Fiducial point optimization

Patent metadata

Field	Value
Publication number	US-2016144092-A1
Application number	US-201514950213-A
Country	US
Kind code	A1
Filing date	Nov 24, 2015
Priority date	Nov 26, 2014
Publication date	May 26, 2016
Grant date	—

Abstract

A flow rate of blood through an implantable blood pump is determined based on a parameter related to the flow, such as a parameter related to thrust on the rotor of the pump. An amount of current supplied to the pump is used to determine each of a first flow rate value and second flow rate values. Each of the first and second flow rate values, in combination with the parameter related to thrust on the rotor of the pump, are used to calculate a flow rate of blood through the pump.

First claim

1 . A method for monitoring operation of an implantable blood pump, the method comprising:
determining an amount of current supplied to the pump; determining a first flow rate value and a second flow rate value based on the amount of current supplied to the pump; and determining a flow rate of blood based on a combination of the first and second flow rate values and a weighting parameter such that the combination of the first and second flow rate values varies depending on the weighting parameter.

2 . A method as in claim 1 , wherein the implantable blood pump includes a housing having an axis and a rotor disposed within the housing and rotatable around the axis, and wherein the weighting parameter is related to thrust on the rotor along the axis.

3 . A method as in claim 1 , wherein the weighting parameter increases or decreases monotonically over the range of operable flow rates for the pump.

4 . A method as in claim 3 , wherein the weighting parameter increases or decreases monotonically over a subset of the range of operable flow rates for the pump.

5 . A method as in claim 1 , wherein a weight assigned to each of the first and second flow rate values is determined based at least in part on a relationship between the weighting parameter and a predetermined threshold value.

6 . A method as in claim 5 , wherein the assigned weight for the first flow rate value is inversely proportionate to the relationship between the weighting parameter and the predetermined threshold value, and the assigned weight for the second flow rate value is proportionate to the relationship between the weighting parameter and the predetermined threshold value.

7 . A method as in claim 5 , wherein determining the relationship between the weighting parameter and the predetermined threshold value further comprises comparing the difference between the weighting parameter and the threshold value to a preselected spread value.

8 . A method as in claim 1 , further comprising:
calculating an absolute difference between the weighting parameter and a predetermined threshold value; comparing said absolute difference to a predetermined spread value, wherein the flow rate of blood based is determined based on a combination of the first and second flow rate values only if the absolute difference between the third parameter and a predetermined threshold value is less than the predetermined spread value.

9 . A method as in claim 8 , further comprising:
if said absolute difference is greater than the spread value, and the third parameter is less than the predetermined threshold value, determining the flow rate of blood based on the first flow rate value and not the second flow rate value; and if said absolute difference is greater than the spread value, and the third parameter is greater than the predetermined threshold value, determining the flow rate of blood based on the second flow rate value and not the first flow rate value.

10 . A method as in claim 8 , further comprising:
determining a speed of rotation of the rotor; and comparing the determined speed to a threshold value, wherein if said absolute difference is greater than the spread value, the third parameter is less than the predetermined threshold value: the flow rate of blood is determined based on the first flow rate value only if the determined speed is greater than the threshold value, and if the determined speed is less than the threshold speed value, the flow rate of blood is determined based on the third parameter and neither of the first and second flow rate values.

11 . A control circuit for monitoring the operation of an implantable blood pump, the control circuit comprising:
a current determination circuit operative to determine an amount of current supplied to the pump; a flow rate value determination circuit operative to determine a first flow rate value and a second flow rate value based on the amount of current supplied to the pump; a transformation circuit operative to determine a weighting parameter; and a flow rate determination circuit operative to determine a flow rate of blood through the pump based on a combination of the first and second flow rate values and the weighting parameter.

12 . A control circuit as in claim 11 , wherein the implantable blood pump includes a housing having an axis and a rotor disposed within the housing and rotatable around the axis, and wherein the weighting parameter is related to thrust on the rotor along the axis.

13 . A control circuit as in claim 11 , wherein the weighting parameter increases or decreases monotonically over the range of operable flow rates for the pump.

14 . A method as in claim 13 , wherein the weighting parameter increases or decreases monotonically over a subset of the range of operable flow rates for the pump.

15 . A control circuit as in claim 11 , wherein the flow rate determination circuit is further operative to:
determine a relationship between the weighting parameter and a predetermined threshold value; and determine a respective weight for each of the first and second flow rate values based on said relationship.

16 . A control circuit as in claim 15 , wherein the weight for the first flow rate value is inversely proportionate to the relationship between the weighting parameter and the predetermined threshold value, and the weight for the second flow rate value is proportionate to the relationship between the weighting parameter and a predetermined threshold value.

17 . A control circuit as in claim 15 , wherein the flow rate determination circuit is further operative to compare the difference between the weighting parameter and the threshold value to a preselected spread value, wherein the relationship between the weighting parameter and the predetermined threshold value is determined based on said comparison.

18 . A control circuit as in claim 11 , wherein the flow rate determination circuit is further operative to:
calculate an absolute difference between the third parameter and a predetermined threshold value; and compare said absolute difference to a predetermined spread value, wherein the flow rate determination circuit determines the flow rate of blood based on a combination of the first and second flow rate values only if the absolute difference between the third parameter and a predetermined threshold value is less than the predetermined spread value.

19 . A control circuit as in claim 18 , wherein the flow rate determination circuit is further operative to:
determine the flow rate of blood based on the first flow rate value and not the second flow rate value if the absolute difference is greater than the spread value, and the weighting parameter is less than the predetermined threshold value; and determine the flow rate of blood based on the second flow rate value and not the first flow rate value if the absolute difference is greater than the spread value, and the weighting parameter is greater than the predetermined threshold value.

20 . A control circuit as in claim 18 , further comprising a speed determination circuit operative to determine a speed of rotation of the rotor, wherein the flow rate determination circuit is further operative to:
compare the determined speed to a preselected threshold value; determine the flow rate of blood based on based on the weighting parameter and neither of the first and second flow rate values if the absolute difference is greater than the spread value, the weighting parameter is less than the predetermined thr

Assignees

• Heartware Inc

Inventors

• Casas Fernando
• Wolman Justin
• Reyes Carlos

Classifications

• A61M1/1086 Primary

  Human Necessities · mapped topic

• A61M2205/3365

  Rotational speed · CPC title

• A61M1/1046

  Human Necessities · mapped topic

• A61M2205/702

  automatically during use · CPC title

• A61M2205/3334

  Measuring or controlling the flow rate · CPC title