DE102018000775A1 - EMS - Extravasation Monitoring System, device for determining the hydraulic-mechanical properties of veins and tissues in infusion technology - Google Patents

Abstract

An infusion system (1), comprising an infusion source (2), and a tubing (3) leading from the infusion source (2) to a catheter (5) in the vein or tissue of a patient (6), and a fluid which both in the infusion source (2) and in the tubing (3) to the catheter (5) is provided and is conveyed by the infusion source (2) through the tubing (3) and the catheter in the patient, characterized in that a signal generator (8) is provided, which introduces a signal into the liquid, and two signal detecting sensors (9, 10), which are arranged with the signal generator (8) in the infusion system (1), and a control unit (11), which with the sensors (9, 10) is operatively connected, such that a sensor signal output by the sensors (9, 10) generates an input signal of the control unit which is operatively connected to a display such that in dependence on the sensor signals information about the correct catheter layer (5) can be displayed.

Description

The innovation relates to an infusion system according to the preamble of claim 1.

In intensive care, highly effective drugs must be given as an infusion. It may happen that the infusion solution does not enter the bloodstream. If the catheter is not located in the vein, but in the tissue, the infusion solution is conveyed into this tissue and creates a cavity there, resulting in a so-called extravasation. If the infusion solution passes through the vein wall into the tissue and collects there in a constantly enlarging cavity, this fluid collection in the cavity is also called extravasation. Extravasates are also referred to as infiltrations. They occur in up to 6% of all infusion treatments, in premature babies even in up to 78%. Infiltration can lead to severe damage such as necrosis, nerve disorders and blood poisoning. Particularly critical are drugs for cancer therapy and infusion solutions for artificial nutrition.

Currently, it is not possible to technically monitor or prevent infiltration. Technologies for measuring the resulting accumulation have been published (see appendix), but have never brought it to a functioning, marketable product, partly because they can detect the threat only after massive manifestation. In addition, they can not prevent the damage to the patient.

To prevent infiltration, the extravasation monitoring system (EMS) was developed, with which it is possible to measure the complex, mechanical-hydraulic properties of the vein or tissue at the catheter end.

EMS consists of a sensor-actuator system and a control unit with monitor.

Analogous to electrical engineering, components of a hydraulic structure also have the properties of resistance, capacitance and inductance. While the resistance u.a. depends on the geometry of the flowed tube, the capacity in the considered case in the extensibility of the vein or the tissue and the catheter is justified. The inductance corresponds in the present case, the inertia of the masses, both of the blood in the vein and the surrounding tissue. An overview of this analogy is shown in the following Table 1.

The EMS is placed between infusion source (eg pump) and patient access ( 5 ) (for example catheters) ( ).

In order to measure the hydraulic-mechanical properties, the EMS sensor-actuator system consists of sensors ( 9 . 10 ) for the temporally high-resolution determination of pressure and flow in the infusion line, a valve for closure ( 7 ) of the line and an actuator ( 8th ), with which a pulse is delivered to the infusion line, if necessary. The actuator can for this example consist of a displacement body and a drive. By means of the drive, the displacement body can be moved into the conduit lumen and returned. Also, the actuator may be a pinch valve, which compresses the infusion line to generate the flow, thus partially reducing the conduction lumen. In this case, advantageously an additional valve for closing the line can be dispensed with, since the actuator can also permanently close it.

To determine resistance, compliance and inertia from an unknown system, the complex response to a precisely described signal is recorded and then the amplitude, time and phase shift are determined.

The influence of the system on the signal is frequency dependent. One can perform the system analysis with a monofrequent signal (case a), with a signal with a continuously varying frequency (case b) or a frequency mixture (case c).

To excite the hydraulic-mechanical system, an actuator ( 8th ) or the infusion pump ( 8th ) generates a flux pulse which is generated by the EMS ( 4 ) and the catheter ( 5 ) enters the vein or tissue. The flux change may consist of a flux pulse after the flow has previously been stopped, a flow impulse superimposed on the already running flux, or a modulation of the flux (for example in the form of a sine (case a), sweep (case b), Noise (case c).

• • er wird digital angesteuert (ein/aus). Die sich ergebende Verfahrgeschwindigkeit und der resultierende Fluid-Strom sind reproduzierbar und typisch für die Aktorkonstruktion
• • er wird so angesteuert, dass sich eine gewünschte Fluid-Strom-Änderung einstellt.

For determining the flow, on the one hand, a flow sensor can be used. Alternatively, with hard coupling of the actuator, its travel path can also be used to calculate the induced flow. In the second alternative, the actuator can be controlled in two ways:

• • it is digitally controlled (on / off). The resulting travel speed and the resulting fluid flow are reproducible and typical of the actuator design
• • It is controlled so that a desired fluid flow change occurs.

