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The present study attempted to assess the in vivo
effects of Nd-YAG laser irradiation in different gaseous
environments on liver and brain. Such an investigation is
critical for determining the extent of injury under such
conditions for improving further clinical applications. We
intended to define the influence on laser-tissue interaction of
Room Air, 30% Oxygen, Helium, and Nitrogen. The anesthetized
rats were placed in a special chamber and kept breathtng via a
tracheostomy tube to the outside, and craniotomy or laparotomy
was performed. Nd-YAG laser fiber was directed with a fixed
distance at the exposed brain/liver. The staining drug for
brain study was 2,3,5 triphenyltetrazolium chloride, which was
injected into the aorta before sacrificing the animals. The 44
rats studied were divided into: liver and brain groups. The
resulting lesions were photographed macroscopically. In the
liver group, statistical analysis showed that laser-liver
tissue interaction in helium and nitrogen created a well
defined and less hemorrhagic lesions. Macroscopically, in the
brain group, we found that the target zones were well
delineated with Nitrogen concentration. Moreover, we observed
smaller lesions and more sharply defined areas with Helium
concentration. In Room Air and Oxygen concentrations, more
carbonized and bloodish lesions were found.
Laser-tissue interaction in Helium and Nitrogen
environments produces more sharply defined lesions with less
involvement of the sorrounding tissue, less hemorrhagic lesions
to the target, and reduce smoke production. This effect may be
of benefit in clinical application of Nd YAG laser, where a
more specific target-laser interaction could be achieved
avoiding undesired complications due to penetration on the
surrounding healthy tissue.
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