Venous Air Capture Chamber With Bidirectional Flow for Low-Shear Priming
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Solution Overview
Problem
Conventional venous air capture chambers in hemodialysis suffer from stagnant flow, turbulence leading to blood coagulation, thrombosis activation, and high shear stress, and require complex manual priming processes involving dialyzer inversion.
Innovation Solution
A venous air capture chamber with a chamber body comprising a small and large diameter cylinder portion, bidirectional fluid inlets at 180°, and a fluid outlet with a mesh filter, allowing for bidirectional flow and reducing stagnant areas and shear stress, enabling automated priming without dialyzer inversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional venous air capture chambers are used, then air bubbles can be separated from blood, but stagnant flow areas are created leading to turbulence and blood coagulation
Solution Approach 1:
The chamber body is divided into two distinct portions: a small diameter cylinder portion and a large diameter cylinder portion. This segmentation creates different flow characteristics in each region, allowing effective air separation in the large diameter portion while maintaining laminar flow in the small diameter portion to prevent coagulation.
Solution Approach 2:
The chamber employs asymmetric diameter design where one portion has a small diameter and another has a large diameter. This asymmetry optimizes flow patterns by creating a transition zone that separates air bubbles effectively while avoiding stagnant areas that would cause turbulence and coagulation.
2Productivity
If high flow rate is used to increase productivity, then air separation efficiency improves, but shear stress increases causing red blood cell damage
Solution Approach 1:
The flow path is segmented into two diameter portions, allowing the system to handle higher flow rates in the large diameter portion for improved productivity while the small diameter portion maintains lower shear stress to protect red blood cells from damage.
Solution Approach 2:
The chamber design changes the geometric parameter (diameter) along the flow path. By transitioning from large to small diameter, the system optimizes both flow rate handling capability and shear stress levels, enabling high productivity without excessive shear stress.
3Reliability
If unidirectional flow is used in air capture chamber, then air separation function is maintained, but complex manual priming process is required with dialyzer inversion
Solution Approach 1:
The chamber is designed with bidirectional flow capability, allowing it to perform air capture functions in both flow directions. This multi-functionality enables automated priming without dialyzer inversion, as the chamber can handle fluid flow in either direction while maintaining effective air separation.
Solution Approach 2:
The chamber design allows dynamic adaptation to different flow directions. The asymmetric diameter configuration works effectively whether fluid flows from large to small diameter or vice versa, enabling the system to switch between normal operation and automated priming modes without mechanical inversion.
4Speed
If turbulent flow is allowed for rapid air separation, then separation speed increases, but mixing between blood and air promotes coagulation
Solution Approach 1:
The chamber segments the flow into two diameter portions, creating a large diameter section for rapid air separation and a small diameter section for laminar flow that prevents coagulation. This segmentation allows the system to achieve both fast separation and safe flow conditions.
Solution Approach 2:
The asymmetric diameter design creates different flow regimes in different sections. The large diameter portion allows faster flow for rapid separation while the small diameter portion ensures laminar flow to prevent coagulation, resolving the contradiction between speed and safety.
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 chamber effectively separates air bubbles from blood, minimizes coagulation and thrombosis risks, and simplifies the priming process by allowing bidirectional flow, reducing shear stress and eliminating stagnant areas.
Implementation Method 1
Venous air capture chambers are used in hemodialysis to separate entrained air bubbles from the blood
Implementation Method 2
bidirectional flow to automate aspects of system priming
Implementation Method 3
a mesh filter forming a cylindrical taper having a decreasing diameter
Data Source
Figure 1~2a
Figure 2b
Figure 3a~3b
AI summary
A venous air capture chamber for use in dialysis, includes an upwardly extending fluid inlet terminating in first and second fluid inlet ports (102). The first and second fluid inlet ports (102) are opposedly positioned on the fluid inlet at an angle of about 180°. The venous air capture chamber also includes a fluid outlet (104) at the bottom of the chamber body. The venous air capture chamber provides improved fluid dynamics, reducing both stagnant flow and turbulence. The venous air capture chamber also provides for bidirectional flow of fluid through the chamber.