JP2005080982A - Method of detecting abnormality in blood pump system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of detecting the abnormality in a blood pump system base on the power consumption of a pump actuator. <P>SOLUTION: The differentiation value of the power consumption of the pump actuator in terms of time is plotted with respect to the power consumption to obtain a plot pattern. Changes in the area of the plot pattern and/or the moving of the plot pattern indicates changes in the condition of a pump to enable the setting of the index of the heart pump area (HPA) corresponding to the hourly changes in the area of the plot pattern and the index of the position of the heart pump (HPP) corresponding to hourly changes in the position of the plot pattern (for example, equivalent to the travel distance of the plot pattern). The plotting of the HPA index vs the HPP index enables the monitoring of changes in the condition of the pump and the detection of the abnormality in the pump. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  This application claims the benefit of US Provisional Patent Application No. 60 / 409,923, filed Sep. 10, 2002, which is hereby incorporated by reference and made a part thereof.

The present invention relates to the control of a rotary blood pump that assists a disabled human heart. More specifically, the present invention relates to detection of an abnormal state of an implantable blood pump. Various types of rotary blood pumps have been developed so far for use as cardiac assist devices, and are still under development. Compared to pulsating pumps, rotary blood pumps have several advantages such as small size, high efficiency, and simple design. However, a servo control system for such a rotary blood pump has not been developed yet. Currently, the rotational speed of the pump must be controlled manually, so the operator typically needs to monitor the patient in the intensive care unit to monitor the pump and patient status. When such a rotary blood pump is used as a left ventricular assist device (LVAS), the pump flow rate should increase when the pressure head is depressurized at a constant pump rotational speed. This is because these parameters are automatically adjusted according to the physiological condition of the patient regardless of the fixed rotational speed of the pump impeller. However, if venous return decreases too rapidly due to physiological changes or excessive pumping, high negative pressure can occur at the inlet port of the pump, resulting in aspiration in the atria and veins, resulting in serious damage Cause even death.

  In conventional systems, pump flow is typically measured by a flow meter, and the position of the pump impeller is measured by an ultrasonic sensor. It would be beneficial to detect abnormal conditions in the pump system without using a flow meter or other sensor. Therefore, it is preferable to detect and detect an abnormal state of the pump system from the power consumption of the pump actuator. The method of the present invention has the above and other advantages.

  The present invention provides a method for detecting an abnormal state of a blood pump system based on power consumption of a pump actuator. A plot pattern is obtained by plotting a differential value with respect to time of power consumption of the pump actuator with respect to power consumption. Changes in the plot pattern area and / or movement of the plot pattern indicate changes in the state of the pump, such as the heart pump area (HPA) index corresponding to the change in plot pattern area over time and the change in plot pattern position over time (eg A heart pump position (HPP) index corresponding to the distance traveled) can be set. By plotting the HPA index with respect to the HPP index, it is possible to monitor a change in the state of the pump and detect an abnormal state of the pump.

The present invention relates to the detection of an abnormal condition of an implantable blood pump that does not require a flow meter or other sensor.

The present invention provides a method for detecting an abnormal state of a blood pump system based on power consumption of a pump actuator. There is a correlation between the power consumption of the pump actuator and the state of the pump system. A sudden change in the pump system can be detected by monitoring a differential value with respect to the power consumption of the pump actuator. A plot pattern is obtained by plotting a differential value with respect to time of power consumption of the pump actuator with respect to power consumption. The state of the pump system can then be related to the area of the plot pattern and / or the position of the plot pattern. The abnormal state appears in the form of a change in the area of the plot pattern and / or a change in the position of the plot pattern. For example, if the flow rate of the pump system decreases, the area of the plot pattern decreases and the position of the plot pattern moves. To provide a means of detecting any change in the normal state of the pump system, the change in the area of the plot pattern (cardiac pump area (HPA) relative to the movement of the plot pattern (expressed as the heart pump position (HPP) index)) ) (Expressed as an exponent) is plotted. The abnormal state includes a suction state, an excessive pumping state, an insufficient pumping state, and the like.

The present invention will now be described with reference to the accompanying drawings, in which like elements are numbered identically.

The following detailed description merely provides exemplary preferred embodiments and does not limit the scope, applicability, or configuration of the invention. Rather, the following detailed description of the preferred embodiments provides a description for those skilled in the art to practice the preferred embodiments of the invention. It will be appreciated that various changes can be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims.

The present invention utilizes the correlation between the power consumption of the pump actuator and the state of the pump system in order to detect an abnormal state of the pump system.

