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Safety Considerations and Safety Protocol for Laser Surgery
Symposium on Laser Surgery
Safety Considerations and Safety Protocol for Laser Surgery
Rose M. Mohr, M.D.,* Bernard C. McDonnell, D.O.,t Michael Unger, M.D.,:I: and Theodore P. Mauer, D.O.§
Laser safety depends on precise knowledge of the physics of each laser and tissue effects in a constantly changing environment. The minimum requirement for certification in laser usage at any hospital should include a "hands-on" course that includes basics in laser physics and usage of the laser in an animal laboratory. This usually means at least 5 hours of didactics and 5 hours of laboratory and observation of a few clinical cases performed by a trained physician. It is best to precept for some time, as understanding and using lasers depend on the amount of usage and quality of supervision. 19 In this article focusing on laser safety, the most common lasers used in surgery and medicine are used to illustrate safety principles: the CO 2 , Nd:YAG, and argon lasers.
PROTOCOL FOR LASER USERS AND INFORMED CONSENT General Guidelines Laser safety begins with multiple in-services, both for the user and the assistants. Resident physicians should be required to complete a course just as their teachers and/or precept and show knowledge of laser use to be *Associate Professor of Otorhinolaryngology and Bronchoesophagology, and Director, Chevalier Jackson Center, Temple University Health Sciences Center, Philadelphia, Pennsylvania tVice-Chairman, Otorhinolaryngology, Suburban General Hospital, Norristown, and Clinical Instructor of Otorhinolaryngology, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania :l:Associate Chief, Pulmonary Section, Presbyterian-University of Pennsylvania Medical Center, and Clinical Assistant Professor of Medicine, University of Pennsylvania School of Medicine, Philadelphia; and Co-Director, Institute for Applied Laser Surgery, Bala Cynwyd, Pennsylvania § Professor and Chairman, Otorhinolaryngology, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania
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safe assistants. Laser use by a resident should always be supervised through direct observation. Teaching attachments (such as observer tubes) are requisite. 19 Laser Operator Only extremely well instructed personnel should manage the controls of the laser. Some 80-W CO 2 lasers have more than one scale. No one should operate the CO 2 laser if the scale usage on the laser is not understood. The surgeon using the instrument is the individual who must test the instrument prior to its application to a patient. The setting used should be set by the surgeon and double-checked prior to the first lasing. Most Nd:YAG lasers must be calibrated before each use.!" It is recommended that lasers be used in areas in which a distinct advantage has been shown to exist for the treatment of a patient's condition. When the use of the laser offers no advantage over routine techniques, the laser should not and/or does not have to be utilized. When scheduling, patients should be told that either routine methods or laser methods would be used, depending on findings at the time of the procedure. If the laser is a requisite for the performance of a particular procedure or the patient wants only laser treatment then the patient should be cancelled if the laser is out of order. 23 Special permits are required for the use of the Nd:YAG laser; special permits are not currently required for use of the CO 2 laser. Informed consent is required for both, however, and a careful explanation of the reason for usage and any additional hazards that might be added because of the use of the laser should be carefully explained to the patient and documented on the chart. 19, 23 Laser maintenance should be recorded. If a laser fire and/or any other complication occurs, proper repair records are essential. 19 A laser safety comittee should be established and a laser safety officer appointed. Laser accreditation and quality control groups must be organized. 19
SAFETY AND THE CO 2 LASER CO 2 laser safety measures are the most elaborate because the laser is used in open-field surgery, as well as in the upper respiratory tract, with the route of administration of anesthesia In the field. Combustible gas mixtures and endotracheal tubes must be avoided. The CO 2 laser is absorbed by most surfaces but reflected by shiny ones; it is almost completely absorbed by water. Eye Protection All personnel should wear glass, transparent plastic, or quartz glasses with side protectors when working in a CO 2 laser (10,600 nm) environment. Regular glasses and/or contact lenses protect only the area covered by the lens. The patient, should also have protective eyewear if the laser is tested during the preinduction phase. The operator behind a binocular microscope need not wear protective eyewear. The aiming light on the CO 2 laser allows determination of the direction
