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Physiologic Control Algorithms for Rotary Blood Pumps using Pressure Sensor Input. Edward Bullister, Ph.D. Sanford Reich, Ph.D. APEX Medical, Inc. ISRP 2001 18 August 2001. Why Use Pressure Inputs?. Provides physiologic feedback for pump control. - PowerPoint PPT Presentation
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Physiologic Control Algorithms for Rotary Blood Pumps using Pressure
Sensor Input
Edward Bullister, Ph.D.
Sanford Reich, Ph.D.
APEX Medical, Inc.ISRP 2001
18 August 2001
Why Use Pressure Inputs?
Provides physiologic feedback for pump control. Provides added-value pump diagnostic and monitoring
functions. Increases capability for patient monitoring. Potentially increases patient quality of life.
How to Implement?
Control Algorithm Development Design Strategy to Mimic Patients’ Physiologic Control Control Algorithm Schematic Control Algorithm Detail Control Algorithm Results
Added-Value Diagnostic and Monitoring Functions Patient Monitoring Hardware Considerations Summary
Control Algorithm
Level 1
Average
Integral SpeedController
APS-VADLVDFPInletPressure
+
max
LimitControl
OutletPressure
min
Average ArterialPressure Limits
max
min
--
Level 3
Ventricular Collapse
Detection Algorithm
Retrograde Flow
Detection Algorithm
Level 2 (Exercise)
DP RPM
HR
Limits for Average
Arterial Pressure
LVDFP = Left Ventricular DiastolicFilling Pressure
Desired
APS-VAD CONTROL SCHEME
DP = Differential APS-VAD pressureHR = Heart Rate
Level 1: Basic Control Algorithm
Level 1 Control Input: LVDFP - Left Ventricular Diastolic “Filling Pressure”
Level 1 Control Output: Pump Flow Rate Proportional Integral Control Algorithm
d/dt(Flow) = K * (LVDFP - Pdesired)
K = 0.1 L/min/mmHg
Flow Pressure Simple Robust
Level 1 Results
Level 2: Exercise Control Algorithm
Level 2 Control Inputs: Arterial Pressure Pulse Rate Increase (e.g., during exercise)
Level 2 Control Output: Desired LVDFP
Level 2 Limits: Max/min LVDFP Max/min Arterial Pressure
Level 2 Results
Flow Rate Monitor using Pressure
Pressure Calculated from Pump Speed and Pressure Difference
Independent of Motor Current
Includes High Frequency Content F
low
(L
/min
)Calculated From Pressure
Flow meterMeasurement
Time (sec)
Hydraulic Power Monitor
Hydraulic Power (HP) into Blood Pump: HPpump = Ppump * PumpFlow (continuous) Heart: HPheart ~ Pheart * PumpFlow (measured during systole)
Hardware Considerations
Pressure Sensor Technology Thin-Film Based MEMS Based
Any Rotary VAD Pressure Sensor Placement
Component Analysis
Computational Fluid Dynamics (CFD) Example - Inlet Cannula Establish optimal location for pressure sensor
Calculate pressure coefficient K for nonlinear relationship: P = K*V2
Summary
An initial control algorithm has been implemented to auto-regulate rotary blood pumps using physiological pressure inputs.
Two levels of control for a rotary pump have been tested in a mock loop setup.
The pressure signals produce added-value information. Additional monitoring and control levels have been conceived. Goal is to contribute to patient quality of life.
