Adaptive flow calculation for mechanical cycle support device

Abstract

The present disclosure provides methods and apparatus for determining traffic across a cyclic support device. The method comprises the following steps: receiving a motor current signal from a motor of the cycle support device; determining, within a time window of the motor current signal, a measured current value at which a flow through the cycle support device is maximum; determining an offset value based at least in part on the measured current value; determining whether an abnormal condition has occurred based at least in part on the received motor current signal; adjusting the motor current signal to generate an adjusted motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred; and determining the flow through the cycle support device based at least in part on the adjusted motor current signal.

Description

Technical Field

[0001] The present application relates to adaptive flow calculations, and in particular, to adaptive flow calculations for mechanical circulatory support devices. Background Art

[0002] Fluid pumps, such as blood pumps, are used in the medical field for a wide range of applications and purposes. An intravascular blood pump is a pump that can be advanced through a patient's vasculature (i.e., veins and / or arteries) to a location in the patient's heart or other location within the patient's circulatory system. For example, an intravascular blood pump can be inserted via a catheter and positioned to span a heart valve. An intravascular blood pump is typically placed at the end of a catheter. Once in place, the pump can be used to assist the heart and pump blood through the circulatory system and thereby temporarily reduce the workload on the patient's heart, such as to enable the heart to recover after a heart attack. An exemplary intravascular blood pump is available from ABIOMED, ​​Inc. of Danvers, Massachusetts, under the trade name VIZIUM. A heart pump was purchased.

[0003] Such a pump may be positioned, for example, in a heart chamber, such as the left ventricle, to assist the heart. In this case, the blood pump may be inserted through a hollow catheter via the femoral artery and introduced upward and into the left ventricle of the patient's heart. From this location, the blood pump inlet draws blood, and the blood pump outlet discharges blood into the aorta. In this way, the function of the heart may be replaced or at least assisted by the operation of the pump.

[0004] The intravascular blood pump is typically connected to a corresponding external heart pump controller that controls the heart pump, such as motor speed, and collects and displays operational data about the blood pump, such as heart signal levels, battery temperature, blood flow rate, and tubing integrity. An exemplary heart pump controller is available from Abiomed Corporation under the trade name Automated Impella When the operating data value drops beyond a predetermined value or range, for example, if a leak, suction and / or pump failure is detected, the controller issues an alarm. The controller may include a video display screen on which a graphical user interface configured to display operating data and / or alarms is displayed. Summary of the invention

[0005] Described herein are systems and methods for calculating flow through a mechanical circulatory device.

[0006] In some embodiments of the present technology, a method for determining flow through a circulatory support device is provided. The method includes: receiving a motor current signal from a motor of the circulatory support device; determining a measured current value at which flow through the circulatory support device is maximum within a time window of the motor current signal; determining an offset value based at least in part on the measured current value; determining whether an abnormal condition has occurred based at least in part on the received motor current signal; adjusting the motor current signal to produce an adjusted motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred; and determining the flow through the circulatory support device based at least in part on the adjusted motor current signal.

[0007] In one aspect, the measured current value is a maximum current value or a minimum current value within the time window.

[0008] In an aspect, the measured current value is the minimum current value within the time window.

[0009] In one aspect, the time window is between one and four seconds in length.

[0010] In one aspect, the length of the time window is two seconds.

[0011] In one aspect, determining the offset value is further based at least in part on a speed of the motor.

[0012] In one aspect, the method further includes: storing data associating flow values ​​with motor current values ​​for each of a plurality of motor speeds on at least one storage device, and determining the offset value includes determining an expected current value associated with a maximum flow at the speed of the motor based at least in part on the stored data; and determining the offset value as a difference between the current value and the expected current value.

[0013] In an aspect, adjusting the motor current signal includes adding the offset value to the motor current signal to produce the adjusted motor current signal.

[0014] In one aspect, determining the flow rate through the circulatory support device includes determining the flow rate based further at least in part on the stored data correlating flow rate values ​​to motor current values ​​at the speed of the motor.

[0015] In an aspect, adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal includes using an offset value of zero when it is determined that an abnormal condition has occurred.

[0016] In one aspect, determining whether an abnormal condition has occurred includes determining whether the circulatory support device is in a pumping state or a decoupled state.

[0017] In an aspect, the method further comprises: storing a previously determined offset value in a buffer; and storing the determined offset value in the buffer.

[0018] In one aspect, each of the previously determined offset values ​​in the buffer is a scaled offset value that is scaled based on a speed of the motor when determining the offset value, and storing the determined offset values ​​in the buffer includes scaling the determined offset values ​​based on the speed of the motor and storing the scaled determined offset values ​​in the buffer.

[0019] In an aspect, adjusting the motor current signal includes adjusting the motor current signal based at least in part on a median value of the previously determined offset values ​​in the buffer.

[0020] In one aspect, adjusting the motor current signal includes: transforming the median value based on a current speed of the motor; and adjusting the motor current signal based on the transformed median value.

[0021] In an aspect, the method further includes storing the determined offset value in the buffer only when it is determined that an abnormal condition has not occurred.

[0022] In an aspect, the method further includes filtering the received motor current signal, and adjusting the motor current signal includes adjusting the filtered motor current signal.

[0023] In one aspect, the method further comprises displaying an indication of the determined flow through the circulatory support device on at least one graphical user interface.

[0024] In some embodiments of the present technology, a circulation support device is provided. The circulation support device includes: a rotor; a motor configured to drive the rotation of the rotor at one or more speeds; and at least one controller. The at least one controller is configured to: receive a motor current signal from the motor; determine a measured current value when the flow through the circulation support device is maximum within a time window of the motor current signal; determine an offset value based at least in part on the measured current value; determine whether an abnormal condition has occurred based at least in part on the received motor current signal; adjust the motor current signal to produce an adjusted motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred; and determine the flow through the circulation support device based at least in part on the adjusted motor current signal.

[0025] In one aspect, the measured current value is a maximum current value or a minimum current value within the time window.

[0026] In an aspect, the measured current value is the minimum current value within the time window.

[0027] In one aspect, the time window is between one and four seconds in length.

[0028] In one aspect, the length of the time window is two seconds.

[0029] In one aspect, determining the offset value is further based at least in part on a speed of the motor.

[0030] In one aspect, the at least one controller is further configured to: store data associating flow values ​​with motor current values ​​for each of a plurality of motor speeds on at least one storage device, and determining the offset value comprises: determining an expected current value associated with a maximum flow at the speed of the motor based at least in part on the stored data; and determining the offset value as a difference between the current value and the expected current value.

[0031] In an aspect, adjusting the motor current signal includes adding the offset value to the motor current signal to produce the adjusted motor current signal.

[0032] In one aspect, determining the flow rate through the circulatory support device includes determining the flow rate based further at least in part on the stored data correlating flow rate values ​​to motor current values ​​at the speed of the motor.

[0033] In an aspect, adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal includes using an offset value of zero when it is determined that an abnormal condition has occurred.

[0034] In one aspect, determining whether an abnormal condition has occurred includes determining whether the circulatory support device is in a pumping state or a decoupled state.

[0035] In an aspect, the at least one controller is further configured to: store a previously determined offset value in a buffer; and store the determined offset value in the buffer.

[0036] In one aspect, each of the previously determined offset values ​​in the buffer is a scaled offset value that is scaled based on a speed of the motor when determining the offset value, and storing the determined offset values ​​in the buffer includes scaling the determined offset values ​​based on the speed of the motor and storing the scaled determined offset values ​​in the buffer.

[0037] In an aspect, adjusting the motor current signal includes adjusting the motor current signal based at least in part on a median value of the previously determined offset values ​​in the buffer.