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of the laser beam. A helium-neon laser (630 nm) is the most frequently used aiming guide and can cause photochemical effects in the eye and skin. When a CO 2 laser is in use for any purpose, the doors to the room should be locked. Laser caution signs should be posted, and only personnel familiar with laser safety or usage should be allowed into the treatment area. 19 Prevention of Fires If the treatment area is within the patient's airway, or the endotracheal tube will in any way be exposed or could potentially be exposed to the laser beam, the anesthesiologist is required to take specific precautions to prevent a fire. An endotracheal tube, preferably a red rubber Rusch tube or a Silastic reinforced endotracheal tube that is wrapped with overlapped (V3 to V2 in.) aluminum tape must be used for intubation. The tube can be cleaned with acetone, and benzoin applied before wrapping to prevent dislodging of the tape. Both the surgeon and anesthesiologist should check the tube before use." 10 The tube wrap can cause tube kinking and become a foreign body if dislodged. The cuff should be inflated with sterile saline and be protected with wet neurosurgical cottonoids. The cottonoid strings should also be wet or replaced with wire. If the cuff is perforated with saline in it, it acts as a heat sink and prevents combustion;" If methylene blue is added to the cuff solution, it will stain the cottonoids, thus allowing earlier recognition of cuff perforation. The use of a polyvinyl chloride (PVC) endotracheal tube is not recommended. Fire-breakdown products and tissue destruction associated with combustion of this tube are quite severe. Breakdown products from the red rubber tube are intermediate between those of PVC and Silastic. The Silastic tube, if it does combust, forms silica ash. The tissue effects from the silicone tube are minimal, but the effects of silica ash are unknown. 16, 22 There has been no laser fire associated with the combustion of a Silastic tube. Continuous lasing for several seconds without protection on the Silastic tube finally perforates the tube, and if an oxygen-rich environment is within the tube, it will combust and form silica ash. The level of combustion for a PVC tube is somewhere around 149°F; for a Silastic tube, 700°F; and for a red rubber tube, somewhere inbetween. 3, 5, 9, 16, 22 Tubes with "laser guard and/or nonreinforced Silastic tubes should be used with caution as they have not had much clinical usage. Silastic tubes without reinforcement are extremely soft, and when inflating the cuff with saline, the lumen of the endotracheal tube can be reduced. Metal Norton endotracheal tubes are available; however, they " have a small inner diameter and no cuff. The anesthetic mixture should be carefully controlled. Oxygen percentage should remain below 40 per cent. Nitrous oxide is contraindicated, as it is combustible. Combining nitrogen, oxygen, and compressed air with an inhalation agent or using neuroleptic agents and monitoring the oxygen input continuously during the procedure is the safest method. Blenders incorporated within anesthesis machines are available to control the percentage of oxygen intake. Continuous oxygen-monitoring during the proH
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cedure with ear oximetry or percutaneous oximeters in addition to arterial blood gases is recommended. Other Necessary Precautions Wet towels should be placed around any surgical field associated wih a CO 2 laser. Paper drapes do not wet and can be ignited with a stray laser beam. 26 Blackened Instruments. The use of blackened instruments or glassbead-dusted instruments is recommended to prevent full reflection of the laser beam, should it accidentally strike the instruments. Blackened laser platforms below the area being lased prevent accidental lasing of normal tissue. Lubricants. During the intubation, the use of any oil-containing compound should be avoided. Oil-base anesthetic lubricants on endotracheal tube tips may be combustible. Noncombustible lubricants should also be avoided. Water-soluble lubricants may be used to coat the structures the surgeon wishes to lase. The CO 2 laser is almost entirely absorbed by water and water-soluble compounds. The effectiveness of the surgery might be altered. Instrument Off. The laser should always be on stand-by or off when lasing is not in progress. The operator's foot should be off the foot pedal when the laser is not in use, to prevent accidental discharge. Smoke Clearance. Constant suctioning should be