BLOOD PUMP AND METHOD OF SUCTION DETECTION
A system and method for detecting and mitigating a suction condition are disclosed. The method may include characterizing pump waveform signal, identifying and evaluating a characteristic of the waveform for an existence of a suction condition. In various embodiments, a change in harmonic spectral distribution will identify a probability of a suction condition. A speed of the pump may be adjusted to mitigate the suction condition.
1 . A method of detecting a suction event in a blood pump, comprising:
determining at least one operating parameter of a blood pump;
determining, based on the at least one operating parameter of the blood pump, a characteristic waveform signal of the blood pump;
calculating a suction index of the characteristic waveform signal; and
determining when the suction index exceeds a predefined threshold; and
identifying the occurance of a suction event when the suction index exceeds the predefined threshold.
2 . The method of detecting a suction event in a blood pump of claim 1 , wherein the at least one operating parameter comprises:
pump power;
pump voltage;
pump current;
pump speed.
3 . The method of detecting a suction event in a blood pump of claim 1 , wherein the characteristic waveform signal comprises:
a representation of flow per time, current per time or power per time of the blood pump.
4 . The method of detecting a suction event in a blood pump of claim 1 , wherein the suction index is calculated based on a Harmonic Spectral Distribution by executing a Fast Hartley Transform on the characteristic waveform signal.
5 . The method of detecting a suction event in a blood pump of claim 4 , wherein calculating the Harmonic Spectral Distribution further comprises:
executing a Discrete Bracewell Transform to evaluate the Fast Hartley Transform.
6 . The method of detecting a suction event in a blood pump of claim 1 , wherein determining whether the suction condition exists comprises:
determining whether the suction index is greater than 20%.
7 . The method of detecting a suction event in a blood pump of claim 1 , further comprising:
lowering a speed of the blood pump using a binary search method in response to a determination that the suction event has occurred.
8 . The method of detecting a suction event in a blood pump of claim 7 , wherein lowering the speed of the blood pump comprises:
lowering the speed of the pump to a speed which is based at least in part on the Harmonic Spectral Distribution and a low pump speed limit.
9 . The method of detecting a suction event in a blood pump of claim 7 , further comprising:
increasing the speed of the blood pump using a binary search method until a set-point speed is restored.
10 . The method of detecting a suction event in a blood pump of claim 1 , further comprising:
determining if the characteristic waveform signal is valid based at least in part on at least one pump performance characteristic of the blood pump; and
providing a notification when the characteristic waveform signal is not valid.
11 . A method of detecting a suction event in a blood pump, comprising:
determining a characteristic waveform signal based on an operating parameter of the blood pump;
calculating a pulse suction index (Ψ) of the waveform signal as Harmonic Spectral Distribution (HSD):
Ψ
=
HSD
=
100
×
(
∑
x
=
2
x
=
n
H
x
+
H
1
/
2
)
H
1
Where
,
H
x
=
Value
of
Harmonic
x
.
=
n
Minimum
value
is
2
and
maximum
is
from
5
to
9.
determining when the pulse suction index exceeds a predefined threshold; and
identifying the occurance of a suction event when the pulse suction index exceeds the predefined threshold.
12 . The method of claim 11 , wherein HSD is calculated in consecutive time intervals to identify the change in HSD over a period and calculating MEAN value of HSD.
13 . The method of claim 11 , wherein an increase in MEAN value of HSD indicates a suction event.
14 . The method of claim 12 , wherein a decrease in MEAN value of HSD with the decrease in speed may additionally indicate recovery from suction condition.
15 . The method of claim 11 , wherein a lowest allowable pump speed for recovery from suction condition is based on a Low Speed Limit.
16 . The method of claim 11 , further comprising, decreasing a speed of the pump in response to identification of the existence of a suction condition.
17 . A pump system, comprising:
a blood pump; and
a controller that is configured to control the blood pump, the controller configured to:
determine at least one operating parameter of a blood pump;
determine, based on the at least one operating parameter of the blood pump, a characteristic waveform signal of the blood pump;
calculate a suction index of the characteristic waveform signal;
determine when the suction index exceeds a predefined threshold; and
identify the occurance of a suction event when the suction index exceeds the predefined threshold; and
provide an output based on the identification of the suction event.
18 . The system of claim 17 , wherein the at least one operating parameter comprises:
pump power;
pump voltage;
pump current;
pump speed.
19 . The system of claim 17 , wherein the characteristic waveform signal comprises:
a representation of flow per time, current per time or power per time of the blood pump.
20 . The system of claim 1 , wherein calculating the Harmonic Spectral Distribution comprises:
executing a Fast Hartley Transform on the characteristic waveform signal.
21 . The system of claim 20 , wherein calculating the Harmonic Spectral Distribution further comprises:
executing a Discrete Bracewell Transform to evaluate the Fast Hartley Transform.