[0038] In one aspect, adjusting the motor current signal includes: transforming the median value based on a current speed of the motor; and adjusting the motor current signal based on the transformed median value.

[0039] In an aspect, the at least one controller is further configured to store the determined offset value in the buffer only when it is determined that an abnormal condition has not occurred.

[0040] In an aspect, the at least one controller is further configured to filter the received motor current signal, and adjusting the motor current signal includes adjusting the filtered motor current signal.

[0041] In one aspect, the at least one controller is further configured to display an indication of the determined flow through the circulatory support device on at least one graphical user interface.

[0042] In some embodiments of the present technology, a controller for a circulatory support device is provided. The controller includes at least one hardware processor configured to: receive a motor current signal from a motor of the circulatory support device; determine a measured current value at which flow through the circulatory support device is maximum within a time window of the motor current signal; determine an offset value based at least in part on the measured current value; determine whether an abnormal condition has occurred based at least in part on the received motor current signal; adjust the motor current signal to produce an adjusted motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred; and determine the flow through the circulatory support device based at least in part on the adjusted motor current signal.

[0043] In one aspect, the measured current value is a maximum current value or a minimum current value within the time window.

[0044] In an aspect, the measured current value is the minimum current value within the time window.

[0045] In one aspect, the time window is between one and four seconds in length.

[0046] In one aspect, the length of the time window is two seconds.

[0047] In one aspect, determining the offset value is further based at least in part on a speed of the motor.

[0048] In one aspect, the at least one hardware processor is further configured to: store data associating flow values ​​with motor current values ​​for each of a plurality of motor speeds on at least one storage device, and determining the offset value comprises: determining an expected current value associated with a maximum flow at the speed of the motor based at least in part on the stored data; and determining the offset value as a difference between the current value and the expected current value.

[0049] In an aspect, adjusting the motor current signal includes adding the offset value to the motor current signal to produce the adjusted motor current signal.

[0050] In one aspect, determining the flow rate through the circulatory support device includes determining the flow rate based further at least in part on the stored data correlating flow rate values ​​to motor current values ​​at the speed of the motor.

[0051] In an aspect, adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal includes using an offset value of zero when it is determined that an abnormal condition has occurred.

[0052] In one aspect, determining whether an abnormal condition has occurred includes determining whether the circulatory support device is in a pumping state or a decoupled state.

[0053] In an aspect, the at least one hardware processor is further configured to: store a previously determined offset value in a buffer; and store the determined offset value in the buffer.

[0054] In one aspect, each of the previously determined offset values ​​in the buffer is a scaled offset value that is scaled based on a speed of the motor when determining the offset value, and storing the determined offset values ​​in the buffer includes scaling the determined offset values ​​based on the speed of the motor and storing the scaled determined offset values ​​in the buffer.

[0055] In an aspect, adjusting the motor current signal includes adjusting the motor current signal based at least in part on a median value of the previously determined offset values ​​in the buffer.

[0056] In one aspect, adjusting the motor current signal includes: transforming the median value based on a current speed of the motor; and adjusting the motor current signal based on the transformed median value.

[0057] In an aspect, the at least one hardware processor is further configured to store the determined offset value in the buffer only when it is determined that an abnormal condition has not occurred.

[0058] In an aspect, the at least one hardware processor is further configured to filter the received motor current signal, and adjusting the motor current signal includes adjusting the filtered motor current signal.

[0059] In an aspect, the at least one hardware processor is further configured to display an indication of the determined flow through the circulatory support device on at least one graphical user interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1A Pump systems according to some embodiments of the present technology are described.

[0061] Figure 1B yes Figure 1A Cross-sectional view of a portion of a pump system.

[0062] Figure 2 is a graph illustrating the change in measured minimum motor current of a pump system over time.

[0063] Figure 3 is a flow chart of a process for adapting a motor current signal suitable for determining flow through a pump system in accordance with some embodiments of the present technology.

[0064] Figures 4A to 4C A process for determining flow rate based on sensed motor current according to some embodiments of the present technology is schematically illustrated.

[0065] Figure 5 A plurality of flow curves at different motor speeds are illustrated, wherein the flow curve describes the relationship between flow through the pump system and motor current.

[0066] Figure 6 is a flow chart of a process for determining an offset value for adjusting a measured motor current value in accordance with some embodiments of the present technology.

[0067] Figure 7 Shifting a flow curve based on a determined offset value according to some embodiments of the present technology is schematically illustrated.

[0068] Figure 8 The results of adjusting the motor current of a pump system by applying an offset value to the measured motor current in accordance with some embodiments of the present technology are described.

[0069] Figures 9A to 9C Describes flow calculation when motor current regulation remains in effect despite detection of an abnormal condition.

[0070] Figures 10A to 10C Techniques for more accurately calculating flow when a puff condition is detected in accordance with some embodiments of the present technology are described.

[0071] Figures 11A to 11D Techniques for more accurately calculating flow when a decoupling condition is detected in accordance with some embodiments of the present technology are described.

[0072] Fig.12 A flow chart illustrating a process for conditioning a motor current signal suitable for determining flow through a pump system in accordance with some embodiments of the present technology. DETAILED DESCRIPTION

[0073] Traditionally, blood flow through a mechanical circulatory support device (e.g., a catheter-based heart pump inserted into a patient's ventricle) is calculated based on the motor speed and motor current sensed from the pump motor. For example, data characterizing the relationship between flow and motor current for each of a plurality of motor speeds (also referred to herein as a Q versus MC curve) may be stored, and the stored data and measured motor current values ​​may be used to estimate the flow when the pump motor is operated at a particular speed. In some intravascular heart pump systems, the pump motor is positioned near the pump within the patient's body. For example, once placed within the patient's body, the pump may be positioned in the left ventricle, and the pump motor may be positioned across the aortic valve in the aorta. In this configuration, the sensed motor current may be considered stable enough to accurately estimate the flow using the techniques described above. Some pump systems may position the pump motor outside the patient's body (and therefore must be at a distance from the pump) to reduce the maximum outer diameter of the pump when it is inserted into and removed from the patient. In this configuration, over time, the sensed motor current may not be stable enough to accurately calculate the flow through the pump. As described in more detail below, some embodiments of the present technology address instabilities in sensed motor current in such configurations by making continuous or near-continuous adjustments (eg, adjustments to the motor current signal) during the flow calculation process.

[0074] exist Figure 1A and 1B1 shows a pump system 100 for use with some embodiments of the present technology. As shown, the pump system 100 is coupled to a control unit 200. The pump 100 includes a distal atraumatic tip 102, a pump housing 104 surrounding a rotor 108, an outflow tube 106, a distal bearing 110, a proximal bearing 112, an inlet 116, an outlet 118, a catheter 120, a handle 130, a cable 140, and a motor 150. The pump housing 104 can be configured as a frame structure formed by a grid having an opening, which can be at least partially covered by an elastic material. The proximal portion of the pump housing 104 extends into and is mounted in the hollow interior of the outflow tube 106, and the distal portion of the pump housing 104 extends distally beyond the distal end of the outflow tube 106. The exposed opening in the pump housing 104 that extends distally beyond the outflow tube 106 forms the inlet 116 of the pump 100. The proximal end of the outflow tube 106 includes a plurality of openings that form an outlet 118 for the pump 100. The rotor 108 is rotatably mounted between the distal bearing 110 and the proximal bearing 112 and is coupled to the distal end of the drive shaft 114. The drive shaft 114 is flexible and extends through the conduit 120, through the hollow interior of the outflow tube 106, into the handle 130, and is coupled to a motor 150 housed in the handle 130. The proximal end of the handle 130 is coupled to the control unit 200 via a cable 140. Fluid may circulate through the conduit 120 near the drive shaft 114 and in the space surrounding the distal bearing 110 and the proximal bearing 112 to lubricate the components and reduce friction during operation of the pump 100.