used to remove the smoke from the environment so that it is not inhaled by the patient and/or operating room personnel. The smoke is probably mutagenic and/or carcinogenic.:" Smoke particles heat suction lines and can cause costly repairs; filters in suction lines are mandatory. Smoke impairs the vision of the surgeon and is potentially composed of flammable particles; it can reflect the laser beam. Safest Anesthesia Methods. The use of Venturi or rapid ventilation techniques during laser surgery works for selected patients. We helieve that the safest method is a wrapped, noncollapsible endotracheal tube with routine ventilation methods with control of the oxygen environment. The patients should be instructed to breathe on their own when the tracheobronchial tree is to be lased with a local stand-by technique that monitors the oxygen-nitrogen inhalation concentrations being administered through a ventilating rigid bronchoscope. Laryngeal surgery requires complete relaxation for precise work. 1, 3, 5, 11, 20 User Knowledge ofTissue Effects. Safety of surgical procedures utilizing the laser depends on the user's knowledge of the effects on the tissue. The laser is safe when used in short spurts; the surgeon should use the highest power and the lowest time setting that is comfortable. Continuous lasing should be avoided, and rest periods should be used; skip areas should be left. 2 , 14, 15, Intermittent iced saline irrigation should be used to prevent heat transfer to surrounding tissues. Drapes and cottonoids should be periodically rewet.P Constantly Changing Effects. The laser user has to be aware that tissue effects change as the distance of the lesion changes in relation to the laser beam. 24 When lasing in the lung, the operator should preferably lase during
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the same phase of respiration throughout the entire procedure. 1, 6,7 It is always wise to lase along the margins of the tracheobronchial tree with the incident beam parallel to the wall; this prevents accidental deep penetration. Do not lase spurs, as they often harbor vessels underneath. Only luminal extensions of tumors or scars should be lased in the tracheobronchial tree. 1, 3, 6 Control of Bleeding. The CO 2 laser is predominantly a vaporizer, not a coagulator. Bleeding is best controlled when defocused. It may be necessary to switch to another laser, such as a Nd:YAG or argon laser to better coagulate the bleeding tissue. At present, the CO 2 laser is not transmittable through flexible cables, and thus rigid bronchoscopy is mandatory for its use. The requisite for rigid bronchoscopy affords better suction capabilities and better control of bleeding and tumor removal. 1, 3, ,5, 6 CO2 Laser Fire Management Fires can occur with rigid bronchoscopes because added cuffs or endotracheal tubes used along side are ignited by flaming tissue; the flame is perpetuated by an oxygen-enriched environment.P" Such fires should not occur to either the experienced laser operator or anesthesiologist. Everyone in the room must be oriented toward laser knowledge and safety; a laser fire is inexcusable. 22 If a laser fire should occur, the oxygen must be turned off within 1 second, as the patient is extubated to get rid of the flame and/or offending burning endotracheal tube or hot bronchoscope. 22 The patient should then be bagged with oxygen and reendoscoped to assess the damage and then reintubated. Any debris in the larynx and tracheobronchial tree should be removed and the area irrigated. If severe damage occurs, it is usually at the tip where the airway was lying. In this case, a tracheotomy might have to be performed below the injury. Ventilatory support is then most likely necessary for a period of time. Stenosis and permanent tracheobronchial damage can occur if the fire is allowed to smolder. Antibiotics should be given, along with steroids. 22 Special Precautions Outside the Airway CO 2 laser usage anywhere in the body requires the use of the same basic principles as those described for use in the tracheobronchial tree, although they are not quite as elaborate. If the airway is not in the field, the operator should protect areas from damage with water, and from materials such as moistened neurosurgical cottonoids, wet lap pads, or vaginal gauze. Paper drapes should be protected or not used. Smoke control and suction filters are more important with nonairway procedures because of the increased volume of smoke. When the CO 2 laser is used in the colon or in the area of any other flammable gas, a noncombustible gas (most likely CO 2) must be insufflated into the environment to prevent an explosion. Meticulous care of the CO 2 laser system and avoidance of disruption of the mirror system is essential in safety for all personnel. If mirror alignment is disrupted, the aiming and precision of the laser are impaired. 23
