What are the hazards of laser laryngoscopy to patients, operating room personnel, and anesthesia equipment?

What are the hazards of laser laryngoscopy to patients, operating room personnel, and anesthesia equipment?

Administrative organizations have taken steps to mini-mize laser-related problems. The US Food and Drug Administration (FDA), the American National Standards Institute (ANSI), as well as the National Fire Protection Association (NFPA) have developed rigorous safeguards to help protect patients and operating room personnel from laser-device-related injuries. The Occupational Health and Safety Administration (OSHA) has been empowered to protect operating room personnel from laser injury. Most health care facilities prohibit the use of lasers by uncreden-tialed practitioners.

One of the most dramatic and unique hazards of laser laryngoscopy is airway fire. Ideally, anesthetic techniques should minimize the risk of anesthetic gas combustion while providing adequate patient oxygenation. Frequently, these goals are conflicting and difficult to achieve because patients with the greatest need for laser laryngeal surgery often present with compromised vital organ function. To further complicate matters, these procedures are usually performed on an ambulatory basis.

Other laser hazards include unintentional perforation of adjacent structures, embolic phenomena (usually occur-ring during gynecologic surgery), inappropriate energy transfer, and atmospheric contamination. Perforation of an adjacent structure may occur as an esophageal perfora-tion during posterior laryngeal laser surgery. Inappropriate energy transfer harms the patient or operating room personnel. Examples include ignition of an endotracheal tube or surgical drapes. Avoiding such hazards mandates depression of the laser foot pedal control only after aiming the target light beam.

Atmospheric contamination may be the single most common complication of laser surgery. Tissues vaporized by laser light emit a plume of smoke containing pyrogens and other materials, such as viral particles. These particles are released into the atmosphere and distributed to exposed skin of the patient and operating room personnel. Therefore, total body covering during laser procedures may be indicated. Operating room personnel should wear specially designed facemasks that are resistant to the laser plume’s particulate matter, in an effort to reduce the risk of dissemination into the tracheobronchial tree.

Applying an aqueous-based lubricant, taping the eyes closed, and covering with moist gauze or metallic eye shields may avoid ocular damage to the patient. The patient’s face, head, and neck should be surrounded with wet surgical towels to reduce the risk of ignition. Special wrap-around goggles designed for each laser frequency are available to protect the eyes of operating room personnel. Clear wrap-around goggles block far-wavelength light associated with CO₂ lasers. Specific color-tinted goggles protect against near-wavelength lasers, such as the Nd-YAG and argon lasers.

Lasers also jeopardize anesthesia equipment. Errant beams have ignited endotracheal tubes. Polyvinyl chloride (PVC) tubes burn most easily and consequently are least desirable for laser surgery. Red rubber and silicon endotra-cheal tubes are not as highly combustible as PVC types. Although metal tubes present the least combustion hazard, they do not eliminate the risk entirely, since their cuffs may still ignite. Covering the cuff with saline-soaked gauze and inflating it with saline instead of air reduces the poten-tial for airway fire. Saline-soaked gauze can also be used to protect nonoperative airway sites. Wrapping the anesthesia breathing circuit in aluminum foil protects it from errant laser beams. The aluminum foil wrapping should also include the CO₂ sampling tubing, which is no less com-bustible than the anesthesia circuit. Similarly, nonmetallic endotracheal tubes may be surrounded with metallic tape. At the time of writing, only the Mericel® laser guard wrap is FDA-approved among all commercially available metal-lic wraps. Copper tape protects against CO₂, argon, and the KTP-Nd-YAG laser, but not the YAG laser alone. Metallic wraps increase the endotracheal tube’s external diameter in some cases. A small number of laser-shielded endotracheal tubes are offered for sale. One such tube consists of aluminum powder in a silicon base. These tubes contain silicone cuffs which, if ruptured, can propel silica into the distal trachea.