[0075] The control unit 200 includes one or more memories 202, one or more processors 204, a user interface 206, and one or more current sensors 208. The processor 204 may include one or more microcontrollers, one or more microprocessors, one or more application specific integrated circuits (ASICs), one or more digital signal processors, program memory, or other computing components. The processor 204 is communicatively coupled to the other components of the control unit 200 (e.g., the memory 202, the user interface 206, the current sensor 208), and is configured to control one or more operations of the pump 100. As a non-limiting example, the control unit 200 may be implemented as an Automated Impella from Abiomed, Inc. of Danvers, Massachusetts. In some aspects, memory 202 is included as part of processor 204 rather than being provided as a separate component.

[0076] During operation, the processor 204 is configured to control the electrical power delivered to the motor 150 by the power supply line (not shown) in the cable 140 (e.g., by controlling the power supply (not shown)), thereby controlling the speed of the motor 150. The current sensor 208 can be configured to sense the motor current associated with the operating state of the motor 150, and the processor 204 can be configured to receive the output of the current sensor 208 as a motor current signal. The processor 204 can be further configured to determine the flow through the pump 100 based at least in part on the motor current signal and the motor speed, as described in more detail below. The current sensor 208 can be included in the control unit 200, or can be located along any portion of the power supply line in the cable 140. Additionally or alternatively, the current sensor 208 can be included in the motor 150, and the processor 204 can be configured to receive the motor current signal via a data line (not shown) in the cable 140 coupled to the processor 204 and the motor 150.

[0077] Memory 202 may be configured to store computer-readable instructions and other information for controlling various functions of the components of unit 200. In one aspect, memory 202 includes volatile and / or nonvolatile memory, such as electrically erasable programmable read-only memory (EEPROM).

[0078] The user interface 206 may be configured to receive user input via one or more buttons, switches, knobs, etc. Additionally, the user interface 206 may include a display configured to display information and one or more indicators for conveying information and / or providing alerts regarding the operation of the pump 100, such as light indicators, audio indicators, etc.

[0079] The pump 100 is designed to be inserted into the patient using an introducer system, for example, into the left ventricle of the heart. In one aspect, the housing 104, the rotor 108, and the outflow tube 106 can be radially compressed to enable the pump 100 to achieve a relatively small outer diameter of, for example, 9 Fr (3 mm) during insertion. When the pump 100 is inserted into the patient (for example, into the left ventricle), the handle 130 and the motor 150 remain disposed outside the patient's body. During operation, the motor 150 is controlled by the processor 204 to drive the rotation of the drive shaft 114 and the rotor 108 to deliver blood from the inlet 116 to the outlet 118. It should be understood that the rotor 108 can be reversely rotated by the motor 150 to deliver blood in the opposite direction (in this case, the opening of 118 forms the inlet and the opening of 116 forms the outlet). In one aspect, the pump 100 is expected to be used for a duration of up to 6 hours during a high-risk procedure, but it should be understood that the technology described herein is not limited to any particular type of procedure and / or duration of use.

[0080] Since the motor 150 of the pump 100 drives the rotation of the rotor 108 via the flexible drive shaft 114 disposed in the catheter 120, the motor current sensed by the current sensor 204 is not stable, but instead changes over time, particularly within an initial period after the pump is placed in the patient's heart (e.g., within the first thirty minutes after placement). The instability of the sensed motor current signal can be caused by, among other things, changes in properties associated with the rotation of the flexible drive shaft 114 (e.g., a reduction in friction) because the viscosity of the lubricating fluid also changes during operation. Figure 2 An example is shown of how the minimum motor current determined from a portion of the motor current signal decreases over time during operation of the pump 100. Figure 2 In a graph of FIG. 1 , the y-axis represents the minimum motor current (in mA) determined during a two-second window of the sensed motor current signal, and the x-axis represents time. The inventors have recognized and appreciated that previous flow calculation techniques or algorithms that assume a steady motor current signal cannot be used to accurately calculate flow through a pump 100 where the motor current changes over time. To this end, some embodiments of the present technology account for changes in the motor current signal by adaptively updating the motor current signal before calculating flow based on the motor current signal sensed from the pump 100.

[0081] The flow calculation techniques described herein may be implemented in the control unit 200 of the pump system 100. For example, computer readable instructions for one or all of the techniques described herein may be stored in the memory 202 and executed by the one or more processors 204 of the control unit 200 during use of the pump 100. In addition, parameters and settings of the one or more processors used in the techniques described herein (e.g., predetermined thresholds, predetermined time window lengths, and / or any other parameters and settings of the techniques described herein) may be stored in the memory 202.

[0082] Figure 3 1 is a flow chart of a process 300 for determining flow through a mechanical circulatory support device (e.g., pump 100) based at least in part on a motor current signal associated with a motor of the device in accordance with some embodiments of the present technology. In act 310, a motor current signal is received, for example from one or more motor current sensors 208, as described above in conjunction with Figure 1A Process 300 then proceeds to act 320, where a time window of a predetermined length (e.g., between 1 second and 4 seconds) of the motor current signal is analyzed. In some embodiments, the predetermined length of the time window is 2 seconds. It should be appreciated that in act 320, other durations less than or greater than 2 seconds (e.g., 1 second, 5 seconds, etc.) may be used for the predetermined length of the time window.

[0083] Within the time window, a motor current value associated with a maximum flow through the pump is determined. The flow through the pump is based on the pressure difference between the inlet and outlet of the pump through which blood is transported when the pump is in operation. During contraction, the pressure difference between the inlet and outlet of the pump is zero, resulting in a maximum flow through the pump. Depending on the pump design, the minimum motor current value during the time window may correspond to the maximum flow (when contracting), or the maximum motor current value during the time window may correspond to the maximum flow (when contracting). Therefore, the technology described herein can be configured to determine the minimum motor current value or the maximum motor current value in the time window depending on the type of pump design.

[0084] Process 300 then proceeds to action 330, where it is determined whether an abnormal event has occurred. Continuously or nearly continuously adjusting the motor current during operation of the pump can provide reliable flow calculations under normal operating conditions. However, the inventors have recognized and appreciated that continuing to adjust the motor current when the pump is not operating normally can result in incorrect flow calculations. Therefore, in some embodiments, the presence of an "abnormal event" during operation of the pump is detected, and the adaptation of the motor current using the technology described herein is modified (e.g., suspended) during the occurrence of the abnormal event. Abnormal events may include, but are not limited to, suction events (wherein the inlet of the pump is blocked by cardiac tissue or other materials, thereby blocking the flow through the pump) and decoupling events (which may occur before the suction event). Non-limiting examples of techniques for detecting suction and decoupling events are described in more detail below. Abnormal events other than suction events and decoupling events may also be detected, and motor current adaptation is suspended in response to the detection, because embodiments of the present technology are not limited in this regard.

[0085] If it is determined in act 330 that an abnormal event has not been detected (eg, the pump is operating under normal conditions), then process 300 proceeds to act 340 where an offset value is determined. Figure 6 Flowchart 300 describes an exemplary technique for determining an offset value according to some embodiments. After determining the offset value, process 300 proceeds to act 350, where the measured motor current signal is adjusted based at least in part on the offset value determined in act 340. Process 300 then proceeds to act 360, where the flow through the pump is determined based at least in part on the adjusted motor current signal. An illustrative example of determining the flow through the pump based on the motor current signal is discussed in further detail below with respect to Figures 4 and 5. Process 300 then returns to act 320, where a measured current value associated with the maximum flow within a new time window (e.g., the next 2 second time window) is determined, and acts 320 to 360 may be repeated, thereby adapting the motor current signal in a "continuous" manner until flow calculations are no longer required.

