DD141617A1 - METHOD FOR THE AUTOMATIC REGULATION OF BLOOD SUGAR HOMOEOSTASE IN INSULINED DIABETICS - Google Patents

Abstract

According to the invention with an analog or digital computer the measured values plasma glucose over the functional units static Nonlinearity, extrapolation and averaging over one Mixed point supplied to a PID control algorithm and processed there. The output signal is via an adjustment element of a Dosing device abandoned. This can be done by stress fluctuating, or caused by the individual patient Insulin requirements are largely automatic, timely and adequate be supplied.

Description

Title of the invention

Method for automatic regulation of blood sugar homeostasis in insulin-dependent diabetics

Field of application of the invention

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The invention relates to a method for the automatic control of blood sugar homeostasis in patients with insulin-dependent diabetes mellitus. Automated, timely and adequate insulin dosing keeps plasma glucose within physiological limits and normalizes the metabolic abnormalities due to relative or absolute insulin deficiency in diabetics.

Characteristic of the known technical solutions

It is known that under physiological conditions there is a high correlation between the measured plasma glucose (PG) and the insulin levels in the organism. Also known are measurement-dependent control and computing devices for keeping plasma glucose constant, which meter insulin into the bloodstream. The mathematical relationship of the amount of insulin to plasma glucose has been presented in various ways with linear and nonlinear equations. Are known

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Further inventions of Albisser and Clemens OS 2601893 and OS 2720482, which have non-linear controllers to the content. These controllers have non-linear P- or PD-like transmission characteristics. Other linear schemes for keeping plasma glucose constant also involve PD behavior.

The known nonlinear control algorithms with hyperbolic tangent or biquadratic punctures result in high plasma glucose levels in insulin overdoses, which do not correspond to the known therapeutic methods of the Komatherapie. Contrary to what is shown in the above descriptions of the invention, in clinical observations, with the devices operating according to these principles, to prevent hypoglycaemia in maintaining basal plasma glucose levels, glucose infusions become necessary. These deficiencies can be explained by the P or PD control algorithm.

Despite the high flexibility of the machines, a normalization of the metabolic situation over longer periods without additional corrections is not possible. As a result, they are only usable in the clinic under supervision. Changes in the relationship plasma glucose and insulin requirements (for example, in stress, in infections, in pregnancy, in muscle work, etc.) are corrected only incompletely.

Linear relationships apply only in a very small range, which is already present in normally occurring disturbances, e.g. when eating, is not respected.

Object of the invention

The aim of the invention is to keep the plasma glucose under physiological conditions under rest and stress conditions in patients with diabetes mellitus with an automatic, timely and adequate insulin dosage and thus to achieve a normalization of disturbed metabolism, which is the basis of treatment to avoid late complications is "

With the help of microelectronics, such a device is optionally portable or implantable and out-of-order. nisch applicable.

Explanation of the essence of the invention

- The technical problem which is solved by the invention.

It is the object of the invention to develop a method for the automatic regulation of blood sugar homeostasis in patients with insulin-dependent diabetes mellitus, which is described with such an algorithm, which adapts fully automatically to the respective condition of the patient.

Features of the invention

The object of the invention is achieved in that, in contrast to the known technical solutions, a static Uichtlinearität a dynamic PID structure is connected downstream and the control structure with the integral portion (I-share) the insulin need for a variety of loads in the organism

corrected. The combination of the I component with the known, nonlinear PD structures, but in a linear relationship, makes it possible, by means of known optimization methods, to use the parameters proportional band ^ t »reset time T _n and derivative time Τ _γ for the majority of patients with different physical loads to adjust. According to the invention, the following method steps result.

Blood is taken from the human organism by an analysis system and plasma glucose is determined. The measured value is fed via the functional units, static U-linearity and extrapolation with averaging, to a PID controller. The order of the functional units is arbitrary. The output signal of the PID controller is preferably fed via an adjustment member of a metering device, which promotes insulin from a depot into the metering point on the human organism.

The static density linearity preferably has a bilogarithmic zero-suppressed behavior. Due to the steep curve in the normal range of the measured plasma glucose, further processing to the later downstream, linear PID controller is functionally modified so that in connection with the other functional units an overdose of insulin and thus hypoglycemia is avoided.

With the extrapolation and averaging function unit, the PID controller receives information that makes up for the time lag of the analyzer system and leads to sharper or more effective setting of the controller parameters. The output signal of the controller, which is preferably composed of an additive of PD and I components, is transmitted via an adaptation element for triggering the insulin

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supplied lin metering. Advantageous feature over known methods and devices is u. a. the integral part of the PID regulator, which tracks insulin requirements at different physical loads on patients. The dynamic, linearly operating controller is designed so that its parameters (proportional range χ, overtime T and derivative time T) are preferably changed by controlled or controlled adaptation. Thus, the. "Patients should be given an optimal insulin dosage, which ensures the parameter setting on the PID controller by the extrapolation, in a timely and adequate manner, under physiological limits under resting and loading conditions, over the other procedures and devices ,

embodiments

The invention will be explained below with reference to exemplary embodiments and block diagrams.

Fig. 1 generally shows the control loop with the method steps.

Pig. FIG. 2 illustrates the detailed method steps in a preferred series connection for an analog PID controller and a z. B. frequency-dependent controlled insulin dosing.

Pig. Fig. 3 shows the control loop for a preferred digital PID control method with adaptive change of the parameters on the controller and the static density linearity.

Pig. 4 shows some curves of the static Uichtlinearität the measured value plasma glucose.

