Steam Bubble Maintenance in Surgical Ablation
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Solution Overview
Problem
Infrared laser energy is inefficiently transferred to surgical targets in water-based environments due to the 'Moses Effect,' where a significant portion of energy is consumed in boiling water, leading to incomplete absorption and chaotic bubble formation, which complicates surgical procedures like lithotripsy and soft tissue ablation.
Innovation Solution
A dual wavelength, dual mode surgical laser system that combines a high-power pulsed laser for therapeutic emission with a low-power continuous-wave laser to maintain a steam bubble, ensuring efficient energy delivery through the steam bubble by using a crystalline beam combiner and optimizing fiber optic construction to contain the CW emission within a secondary numerical aperture, thereby reducing energy loss and maintaining a stable 'Moses corridor' for unimpeded surgical pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pulsed laser is used to ablate tissue in a water-based environment, then surgical ablation can be achieved, but a significant portion of laser energy is consumed in boiling water to create steam bubbles, reducing energy efficiency
Solution Approach 1:
A low-power continuous-wave laser is used beforehand to pre-vaporize the water pathway between the fiber tip and target tissue, creating a steam-filled corridor. This preliminary action removes the water that would otherwise absorb the therapeutic pulsed laser energy, allowing the subsequent high-power pulses to deliver energy efficiently to the target.
Solution Approach 2:
The low-power continuous-wave laser acts as an intermediary that prepares the medium by creating a steam bubble corridor. This intermediary component modifies the optical properties of the medium between the fiber and target, enabling efficient energy transfer of the therapeutic laser without direct interaction between the high-power pulses and water.
2Productivity
If high-power pulsed laser is used to ensure sufficient energy reaches the target, then ablation efficacy is maintained, but chaotic bubble formation and collapse occurs causing retropulsion and thermal stress on surrounding tissues
Solution Approach 1:
The continuous-wave laser pre-vaporizes the water pathway before the therapeutic pulsed laser is applied. By removing water from the pathway in advance, the high-power pulses no longer cause chaotic bubble formation and collapse, eliminating retropulsion and reducing thermal stress on surrounding tissues while maintaining ablation efficacy.
Solution Approach 2:
The invention converts the harmful effect of laser energy being absorbed by water (which causes unwanted heating and bubble formation) into a beneficial pre-vaporization process. The low-power continuous-wave laser intentionally creates a steam corridor that then serves to protect surrounding tissues from the harmful effects of high-power pulse interaction with water.
3Loss of energy
If the fiber tip is positioned close to the target to minimize energy loss in water, then energy coupling efficiency is improved, but the surgical field access and maneuverability are limited
Solution Approach 1:
The low-power continuous-wave laser creates an intermediary steam-filled corridor that allows the fiber tip to be positioned at an optimal distance from the target. This steam corridor acts as a mediator that enables efficient energy transfer even when the fiber is not in direct contact with or extremely close to the target, providing both energy efficiency and operational flexibility.
Solution Approach 2:
The invention changes the physical state of the medium in the fiber-to-target pathway from liquid water to steam vapor. This parameter change (phase transition) fundamentally alters the optical properties of the medium, enabling efficient energy transfer at larger fiber-to-target distances and providing greater maneuverability while maintaining energy coupling efficiency.
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 significantly increases the percentage of therapeutic laser energy that reaches the target, with greater than 90% of the power output being delivered effectively, reducing retropulsion and thermal stress on surrounding tissues, while minimizing the chaotic bubble formation and collapse cycle, thus enhancing surgical efficacy and fiber longevity.
Implementation Method 1
Absorption of laser energy by water is the basis of laser to tissue interaction of infrared lasers
Implementation Method 2
the first portion of each laser pulse is spent in boiling water, producing a steam bubble referred to as a 'Moses bubble'
Implementation Method 3
laser energy traveling in a liquid medium toward a target tissue will be absorbed, but that absorption may be less than expected due to the 'Moses Effect'. As in the Biblical reference, the waters are parted by a first component of the pulse energy in producing a vapor bubble (Moses bubble) within the liquid medium. The remaining pulse energy passes through the far less attenuating medium of the bubble
Implementation Method 4
therapeutic laser emission providing ablation of the surgical target
Data Source
AI summary
A surgical method and tool for establishing a steam bubble between a fiber tip and a surgical target. The device and process capable of maintaining the steam bubble by providing a low-power, continuous-wave laser emission. Furthermore, the method and tool capable of delivering to the surgical target through the steam bubble a therapeutic laser emission providing ablation of the surgical target.