Laser Lithotripsy Spacer Tip for Retro-repulsion Control
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Solution Overview
Problem
Retro-repulsion during laser lithotripsy procedures remains a challenge due to the collapse of bubbles formed between the laser fiber tip and the stone, requiring frequent adjustments and prolonging the procedure, as existing methods necessitate delays between pulses to regenerate bubbles and can increase stone movement.
Innovation Solution
The method employs a spacer tip or standoff sleeve to maintain an air bubble by using low power continuous laser radiation, high-frequency therapeutic pulses, or air/gas supply to prevent bubble collapse, eliminating the need for gas-generating charges and reducing fluid ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bubble collapse is allowed to occur naturally between laser pulses, then the procedure follows conventional treatment protocols, but retro-repulsion increases and requires frequent fiber tip adjustments
Solution Approach 1:
The patent applies low power continuous laser radiation before and between therapeutic pulses to proactively maintain the bubble in an expanded state, preventing collapse before it occurs. This preliminary action eliminates the need for corrective fiber tip adjustments and maintains continuous treatment effectiveness throughout the procedure
Solution Approach 2:
The patent maintains continuous bubble expansion through uninterrupted low power laser radiation between therapeutic pulses, ensuring the bubble remains in a useful state throughout the entire procedure. This continuous maintenance of the air path eliminates interruptions and maintains constant lasing efficiency
2Reliability
If delays are introduced between therapeutic pulses to regenerate bubbles, then bubble formation is ensured, but treatment continuity is interrupted and procedure time increases
Solution Approach 1:
The patent employs periodic low power laser radiation pulses that are synchronized with the therapeutic pulse sequence, creating a rhythmic maintenance pattern that keeps the bubble expanded during intervals. This periodic reinforcement ensures reliable bubble presence without requiring extended delays between treatments
Solution Approach 2:
The patent changes the power parameter of laser radiation, using low power continuous radiation between pulses instead of high power therapeutic pulses. This parameter change allows the bubble to be maintained in an expanded state during intervals without requiring time delays, as the low power radiation continuously prevents collapse
3Power
If high power therapeutic pulses are applied continuously, then treatment effectiveness is maximized, but bubble collapse occurs and causes retro-repulsion
Solution Approach 1:
The patent applies low power continuous laser radiation as a cushioning measure before and between high power therapeutic pulses. This preliminary low power radiation creates and maintains a protective air path that cushions against the harmful retro-repulsion effects when high power pulses are applied, preventing bubble collapse and associated stone movement
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 approach effectively reduces retro-repulsion by maintaining a stable air path between the fiber tip and the stone, allowing for continuous treatment without delays and minimizing stone movement, thus shortening procedure time and enhancing lasing efficiency.
Implementation Method 1
application of laser radiation that causes liquid in the path of the laser radiation to form a bubble
Implementation Method 2
U.S. Pat. No. 9,678,275 discloses use of surface tension to prevent collapse of an air bubble formed by the passage of treatment radiation
Data Source
AI summary
A method of reducing retro-repulsion of a stone during a laser lithotripsy procedure involves the use of a spacer tip or standoff sleeve to create a passage between the tip of a fiber and a stone, and to prevent collapse of a bubble formed by vaporization of and/or gas pressure on liquid present in the passage. The laser radiation may consist of continuous or quasi-continuous wave radiation that is relatively low in power compared to the therapeutic pulses, or may consist of the therapeutic pulses if the pulse frequency is high enough to prevent collapse of the bubble between pulses. The spacer tip or standoff sleeve further prevents collapse of the bubble and ingress of liquid into the laser path. The spacer tip or standoff sleeve may be a generally-cylindrical protective cap that is fitted to an end of the optical fiber and that extends beyond the fiber tip to provide a predetermined spacing or standoff between the fiber tip and the stone when the protective cap is in contact with the stone. Alternatively, the spacer tip or standoff sleeve may be a catheter sleeve that permits axial adjustment of fiber position within the sleeve.