[0086] As discussed above, the inventors have recognized and appreciated that when the pump is not operating normally (e.g., when an abnormal event is detected in act 330 of process 300), the technique of continuously adapting the motor current signal based on the calculated offset value as discussed above in conjunction with acts 340 and 350 may result in an incorrect flow determination in act 360. Therefore, when an abnormal event is detected in act 330, process 300 proceeds to act 370, where one or more previously determined offset values ​​are used to adjust the measured motor current signal in act 350. For example, each time an offset value is determined in act 340, the determined offset value may be stored in a memory (e.g., memory 202). After an abnormal event is detected, the motor current signal may be adjusted using the previously determined offset value stored in the memory. In this way, when an abnormal event continues to be detected in act 330, the continuous adjustment of the motor current is suspended, and the same previously determined offset value is used to adjust the motor current signal during each new time window.

[0087] In some embodiments, multiple determined offset values ​​are stored in a buffer in memory rather than a single previously determined offset value stored in memory, and the offset value used to adjust the motor current signal during an abnormal event is based on the multiple offset values ​​stored in the buffer. For example, the buffer may store the five most recently determined offset values, and the median of the five offset values ​​stored in the buffer may be used to adjust the motor current signal during an abnormal event. Other statistical measures other than the median of the values ​​in the buffer may be used alternatively, including but not limited to the average of the stored values ​​or the weighted average of the stored values. It should be understood that the buffer may store any suitable number of values, and storing five values ​​is only one possibility. For example, the buffer may be configured to store two values, three values, ten values, or more than ten values. By storing multiple offset values ​​in the buffer and selecting the offset value based on the multiple stored offset values, the motor current adaptation exhibits hysteresis to make the transition of the motor current adjustment smoother than if only a single previously determined offset value were stored and used in action 370. In some embodiments, the offset value is added to the buffer only when no abnormal value is detected in act 330 (eg, during normal operation of the pump). In this way, the offset value in the buffer remains static during the course of the abnormal event.

[0088] Figures 4A to 4C A technique for calculating flow rate based on a motor current signal within a time window according to some embodiments is schematically illustrated. Figure 4AA motor current (MC) signal during a single cardiac cycle is illustrated, with motor current in milliamperes (mA) represented on the y-axis and time represented on the x-axis. Based on the value of the motor current signal, a corresponding flow through the pump can then be calculated using a stored relationship relating flow values ​​through the pump to motor current (also referred to herein as a "flow curve" or "Q versus MC curve"), an example of which is shown in FIG. Figure 4B , where flow is represented on the y-axis and motor current is represented on the x-axis. For example, the values ​​graphically represented as a flow curve may be stored in a memory as a lookup table correlating motor current values ​​with flow values ​​at a particular motor speed.

[0089] The flow curves at different motor speeds can be determined during an "offline" test procedure that approximates normal operation of the device in a patient. During the test procedure, flow and motor current are measured at different motor speeds, and multiple flow curves are determined based on the measured data, one flow curve for each motor speed. Figure 4B Multiple flow curves determined for multiple pumps tested at the same motor speed are shown. The average flow curve across the multiple tested pumps can be stored and used to calculate the flow rate during operation of the pump.

[0090] Figure 5 Displays multiple flow curves at different motor speeds. Figure 5 The motors are labeled P1 to P9, where P1 is the slowest speed of the motor and P9 is the fastest speed of the motor. Figure 4B The graphs in Figure 2 illustrate the measurements at a single motor speed. Figure 5 In the graph of , multiple flow curves are also shown at each of the motor speeds P1 to P9. For each of the motor speeds, the value corresponding to a single flow curve (e.g., as an average of the displayed flow curves) can be stored as a lookup table that can be used to calculate the flow during operation of the pump.

[0091] Figure 6 An example implementation of process 340 for determining an offset value for adaptively adjusting a motor current signal of a pump is described in accordance with some embodiments. In act 610, a current motor speed is determined. The current motor speed may be determined in any suitable manner. For example, the motor may be configured to operate at one of a plurality of fixed speeds (e.g., designated as P1 to P9), and the current motor speed may be determined as the fixed speed at which the motor is currently configured to operate. The process then proceeds to act 620, where an expected motor current value associated with a maximum flow through the pump at the current speed of the motor is determined. As described above in conjunction with Figure 5Discussion, some embodiments store data describing the relationship between the flow rate through the pump and the motor current at each of a plurality of fixed motor speeds, also referred to herein as flow curves. The highest point along the y-axis of each of these flow curves represents the expected maximum flow rate when the motor is operated at the particular motor speed associated with the flow curve and the corresponding expected motor current associated with the maximum flow rate. Therefore, by knowing the current speed of the motor, the expected motor current value associated with the maximum flow rate at the current motor speed can be determined by reference to the flow curve data associated with the motor speed.

[0092] Figure 6 The process then continues to act 630 where an offset value is determined based on a comparison of the expected motor current value when flow is maximum determined in act 620 with a measured or "actual" motor current value determined within a particular analysis time window of the motor current signal.

[0093] As discussed above, flow through the pump is greatest during systole during the cardiac cycle because the pressure difference between the inlet and outlet of the pump is minimal (e.g., zero) at this time. For pump designs where the minimum motor current value corresponds to the maximum flow, the minimum motor current value within the analysis time window is determined to be Figure 6 The measured motor current value is used in the comparison of act 630 of the process. Figure 4A In the example of , the minimum motor current value occurs immediately after 1 s during the time window. The difference between the measured minimum motor current value and the motor current value associated with the highest point in the relevant flow curve (i.e., the expected motor current value at the maximum flow for the current motor speed) is used to determine an offset value for the analysis time window, which is used to adjust the motor current signal before determining the flow. For example, in some embodiments, the measured motor current signal can be adjusted using the following equation:

[0094] adj mc =MC+(Min mc –C),

[0095] Where MC is the pump motor current, C is the expected motor current at maximum flow for the current pump speed, Min mc is the minimum measured motor current within the analysis time window, and adj mc is the conditioned motor current signal, which can then be used to calculate the flow through the pump.

[0096] In some embodiments of the present technology, it is assumed that the shape of the flow curve used to determine the flow rate during operation of the pump is constant across the same design (e.g., Figure 1A and 1BThus, a common set of flow curves can be used to calculate flow based on measured motor current, and as described herein, adjusting the motor current based on a determined offset value can be accomplished by shifting the flow curve at the current speed of the motor to the right or left along the motor current axis and then performing the flow calculation using the values ​​in the shifted flow curve.

[0097] Figure 7 Shifting a flow curve by applying an offset value in accordance with some embodiments is schematically shown in . For example, a reference flow curve 710 may have been determined based on an off-line analysis of a plurality of pumps, during which flow and / or motor current were measured during testing to derive values ​​in the flow curve. Flow curve 712 illustrates an example of a hypothetical flow curve associated with a pump during operation. As shown, flow curve 712 is located to the right of flow curve 710 in the graph, such that the same motor current value corresponds to a smaller flow for the reference pump as compared to the operating pump. Therefore, if the motor current signal is not adjusted in this case, it will be assumed that flow curve 710 is correct, and the flow calculation will be incorrectly low. It will be appreciated that due to the steepness of the flow curve, even a small difference in the measured motor current and the expected motor current can still result in a large difference in the flow calculation.

