Treating warts with Cryotherapy by understanding its principles
How does cryosurgery/cryotherapy work ?
- Cryotherapy acts by taking the heat out of tissues.
- To take the heat out conduction of heat is important: it is highest for metals ( for example with probes), then ice (for example freezing just after having done it once), then water (by wetting the lesion to be treated and leaving a margin of 1-2mm around the lesion)…and is the lowest for air (for example when treating a lesion normally)
What it means
- A better effect is observed
- if water is applied
- if a second freezing cycle is done when ice is already present
Air on the other hand is a bad conductor and a dry lesion frozen for the first time will be less reactive to the cryogen.
Are all the areas of the lesion at a same temperature ?
- The directly frozen area easily achieves -50 to -80 celcius
- However the temperatures around rise quickly. They are at identical temperatures in rings and are called isotherms.
In practice:
- 50 degrees is needed to destroy cells.
- 2 cycles of freezing-thawing are needed
What does this teach us when treating warts practically ?
- Treat lesion for the first time normally.
- When treating the wart the second time, consider wetting the lesion 30 seconds before doing cryotherapy. Leave a margin of 1 to 2mm around the lesion because the is a risk of treating the centre effectively but leaving the wart in the periphery (“donut effect”).
Contributors
Dr Christophe Hsu – dermatologist. Geneva, Switzerland
Source of information: 2014 (03) – Pasquali P, new approaches to cryosurgery. 72nd AAD (American Academy of Dermatology) Annual Meeting (Denver, CO, United States of America)
