Blood Treatment Air Separator Fill Level Monitoring via Pressure Pulse Analysis
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Solution Overview
Problem
Existing extracorporeal blood treatment devices face challenges in user-friendly and efficient air removal from the venous line portion, requiring complex and expensive sensor systems to monitor the fill level in air separators, which can lead to air bubbles or foam formation impairing the air separation function.
Innovation Solution
Incorporating a pressure detection sensor to detect pressure pulses generated by the blood pumping device, which allows for estimation of the fill level in the air separator chamber by analyzing pressure pulse amplitude and width, eliminating the need for additional fill level sensors and using the blood pumping device to adjust the fill level automatically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gage detectors are used to monitor the fill level in the air separator, then air separation function is maintained, but the device complexity and cost increase
Solution Approach 1:
The pressure sensor is designed to serve multiple functions: monitoring fill level in the air separator, detecting air bubbles in the venous line, and providing pressure data for patient safety monitoring. This multi-functionality eliminates the need for separate dedicated sensors for each monitoring task, thereby reducing overall device complexity while maintaining reliable air separation function.
Solution Approach 2:
The system uses the existing blood pump's pressure generation capability to automatically adjust and maintain the optimal fill level in the air separator. The pressure sensor detects pressure changes that indicate fill level status, and the system self-regulates by adjusting pump parameters or air venting, eliminating the need for complex manual intervention systems or additional dedicated fill level sensors.
2Measurement precision
If multiple specific sensors are used to detect air and fill level, then monitoring precision is improved, but the manufacturing cost increases
Solution Approach 1:
A single pressure sensor is engineered to perform multiple detection tasks with sufficient precision: measuring fill level height in the air separator through pressure differential, detecting air bubbles in the venous line via pressure anomalies, and monitoring overall system pressure. This consolidates what would traditionally require multiple specialized sensors into one versatile component, significantly reducing manufacturing cost while maintaining adequate measurement precision for all functions.
Solution Approach 2:
The system monitors changes in pressure parameters over time and across different operating conditions to infer fill level and air presence. By analyzing pressure trends, rate of change, and threshold deviations rather than requiring absolute precision measurements, the system achieves reliable detection with a single pressure sensor, reducing the need for expensive high-precision specialized sensors.
3Ease of operation
If the blood filler neck opening is above the blood level, then air can escape easily, but air bubbles or foam form in the chamber
Solution Approach 1:
The pressure sensor provides continuous feedback on the fill level and air presence in the air separator chamber. When the blood filler neck opening is above the blood level facilitating air escape, the pressure sensor detects resulting pressure changes or air bubble formation. This feedback enables the control system to dynamically adjust the neck opening position or blood flow rate to prevent foam formation while maintaining efficient air escape, thus preserving air separation reliability.
Solution Approach 2:
The system dynamically adjusts the position of the blood filler neck opening or the blood flow rate into the air separator based on real-time pressure sensor data. When air escape is prioritized, the neck opening is positioned higher; when foam prevention is needed, the system lowers the opening or reduces flow rate. This dynamic adjustment allows the system to optimize between air escape efficiency and air separation reliability under different operating conditions.
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
This solution simplifies the monitoring of the fill level, reduces the complexity and cost of sensor systems, and ensures continuous air-free blood circulation by automatically adjusting the fill level, preventing air bubbles from entering the patient's blood.
Implementation Method 1
detecting the pressure pulse introduced by the blood pumping device (8)
Implementation Method 2
a blood pumping device (8) configured to pump the blood and to generate pressure pulses with a predefined frequency in the blood conducting system
Implementation Method 3
a hollow space remains above the blood level/gage formed in this way, into which the air contained in the blood can outgas and can then escape via an outlet opening
Data Source
AI summary
A blood treatment device for extracorporeal blood treatment and a method for monitoring the fill level of blood with the blood treatment device. The device includes at least one blood conducting system and at least one chamber container for separating bubbles from the blood to be treated. The device further includes a blood pumping device designed to pump the blood and generate pressure pulses with a predefined frequency in the blood conducting system. The blood treatment device additionally has at least one pressure detection sensor for capturing the pressure pulse introduced by the blood pumping device and a data processing unit designed to derive a fill level parameter from the pressure pulse captured and to modify the state of an information signal as a function of the fill level parameter. At least one alarm device is activated as a function of the state of the information signal.