[0098] Using the techniques described herein, including the assumption that the flow curve shape remains constant across the pump, an offset value can be calculated and flow curve 712 can be shifted leftward to the location of flow curve 710. For example, within the analysis time window, the minimum motor current can be determined, which corresponds to the highest point (maximum flow) of flow curve 712. Figure 7 In the example of , this value is about 280 mA. The expected motor current value corresponding to the maximum flow is the highest point of the flow curve 710, which is at Figure 7 is shown to be about 270mA. Figure 7 In the example of , the offset value is 280 mA - 270 mA = 10 mA. Therefore, by subtracting an offset value of 10 mA from each of the data points in flow curve 712, flow curve 712 may be shifted to the left by an appropriate amount.

[0099] Flow curve 714 shows another hypothetical curve 714 where the measured value of the motor current corresponding to the maximum flow is lower than the expected value associated with flow curve 712, which would cause the flow calculation to be incorrectly high if the motor current was not adjusted. For example, without motor current adjustment, a measured motor current of 280 mA results in a flow of approximately 4 l / min based on reference flow curve 710, while the actual flow based on flow curve 714 is substantially lower, at approximately 2.25 l / min. In order to adjust the motor current prior to calculating the flow, the flow curve 714 can be shifted to the right by applying an offset value determined using the techniques described herein. For example, within the analysis time window, a minimum motor current can be determined that corresponds to the highest point (maximum flow) of flow curve 714. In the Figure 7 In the example of , this value is about 250 mA. The expected motor current value corresponding to the maximum flow is the highest point of the flow curve 710, which is at Figure 7 is shown to be about 270mA. Figure 7 In the example of , the offset value is 250mA-270mA=-20mA. Therefore, by adding an offset value of 20mA from each of the data points in the flow curve 714 (e.g., by subtracting an offset value of -20mA), the flow curve 714 can be shifted to the right by an appropriate amount. By shifting the flow curve 714 to the right, the measured motor current signal can be adjusted upward, such as Figure 8 Specifically, Figure 8 Measured motor current signal 810 and adjusted motor current signal 820 are shown after taking into account the offset value using the techniques described herein. In this way, the measured motor current can be continuously adjusted prior to flow calculation to provide a more accurate flow calculation based on the motor current signal.

[0100] Continuous adaptation of the measured pump motor current may be desirable to accommodate instabilities in the motor current signal, for example due to reasons other than changes in flow through the pump. However, the inventors have recognized and appreciated that providing continuous adaptation of the motor current will only result in accurate flow calculations if the adjustments are made while the pump is operating under normal conditions. As discussed above, during operation of the pump, there may be times when the pump is not operating normally. Accordingly, some embodiments are directed to identifying such abnormal conditions and modifying the continuous motor current adaptation techniques described herein to improve flow calculations during the occurrence of such abnormal conditions. Modifying the continuous motor current adaptation based on the detection of abnormal events in pump operation is also referred to herein as "dynamic offset."

[0101] Figures 9A to 9C The effect of keeping continuous motor current adjustment in effect during an abnormal event is described, resulting in an overestimation of flow when the abnormal event occurs. Fig. 9AThe motor current signal of the pump is shown with motor current (mA) represented on the y-axis and time represented on the x-axis. As can be observed, over time, there are characteristic changes in the motor current signal that indicate an abnormal event has occurred, indicating that the pump is not operating properly. Fig. 9C It is demonstrated that continuous adjustment of the motor current signal using the techniques described herein remains in effect regardless of whether an abnormal event is detected. Fig. 9B , arrows indicate points in time when the calculated flow is overestimated when the pump experiences an abnormal event (eg, a suction event) that prevents normal flow through the pump.

[0102] Figures 10A to 10C The following effect is illustrated: the continuous motor current adjustment is modified during abnormal events, resulting in flow calculations that would be expected during such events. Fig. 10A The motor current signal of the pump is shown, where the motor current (mA) is represented on the y-axis and time is represented on the x-axis. Fig. 10A shows that, over time, Fig. 10A There are characteristic changes in the motor current signal that indicate an abnormal event has occurred, indicating that the pump is not operating normally. Fig. 10C The continuous adjustment of the motor current signal using the techniques described herein is demonstrated to be modified (e.g., shut down or "anchored") during a detected abnormal event. Fig. 10B , the arrow indicates that shutting down motor current adaptation during the occurrence of a detected abnormal event (e.g., a suction event) causes the calculated flow to decrease during the duration of the abnormal event, which is what would be expected since normal flow through the pump is interrupted.

[0103] Figures 11A to 11D Another example of the effect of modifying the continuous motor current adjustment during abnormal events, resulting in flow calculations that would be expected during such events, is illustrated. Fig.11A The motor current signal of the pump is shown, where the motor current (mA) is represented on the y-axis and time is represented on the x-axis. Fig.11A , the motor current signal includes multiple types of abnormal events. Before the puff event starting at about the 844 minute mark, a decoupling event starting at about the 836 minute mark can be observed as another type of abnormal event. Fig. 11C Illustrate the output of the puff event detection logic that indicates when a puff event may be detected. Fig.11D Description To account for the presence of both an early decoupling event and a subsequent puff event, the continuous adjustment of the motor current signal using the techniques described herein is modified (eg, shut down or "anchored") during the two detected abnormal events. Fig. 10B, shutting down motor current adaptation during the occurrence of a detected abnormal event causes the calculated flow to decrease smoothly during the duration of the abnormal event, as would be expected since normal flow through the pump is interrupted.

[0104] Abnormal events including but not limited to decoupling events and puff events may be detected in any suitable manner, examples of which are discussed below. In some embodiments, the motor current signal is analyzed to detect one or more metrics for detecting abnormal events. Such metrics include but are not limited to pulsatility index (PI) and minimum bandpass signal (MBS).

[0105] Anomaly detection using pulsation index

[0106] In one aspect of the present technology, a pulsatility index is used to detect abnormal events, such as aspiration events, in a pump system (e.g., pump system 100). For example, in the field of medical ultrasound analysis of blood flow, the pulsatility index is defined as the difference between the peak systolic and end-diastolic blood flow velocities divided by the time-averaged flow velocity. This pulsatility index is assumed to reflect the vascular resistance in an artery located distal to a soundproof location. As described herein, the principles of systolic and diastolic flow velocity pulsations can be extended to the motor current signal of a blood pump to calculate a pulsatility index (PI) of the motor current and used to detect aspiration events.

[0107] For example, in one aspect of the present technique, to calculate the PI of the motor current signal, each of the maximum motor current (Max MC) and the minimum motor current (Min MC) within a predetermined duration time window (Predetermined Time Window) is detected by the processor 204. In addition, the average motor current (Average MC) is calculated by the processor 204 by averaging the motor current samples within the predetermined time window:

[0108]

[0109] Wherein N represents the number of samples collected in the predetermined time window. On the one hand, the predetermined time window is 2 seconds, and the number of samples N collected in the predetermined time window is 500. The 2 second time window is selected to provide a balance between sensitivity and stability when used to detect a puff event using the technology herein. In this regard, the 2 second time window is short enough to enable the method to be sensitive enough to detect a puff event, while also being long enough to enable the method to be stable. It should be understood that other durations less than or greater than 2 seconds (e.g., 1 second, 5 seconds, etc.) for the predetermined time window are considered within the scope of the technology described herein.

[0110] Using the now calculated maximum MC, minimum MC, and average MC, processor 204 calculates the normalized PI of the motor current signal, as defined below:

[0111]

[0112] When a puff event occurs, it causes the PI of the motor current to decrease and the minimum motor current to increase. For example, this effect occurs in Fig. 10A , where the minimum motor current line traces the bottom of the pulsating waveform corresponding to the original motor current. As shown, the pulsation of the original motor current during the puff event is changed. In this regard, as shown Fig. 10A , it is shown that during a puff event, the PI of the motor current decreases and the minimum motor current increases relative to the minimum motor current measured outside of (before and after) the puff event.

