Although Nd-YAG laser surgery is a very effective treatment-modality to reopen
malignant airway obstruction, fatal complications such as perforations of airway and
intrathoracic great vessels were reported and these complications were due to excess of
irradiation dosage and/or many factors affecting laser effects.
Considering Nd-YAG laser is an light energy with its own wavelength (1064 ㎚), it
might be expected that laser-induced tissue damage and safe dosage may be different
according to the color of the target tissue. And there is variety of color in malignant
tissue of tracheobronchial tree, ie, reddish hemorrhage, blackish anthracosis, whitish
necrosis or natural-colored tumor.
An experiment was performed to determine the chromatic effects of Nd-YAG laser
using colored papers, porcine tracheas. and esophagi. Eight kinds of. colored
papers-ivory, red, orange, yellow, green, blue, violet ,and black-were irradiated with 1∼
50 J of Nd-YAG laser with 90° of radiation angle in 5 mm distance between laser tip
and papers, and porcine tracheas and esophagi were also irradiated with 5∼495 J of
Nd-YAG laser by the same manner as used in papers after were stained with congo
red, methylene blue and black ink.
The effects of Nd-YAG laser were analyzed according to the colors of irradiated
materials.
In colored papers, the damage was most makes in black followed by blue, violet,
green, yellow, orange, red, and ivory in the same dosage of laser irradiation (p<0.01).
And in porcine tracheas and esophagi, the tissue damage was also most marked on
blackish stained tissue followed by blue, red and natural color(p<0.01).
It is concluded that the tissue damage by Nd-YAG laser irradiation is dependent on
the color of target tissue and the degree of damage is relatively reciprocal to
wavelength of color itself. And the safe dosage of Nd-YAG laser in tracheobronchial
tree should be changed according to the color of irradiated tissue.
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