minutes, 1 hour or even several hours, e.g. 6 hours or 12 hours. The time interval can also include the entire duration of the patient's stay in the intensive care unit, for example several days.

Thereupon, as shown in FIG. 1 b, a preferably time-discrete transfer function P [z] is created on the basis of the collected data, which represents a relationship between the data relating to the cumulative fluid supply CFI to the patient and the cumulative fluid balance CFB of the patient. Here, the course of the cumulative fluid supply CFI to the patient, in this example since

Recording in the intensive care unit, used as the input sequence of the transfer function and the course of the cumulative fluid balance CFB of the patient, in this example used since the patient was admitted to the intensive care unit, as the output sequence of the transfer function.

The transfer function P [z] describes a relation or a

Relationship between the cumulative fluid supply CFI to the patient and the cumulative fluid balance CFB of the patient (i.e. the transfer function indicates how CFB changes depending on CFI). If you have the cumulative data

Fluid supply CFI or the approximate data of the cumulative fluid supply CFI as input sequence and the transfer function P [z], the associated values of the cumulative fluid balance CFB can thus be calculated.

As shown in FIG. 1 c, a prediction for the further course of CFI and CFB in is then based on the course of CFI and CFB determined in the time interval from tO to t1 on the basis of the collected data relating to the patient's CFI and CFB a future time interval from t1 to t2.

First of all, the inflection point in the course of CFI is determined using the approximation method described above (in order to obtain the approximated CFI so far) by examining stepwise points along the course as potential inflection points and the closest one to the actual inflection point

potential inflection point (e.g. the inflection point with the lowest RSME value with respect to the actual inflection point) is selected.

In the approximation method (approximation), a first straight line is drawn through the origin and the potential turning point, which represents the course of CFB or CFI for the section between tO (origin) and the potential turning point. A further linear regression is then used to lay a second straight line through the turning point, which represents the course of CFB or CFI for the section between the potential turning point and t1.

This second straight line, in particular the slope of the second straight line, can, as shown in FIG. 1 c, be used for the future course of CFB or CFI for the future, in this example for a course going beyond time t1

Time interval from t1 to t2 to predict.

The diagrams shown in FIG. 1 c correspond to one example

treating doctor on a display device displayed data or courses of the cumulative fluid supply or fluid balance of the patient.

As shown in FIG. 1 d, the treating physician can set a target value or a target course of CFI or CFB for the patient. In the example from Fig. 1 d A target curve of the cumulative fluid balance CFB was determined for the time interval from t1 to t2. Here, a value kMaint is set, which represents a desired gradient in the course of CFB for the time interval from t1 to t2. A value of (-A) was set in FIG. 1 d, which represents a desired, in this example negative, slope of the course of CFB for the time interval from t1 to t2.

As shown in FIG. 1 e, a cumulative target fluid balance or a target profile of the cumulative fluid balance cfbgoai is then created on the basis of the target profile of the cumulative fluid balance CFB. According to this target course of

cumulative fluid balance CFB, by embedding the transfer function P [z] in a control loop in the form of an inverse transfer function V (z), a proposal for a course of fluid supply to the patient cfisugg is determined, for which the control loop predicts that with such a course the Fluid supply to the patient, the predicted course of the fluid balance cfbpred corresponds to the set course of the cumulative fluid balance CFB cfbgoai.

The proposal for the course of the cumulative fluid supply to the patient cfisugg is adapted by means of a control loop R [z], so that the proposal for the course of the cumulative fluid supply to the patient cfisugg corresponds exactly to the course of the cumulative fluid supply, which according to the transfer function P [ z] leads to the predicted course of the fluid balance cfbpred, which corresponds to the target course of the cumulative fluid balance cfbgoai.

Thereupon fluid is supplied to the patient with the calculated course of the cumulative fluid supply cfisugg, so that the desired course of the cumulative

Fluid balance CFB is reached.

The figures 2a to 2e show the various steps of an example

Approximation method for determining the trajectory of the cumulative fluid supply CFI and at the same time determining an inflection point in the course of the cumulative

CFI fluid delivery to a patient. Alternatively or additionally, the trajectory including the turning point can also be determined in the course of the patient's cumulative fluid balance CFB. As shown in Figs. 2a to 2e, the course of the cumulative fluid supply CFI (B) to a patient is simulated in a time interval from tO (origin) to t1 by means of a linear regression or interpolation (A). Different points along the course are examined as potential turning points (C).

In FIGS. 2a to 2e, the potential turning points tp1, tp2, tp3, tp4 and tp (n-m) are shown by way of example, in which the two straight lines of the linear regression / interpolation of the course in the first and second section of the

Cut the time interval from tO to t1.

For each potential inflection point, the deviation of the approximated cumulative fluid supply from the actual cumulative fluid supply is determined. Specifically, in this embodiment, the deviation is determined by determining a root mean squared error value (RSME), which indicates the deviation of the approximated curve from the actual curve. The smaller the RSME value, the closer the potential turning point is to the actual one

Turning point (D).

In the case of the figures 2a to 2e, the potential inflection point tp3 shown in FIG. 2c corresponds to the actual inflection point and therefore has the lowest RMSE value (RMSE min).