[0113] The reduction in the pulsation of the motor current exhibited during a puff event can be used to detect abnormal events during operation of the pump, such as a puff event. Since the calculated PI is normalized (by dividing by the average motor current), a global threshold can be defined across all pump speeds and in view of the decrease in motor current over time. Then, when the pump is operating, the global threshold can be compared to the calculated PI of the motor current to detect whether a puff event has occurred. For example, the threshold can be about (e.g., + / - 10%) 0.15, but it should be understood that a different threshold can be used alternatively.

[0114] Abnormal event detection using normalized minimum passband signal

[0115] An additional or alternative technique for detecting abnormal events, such as suction events, involves filtering the motor current signal using a bandpass filter that passes frequencies within a predetermined range, such as 0.5 to 5 Hz. The predetermined range, such as 0.5 to 5 Hz, may be selected based on a typical heart rate range of 30 to 300 beats per minute (BPM). It should be appreciated that the predetermined range may be 0.5 to 3 Hz, 0.5 to 5 Hz, 0.5 to 8 Hz, 0.5 to 10 Hz, or any other suitable range that contains sufficient information about the pulsation of the patient's heartbeat. The range of 0.5 Hz to 5 Hz may balance sensitivity and stability when used to detect abnormal events, as described in more detail below.

[0116] Bandpass filtering is similar to extracting pulsation information from the motor current signal, assuming a typical heartbeat range of 30 to 300 BPM. The bandpass filter may be implemented as a digital filter applied by the processor 204 (e.g., filter software that may be stored in the memory 202 and executed by the processor 204). Alternatively, the processor 204 may control one or more analog filter circuits (including a suitable bandpass filter), such as included in the control unit 200 or external to the control unit 200, to bandpass filter the motor current signal. In yet further embodiments, a combination of analog and digital filters may be used to implement the bandpass filter.

[0117] In one aspect, the bandpass filter may be a sixth order elliptic filter that passes frequencies within a predetermined range (e.g., 0.5 to 5 Hz). As described above, the normalization of the signal used in the abnormal event detection techniques described herein allows the use of an absolute threshold to detect such events, even though the motor current may vary over time (e.g., trending downward). Thus, the bandpass filtered signal may also be normalized. For example, in one aspect, the processor 204 normalizes the bandpass signal according to the following equation:

[0118]

[0119] i=0 to N

[0120] Wherein the equation is performed as a point-wise operation such that each sample i of the bandpass filtered signal (MC(bandpass(i))) is divided by each sample i of the lowpass filtered signal (MC(lowpass(i))) to produce a normalized bandpass signal.

[0121] Next, the processor 204 calculates a normalized minimum bandpass signal index (referred to herein as the MBS index) by detecting a minimum value of the normalized bandpass filtered signal within a predetermined time window of the signal and evaluating the MBS index relative to a threshold. In one aspect, the absolute value of the minimum value detected within the predetermined time window (i.e., abs(MBS)) is compared to the threshold. Using the absolute value of the MBS can facilitate the determination of abnormal events, such as events from the motor current signal.

[0122] In some embodiments, both the PI of the motor current and the MBS index described above are combined to detect abnormal events. Combining the PI and MBS index in a single method can produce more sensitive and stable results for abnormal event detection. In the abnormal event detection techniques described herein, there is generally a trade-off between sensitivity and specificity. In this regard, increasing the sensitivity of the detection technique can reduce its specificity.

[0123] Fig.12 Flowchart illustrating an example process 1200 for continuously adjusting a motor current suitable for calculating flow through a mechanical circulatory support device (e.g., pump 100) according to some embodiments. In act 1210, a motor current (MC) signal is received from a motor of the pump during operation. Process 1200 then proceeds to act 1212, where a 2 second window of the motor current signal is extracted for analysis. As described above in conjunction with Figure 3 As discussed in action 320 of process 1200, any suitable length of window may be used, and the example of using a 2 second window in process 1200 is not limiting.

[0124] Process 1200 then proceeds to action 1214, where the motor current signal within the 2 second time window is analyzed to determine one or more characteristics of the motor current signal, examples of which include but are not limited to the maximum MC, the minimum MC, the pulsation index (PI), and the minimum band pass signal (MBS). Then, one or more of the determined characteristics are provided as input to a state machine 1216. State machine 1216 is configured to process the value input from action 1214 and determine whether an abnormal event has occurred (e.g., by comparing the input value to one or more thresholds). For example, determining whether an abnormal event has occurred is discussed in conjunction with action 330 above. In some embodiments, at least some of the characteristics determined in action 1214 can be used to determine other characteristics or metrics for detecting abnormal events. For example, the maximum MC and the minimum MC can be used to determine the PI and / or MBS as described above. Additionally or alternatively, one or more characteristics (e.g., PI, MBS) determined in action 1214 can be provided directly to state machine 1216 for abnormal event detection. In some embodiments, the state machine is implemented as a finite state machine model where the offset value used to adjust the motor current is scalar-controlled (anchored to update) by one or both of the PI and MBS values ​​provided as inputs to the state machine.

[0125] If it is determined by state machine 1216 that an abnormal event has occurred (e.g., based on one or both of the PI and the MBS), then process 1200 proceeds to act 1218, where the offset value is not determined (or alternatively, the offset value is set to 0). Process 1200 then proceeds to acts 1220 and 1222, where an offset value for the motor current adaptation process is determined, e.g., as previously discussed in connection with act 340 of process 300. As shown, some embodiments store a plurality of previously determined offset values ​​in a buffer (e.g., corresponding to a 10 second window of the motor current signal), and a median of the values ​​stored in the buffer may be selected in act 1222 as the offset value for adapting the motor current.

[0126] The motor current signal 1210 may be adapted in act 1228 based on the results of the previous acts in process 1200. Adapting the motor current signal based on the determined offset value is discussed in greater detail herein in conjunction with act 350 of process 300. As shown, in some embodiments, the motor current signal 1210 may be smoothed (e.g., filtered using a low pass filter) in act 1226 prior to adaptation in act 1228. During adaptation in act 1228, an offset value (e.g., based on the median minimum motor current in the buffer or 0) is subtracted from the minimum motor current when the pressure difference between the inlet and outlet of the pump is minimum (dp=0, as shown by element 1224 in process 1200) (as discussed above, this corresponds to a point in time when the flow through the pump is maximum (during contraction)). The value is then added to the smoothed motor current signal in act 1228 to produce an adjusted motor current signal. Process 1200 then proceeds to act 1230, where the adjusted motor current signal is used to calculate the motor current using stored data relating motor current to flow (e.g., as described above in conjunction with Figure 5 Determining the flow rate based on the adjusted motor current is described in more detail herein in conjunction with act 360 of process 300.

[0127] Process 1200 then proceeds to act 1232, where the flow rate determined in act 1230 is provided as an output (e.g., to a user). In some embodiments, the calculated flow rate determined in act 1232 can be used to change the operation of control unit 200. For example, an indication of the calculated flow rate can be provided via user interface 206 of control unit 200, as described herein in conjunction with Figure 1A Description. An indication of the calculated flow rate may be provided in any suitable manner. For example, a numerical value indicating the flow rate may be provided on a display associated with a user interface. Additionally or alternatively, a graphical value indicating the flow rate may be displayed, one or more visual indicators (e.g., one or more lights, such as LEDs) may be activated based on the calculated flow rate, or one or more auditory signals may be provided to indicate the calculated flow rate. In some embodiments, the calculated flow rate may be used to control one or more operations of the pump itself (e.g., by changing the operation of the motor 150). In such embodiments, the continuous motor current adaptation provided by the present technology may provide feedback control of the pump that enables the flow rate to be maintained within specified limits, thereby optimizing the flow rate for an individual patient.

