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: In laser resection of upper airway lesions, tracheal intubation is optional. Techniques that do not involve an endotracheal tube allow better visualization of the operative field by the surgeon and also remove potentially flammable materials from the airway. Clearly the airway is being shared by surgeon and anesthesiologist, and a discussion of the operative course before the procedure begins is important.
image Lower airway lesions: The CO2 laser beam is directed at the lesion through a rigid metal bronchoscope, coated with a matte finish to reduce reflected laser light. Ventilation is accomplished through the side arm of the bronchoscope, using saline-soaked gauze to form a seal around the bronchoscope. Jet ventilation is another option. In certain instances (e.g., lower tracheal and bronchial lesions) the laser approach is via fiber optic, and the Nd:YAG laser is required because it can travel through fiber-optic cables, whereas the CO2 laser cannot.

5 Describe ventilation techniques commonly encountered during airway laser surgery

image Jet ventilation: In this technique the surgeon aims a high-velocity jet of O2 at the airway opening. The high flow of O2 entrains room air as a result of the Venturi effect, thus ventilating the lungs with a high volume of O2–air mixture. Ventilation is accomplished by attaching a suction catheter to wall O2 and a Sanderson-type jet injector. This apparatus is mounted to the operating laryngoscope. Sometimes the mass of the airway lesion makes this method impossible. If the jet stream is not aimed in the trachea, gastric dilation may occur. Barotrauma to the airway and subsequent pneumothorax are also risks and may in turn lead to mediastinal or subcutaneous air. An intravenous anesthetic is necessary for this procedure.
image Spontaneous ventilation: Allowing the patient to inhale volatile agents via the operating laryngoscope is also an option, although it is not feasible for some procedures. It is difficult to control the depth of anesthesia during spontaneous ventilation, and it is often necessary to paralyze the patient during many airway procedures. Hypoventilation, hypercarbia, and aspiration (surgical debris, secretions, vomitus, and smoke) are additional complications related to both jet and spontaneous ventilation.
image Endotracheal intubation: This method allows excellent ventilation and airway protection of the anesthetized patient but often obscures the operative field and puts flammable materials in the path of the laser beam.

6 What are the three essential components necessary to create an operating room fire?

The fire triad consists of:

1. Oxidizers. Within the OR environment they are O2 and nitrous oxide.
2. Ignition sources include electrosurgical or electrocautery devices, lasers, argon beam coagulators, fiber-optic light cables, defibrillator pads, heated probes, and drills and burrs. When not in use, electrocautery devices should remain within appropriate holders, not lying on the surgical drapes. They first three ignition sources listed are the most common ignition sources.
3. Fuel sources include the following: endotracheal tubes, sponges, drapes, gauze, alcohol-containing preparation solutions, the patient’s hair, surgical dressings, gastrointestinal tract gases, and packaging materials. When using alcohol-containing preparation solutions, they should be allowed to dry before the patient is draped and ignition sources used. Surgical sponges, gauze, and the like are less likely to be fuel sources when they are wet rather than dry.

7 What are high-risk procedures for operating room fires?

They include but are not limited to tonsillectomies, tracheostomies, removal of laryngeal papillomas, cataract or other eye surgery, burr hole surgery, and removal of lesions about the head, neck, or face.

8 What strategies can reduce the incidence of airway fires?

image Laser-resistant endotracheal tubes should be chosen. The cuffs should be filled with saline, not air, and it is also recommended that the saline contain a small quantity of methylene blue to help identify rupture of the cuff, should this happen (as in an airway laser procedure). Many laser specialty tubes already have dye crystals within the cuffs. Cuffed tubes are also preferable to uncuffed tubes.
image Some authors advocate wrapping the endotracheal tube with metal tape; however, this method limits the pliability of the tube and increases the risk of a reflected laser beam and loss of metal tape fragments in the trachea.
image Nitrous oxide should not be used in high-risk procedures. Use only the lowest possible O2 concentration necessary to maintain the patient’s O2 saturation.
image Ignition sources such as electrosurgical devices should not be allowed to enter the trachea. If they are required, the anesthesiologist should be warned of this by the surgeon, and a suitable period allowed to decrease the delivered O2 concentration to the minimum amount tolerated by the patient.

9 What are signs that a fire has occurred?

A flame or flash may be noted; unusual sounds heard (pop, snap or foomp); and unusual odors, smoke, discoloration of the drapes or heat detected. Abnormal movements of the surgical drapes have also been noted in some fires.

10 Should an airway fire occur, what are the recommended practices for its management?

image Halt the procedure.
image Remove the endotracheal tube.
image Stop the flow of all airway gases.
image Flood the surgical field with saline and remove all flammable and burning materials.
image Mask-ventilate the patient with 100% O2 and reintubate.
image Perform rigid laryngoscopy and bronchoscopy to assess the damage and remove debris.
image Monitor the patient for 24 hours.
image Use short-term steroids.
image Continue ventilatory support and antibiotics as needed.

KEY POINTS: Appropriate Scheme to Manage an Airway Fire image

1. Stop ventilation.
2. Disconnect the O2 source, remove the endotracheal tube, and flood the surgical field with saline.
3. Mask-ventilate the patient with 100% O2 and reintubate.
4. Perform rigid laryngoscopy and bronchoscopy (using Venturi jet ventilation) to assess the damage and remove debris.
5. Monitor the patient for 24 hours.
6. Use short-term steroids.
7. Continue ventilatory support and antibiotics as needed.

11 Are there additional recommendations for a fire not involving the airway?

For an intubated patient it is not necessary to halt the flow of ventilator gases. However, if the patient is receiving O2 by nasal cannula or mask, stopping the flow of these gases may eliminate the oxidizing source. The burning drapes should be removed. Fire extinguishers of the CO2 type may be needed. An out-of-control fire may require removal of the patient from the OR. The best way to manage any fire is to have a preestablished, practiced algorithm in which every member of the OR team understands his or her role.

Website image

Emergency Care Research Institute: The patient is on fire: Medical Device Safety Reports.

http://www.mdsr.ecri.org

SUGGESTED READINGS

1. American Society of Anesthesiologists. Practice advisory for the prevention and management of operating room fires. Anesthesiology. 2008;108:786-801.

2. Rampil I.J. Anesthesia for laser surgery. In: Miller R.D., editor. Miller’s anesthesia. ed 6. Philadelphia: Elsevier Churchill Livingstone; 2005:2573-2587.

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