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From: Proceedings 10th World Congress of Cryosurgery
Some theoretical aspects of cryosurgery

November 1998
VV Shafranov, DI Tsyganov, AV Taganov, EN Borkhunova Pediatric Surgery Department, Russian State Medical University, Moscow, Russia
The advantages of cryosurgery are known and it seems natural to expect that increasing the power of freezing helps to destroy the large area of biologic tissue. In actuality, the analysis of mechanism of cryodestruction has shown that the basic process of destruction is limited by the forming of ice at the level of micro-circulation because of the high degree of density of biological tissue- 10^ 10- 10^ 12 cells in cm^3. The thermal resistance of biological is very as I gm. of the mass of human body produce the heat in 10,000 times more than I gm. of the mass of the sun. To estimate the area of destruction, it is much better to take into consideration the heat from all the mass of human body. It is the main reason of the absence of success of local freezing of large zone of pathological tissue. While analyzing published data on curves of freezing, we have constructed a generalized curve for all regimes of cryo-applications. Effective time of cryodestruction is not too long, about 10-20 minutes, after which thermodynamic equilibrium is established. The measures of temperatures with the use of thermocouples and/or other tools reveal a drop in temperature from +37C at the deep 1-2 cm to -60C on the surface, so it is difficult to estimate a real temperature profile. That is why the mathematical simulation of the freezing zone is the best way to find the adequate zone of freezing. The experience of the doctor, and coordination of clinical results and mathematical simulations would establish optimal regimes of cryodestruction.

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