[0128] Thus, having described several aspects and embodiments of the technology presented in this disclosure, it should be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. For example, while aspects of the technology relate to an apparatus and method for detecting, separating, purifying, and / or quantifying bacteria as described herein, the inventors have recognized that such apparatus and methods are broadly applicable to other organisms of interest, such as viruses, yeast, and aspects of the technology are not limited in this regard.

[0129] Such changes, modifications and improvements are intended to be within the spirit and scope of the technology described herein. For example, a person of ordinary skill in the art will readily envision various other components and / or structures for performing functions and / or obtaining results and / or one or more advantages described herein, and each of such changes and / or modifications is considered to be within the scope of the embodiments described herein. Those skilled in the art will recognize or be able to determine many equivalents for the specific embodiments described herein using only routine experiments. Therefore, it should be understood that the aforementioned embodiments are presented only by example, and within the scope of the appended claims and their equivalents, the inventive embodiments may be practiced in a manner other than the specific description. In addition, if two or more features, systems, articles, materials, sets and / or methods described herein are not inconsistent with each other, any combination of such features, systems, articles, materials, sets and / or methods is included within the scope of the present disclosure.

[0130] The embodiments described above can be implemented in any of several ways. One or more aspects and embodiments of the present disclosure related to the execution of a process or method can utilize program instructions that can be executed by a device (e.g., a computer, a processor, or other device) to execute a process or method or control the execution of a process or method. In this regard, various inventive concepts can be embodied as a computer-readable storage medium (or multiple computer-readable storage media) (e.g., a computer memory, one or more floppy disks, optical disks, optical disks, tapes, flash memory, circuit configurations in field programmable gate arrays or other semiconductor devices, or other tangible computer storage media) encoded using one or more programs, and the one or more programs, when executed on one or more computers or other processors, perform the method of implementing one or more of the various embodiments described above. The computer-readable medium can be portable, so that the program stored thereon can be loaded onto one or more different computers or other processors to implement the various aspects described above. In some embodiments, the computer-readable medium can be a non-transitory medium.

[0131] The above-described embodiments of the present technology can be implemented in any of several ways. For example, the embodiments can be implemented using hardware, software, or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or set of processors, whether provided in a single computer or distributed throughout multiple computers. It should be understood that any component or set of components that perform the functions described above can be generally regarded as a controller that controls the functions described above. The controller can be implemented in several ways, such as using dedicated hardware or using general-purpose hardware (e.g., one or more processors) that is programmed using microcode or software to perform the functions described above, and when the controller corresponds to multiple components of the system, it can be implemented in a combination of several ways.

[0132] Furthermore, it should be appreciated that a computer may be embodied in any of a number of forms, such as, by way of non-limiting example, a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally regarded as a computer but having suitable processing capabilities, including a personal digital assistant (PDA), a smart phone, or any other suitable portable or fixed electronic device.

[0133] In addition, a computer may have one or more input and output devices. These devices may be used, among other things, to present a user interface. Examples of output devices that may be used to provide a user interface include a printer or display screen for visual presentation of output and a speaker or other sound generating device for auditory presentation of output. Examples of input devices that may be used for a user interface include a keyboard and a pointing device, such as a mouse, a touch pad, and a digitizing tablet. As another example, a computer may receive input information through speech recognition or in other auditory formats.

[0134] Such computers may be interconnected by one or more networks in any suitable form, including local or wide area networks, such as enterprise networks and intelligent networks (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks, or fiber optic networks.

[0135] In addition, as described, some aspects may be embodied as one or more methods. The actions performed as part of the methods may be ordered in any suitable manner. Thus, embodiments may be constructed in which the actions are performed in an order different from that described, which may include performing some actions simultaneously, even though they are shown as sequential actions in an illustrative embodiment.

[0136] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0137] The indefinite articles "a" and "an" as used herein in the specification and claims should be understood to mean "at least one", unless explicitly indicated to the contrary.

[0138] The phrase "and / or" as used herein in the specification and claims should be understood to mean "either or both" of the elements so combined (i.e., elements that are presented in combination in some cases and separately in other cases). Multiple elements listed using "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements so combined. In addition to the elements explicitly identified by the "and / or" clause, other elements may optionally be present, whether related or unrelated to the elements explicitly identified. Thus, as a non-limiting example, when used in conjunction with an open-ended term such as "comprising"), a reference to "A and / or B" may refer to only A (optionally including elements other than B) in one embodiment; to only B (optionally including elements other than A) in other embodiments; to both A and B (optionally including other elements) in yet another embodiment; and so on.

[0139] With respect to a list of one or more elements, the phrase "at least one" as used herein in the specification and claims should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but does not necessarily include at least one of each element explicitly listed in the list of elements and does not exclude any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than the elements explicitly identified in the list of elements to which the phrase "at least one" refers, whether related to or unrelated to the elements explicitly identified. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently, "at least one of A and / or B") may refer to at least one (optionally including more than one) A, without B (and optionally including elements other than B); in another embodiment, may refer to at least one (optionally including more than one) B, without A (and optionally including elements other than A); in yet another embodiment, may refer to at least one (optionally including more than one) A and at least one (optionally including more than one) B (and optionally including other elements); and so on.

[0140] In addition, the words and terms used herein are for descriptive purposes and should not be considered limiting. The use of "including," "comprising," or "having," "containing," "involving," and variations thereof herein is intended to encompass the items listed thereafter and their equivalents as well as additional items.

[0141] In the claims and in the above description, all transitional phrases such as "comprising", "including", "carrying", "having", "containing", "involving", "maintaining", "consisting of", etc. should be understood as open-ended, i.e., meaning including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" should be closed or semi-closed transitional phrases, respectively.

[0142] The use of sequential terms (such as "first", "second", "third", etc.) in the claims to modify the claimed elements themselves does not indicate any priority, precedence, or order in which one claimed element is superior to another or the time order of the actions of performing the method, but is merely used as a label to distinguish one claimed element with a specific name from another element with the same name (if no sequential terms are used) to distinguish the claimed elements.

Claims

1. A method of determining flow through a circulatory support device, the method comprising: receiving a motor current signal from a motor of the circulatory support device; determining within a time window of the motor current signal a measured current value at which flow through the circulatory support device is maximum; determining an offset value based at least in part on the measured current value; determining whether an abnormal condition has occurred based at least in part on the received motor current signal; adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal; and The flow rate through the circulatory support device is determined based at least in part on the adjusted motor current signal. 2 . The method according to claim 1 , wherein the measured current value is a maximum current value or a minimum current value within the time window. The method of claim 2 , wherein the measured current value is the minimum current value within the time window. The method of claim 1 , wherein the time window is between one second and four seconds in length. The method of claim 4 , wherein the length of the time window is two seconds. The method of claim 1 , wherein determining the offset value is further based at least in part on a speed of the motor.

7. The method according to claim 6, further comprising: storing data on at least one storage device relating flow values ​​to motor current values ​​for each of a plurality of motor speeds, and Wherein determining the offset value comprises: determining an expected current value associated with a maximum flow rate at the speed of the motor based at least in part on the stored data; and The offset value is determined as a difference between the current value and the expected current value. 8 . The method of claim 7 , wherein adjusting the motor current signal comprises adding the offset value to the motor current signal to produce the adjusted motor current signal.

9. The method of claim 7, wherein determining the flow through the circulatory support device comprises: The flow rate is further determined based at least in part on the stored data relating flow rate values ​​to motor current values ​​at the speed of the motor.

10. The method of claim 1, wherein adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal comprises using an offset value of zero when it is determined that an abnormal condition has occurred.

11. The method of claim 10, wherein determining whether an abnormal condition has occurred comprises determining whether the circulatory support device is in a pumping state or a decoupled state.