In the approximation method according to the invention, the potential turning point with the lowest RSME value is selected step by step. For example, the potential turning point tp1 shown in FIG. 2a is first examined. As shown in FIG. 2a, however, tp1 does not come very close to the actual turning point and the associated RMSE value is correspondingly large (RSME ^TT ). The potential inflection point tp1 and the associated RMSE value and the associated straight lines of the linear regression / interpolation are then stored.

In the next pass of the approximation process, the potential turning point tp2 shown in FIG. 2b is examined. As shown in Fig. 2b, tp2 comes to that actual turning point closer than the potential turning point tp1 and the RMSE value associated with the potential turning point tp2 is correspondingly smaller (RSME †) than the RMSE value associated with the potential turning point tp1 (RSME ††). The potential inflection point tp2 and the associated RMSE value and the associated straight lines of the linear regression / interpolation are then stored and the potential inflection point tp1 is rejected.

In the case of the potential inflection points tp1 and tp2 shown in FIGS. 2a and 2b, the approximate determination of the potential inflection point tp3 was carried out by gradually shifting the potential inflection point to be examined in the positive direction of the X axis (in FIGS. 2a and 2b, starting from the origin right).

As shown in FIGS. 2d and 2e, the approximate determination of the potential turning point tp3 can alternatively or additionally also be carried out by gradually shifting the potential turning point to be examined in the

opposite direction of the X axis (in Figures 2d and 2e along the X axis towards the origin). In the model, each point in the course is tested as a potential inflection point in a certain interval starting from tO until the end of the course (t1) has been reached. If you find the best turning point somewhere in the middle (which you don't know at the time), the RMSE will get bigger in the next few steps, but you still have to go through the entire time series until the end (t1) to get one Lower RMSE value cannot be overlooked. The examination takes place from the first step to the last step, starting from the origin to the right.

The method could also be started at t1 and ended at tO. Then the method would not change the direction in the middle, but would move along the X axis to the origin in each step.

Claims

Expectations

1. Method for fluid balancing at least one patient, with the step

- Creating a transfer function (P [z]) for the at least one patient, by means of which a continuous course of the preferably cumulative fluid supply (CFI) and / or the preferably cumulative fluid balance (CFB) of the at least one patient can be simulated for the past and one continuous course of preferably

cumulative fluid balance (CFB) and / or the preferably cumulative fluid supply (CFI) can be predicted for the future, whereby on the basis of the continuous course for the past calculated by means of the transfer function (P [z]) in combination with the approximation method and the predicted continuous course for the future a turning point (tp3) of the cumulative fluid balance (CFB) and / or the cumulative fluid supply (CFI) is determined at which the at least one patient changes from the ebb phase of the shock to the flow phase of the shock .

2. The method according to claim 1, comprising the steps:

Collecting data relating to the cumulative fluid supply (CFI) to the at least one patient and the cumulative fluid balance (CFB) to the at least one patient;

- Creation of a transfer function (P [z]) for the at least one patient on the basis of the recorded data relating to the cumulative

Fluid supply (CFI) and the cumulative fluid balance (CFB), whereby the cumulative fluid supply () using the transfer function (P [z]) in combination with an approximation method from the data relating to the cumulative fluid supply (CFI) and / or the cumulative fluid balance (CFB) CFI) and / or the cumulative fluid balance (CFB) of the at least one patient can be determined, and

- Calculate using the transfer function (P [z]) in combination with the

Approximation method of a continuous course of the cumulative Fluid supply (CFI) and / or the cumulative fluid balance (CFB) of the at least one patient for the past and a predicted continuous progression of the cumulative fluid supply (CFI) and / or the cumulative fluid balance (CFB) of the at least one patient for the future.

3. The method according to any one of the preceding claims, further comprising the steps:

- Setting a target value or target course of the cumulative fluid balance (CFB) for the at least one patient; and

- Calculate a history of the cumulative fluid supply (CFI) to the

at least one patient, by means of which an actual value or an actual profile of the cumulative fluid balance (CFB) for the at least one patient is brought to the set value or target profile of the cumulative fluid balance (CFB).

4. The method according to claim 1, wherein the inflection point of the cumulative fluid balance (CFB) and / or the cumulative fluid supply (CFI) is determined by means of an approximation method in which iteratively from a plurality of potential inflection points (tp1, tp2, tp3, tp4, tp (nm)) of an actual

Inflection point closest potential inflection point (tp3) is selected.

5. The method according to any one of the preceding claims, wherein the transfer function (P [z]) for the at least one patient is updated periodically at predetermined time intervals.

6. The method according to any one of the preceding claims, wherein the creation of the transfer function (P [z]) for the at least one patient is based on patient cohort-specific information, in each of which a specific patient cohort that a group of patients with certain common

Features is linked to a specific transfer function (P [zj) to be used for each patient in this patient cohort.

7. The method of claim 6, wherein the patient cohort-specific information is generated by having common features for a particular one

Patient cohort of transfer functions created in the past (P [z])

in particular by means of statistical methods, artificial intelligence, neural networks, machine learning or logistic regression and the characteristics identified in this way are used as a basis for the creation of the transfer function (P [z]) for a patient belonging to this particular patient cohort.

8. The device, which is designed to carry out the method according to one of claims 1 to 8.

9. The device according to claim 8, wherein the device is a device for

extracorporeal blood treatment, a drug delivery system, a

Fluid management system or an infusion pump or another device that is directly or indirectly related to the fluid balance of the patient.

10. Program product which causes a device to carry out the method according to one of claims 1 to 7.