Experimental Study of Endoscopic Laser Hyperthermia Using Low Power Nd:YAG Laser for Central Airway Malignancies

Nd:YAG laser irradiation of 25-50W is useful in the bronchoscopic treatment of central air way malignancies, but is associated with complications such as bleeding and perforation. In recent years, laser hyperthermia using low power Nd:YAG laser under 5W was investigated or clinically applied in many fields due to its ability to heat a very restricted region effectively. An experimental study applying laser hyperthermia into bronchoscopic treatment of central air way malignancies was performed and results compared with those of high power Nd:YAG laser irradiation which is widely used. The following results were obtained: (1) Laser hyperthermia using 2.5W Nd:YAG laser produced a lower volume of defect and carbonization and a greater volume of coagulation in irradiated tissues than high power Nd:YAG laser irradiation with 25W. (2) By repeatedly switching the power with the foot switch, it was possible to maintain the temperature between 42.5 and 43.5 degrees Centigrade 5mm from the frosted probe during laser hyperthermia using 2.5W, 0.5sec-pulse mode. (3) In the investigation using resected Beagle trachea, pin-hole perforation was recognized at the site between cartilages after 1 minute of laser hyperthermia using 2.5W, 0.5sec-pulse mode. While at sites on the cartilage, defect of irradiated tissue was restricted within the cartilage, and there was no perforation detected. (4) Though laser hyperthermia using low power Nd:YAG laser is inferior to high power Nd:YAG laser irradiation with respect to immediate relief of air way stenosis, there are some advantages such as lower risk of bronchial perforation or bleeding, decreased smoke generated and deeper anti-tumor effect. Thus it is considered a promising method which is easily performed after minimum widening of the air way by high power Nd:YAG laser irradiation.

レーザー温熱療法

Nd:YAG レーザー

中枢気道悪性病変

気管支内視鏡的治療