Blood pump system and method of operation
A blood pump system includes a blood pump having a motor with a rotor and a stator. The stator has a plurality of stator windings situated therein. A motor controller is coupled to the motor, and a processor has inputs coupled to the motor controller for receiving a time continuous signal from the pump. The processor is programmed to transform the time continuous signal to the frequency domain, and control the pump and detect excess suction in response to the time continuous signal in the frequency domain.
1. A method of controlling a blood pump, comprising:
sampling a time continuous signal from the blood pump;
transforming the sampled time continuous signal to the frequency domain;
analyzing the sampled time continuous signal in the frequency domain;
controlling the blood pump in response to the analysis of the sampled time continuous signal in the frequency domain; and
detecting excess suction in response to analysis of distortion in the sampled time continuous signal in the frequency domain.
2. The method of claim 1 , further comprising determining parametric data in response to the analysis of the sampled time continuous signal in the frequency domain.
3. The method of claim 2 , wherein the parametric data include heart rate.
4. The method of claim 3 , further comprising zero padding the time continuous signal.
5. The method of claim 4 , wherein sampling the time continuous signal from the blood pump includes sampling less than about 200 data points of the time continuous signal.
6. The method of claim 5 , further comprising zero padding at least about 3800 data points.
7. The method of claim 2 , wherein the parametric data include respiratory rate.
8. The method of claim 2 , wherein the parametric data include pump flow rate.
9. The method of claim 1 , further comprising validating the sampled time continuous signal in response to the analysis of the sampled time continuous signal in the frequency domain.
10. The method of claim 9 , wherein validating the sampled time continuous signal includes evaluating the signal to noise ratio.
11. The method of claim 9 , wherein validating the sampled time continuous signal includes evaluating the signal to noise plus distortion ratio.
12. The method of claim 1 , wherein the time continuous signal comprises the pump flow rate.
13. The method of claim 1 , wherein the time continuous signal comprises the pump speed.
14. The method of claim 1 , wherein the time continuous signal comprises the pump current.
15. A blood pump control system, comprising:
a processor adapted to receive a time continuous signal from a blood pump; and
wherein the processor is programmed to transform the time continuous signal to the frequency domain, and to detect excess suction in response to distortion in the transformed time continuous signal.
16. The system of claim 15 , wherein the processor is further programmed to determine parametric data based on the transformed time continuous signal, the processor including an output terminal for outputting the parametric data.
17. The system of claim 15 , wherein the processor is programmed to validate the time continuous signal based on the transformed time continuous signal.
18. The system of claim 17 , wherein the processor is programmed to calculate the signal to noise ratio of the transformed time continuous signal.
19. The system of claim 17 , wherein the processor is programmed to calculate the signal to noise plus distortion ratio of the transformed time continuous signal.
20. The system of claim 15 , further comprising a flow measurement device adapted to transduce the pump flow rate, and wherein the processor is adapted to receive a signal indicating the pump flow rate.
21. The system of claim 15 , wherein the processor is connected to the pump to receive a signal indicating the pump speed.
22. The system of claim 15 , wherein the processor is connected to the pump to receive a signal indicating the pump current.
23. The system of claim 15 , farther comprising:
an analog to digital converter having a sampling rate and that digitizes at least a portion of the time continuous signal; and
a sample mode selector connected to the analog to digital converter, the sample mode selector setting one of a synchronous sample mode or an asynchronous sample mode, wherein
if the asynchronous sample mode is set, the sampling rate of the analog to digital converter is set by a reference clock; and
if the synchronous sample mode is set, the sampling rate of the analog to digital converter is set according to the frequency of the time continuous signal.
24. A blood pump system, comprising:
a blood pump comprising a rotor and a stator, the stator including a plurality of stator windings;
a controller operatively coupled to the pump;
a processor operatively coupled to the controller and adapted to receive a time continuous signal from the pump; and
wherein the processor is programmed to transform the time continuous signal to the frequency domain, and to detect excess suction in response to distortion in the transformed time continuous signal.
25. The blood pump system of claim 24 , wherein the controller applies current to the stator windings in a sequence to create a rotating field, and wherein the time continuous signal includes one or more stator winding current.
26. The blood pump system of claim 24 , further comprising a flow measurement device coupled to the processor and providing a signal representing the pump flow rate, wherein the time continuous signal includes the pump flow rate.
27. The blood pump system of claim 24 , wherein the processor is programmed to zero pad a digital representation of the received time continuous signal.
28. The blood pump system of claim 27 , wherein the digital representation of the received time continuous signal from the blood pump comprises less than about 200 data points of the time continuous signal.
29. The blood pump system of claim 28 , wherein the processor is programmed to zero pad at least about 3800 data points.
30. A method of determining heart rate, comprising: sampling a time continuous signal from a blood pump at a predetermined sampling frequency for a predetermined time period to obtain a sample N; zero padding the sampled time continuous signal to achieve a sample M, where M is greater than N; transforming the zero padded time continuous signal to the frequency domain; and determining a heart rate based on the frequency domain representation.
31. The method of claim 30 , wherein the frequency domain representation of the zero padded time continuous signal comprises a spectral peak at a frequency proportional to the heart rate.