Application of Laser Light in ENT (Otolaryngology)
Otolaryngologi sts use lasers for many surgical applications. Within the past few years, a lightweight, portable,980-nm wavelength diode laser with a fiberoptic delivery system was introduced to the field of otolaryngology. Light at its particular wavelength is absorbed by tissues relatively independent of tissue type, which allows for homogeneous distribution at the surgical site.
As early as the late 20th century, the diode laser has been subjected to extensive experimental investigation, including pathologic and histologic studies to determine appropriate dosimetry. It has been used in clinical trials for wound care and the treatment of facial and leg telangiectasias, endobronchial tumors, and disk compression.
There are three distinct application techniques for the diode laser: .
• First, it can be used in contact mode, in which the tip of the fiber is placed directly on the surface of the tissue. This mode is effective for both photocoagulation and vaporization of tissue, depending on the power density . At the low- or mid-power range, coagulation occurs; at a higher level, vaporization occurs.
• Second, the laser can be used in near-contact mode, in which the tip of the fiber remains several millimeters apart from the tissue. This mode is largely used for tissue photocoagulation.
• Third , the laser can be used for interstitial laserinduced thermotherapy, a minimally invasive method of treating both benign and malignant tumors.The laser is placed through puncture holes in the skin, and its energy is absorbed by local tissues. This hyperthermic state causes either immediate or delayed tissue necrosis via coagulation.
The 980-nm diode laser emits light in the near-infrared range (800 to 1,100 nm). This wavelength allows it to be transmitted via a thin, flexible quartz fiberoptic cable . Tissue response at this wavelength is determined by the absorption of water as well as by absorption of endogenous components such as hemoglobin and melanin. As a result, the diode laser has a large (up to 10 mm) penetration depth in biologic tissue, which makes it ideal for photocoagulation.
By contrast, the CO2 laser has a very shallow penetration depth and thus is best used for tissue vaporization. The potential role for a portable, lightweight, versatile laser with the properties of diode lasers is quite large. Our preliminary results with this laser are encouraging, and we have demonstrated its clinical usefulness. Moreover, the fact that this laser can be applied in conjunction with topical anesthesia alone is testament to its convenience.
