Variable Sampling Control for Extracorporeal Blood Pressure Monitoring
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Solution Overview
Problem
Existing extracorporeal blood treatment apparatus require significant memory and computational power to process pressure signals efficiently, with performance negatively affected by constant sampling frequency, leading to inefficient data processing and hardware/software demands.
Innovation Solution
A blood treatment apparatus with a control unit that samples pressure signals at a frequency dependent on the velocity of the peristaltic pump, using a position sensor to determine predefined positions for variable sampling, allowing for efficient data processing with minimal hardware and software updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If constant sampling frequency is used for pressure signals, then the sampling process is simple, but the number of samples acquired decreases as pump rotation velocity increases, leading to insufficient data processing quality
Solution Approach 1:
The sampling frequency is made dynamic by linking it to the pump rotation velocity. The control unit adjusts the sampling frequency proportionally to the pump speed, ensuring that the number of samples per rotation remains constant regardless of the pump's operating speed. This resolves the contradiction by making the sampling system adaptive rather than fixed.
Solution Approach 2:
The system uses feedback from the pump rotation velocity sensor to continuously adjust the sampling frequency. The control unit receives information about the current pump speed and automatically modifies the sampling rate accordingly, creating a closed-loop control system that maintains optimal data acquisition quality across varying operating conditions.
2Productivity
If large memory capacity and computational power are used to process pressure signals, then efficient signal processing is achieved, but hardware requirements and system complexity increase
Solution Approach 1:
Instead of continuously sampling at high rates regardless of pump operation, the system samples only when the pump is rotating, and adjusts the sampling rate to match the actual operational needs. This partial action approach avoids unnecessary data acquisition and processing, reducing computational burden while maintaining processing efficiency for the actual signal of interest.
Solution Approach 2:
The system dynamically changes the sampling frequency parameter based on pump rotation velocity. By adjusting this key parameter to match operational conditions, the system optimizes the balance between data quality and processing requirements, avoiding the need for excessive computational resources while maintaining efficient signal processing.
3Measurement precision
If the number of samples per pump rotation varies with pump speed, then constant sampling frequency is easy to implement, but the representation of physiological pressure data becomes inaccurate
Solution Approach 1:
The sampling system transitions from a static, fixed-frequency approach to a dynamic, velocity-proportional approach. The sampling frequency automatically adapts to pump speed changes, ensuring consistent data quality across the full operating range while maintaining relatively simple implementation through proportional control.
Solution Approach 2:
The system changes the sampling frequency parameter in direct proportion to the pump rotation velocity. This parameter adjustment ensures that the sampling rate matches the operational dynamics, providing accurate physiological pressure data representation without requiring complex variable-rate sampling algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient monitoring and analysis of physiological pressure generators with reduced computational effort, using variable sampling frequency to maintain accurate data processing without excessive resource requirements.
Implementation Method 1
a peristaltic pump operatively coupled to the extracorporeal blood circuit circulates the blood in the circuit
Implementation Method 2
a treatment unit (for example a dialyser or filter or an ultrafilter or a plasma filter or a filter unit of a different type) having a semi-permeable membrane which separates the treatment unit into two chambers
Implementation Method 3
at least a pressure sensor (13, 14) associated to the extracorporeal blood circuit (2) and configured to enable determination of pressure values in said extracorporeal blood circuit (2)
Data Source
AI summary
An apparatus for extracorporeal blood treatment (1) is described, comprising a treatment unit (3) having at least a first chamber (4) and at least a second chamber (5) separated from one another by a semi-permeable membrane (6); at least a blood removal line (7) connected to an inlet port (4a) of the first chamber (4) and predisposed to remove blood from a patient (P); at least a blood return line (8) connected to an outlet port (4b) from the first chamber (4) and predisposed to return treated blood to the patient (P), wherein the blood removal line (7), the blood return line (8) and the first chamber (4) are part of an extracorporeal blood circuit (2); at least a peristaltic pump (9) operating at the extracorporeal blood circuit (2) for moving the blood in the circuit; at least a pressure sensor (13, 14) associated to the extracorporeal blood circuit (2) and configured to enable determining pressure values in the extracorporeal blood circuit (2); at least a fluid drainage line (23) connected to an outlet port of the second chamber (5); a control unit (CU) connected to the at least a pressure sensor (13, 14) and to the peristaltic pump (9) and configured to: move the peristaltic pump (9) with a cyclic motion to generate a blood flow; receive from the at least a pressure sensor (13, 14) a signal (Ps) indicating the pressure of the blood in the extracorporeal blood circuit (2). The signal (Ps) indicating the blood pressure is detected with a time do main frequency depending on the velocity.