The measurement of the fluid flow can advantageously be dispensed with in the case of known actuator control since the flow signal is largely independent of the downstream system to be investigated.

To illustrate the analogy with electrical engineering, the and the system for infusion therapy including EMS ( 12 ) based on the electrical analogue wiring diagram. Each component consists of a resistor ( 13 ) and a series-connected inductance ( 14 ) and a parallel connected capacity ( 15 ). The section vein ( 16 ) or tissue ( 18 ) is representative of all components at the catheter end. Correctly, the vein consists of a series of many of the pictured elements, but can not be simplified into a simple three-pole consisting of R, C and L. Before the measurement, the characteristics of the EMS ( 12 ) and the catheter ( 17 ), so that the properties of the vein ( 16 ) or the tissue ( 18 ) can be determined.

As a reference, a short series of measurements consisting of several test flow signals is carried out at the beginning of the measurement after successful puncture of the vein and evaluated by the control unit. After the venipuncture, the medical staff will perform a blood aspiration to check the correct position. This is done by observing whether blood escapes from the catheter after retraction of the puncture needle. Retraction of the puncture needle can automatically initiate this series of measurements if the sensor-actuator system is integrated with or attached to the catheter. Alternatively, the calibration routine can be initiated by a button. The EMS calibration feature records the characteristics of the vein at the beginning of treatment. Thereafter, the measurements are made continuously or at regular intervals.

For the detection of the blood aspiration at the beginning of the infusion, a photosensor can be contained in the EMS, which examines the infusion solution for blood during the return movement of the actuator. The EMS can also include an accelerometer to detect motion artifacts.

The monitor displays the course of venous characteristics and can trigger an alarm if warning limits are violated. For safety's sake, the infusion flow can also be stopped, for example, by a pinch valve or the actuator.

The actor ( 8th ) for pulse generation can be placed both in the EMS on the catheter and in or on the infusion pump. The EMS can be integrated into the catheter, placed between the infusion device and the catheter, or clamped to the outside of the tube.

In order for the EMS to know the characteristics of the disposable article, the article can be identified by means of a machine-readable marking (RFID, barcode, etc.). The properties of the permissible parts of the infusion system are stored in the EMS. For other parts, a calibration routine can be performed via the control unit.

In case of infiltration, the catheter is either next to the vein or the infusion solution passes through damage in the vein wall into the surrounding tissue. In any case, the mechanical properties differ at the end of the catheter as opposed to the correct location in the intact vein. If the catheter is extravascular in the forming cavity, then the measured properties are changed, since, for example, the extensibility of the tissue and the venous system and the inertia differ. In one case, the system can only be described by a combination of many three poles, in the other by a simple approach.

Even in cases of pathological changes of the veins, the EMS can determine the differences in the hydraulic-mechanical properties. Thus, in a phlebitis the vein wall thickened, resulting in an increased resistance with decreasing compliance. In allergic reactions, the diameter of the veins increases. This leads to a reduction of the resistance and can thus be registered.

In addition to infusion technology, the EMS can also be used in all other areas where access to fluid-filled areas of the body is established (dialysis, heart-lung machine, enteral nutrition, intracranial pressure measurement, etc.).

Various patents have been filed in the past to measure infusion pressure curves at various flow rates. Measurements of the infusion line resistance have also been performed and published several times.

What is new about the presented invention is, on the one hand, the determination of the complex system properties of the venous system in the case of a correct position or the determination of the simple properties of the cavity that is being formed. This is comparable with the impulse oscillometric method for respiratory diagnostics, in which a short, multifrequency impulse is used to characterize the respiratory tract and lung tissue.

Another new feature is a determination of the complex resistance of infusion device, catheter and vein / tissue. The synchronous recording of pressure and flow characteristics on the catheter with subsequent frequency analysis is also new. Also new is the elimination of the difficult flow measurement by impressing a defined flow change by the actuator.

This object is achieved by an infusion system according to claim 1 solved. Advantageous embodiments are described in the subclaims. Table 1: Overview of the electrical, hydraulic and mechanical properties electrical hydraulic mechanically resistance resistance damping capacity compliance elasticity inductance inertia inertia electricity River speed charge volume shift tension print tension

