Apheresis Pressure Sensor Placement for Accurate Venous Monitoring
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Solution Overview
Problem
Current apheresis systems inaccurately measure venous pressure due to distance between pressure measurement points and the needle tip, leading to potential vein lesions and suboptimal procedure conditions.
Innovation Solution
The system uses two pressure sensors on the return line to measure pressure at known fluid resistance points, allowing for precise determination of venous pressure independently of fluid characteristics and flow rate, enabling real-time control of the return flow rate to maintain safe and optimized conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pressure is measured at a distance away from the needle tip, then the measurement is easier to implement, but the measurement accuracy deteriorates
Solution Approach 1:
The system changes the parameter of pressure measurement location from distant (easier implementation) to near the needle tip (higher accuracy). By placing the pressure sensor at or near the needle tip, the patent achieves accurate venous pressure measurement while compensating for the increased complexity through automated calculation algorithms that account for pressure drops across known resistance elements.
2Measurement precision
If pressure is measured closer to the needle tip, then measurement accuracy improves, but the complexity of the system increases
Solution Approach 1:
The patent introduces known resistance elements as intermediaries between the needle tip and the pressure sensor. These resistance elements with precisely known flow resistance values allow the system to calculate the pressure at the needle tip by measuring pressure at a slightly removed location and adding the pressure drop across the known resistance, thereby reducing sensor placement complexity while maintaining accuracy.
Solution Approach 2:
The system replaces direct mechanical pressure measurement at the needle tip with an indirect measurement approach using pressure sensors located at accessible positions, combined with computational calculation. The control system uses algorithms to compute the needle tip pressure based on sensor readings and known resistance values, substituting complex mechanical sensor placement with simpler electronic measurement and calculation.
3Measurement precision
If a sensor is placed within the vein, then the most accurate pressure measurement is achieved, but the invasiveness and risk to the patient increases
Solution Approach 1:
The patent uses the blood itself and known resistance elements as intermediaries to transmit pressure information from the needle tip to an external sensor. Instead of placing the sensor directly in the vein, the system measures pressure in the return line and uses the known flow characteristics and resistance values to calculate the venous pressure, eliminating the need for invasive intravascular sensing.
Solution Approach 2:
The system creates a mathematical model (copy) of the venous pressure based on measurements taken at accessible locations and known system parameters. By calculating pressure values rather than measuring them directly at the vein, the system obtains accurate pressure information without the risks associated with intravascular sensors.
4Productivity
If the apheresis procedure is performed at higher speed, then productivity increases, but the safety risk increases due to pressure control issues
Solution Approach 1:
The patent implements a feedback control system that continuously monitors pressure at known resistance points and uses this information to calculate and control the flow rate. The system adjusts the pump speed to maintain pressure within safe ranges, allowing high productivity when pressure conditions permit while automatically reducing speed when pressure limits are approached, thereby ensuring safety throughout the procedure.
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 approach accurately measures subject access pressure without a sensor in the vein, reducing the risk of vein lesions and optimizing apheresis procedures by controlling flow rates effectively.
Implementation Method 1
The two measurement points (P1 and P2) may be located a distance away from the needle tip within the donor vein. The measurement points may delimit two portions of a line(s) having a known fluid resistance R1 and R2. R may be defined as the change in pressure between the two pressure measurement points divided by a flow rate
Data Source
AI summary
A blood processing device includes a venous-access device, a blood component separation device, a return line, a draw line, a first pressure sensor, a second pressure sensor, and a first pump. The first pressure sensor is located on the return line between the blood component separation device and the venous-access device, and determines a first pressure. The second pressure sensor is located on the draw line between the blood component separation device and the venous-access device, and determines a second pressure. The first pump is connected to at least one of the return line and the draw line and controls a flow rate within the connected line based on a subject access pressure determined based upon the first and second pressures.