Blood pump and method of suction detection

• US 9,623,161 B2
• Filed: 08/25/2015
• Issued: 04/18/2017
• Est. Priority Date: 08/26/2014
• Status: Active Grant

• Current Assignee: TC1 LLC (Abbott Laboratories)
• Original Assignee: TC1 LLC (Abbott Laboratories)
• Inventors: Medvedev, Alexander, Rainier, J. Bradford, Sami, Muhammad K.
• Primary Examiner(s): Wieland, Robert N
• Application Number:
  US14/834,757
• Publication Number:
  US 20160058929A1
• Time in Patent Office: 602 Days
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/216 including a rotating member acting on the blood, e.g. impeller
• CPC Class Codes: A61M 60/419 the force acting on the blood contacting member being permanent magnetic, e.g. from a rotating magnetic coupling between driving and driven magnets
• CPC Class Codes: A61M 60/422 the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
• CPC Class Codes: A61M 60/546 of blood flow, e.g. by adapting rotor speed
• CPC Class Codes: A61M 60/824 Hydrodynamic or fluid film bearings

Abstract

A system and method for detecting and mitigating a suction condition are disclosed. The method may include estimating a flow waveform of the pump, identifying pulses in the flow waveform, determining a negative flow based on a valid identification of a pulse, and evaluating a characteristic of the pulse for an existence of a suction condition. In various embodiments, a suction marker is located based on a minimum in a diastolic phase, and the suction marker location is used to identify a probability of a suction condition. A speed of the pump may be adjusted to mitigate the suction condition. A system and method for estimating flow is further disclosed. The method may include interpolating data sets defining pump power to flow for various pump speed values.

Claims

1. A method of detecting a suction event of a blood pump, comprising:

determining a flow waveform of a fluid output of the blood pump;

identifying a pulse in the flow waveform;

determining a negative flow pulse based on a valid identification of the pulse;

evaluating a characteristic of the pulse for an existence of a suction condition by;

locating a suction marker reference point in the pulse based on a midpoint in a diastolic phase of the pulse;

identifying a suction marker location in the pulse where a suction marker flow minimum is reached; and

using the suction marker location to identify a probability of a suction condition; and

modifying operation of the blood pump based at least in part on the existence of the suction condition.

2. The method as in claim 1 wherein the flow is estimated by solving for the following quadratic equation:

F=Ap²+Bp+C

where,

F=Flow Rate (LPM);

p=Pump Power (W) adjusted for hematocrit;

A=Interpolated X2 Polynomial coefficient for a given pump speed;

B=Interpolated X1 Polynomial coefficient for the given pump speed; and

C=Interpolated X0 Polynomial coefficient for the given pump speed.

3. The method as in claim 1, wherein identifying the pulse comprises determining pulse segmentation using a selection from a group consisting of:

the Pulse Average, the Pulse Minima (Turf), the Pulse Maxima (Crest), the pulse falling cross-over point, the Systolic Average (SSA), the Diastolic Average (DSA), the Systolic Pulse Index (SPI), the Diastolic Pulse Index (DPI), the Pulse Flow Index (PFI), the Negative Flow Correction, the Pulse Asymmetry Index, the Pulse Suction Index (Ψ

), the Pulse Duty Cycle (PDC), the Pulse Frequency (PHZ), and a combination of the same.

4. A method to determine a quantity of a suction condition in a blood pump, comprising:

calculating a pulse suction index (Ψ

) according to the formula;

5. The method as in claim 4, further comprising:

controlling pump speed of the blood pump using the (Ψ

), wherein a binary search algorithm of possible pump speeds is used to increase or decrease the pump speed when a determined suction criteria is met, and a step change of the pump speed is bounded by an upper limit identified as safe for a given patient population.

6. The method as in claim 4, wherein an increase in MIN(DSA) with a decrease in speed designates recovery from the suction condition, where MIN(DSA)=Minimum Pulse Diastolic Average.

7. The method as in claim 4, wherein a decrease in MEAN(WAI) with a decrease in speed designates recovery from the suction condition, where MEAN(WAI)=Mean Waveform Asymmetry Index.

8. The method as in claim 4, wherein a decrease in MEAN(PAI) with a decrease in speed designates recovery from the suction condition, where MEAN(PAI)=Mean Pulse Asymmetry Index.

9. The method as in claim 4, wherein a decrease in MEAN(DPI) with a decrease in speed designates recovery from the suction condition, where MEAN(DPI)=Mean Diastolic Pulse Index.

10. The method as in claim 4, wherein a decrease in PSI(Ψ

) with a decrease in speed designates recovery from the suction condition, where PSI(Ψ

)=Pulse Suction Index.

11. The method as in claim 6, wherein a lowest allowable pump speed for recovery from the suction condition is bounded by a Low Speed Limit.

12. A system, comprising:

a blood pump;

a controller configured to operate the blood pump, the controller configured to;

determine a flow waveform of a fluid output of the blood pump;

identify a pulse in the flow waveform;

determine a negative flow pulse based on a valid identification of the pulse;

evaluate a characteristic of the pulse for an existence of a suction condition by;

locating a suction marker reference point in the pulse based on a midpoint in a diastolic phase of the pulse;

identifying a suction marker location in the pulse where a suction marker flow minimum is reached; and

using the suction marker location to identify a probability of a suction condition; and

provide an output based on the existence of a suction condition.

13. The system as in claim 12, wherein the controller estimates the flow by solving for the following quadratic equation:

F=Ap²+Bp+C

where,

F=Flow Rate (LPM);

p=Pump Power (W) adjusted for hematocrit;

A=Interpolated X2 Polynomial coefficient for a given pump speed;

B=Interpolated X1 Polynomial coefficient for the given pump speed; and

C=Interpolated X0 Polynomial coefficient for the given pump speed.

14. The system as in claim 12, wherein identifying the pulse comprises determining pulse segmentation using a selection from a group consisting of:

the Pulse Average, the Pulse Minima (Turf), the Pulse Maxima (Crest), the pulse falling cross-over point, the Systolic Average (SSA), the Diastolic Average (DSA), the Systolic Pulse Index (SPI), the Diastolic Pulse Index (DPI), the Pulse Flow Index (PFI), the Negative Flow Correction, the Pulse Asymmetry Index, the Pulse Suction Index (Ψ

), the Pulse Duty Cycle (PDC), the Pulse Frequency (PHZ), and a combination of the same.