attachment

technology Patent holder Patent number flow resistance Alaris, E-Z-Em, Inc. Pressure pulse due to overpressure Ivac US4534756 A Pressure pulse by storing the medium Baxter Under pressure pulse Dean L Kamen Sound measurement of the infusion flow MALLINCKRODT INC WO002009042621A3 Sonoreflex image comparison before / after injection MEDISON CO LTD EP000002127601A1 Use test fluid MEDRAD INC, US LAITENBERGER PETER G, UK; W0002007140199A3 Sonorelfex of infused air bubbles MALLINCKRODT INC, US; POOLEY DAVID M, GB Sonoreflex of the Paravasat Chad E. Bouton US20140228686 Doppler measurement of the injection fluid NEORAD AS (for contrast agents) EP1569707 Measuring skin tension LEE ROBIN M, GB; MALLINCKRODT INC, US Change of the river SAGE BURTON H JR XIULI ZHANG, CN; Acist Medical Swelling of the skin / leakage Systems, Inc. ACIST: DE000069735316T2 . US805740E impedance E-Z-Em, Inc. US5947910 A EM-reflection Medrad Inc. (Bayer); Battelle Memorial Institute DE000060215668T2 ; WO0020130331 EM-temperature measurement M / A-Com, Inc. US4647281A Measuring the resistance at three points in the infusate and on the body Rudolf Duenki et al. WO1999029356 A1 Measuring the resistance between two points for short-circuit detection Baxter EP1401518 B2 Superposition of two wavelengths ivWatch US020130324854A1 Measuring the resistance between infusion needle and electrode FMC US8105277 B2 Image analysis of an X-ray University of Massachusetts, Medical Center US020020172323A1 capacitance measurement Hirschmann US020030004433A1 Injecting light with multiple sources UNIV PENNSYLVANIA, US US6487428B1 Reflection of blood next to the puncture MEDRAD INC, US WO002006074415A3 ; US0200601733 Irradiation and detection of light Smith & Nephew Reflection of a light source MALLINCKRODT INC., Nemoto Kyorindo Co., Ltd. Nemoto: DE602004010863T3 Temperature comparison skin infusate change of liquid crystal Robert F Shaw Whitman Medical Corporation US4010749A Temperature and pressure measurement (surface tension) L G MED LTD, IL US000006425878B1

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4534756 A [0026]
• WO 002009042621 A3 [0026]
• EP 000002127601 A1 [0026]
• WO 002007140199 A3 [0026]
• US 20140228686 [0026]
• EP 1569707 [0026]
• DE 000069735316 T2 [0026]
• US805740E [0026]
• US 5947910A [0026]
• DE 000060215668 T2 [0026]
• WO 0020130331 [0026]
• US 4647281 A [0026]
• WO 1999029356 A1 [0026]
• EP 1401518 B2 [0026]
• US 020130324854 A1 [0026]
• US 8105277 B2 [0026]
• US 020020172323 A1 [0026]
• US 020030004433 A1 [0026]
• WO 002006074415 A3 [0026]
• US 0200601733 [0026]
• DE 602004010863 T3 [0026]
• US 4010749A [0026]
• US 000006425878 B1 [0026]

Claims (11)

An infusion system (1), comprising an infusion source (2), and a tubing (3) leading from the infusion source (2) to a catheter (5) in the vein or tissue of a patient (6), and a fluid which both in the infusion source (2) and in the tubing (3) to the catheter (5) is provided and is conveyed by the infusion source (2) through the tubing (3) and the catheter in the patient, characterized in that a signal generator (8) is provided, which introduces a signal into the liquid, as well as two signal detecting sensors (9, 10), which are arranged with the signal generator (8) in the infusion system (1), and a control unit (11), which with the sensors (9, 10) is operatively connected, such that a sensor signal output by the sensors (9, 10) generates an input signal of the control unit, which is operatively connected to a display such that in dependence on the sensor signals n can be displayed via the correct catheter layer (5). Infusion system after Claim 1 , characterized in that the sensors (9, 10) are designed as flow and pressure sensors. Infusion system after Claim 1 , characterized in that only one sensor (9) or (10) is used. Infusion system after Claim 1 , characterized in that the signal generator (8) is designed as a pressure generator, such that by means of the pressure generator, a pressure signal in the liquid or in the hose line (3) can be introduced. Infusion system after Claim 1 , characterized in that the signal generator (8) is designed as a flux generator, such that by means of the flux generator, a flow signal in the liquid or in the hose line (3) can be introduced. Infusion system according to one of the preceding claims, characterized in that the signal transmitter (8) is integrated in the infusion source (2). Infusion system according to one of Claims 1 to 5 , characterized in that the signal generator (8) outside the infusion source (2) to the hose line (3) is connected. Infusion system according to one of the preceding claims, characterized in that the sensors (9, 10) as an actuator / sensor element (A / S) is configured. Infusion system after Claim 7 , characterized in that the infusion system (1) is designed such that the signal in the form of one pulse or more, designed as a pulse sequence, pulses is delivered. Infusion system after Claim 7 , characterized in that the infusion system (1) is designed such that the pulse is delivered in the form of a modulated signal having different frequencies. Infusion system according to the preceding claims, characterized in that the infusion system (1) is designed such that by means of sensors (9, 10) or an actuator / sensor element (A / S) pressure and flow characteristics are recorded and from the mechanical properties of the Vein (15) and / or tissue (16) which are connected to the catheter (5) are determined.

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