Four-way Stopcock with Nested Needleless Valve Stem
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Solution Overview
Problem
Conventional four-way medical stopcocks trap a substantial amount of fluid in the side stem when fluid flow is interrupted, requiring a flushing procedure that is time-consuming and increases the risk of breakage and infection.
Innovation Solution
The design incorporates a short side stem and a fluid transport device with a long stem, such as a needleless valve or male Luer lock, to minimize residual fluid, with the valve stem or Luer lock stem positioned within the side stem to reduce trapped volume, and optionally fixed using ultraviolet-curable adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a conventional four-way medical stopcock with a standard side stem is used, then the device structure is simple and easy to manufacture, but a substantial amount of fluid is trapped in the side stem requiring time-consuming flushing procedures
Solution Approach 1:
The needleless valve stem is nested within the side stem of the stopcock, with the valve stem positioned coaxially inside the side stem cavity. This nesting arrangement allows the valve stem to occupy the internal volume of the side stem, thereby minimizing the residual fluid volume trapped when the stopcock is in the closed position. The valve stem effectively fills the deadspace that would otherwise contain trapped fluid.
Solution Approach 2:
The design changes the geometric parameters of the side stem and valve stem to minimize residual volume. Specifically, the side stem is designed with a reduced internal volume and the valve stem is positioned at a specific distance (approximately 0.005 inches) from the cock to optimize the remaining fluid capacity. This parameter optimization reduces the trapped fluid volume to approximately 0.09 mL or less, eliminating the need for flushing procedures.
2Loss of substance
If the side stem is shortened to reduce residual fluid volume, then less fluid is trapped, but the device may be more difficult to operate in tight spaces
Solution Approach 1:
The needleless valve is integrated within the side stem structure, with the valve body and stem nested inside the side stem cavity. This nested configuration allows the valve components to occupy the internal volume of a shortened side stem, thereby reducing residual fluid volume while maintaining a compact overall device profile that is easier to operate in tight spaces.
3Loss of substance
If a needleless valve with a long stem is used to minimize deadspace, then residual fluid volume is reduced, but the device complexity increases
Solution Approach 1:
The needleless valve is merged with the stopcock assembly by integrating the valve stem within the side stem of the stopcock. This combination eliminates the need for separate external valve components and connections, thereby reducing residual fluid volume while avoiding excessive device complexity. The unified structure allows the valve and stopcock to function as an integrated system.
Solution Approach 2:
The needleless valve stem is nested within the side stem of the stopcock, creating a compact integrated assembly. This nesting arrangement allows the valve components to be housed within the existing side stem volume, minimizing residual fluid space while maintaining a relatively simple overall device structure that does not require additional external components.
4Loss of substance
If the valve stem is positioned close to the cock to reduce internal volume, then residual fluid is minimized, but manufacturing precision requirements increase
Solution Approach 1:
The design specifies a concrete parameter for the distance between the valve stem and the cock (approximately 0.005 inches), which optimizes the residual fluid volume to about 0.09 mL. This specific parameter specification provides clear manufacturing guidance, balancing the need to minimize residual volume with the practical requirements of manufacturing precision and assembly tolerances.
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 configuration significantly reduces the need for flushing, minimizing the risk of breakage and infection, and allows for easier operation in tight spaces by eliminating deadspace and enabling simple fabrication.
Implementation Method 1
the valve stem is fixed within the side stem with an ultraviolet-curable adhesive
Data Source
AI summary
In general, one aspect disclosed features a medical device, comprising: a four-way medical stopcock, comprising: a body defining a cock barrel and comprising: a first stem having a first port, a second stem having a second port, and a side stem having a side port; and a rotatable cock disposed within the cock barrel, wherein: the cock places the first port and second port in fluid communication when the cock is in a first position, and the cock places the first port, second port, and side port in fluid communication when the cock is in a second position; and a needleless valve having a valve stem, wherein the valve stem is disposed within the side stem such that an internal volume defined by the side stem, the valve stem, and the cock when the cock is in the third position, is approximately 0.09 ml.