Example 1 . ,

The analog measurement signal plasma glucose (PG) coming from the analyzer system 2 is connected to the bloodstream of the human. lent organism 1 and processed via a static nonlinearity 3 for the PID controller 6. In this case, preferably the bilogrammarithmic puncture 22

χ = a In [b In (PG - PG _A )] PG - PG ₁ > 1

applied. With χ is the linearized for the PID controller 6 measurement, with PG the measured plasma glucose and with PG. The initial value for the linearization of the plasma glucose is designated. The factors a and b change the shape and the range of the applied non-linearity 3. It is preferable to process discontinuous measurement values which are electronically passed through an amplifier with a non-linearity connected in the feedback and realize the described equation. The nonlinear measured values are then fed through a puncturing unit for extrapolation and averaging 4 to a first-order holding element 5. The puncture unit extrapolation and averaging 4 preferably consists of six memory locations, which further push their memory contents upon input of a 'new measured value χ and precalculated with a summation via an operational amplifier the measured value χ for the next half cycle. The equation is preferably:

χ 5 - 13 1 1

X = - X /% - - X / -. \ + - X / "\ + · * * -

16 ^(a) 16 ^(b) 4 ^(c) 4

1 17 16 ^(e) 16

where χ at the time (f) is the last, χ at the time (e) is the penultimate, etc., measured value. The downstream holding member 5 has the task of smoothly supplying the discrete measured values to the analog PID controller 6, wherein a mixing point 7 for the comparison signal w, which corresponds to the hormonal value of the plasma glucose, is arranged at the input of the PID controller a difference is formed with the pending at the output of the holding member measured value χ. The measuring

χ ** . x ^X (1 - β

t is a time constant that depends on the cycle of the discontinuous measured values and is matched with the derivative time T of the PID controller 6. The difference between the predetermined desired value w and the measured value χ is referred to as x _w .

x _w = χ - w

The difference signal x ^ is fed to the linearly operating PID controller 6. This works preferably according to the structural equation

and is composed of the differentiator 8, the proportional member 10 and the integrator 9. The parameters χ, T and T _n are determined according to known optimization methods for continuous linear controllers and set for the respective patient

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The output signal y of the PID controller 6 is fed via a manual-automatic switch 13 "at" automatic "-S deployment of a preferred e - puncture as an adjustment member 14. Nach, the manual-automatic switch 13» the at position " If the signal y is received from a manual device 12 fed by a constant voltage, a feedback circuit - integral saturation prevention arw (anti reset windup) 11 of the integrator 9 - is inserted at the mixing point in connection with the functional unit of static linearity 3 the overshooting of the measured value plasma glucose zu.Hypoglykämien eg in case of disturbances by muscle work.

A transducer 15 preferably controls a discretely operating metering device 17 for insulin delivery from a depot 16 into the human body 1 at the metering point 18.

All puncture units are e.g. from building blocks of microelectronics, which are kept low power and small, preferably realized in the order described.

Example 2

The blood taken from the human organism 1 is determined by the analysis system 2 for the plasma glucose measurement. The measured value is input to a digital microcomputer 21 for further processing, preferably as a keyed signal.

In addition to the method illustrated in Example 1, the parameters of the PID controller 6 and the static ones are preferably with an adaptation device 20

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Nonlinearity 3 changed so that a predetermined quality criterion is met as best as possible.

The puncturing unit control algorithm 19 contains the above-described puncturing units extrapolation with averaging 4, the PID controller 6, the adaptation member 14 and the V / orler 15. A fixed setpoint w is here also the Iiormalwert the plasma glucose with the actual measured value χ preferably on. .the Mi π rh st rush 7 compare "the output y of the digital microcomputer 21 is formed so as to allow the metering device 17 promotes insulin from a repository 16 at a dosing point 18 in the human organism. 1

Since the relationship plasma glucose insulin in the human organism 1 has a non-linear transmission behavior and the inserted puncture unit 3 does not bring about absolute linearization of the control loop, the parameters of the PID controller 6 and of the static nonlinearity 3 are corrected by preferably controlled adaptation 20.

Claims (1)

1 I 879 invention claims Point 1: Method for automatic regulation of blood sugar homeostasis in insulin-dependent diabetics from continuous or unsteady measured values, characterized in that the measured values plasma glucose via puncturing units static linearity (3) j extrapolation and averaging (4) with an analog or digital computer, preferably a microcomputer (21), be supplied via a mixing point (7) a PID control algorithm (6) and processed there, the output signal has an integral saturation prevention (11) and via an adjustment member (H) of a metering device (17) is abandoned. Point 2: Method according to item 1, characterized in that the measured values plasma glucose prior to further processing in the PID control algorithm (6) by means of analog or digital computer, preferably according to the equation χ = a In fb In (PG-PG ^ calculated and inserted as static nonlinearity (3), where χ = non-linear measurement of plasma glucose PG β plasma glucose
PG. s = plasma glucose initial value a, b = pacts, which determine the course of the static linearity (3)
mean. Point 3: Method according to item 1, characterized in that the dead and delay times of the measured values plasma glucose, which are conditioned by the analysis system (2), are compensated by extrapolation and averaging (4) and the measured values are calculated in advance. Point 4: Method according to item 1, characterized in that a holding member (5) is connected upstream of the analog computer, preferably with the .PID adjustment algorithm (6), for processing discontinuous signals. Point 5: Method according to item 1, characterized in that the measured values plasma glucose by a PID control algorithm (6), preferably according to the equation are processed. Point 6: Method according to item 1, characterized in that the I-element (9) of the PID-regulator (6) is monitored for integral saturation (11) and stops at the given limits the integrator. Point 7: Method according to item 1, characterized in that from the measured value plasma glucose preferably an adaptive control device (20) the parameters proportional range (sO> reset time (T) and derivative time (T _v ) of the PID control algorithm (6) and the static ITichtlinearität (3) according to the changing conditions in the organism of the most diverse patients according to a quality criterion. For this ... iLi .. pages drawings