Cannula Conical Tip and Valve Flow Control
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Solution Overview
Problem
Existing cannulas do not effectively manage fluid velocity and perfusion distribution, particularly in arterial applications, leading to inefficiencies in blood flow and potential supply issues for lower extremities during cardiac systole.
Innovation Solution
A cannula design featuring a conically tapered tip with a reduction in inner diameter, accompanied by lateral holes and a valve mechanism, which adjusts flow distribution between the cannula center and lateral holes based on pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the cannula has a uniform diameter throughout its length, then the manufacturing is simple, but the fluid velocity cannot be effectively reduced at the tip
Solution Approach 1:
The cannula features a caliber constriction (reduced inner diameter section) located at a specific position between the tip and lateral holes, creating a localized change in flow characteristics. This local modification reduces fluid velocity at the tip without requiring complex changes to the entire cannula structure, resolving the contradiction between simplicity and velocity control.
2Quantity of substance
If all blood flow is directed through the cannula center to the tip, then the tip receives adequate perfusion, but the lower extremities suffer from insufficient blood supply
Solution Approach 1:
The cannula divides blood flow into two separate paths: flow through the center to the tip, and flow through lateral holes to the lower extremities. The caliber constriction positioned between the lateral holes and tip creates a flow distribution mechanism that ensures both pathways receive adequate blood supply, resolving the contradiction between tip perfusion and lower extremity blood flow.
Solution Approach 2:
The caliber constriction acts as an intermediary element that regulates and distributes flow between the two pathways. By positioning the reduced diameter section between the lateral holes and the tip, it mediates the flow distribution to ensure both the tip and lower extremities receive appropriate blood supply during cardiac systole.
3Adaptability or versatility
If the cannula lacks a valve mechanism, then the structure remains simple, but flow distribution cannot be adjusted based on pressure changes
Solution Approach 1:
The cannula incorporates a dynamic valve mechanism with flaps that respond to pressure changes. The valve allows flow distribution to be automatically adjusted based on prevailing pressure conditions, enabling the cannula to adapt to varying physiological conditions while maintaining a relatively simple overall structure.
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 design reduces fluid velocity at the tip, enhances perfusion of lower extremities by redirecting flow through lateral holes, and maintains effective blood supply during cardiac systole by adjusting the valve accordingly.
Implementation Method 1
the caliber constriction (10) between two cannula sections (3, 2) with different diameters
Implementation Method 2
leads to a jet stream at the cannula tip, in the short insertion length or in the reduced diameter cannula area
Implementation Method 3
The stronger flow during pump acceleration causes the valve to open. The ratio of relative valve opening to volume flow can be adjusted by positioning and designing the valve
Implementation Method 4
at least one flap has a spring mechanism. This spring mechanism can be achieved by a spring or by the material selection and design of the flaps
Implementation Method 5
the arrangement of such holes in the cannula ensures perfusion of the lower extremities and reduces afterload
Data Source
Figure 1~8
Figure 9~11
AI summary
The invention relates to a cannula comprising a tip and an outlet, said cannula having a reduction in the internal diameter, which reduction is designed as a conically tapering tip the end of which has a length that is shorter than the internal diameter of the adjoining portion of the cannula.