Spinal Cannula Prism for CSF Detection
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Solution Overview
Problem
Spinal cannulas face difficulty in optically recognizing the clear, colorless cerebrospinal fluid (CSF) backflow due to its transparency, making it hard to determine correct needle positioning in the subarachnoid cavity.
Innovation Solution
Incorporating a means for refracting or reflecting light, such as a roof prism or triple prism, within the transparent area of the needle hub, which changes the optical image based on the presence of CSF, allowing clear differentiation between air and fluid presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transparent area is provided in the needle hub to observe liquor backflow, then the ability to detect CSF is improved, but the difficulty in optically recognizing the clear, colorless liquor increases
Solution Approach 1:
A prism is introduced as an intermediary optical element between the observer and the CSF. The prism refracts and reflects light in a way that creates a visible optical image when CSF is present, serving as a mediator that transforms the invisible clear fluid into a visible detection signal.
Solution Approach 2:
The patent utilizes optical property changes rather than color changes. The prism creates different optical images (patterns of light reflection and refraction) when CSF is present versus when air is present, providing visual differentiation without requiring the fluid itself to change color.
2Measurement precision
If a magnifying lens is formed in the transparent area to recognize liquor backflow, then the visibility of CSF is improved, but the device complexity increases
Solution Approach 1:
Instead of using a single complex magnifying lens, the patent segments the optical function into a prism structure with multiple reflective and refractive surfaces. This segmentation allows for simpler manufacturing while achieving the detection goal through multiple light interaction paths.
3Measurement precision
If a liquor control chamber with flat wall areas is formed to ensure recognizable liquor backflow, then the detection clarity is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by placing the prism specifically in the transparent area where light observation occurs, rather than requiring the entire control chamber to have complex geometries. The prism provides the necessary optical differentiation locally at the observation point.
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
Facilitates clear recognition of CSF backflow by altering the refraction or reflection of light, enhancing the visibility of fluid presence and improving needle positioning accuracy.
Implementation Method 1
a means for refracting or reflecting rays of light, for example a roof prism or triple prism, is provided at, on or in the transparent area of the needle hub
Implementation Method 2
a means for refracting or reflecting rays of light, for example a roof prism or triple prism, is provided at, on or in the transparent area of the needle hub
Implementation Method 3
the liquor changes the refraction or reflection of the rays of light and thereby a different optimal image results
Data Source
AI summary
A spinal cannula with a needle hub having a transparent area for observing the liquor flowing through a hollow cavity of the needle hub. A structure for refracting or reflecting rays of light is provided in or at the transparent area of the needle hub. The structure for refracting or reflecting rays of light may be formed as one or more prisms.