75: Laser Surgery and Operating Room Fires

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CHAPTER 75 Laser Surgery and Operating Room Fires

James Duke, MD, MBA

1 What is a laser?

Laser stands for light amplification by stimulated emission of radiation. Within a laser atoms, ions, or molecules are stimulated by an energy source and spontaneously radiate energy in the form of monochromatic light. The radiated light is then amplified and emitted as the laser beam. Laser light has three defining characteristics:

1. Coherence: All waves are in phase, both in time and in space.
2. Collimation: The waves travel in parallel directions.
3. Monochromaticity: All waves have the same wavelength.

Benefits of using lasers are that they are extremely precise in their excision margins and there is minimal dissipation of damaging heat and energy to surrounding tissues.

2 What makes lasers behave differently from each other?

When excited, the source of the laser radiates light of a certain wavelength. The longer the wavelength, the more strongly it is absorbed by the tissue target, and the more shallow is the overall lasing effect. Conversely, the shorter the wavelength, the higher the energy, and the deeper the penetration of the laser light. For example, a carbon dioxide (CO2) laser has a longer wavelength and is absorbed almost entirely at the tissue surface. As a result, precise excision of superficial lesions is possible. Conversely, a neodymium:yttrium-aluminum-garnet (Nd: YAG) laser has a shorter wavelength, deeper penetration, and is useful for heating large tissue masses and tumor debulking (Table 75-1).

TABLE 75-1 Characteristics of Lasers Commonly used in the Operating Room

image

3 What are the hazards of lasers?

image The vaporization of tissue and dispersion of diseased particulate matter are hazards for all operating room (OR) personnel. The smoke produced by vaporization of tissues with lasers may be mutagenic, transmit infectious diseases, and cause acute bronchial inflammation.
image A laser beam in contact with flammable materials such as endotracheal tubes, anesthetic gas tubing, surgical drapes, and sponges may cause fires or explosion. Fires result in minimal or no harm to the patient if the situation is handled swiftly but may be catastrophic if not.
image Although rare, venous gas embolism may occur, especially during laparoscopic or hysteroscopic procedures. Reported cases have been associated primarily with Nd:YAG lasers, in which coolant gases circulate at the probe tips. It is these coolant gases that embolize.
image Inappropriate energy transfer: Laser light vaporizes whatever tissue lies in its path. Precise aim by the surgeon and a cooperative (well-anesthetized, paralyzed) patient are mandatory. In addition, laser light is easily reflected by surgical instruments and may be hazardous to all OR personnel. Laser contact with the eyes may impair vision or cause blindness. The nature of ocular damage depends on the wavelength of the laser light. For example, CO2 lasers cause corneal opacification, whereas Nd:YAG lasers cause damage to the retina. Any plastic lens protects against CO2 laser injury; contact lenses do not. Other lasers require more specialized eye protection.
image Perforation: Misdirected laser energy may perforate a viscus or large blood vessel. Laser-induced pneumothorax after laryngeal surgery also has been reported. Sometimes the perforations do not occur until several days after surgery when edema and tissue necrosis are at a maximum.

4 What are some unique airway considerations for the patient having laser surgery of the airway?

image Upper airway lesions:

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