Algorithm for detecting and presenting suction in down-sampled MCS log files
A method of determining a presence of suction in a patient having an implantable blood pump from down-sampled log files. The method comprising calculating a waveform index for each of a plurality of flow rate data points from the down-sampled log files. The calculated waveform index is compared with a predetermined waveform index threshold. A non-suction trough baseline is calculated from the plurality of flow rate data points. A difference between a measured trough and a calculated non-suction trough baseline is compared with a predetermined threshold. The presence of suction for each of the plurality of flow rate data points is determined if the calculated waveform index is greater than the predetermined waveform index threshold and the difference between the measured trough and a calculated non-suction trough baseline is greater than the predetermined threshold.
1. An implantable blood pump system, the system comprising:
an implantable blood pump comprising a motor, the implantable blood pump being configured to cause blood flow in a patient; and
a controller in communication with the implantable blood pump, the controller comprising processing circuitry configured to:
calculate a waveform index for each of a plurality of flow rate data points from down-sampled log files, wherein each flow rate data point of the plurality of flow rate data points corresponds to a flow rate of the blood flow through the implantable blood pump;
compare the calculated waveform index with a predetermined waveform index threshold;
calculate a non-suction trough baseline from the plurality of flow rate data points;
compare a difference between a measured trough and the calculated non-suction trough baseline with a predetermined threshold;
determine for each of the plurality of flow rate data points whether a suction condition is present at the implantable blood pump, wherein the processing circuitry is configured to determine that the suction condition is present at the implantable blood pump for a flow rate data point in response to:
the calculated waveform index being greater than the predetermined waveform index threshold; and
the difference between the measured trough and the calculated non-suction trough baseline being greater than the predetermined threshold;
determine a measure of suction density based on a number of the plurality of flow rate data points for which the suction condition is present and a total number of the plurality of flow rate data points; and
cause a display device to output an indication of the measure of suction density experienced by the implantable blood pump.
2. The system of claim 1 , wherein if the suction condition is determined for a flow data point of the plurality of flow rate data points, the processing circuitry is further configured to cause the display device to display the flow rate data point in a histogram on the down-sampled log files.
3. The system of claim 2 , wherein displaying the flow rate data point in the histogram includes displaying a number of flow rate data points for which the suction condition is determined to be present during a predetermined number of data points divided by the predetermined number of data points.
4. The system of claim 3 , wherein the predetermined number of data points is less than or equal to 20.
5. The system of claim 1 , wherein calculating the non-suction trough baseline from the plurality of flow rate data points includes:
creating an array of non-suction trough baseline data points, the array only including data points in the plurality of flow rate data points whose calculated waveform index is below the predetermined waveform index threshold.
6. The system of claim 5 , wherein calculating the non-suction trough baseline from the plurality of flow rate data points includes:
calculating an average non-suction trough baseline from the array of non-suction trough baseline data points; and
subtracting from the calculated average non-suction trough baseline a standard deviation of the calculated average non-suction trough baseline multiplied by a standard deviation factor.
7. The system of claim 6 , wherein the standard deviation factor is one.
8. The system of claim 1 , wherein the predetermined threshold is equal to one.
9. The system of claim 1 , wherein the predetermined waveform index threshold is 0.3 to 0.6.
10. The system of claim 1 , wherein the plurality of flow rate data points includes data sampled over 24 hours.
11. The system of claim 1 , wherein the plurality of flow rate data points is equal to 96 data points.
12. The system of claim 1 , wherein to determine the measure of suction density based on the number of the plurality of flow rate data points for which the suction condition is present and the total number of the plurality of flow rate data points, the processing circuitry is configured to divide the number of the plurality of flow rate data points for which the suction condition is present by the total number of the plurality of flow rate data points.
13. The system of claim 1 , wherein the processing circuitry is configured to cause the display device to output an indication of the flow rate.
14. The system of claim 13 , wherein the processing circuitry is configured to cause the display device to output the indication of the flow rate concurrently with the indication of the measure of suction density.
15. The system of claim 1 , wherein the processing circuitry is further configured to cause the display device to output an indication of a current draw of the motor.
16. The system of claim 1 , wherein the controller comprises the display device.