An example embodiment of the inventive method is shown in FIGS. In the present invention, a rapid change in the pump system is detected by monitoring a time-series differential value of power consumption of the pump actuator. FIG. 1A shows a plot of pump actuator power consumption over time. FIG. 1B shows a plot of time series differential values of power consumption of the pump actuator. In the example embodiment of the invention, a differential value of power consumption with respect to time (FIG. 1B) is plotted against power consumption to obtain a plot pattern shown in FIG. 1C. The state of the pump system is related to the area of the plot pattern and the position of the plot pattern. Thus, a change in the area of the plot pattern and / or a position of the plot pattern indicates a change in the state of the pump system. 1A-1C show plots of both normal pump state 5 and abnormal pump state 10. FIG.

For example, as shown in FIG. 2, an abnormal condition occurs when the flow rate changes (eg, by imposing an inflow graft during an in vivo examination). This abnormal state is indicated as a change in the area of the plot pattern and a change in the position of the plot pattern. FIG. 2 shows that as the flow rate decreases, the area appearing in the plot pattern decreases and the plot moves to the left. In the example shown in FIG. 2, for example, a normal flow rate of about 3 liters per minute appears in the plot pattern 12. As the flow rate decreases to about 1 liter per minute, the plot pattern moves to the left as shown in plot pattern 14 and the area decreases. As the flow rate is further reduced to about 0.1 liters per minute, it moves further to the left as shown in plot pattern 16 and the area of the plot pattern further decreases. A heart pump area (HPA) index corresponding to a change in plot pattern area with time and a heart pump position (HPP) index corresponding to a position change of the plot pattern with time (for example, corresponding to a distance traveled by the plot pattern) are set. can do. For example, the normal state can be represented by HPA 1.0 and HPP 1.0. An increase in plot pattern area appears in the form of an increase in HPA index (eg, HPA 1.2) and a decrease in decrease in HPA index. Movement of the plot pattern to the left appears as a decrease in HPP (eg, HPP 0.8), and movement to the right appears as an increase in HPP. As shown in FIG. 3, the state of the pump can be determined by plotting the HPA index against the HPP index.

In the example shown in FIG. 3, a normal flow rate of 4.5 liters per minute is set, and the result is a normal state 24. Abnormal condition 26 is detected when the flow rate is reduced to 3.5 liters per minute or less. In this way, an abnormal condition of the pump system can be detected without the need for a flow meter or other sensors. Once an abnormal condition is detected, the pump system can be controlled to return to a normal condition. The abnormal state may be a suction state, an overpumping state, or an underpumping state. Aspiration status is indicated by an increase in HPA and HPP values. Overpumping conditions are also indicated by increased HPA and HPP values. An underpumping condition is indicated by a decrease in HPA and HPP values.

Thus, it is clear that the present invention provides a suitable and cost effective method for accurately detecting the status of a pump system without the need for flow meters or other sensors.

  While the invention has been described in terms of various embodiments, various modifications and adaptations can be made without departing from the spirit and scope of the claimed invention.

(FIGS. 1A, 1B and 1C). Illustrating the configuration of a plot pattern used to detect an abnormal condition of a pump system according to an example embodiment of the present invention: The plot pattern change corresponding to the flow volume change at the time of pump inflow restriction by the example of an embodiment of the present invention is shown. Figure 5 shows a plot of HPA index against HPP index according to an example embodiment of the present invention.

Claims (9)

Monitoring the power consumption differential value of the pump actuator of the blood pump system;
Plotting a differential value of pump actuator power consumption over time against pump actuator power consumption to obtain a plot pattern;
A method of detecting an abnormal condition of the pump system, wherein a change in the plot pattern indicates a change in the state of the pump system. The method of claim 1, wherein the change in the plot pattern includes at least one of a change in the area or position of the plot pattern. The method of claim 2, wherein a decrease in the area of the plot pattern indicates a decrease in flow rate of the pump system. The method of claim 2, wherein a decrease and movement of the plot pattern area indicates a decrease in flow rate of the pump system. Establishing a heart pump area (HPA) index corresponding to the time course of the area of the plot pattern;
Establishing a heart pump position (HPP) index corresponding to the time course of the position of the plot pattern;
The method of claim 1, further comprising plotting the HPA index against the HPP index.   6. The method of claim 5, further comprising detecting an abnormal condition of the pump system by monitoring a change in the plot of HPA index relative to HPP index. The method of claim 6, further comprising controlling the pump system in response to the detection of the abnormal condition. The method of claim 6, wherein the abnormal condition includes one of a suction condition, an overpumping condition, or an underpumping condition. The aspiration state is indicated by an increase in the size of the HPA and HPP;
9. The method of claim 8, wherein the overpumping condition is indicated by an increase in the size of the HPA and the HPP; and the underpumping is indicated by a decrease in the size of the HPA and the HPP.

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