Pressurized-Chamber APD Pumping Bladder for Accurate Fluid Metering
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Solution Overview
Problem
Existing automated peritoneal dialysis (APD) machines are cumbersome, costly, and require daily disposable sets, which are space-consuming and time-consuming to set up, limiting their portability and efficiency.
Innovation Solution
A reusable APD machine with a plastic or metal chamber and an inflatable bladder, using hydraulic pressure for fluid delivery, combined with a control unit for precise pressure control and a disposable flexible container, employing the ideal gas law to accurately measure fluid volumes and minimize air displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a reusable APD machine with hydraulic pump and inflatable bladder is used, then device portability and cost-effectiveness are improved, but manufacturing precision and reliability of fluid volume measurement become more difficult to achieve
Solution Approach 1:
The patent employs a hydraulic pump system with incompressible fluid to deliver precise volumes to an inflatable bladder. The hydraulic system provides reliable pressure control and volume delivery, while the inflatable bladder expands to match the pump's delivered volume. This combination achieves manufacturing precision through the incompressible hydraulic fluid's ability to transmit pressure uniformly, resolving the contradiction between cost-effectiveness and measurement accuracy.
Solution Approach 2:
The system changes the physical state of the pumping medium from compressible gas to incompressible liquid (hydraulic fluid). This parameter change enables precise volume delivery because incompressible fluids maintain constant pressure and volume relationships, allowing the control unit to accurately calculate and deliver prescribed fluid volumes to the patient.
2Reliability
If daily disposable sets are used in APD machines, then reliability of treatment is improved, but device complexity and space consumption increase
Solution Approach 1:
The system segments the APD machine into permanent reusable components (chamber, pump, control unit) and disposable components (flexible container, tubing). This segmentation allows the complex, expensive, and space-consuming components to be reused, reducing setup complexity while maintaining treatment reliability through the disposable elements that ensure sterility and proper fluid pathways.
Solution Approach 2:
The patent uses disposable flexible containers and tubing instead of complete disposable sets. These inexpensive, short-living components are replaced only when needed, reducing the frequency of setup and teardown operations. The reusable pump and chamber maintain treatment reliability through rigorous cleaning and sterilization protocols, eliminating the need for complex daily disposal procedures.
3Ease of operation
If air is present in the chamber during hydraulic pumping, then ease of operation is improved, but measurement precision and fluid volume accuracy deteriorate
Solution Approach 1:
The control unit performs preliminary venting of air from the chamber before initiating the hydraulic pumping sequence. This preliminary action removes air that would interfere with pressure transmission and volume measurement. By venting air beforehand, the system ensures that subsequent hydraulic pumping delivers accurate fluid volumes while maintaining ease of operation through automated air removal.
Solution Approach 2:
The system uses pressure sensors to monitor chamber pressure during pumping operations. The control unit receives feedback from these sensors and adjusts pumping parameters accordingly. This feedback mechanism compensates for any residual air in the chamber, ensuring accurate fluid volume delivery while maintaining operational simplicity through automated pressure compensation.
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
The system provides a compact, cost-effective, and accurate APD machine that reduces setup time, minimizes air infusion risks, and allows for precise fluid management, enabling portability and efficient dialysis treatments.
Implementation Method 1
A source of motive fluid pressure, such as hydraulic pressure is fluidly connected to the chamber. The motive fluid is incompressible in one embodiment.
Implementation Method 2
A reusable inflatable bladder is located within the chamber
Implementation Method 3
employing the ideal gas law to accurately measure fluid volumes and minimize air displacement
Implementation Method 4
Waste, toxins and excess water pass from the patient's bloodstream, through the capillaries in the peritoneal membrane, and into the dialysis fluid due to diffusion and osmosis
Implementation Method 5
Waste, toxins and excess water pass from the patient's bloodstream, through the capillaries in the peritoneal membrane, and into the dialysis fluid due to diffusion and osmosis
Data Source
AI summary
A peritoneal dialysis system includes a chamber; a hydraulic pump; an inflatable bladder located within the chamber and in hydraulic fluid communication with the hydraulic pump; and a control unit configured to cause a known amount of hydraulic fluid to be metered to the inflatable bladder and to determine (i) a first amount of air before a discharge stroke of the hydraulic pump via a first ideal gas law calculation, (ii) a second amount of air after the discharge stroke of the hydraulic pump via a second ideal gas law calculation, and (iii) a discharge volume of fresh or used dialysis fluid for the discharge stroke by subtracting a difference between the first amount of air and the second amount of air from the known amount of hydraulic fluid metered to the inflatable bladder for the discharge stroke.