Prevention of tissue damage by water jet during cavitation

Abstract

Cavitation bubbles accompany explosive vaporization of water following pulsed energy deposition in liquid media. Bubbles collapsing at the tip of a surgical endoprobe produce a powerful and damaging water jet propagating forward in the axial direction of the probe. We studied interaction of such jet with tissue using fast flash photography and modeled the flow dynamics using a two-dimensional Rayleigh-type hydrodynamic simulation. Maximal velocity of the jet generated at pulse energies of up to 1 mJ was about 80 m/s. The jet can produce tissue damage at a distance exceeding the radius of the cavitation bubble by a factor of 4. We demonstrate that formation of this flow and associated tissue damage can be prevented by application of the concave endoprobes that slow down the propagation of the back boundary of the bubble. Similar effect can be achieved by positioning an obstacle to the flow, such as a ring behind the tip.

Pulsed Laser Ablation of Soft Biological Tissues

“…The bubble collapse near an elastic, tissue-like boundary is characterized by the formation of two liquid jets that are directed both away from and towards the boundary and reach velocities as high as 960 m/s [208]. Jet formation is also induced by the fiber tip itself whereby the jet is usually directed away from the tip in the direction of the fiber axis [188,209]. The jets have been shown to be responsible for collateral damage [209] and to increase the material removal [201,202,210].…”

Electrosurgery With Cellular Precision

“…In pulsed ablation, tissue can also be damaged by mechanical effects of the rapidly expanding and collapsing cavitation bubbles [8], [9]. When the pulse duration is much shorter than the lifetime of the vapor bubble, the process of vaporization is explosive, leading to the formation of large and rapidly expanding vapor cavities.…”

“…When the pulse duration is much shorter than the lifetime of the vapor bubble, the process of vaporization is explosive, leading to the formation of large and rapidly expanding vapor cavities. During collapse of the cavitation bubbles, fast water jets can form near the tissue boundaries, extending the range of mechanical tissue damage [9], [10]. With pulse duration much shorter than the bubble lifetime, up to 10% of the pulse energy can be converted into mechanical energy of the cavity [11], [12].…”

Digital interference microscopy and density reconstruction of picosecond infrared laser desorption at the water-air interface

“…Laser ablation is heavily utilized in numerous surface analysis techniques for the immediate and spatially resolved extraction of materials and has also been successfully applied to a variety of non-analytical applications including pulsed laser deposition, laser machining, and laser surgery. Imaging studies yield information on the characteristics of the ablation plume which is valuable for optimizing the conditions to achieve, e.g., improved material collection in mass spectrometry, 1 minimal tissue damage in laser surgery, [2][3][4] and homogeneous film growth in pulsed laser deposition. 5,6 Beyond that, the spatio-temporal information gained by imaging the ablation plume can be used to form more refined models describing the fundamental processes, leading to ablation and ionization.…”