12. The method according to claim 1, further comprising: storing a previously determined offset value in a buffer; and The determined offset value is stored in the buffer.

13. The method of claim 12, wherein each of the previously determined offset values ​​in the buffer is a scaled offset value that is scaled based on a speed of the motor when determining the offset value, and Wherein storing the determined offset value in the buffer comprises: scaling the determined offset value based on the speed of the motor; and The scaled determined offset value is stored in the buffer.

14. The method of claim 12 or 13, wherein adjusting the motor current signal comprises adjusting the motor current signal based at least in part on a median value of the previously determined offset values ​​in the buffer.

15. The method of claim 14, wherein adjusting the motor current signal comprises: transforming the median value based on a current speed of the motor; and The motor current signal is adjusted based on the transformed median value.

16. The method of claim 12, further comprising: The determined offset value is stored in the buffer only when it is determined that an abnormal condition has not occurred.

17. The method of claim 1, further comprising: filtering the received motor current signal, and Wherein adjusting the motor current signal includes adjusting the filtered motor current signal.

18. The method of claim 1, further comprising: An indication of the determined flow through the circulatory support device is displayed on at least one graphical user interface.

19. A circulatory support device comprising: Rotor; a motor configured to drive rotation of the rotor at one or more speeds; and At least one controller configured to: receiving a motor current signal from the motor; determining within a time window of the motor current signal a measured current value at which flow through the circulatory support device is maximum; determining an offset value based at least in part on the measured current value; determining whether an abnormal condition has occurred based at least in part on the received motor current signal; adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal; and The flow rate through the circulatory support device is determined based at least in part on the adjusted motor current signal.

20. The circulatory support device of claim 19, wherein the measured current value is a maximum current value or a minimum current value within the time window.

21. The circulatory support device of claim 20, wherein the measured current value is the minimum current value within the time window.

22. The circulatory support device of claim 19, wherein the time window is between one second and four seconds in length.

23. The circulatory support device of claim 22, wherein the length of the time window is two seconds.

24. The circulatory support device of claim 19, wherein determining the offset value is further based at least in part on a speed of the motor.

25. The circulatory support device of claim 19, wherein the at least one controller is further configured to: storing data on at least one storage device relating flow values ​​to motor current values ​​for each of a plurality of motor speeds, and Wherein determining the offset value comprises: determining an expected current value associated with a maximum flow rate at the speed of the motor based at least in part on the stored data; and The offset value is determined as a difference between the current value and the expected current value.

26. The circulatory support device of claim 25, wherein adjusting the motor current signal comprises adding the offset value to the motor current signal to produce the adjusted motor current signal.

27. The circulatory support device of claim 25, wherein determining the flow rate through the circulatory support device comprises: The flow rate is further determined based at least in part on the stored data relating flow rate values ​​to motor current values ​​at the speed of the motor.

28. The circulatory support device of claim 19, wherein adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal comprises using an offset value of zero when it is determined that an abnormal condition has occurred.

29. The circulatory support device of claim 28, wherein determining whether an abnormal condition has occurred comprises determining whether the circulatory support device is in a pumping state or a decoupled state.

30. The circulatory support device of claim 19, wherein the at least one controller is further configured to: storing the previously determined offset value in a buffer; and The determined offset value is stored in the buffer.

31. The circulatory support device of claim 30, wherein each of the previously determined offset values ​​in the buffer is a scaled offset value that is scaled based on a speed of the motor when determining the offset value, and wherein storing the determined offset values ​​in the buffer comprises: scaling the determined offset value based on the speed of the motor; and The scaled determined offset value is stored in the buffer.

32. A circulatory support device according to claim 30 or 31, wherein adjusting the motor current signal comprises adjusting the motor current signal based at least in part on a median value of the previously determined offset values ​​in the buffer.

33. The circulatory support device of claim 32, wherein adjusting the motor current signal comprises: transforming the median value based on a current speed of the motor; and The motor current signal is adjusted based on the transformed median value.

34. The circulatory support device of claim 30, wherein the at least one controller is further configured to: The determined offset value is stored in the buffer only when it is determined that an abnormal condition has not occurred.

35. The circulatory support device of claim 19, wherein the at least one controller is further configured to: filtering the received motor current signal, and Wherein adjusting the motor current signal includes adjusting the filtered motor current signal.

36. The circulatory support device of claim 19, wherein the at least one controller is further configured to: An indication of the determined flow through the circulatory support device is displayed on at least one graphical user interface.

37. A controller for a circulatory support device, the controller comprising: At least one hardware processor configured to: receiving a motor current signal from a motor of the circulatory support device; determining within a time window of the motor current signal a measured current value at which flow through the circulatory support device is maximum; determining an offset value based at least in part on the measured current value; determining whether an abnormal condition has occurred based at least in part on the received motor current signal; adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal; and The flow rate through the circulatory support device is determined based at least in part on the adjusted motor current signal.

38. The controller of claim 37, wherein the measured current value is a maximum current value or a minimum current value within the time window.

39. The controller of claim 38, wherein the measured current value is the minimum current value within the time window.

40. The controller of claim 37, wherein the time window is between one and four seconds in length.

41. A controller according to claim 40, wherein the length of the time window is two seconds.

42. The controller of claim 37, wherein determining the offset value is further based at least in part on a speed of the motor.

43. The controller of claim 37, wherein the at least one hardware processor is further configured to: storing data on at least one storage device relating flow values ​​to motor current values ​​for each of a plurality of motor speeds, and Wherein determining the offset value comprises: determining an expected current value associated with a maximum flow rate at the speed of the motor based at least in part on the stored data; and The offset value is determined as a difference between the current value and the expected current value.

44. The controller of claim 43, wherein adjusting the motor current signal comprises adding the offset value to the motor current signal to produce the adjusted motor current signal.

45. The controller of claim 44, wherein determining the flow rate through the circulatory support device comprises: The flow rate is further determined based at least in part on the stored data relating flow rate values ​​to motor current values ​​at the speed of the motor.

46. ​​The controller of claim 37, wherein adjusting the motor current signal based at least in part on the offset value and the determination of whether an abnormal condition has occurred to produce an adjusted motor current signal comprises using an offset value of zero when it is determined that an abnormal condition has occurred.

47. The controller of claim 46, wherein determining whether an abnormal condition has occurred comprises determining whether the circulatory support device is in a pumping state or a decoupled state.

48. The controller of claim 37, wherein the at least one hardware processor is further configured to: storing the previously determined offset value in a buffer; and The determined offset value is stored in the buffer.

49. The controller of claim 48, wherein each of the previously determined offset values ​​in the buffer is a scaled offset value that is scaled based on a speed of the motor when determining the offset value, and Wherein storing the determined offset value in the buffer comprises: scaling the determined offset value based on the speed of the motor; and The scaled determined offset value is stored in the buffer.

50. A controller as claimed in claim 48 or 49, wherein adjusting the motor current signal comprises adjusting the motor current signal based at least in part on a median value of the previously determined offset values ​​in the buffer.

51. The controller of claim 50, wherein adjusting the motor current signal comprises: transforming the median value based on a current speed of the motor; and The motor current signal is adjusted based on the transformed median value.

52. The controller of claim 48, wherein the at least one hardware processor is further configured to: The determined offset value is stored in the buffer only when it is determined that an abnormal condition has not occurred.

53. The controller of claim 37, wherein the at least one hardware processor is further configured to: filtering the received motor current signal, and Wherein adjusting the motor current signal includes adjusting the filtered motor current signal.

54. The controller of claim 37, wherein the at least one hardware processor is further configured to: An indication of the determined flow through the circulatory support device is displayed on at least one graphical user interface.

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