Cryo-Forum
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 +37°C at the deep 1-2 cm to -60°C 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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