Cryoelectrolysis - electrolytic processes in a frozen physiological saline medium
- Published
- Accepted
- Subject Areas
- Bioengineering, Biophysics, Oncology, Surgery and Surgical Specialties
- Keywords
- cryoelectrolysis, cryosurgery, electrolysis, electrolytic ablation, freezing, electro-osmosis, iontophoresis, cancer ablation, focal therapy ablation, minimally invasive surgery
- Copyright
- © 2016 Lugnani et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. Cryoelectrolysis - electrolytic processes in a frozen physiological saline medium. PeerJ Preprints 4:e2474v2 https://doi.org/10.7287/peerj.preprints.2474v2
Abstract
Background: Cryoelectrolysis is a new minimally invasive tissue ablation surgical technique that combines the ablation techniques of electrolytic ablation with cryosurgery. The goal of this study is to examine the hypothesis that electrolysis can take place in a frozen aqueous saline solution.
Method: To examine the hypothesis we performed a cryoelectrolytic ablation protocol in which electrolysis and cryosurgery are delivered simultaneously in a tissue simulant made of physiological saline gel with a pH dye. We measured current flow, voltage and extents of freezing and pH dye staining.
Results: Using optical measurements and measurements of currents, we have shown that electrolysis can occur in frozen physiological saline, at high subzero freezing temperatures, above the eutectic temperature of the frozen salt solution. It was observed that electrolysis occurs when the tissue resides at high subzero temperatures during the freezing stage and essentially throughout the entire thawing stage. We also found that during thawing, the frozen lesion temperature raises rapidly to high subfreezing values and remains at those values throughout the thawing stage. Substantial electrolysis occurs during the thawing stage. Another interesting finding is that electro-osmotic flows affect the process of cryoelectrolysis at the anode and cathode, in different ways.
Discussion: The results showing that electrical current flow and electrolysis occur in frozen saline solutions imply a mechanism involving ionic movement in the fluid concentrated saline solution channels between ice crystals, at high subfreezing temperatures. Temperatures higher than the eutectic are required for the brine to be fluid. The particular pattern of temperature and electrical currents during the thawing stage of frozen tissue, can be explained by the large amounts of energy that must be removed at the outer edge of the frozen lesion because of the solid/liquid phase transformation on that interface.
Conclusion: Electrolysis can occur in a frozen domain at high subfreezing temperature, probably above the eutectic. It appears that the most effective period for delivering electrolytic currents in cryoelectrolysis is during the high subzero temperatures stage while freezing and immediately after cooling has stopped, throughout the thawing stage.
Author Comment
We have added a detailed description of what motivated the concept of cryoelectrolysis. The description is supported by a new figure (Fig1), which draws from the experience in the field of one of the authors (BR). Please see lines 144 to 213 and Fig.1
We have added a section to the introduction that emphasizes the difference between our previous study on cryoelectrolysis and this one. In particular, we introduced the new hypothesis that is examine in this study and the potential clinical value. Please see lines 222 to 253 in the introduction.
The justification for the choice of the currents was missing. Essentially, we chose typical values used in electrolytic ablation processes. In addition, we have done preliminary experiments only with electrolysis to identify current values that will provide us with measurable results in our configuration. Please see lines 320 to 327 in the experimental protocol.
We substantially changed the entire introduction. The difference between our earlier work and this one is explained in detail. In the previous work we delivered first electrolysis and followed with freezing. In this study we delivered electrolysis and freezing/thawing simultaneously. Please see the revised introduction. <!--[if !supportLineBreakNewLine]-->
Former Figure 1, was separated now into Fig 2 and Fig 3. Fig 2 that is relevant to materials and methods was put in the relevant section and Fig 3 was moved to results and Discussion.
We have reorganized the results and discussion into groups, to make them easier to follow and understand.
We have added details on the fundamental scientific principles of this work in both, the introduction and the results and discussion section. The details are supported by two new figures, 1 and 6. Please see the relevant additions on lines 144 to 213 and Fig.1 and lines 747 to 756 and Fig.6.