X-Message-Number: 27662
From: "Basie" <>
Subject: Best cooling rate for cryo patients 
Date: Wed, 1 Mar 2006 23:33:52 -0500

1. Tatsutani, K; Rubinsky, B; Onik, G; Dahiya, R.
Effect of thermal variables on frozen human primary prostatic
adenocarcinoma cells.
Urology, v.48, n.3, (1996): 441-447.

Abstract:
Objectives. Recent advances in imaging technology and cryotechnology have
rekindled interest in prostate cryosurgery. Cryosurgery, however, cannot
be applied precisely without knowing how the thermal variables used during
the procedure affect tissue destruction. The goal of this article is to
provide quantitative values for the relationship between thermal variables
during freezing and the destruction of human primary prostatic
adenocarcinoma cells. Methods. Human primary prostatic adenocarcinoma
cells were frozen with controlled thermal parameters, using a directional
solidification apparatus. Cell viability was determined after thawing,
using trypan blue and a two-dye fluorescent test and correlated to the
thermal variables used during freezing. Results. Human primary prostatic
adenocarcinoma cells are damaged by intracellular chemical damage when
frozen with cooling rates lower than 5 degree C/min and by intracellular
ice formation when frozen with cooling rates higher than 25 degree C/min.
A double freeze/thaw cycle is required to ensure complete cell destruction
at high subzero temperatures, which must be lower than -40 degree C for
the low cooling rates and lower than -19 degree C for the higher cooling
rate. Conclusions. Haphazard freezing does not necessarily destroy tissue
during cryosurgery; however, quantitative data on the relation between
thermal variables and frozen cell destruction can provide the means for
performing cryosurgery more precisely and with greater control over the
outcome of the procedure.

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It appears to me the best cooling RATE for cryo patients would be somewhere 
between 5 and 25 degrees C/min. Is that possible with a whole brain? 
Assuming that that total perfusion with a cryo protectant may not always 
occur.

Basie 

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