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SAFETY AND THE Nd:YAG LASER The Nd:YAG laser is more difficult to learn to use because of its .differential absorption characteristics and forward and backward scatter. This laser has multidisciplinary use, although it is currently approved for clinical usage only in gastrointestinal bleeding, esophageal tumors, and the tracheobronchial tree. All other uses are considered investigational. This laser offers coagulation capabilities and can be used through a flexible fiberoptic system. Eye Protection All personnel should have protective glasses in the blue/green spectrum (ANSI Standard 2136.1), which protects the entire globe. Special filters can be obtained for flexible endoscopes that will prevent the operator from eye damage. If the special filter is not utilized in the endoscope, the operator must wear the protective eye equipment described above. 23 Limited Access Windows in doors and/or scrub areas should be covered. Doors should be locked to prevent accidental entry into the room during laser procedures. Warning signs should be posted, and devices can be installed to automatically turn off the laser when the doors open. Prevention of Fires In the tracheobronchial tree, the same anesthetic precautions as described with the CO 2 should be used. The use of a flexible bronchoscope adds a risk for fire if the tip becomes coated with black debris, as the bronchoscope tip can beome heated and the surface of the bronchoscope may flame. 6, 21, 27, 29 If present within the gastrointestinal tract, methane gas may undergo combustion. Therefore, CO 2 installation is mandatory for visualization as well as prevention of combustion. Safe Anesthesia The precautions described in the section on CO2 lasers apply here, too; also that nitrous oxide should not be used because it can accumulate in the gastrointestinal tract. It is unfortunate that the safety glasses used for the Nd:YAG laser inhibit the anesthesiologist's ability to monitor the patient, in that it is difficult to evaluate the patient's color. Moreso than with a CO 2 laser, we urge the use of constant oxygen monitoring with transcutaneous oximetry and arterial blood gases to assess the patient's status." 11 Laser Fire Management If a fire occurs within the tracheobronchial tree when using an Nd:YAG laser, the same guidelines used with the CO 2 laser should be followed. If a fire occurs within the abdomen it would be unlikely that the patient would survive, as the fire would probably be associated with an explosion.
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Tracheobronchial Tree The use of a rigid bronchoscope is recommended, as it allows the safest management of the airway and provides suction channels that allow for better control of smoke, bleeding, or both. When using the Nd:YAG laser, the incident beam should be parallel to the wall of the trachea or bronchus. The distance from the area being lased is critical in terms of beam penetration; 30 to 50 W with 0.5-second bursts are the safest. Care must be taken to lase in the same phase of the respiratory cycle to prevent unwanted depth or ineffectual lasing. 5, 6, 18 When using a flexible bronchoscope, a 2.6-mm suction channel should be used, which will allow passage of the laser cable as well as provide suction. Lasing in the Esophagus Lasing in the esophagus can be performed with either a rigid or a flexible esophagoscope. Most flexible esophagoscopes have black tips. These tips should be replaced with metal or whitened to prevent heating or combustion of the tip of the endoscope. The same technique as used in the lungs should be used in the esophagus. The operator should always, lase parallel to the wall of the esophagus in the direction of the distal lumen; when a lumen cannot be observed, lasing is not recommended. 5 Lasing in the Gastrointestinal Tract
A CO 2 jet is mandatory when using the Nd:YAG laser in the gastrointestinal tract, as it keeps the field dry and provides a noncombustible environment. Be aware that the CO 2 jet can cause accumulation of gas in the distal GI tract. Abdominal distension should be monitored during these procedures. Margins around bleeding areas should be lased to constrict the blood supply, rather than lasing the center of an ulcer. Repeat lasings have a higher incidence of complications associated with them." Lasing Pigmented Lesions A test area should be lased and observed for up to 6 months before definitive therapy is considered. 4, 5
SAFETY AND THE ARGON LASER The argon laser requires colored eye protection in the orange/yellow range. The anesthesiologist must be aware that this can affect the ability to monitor the patient. The argon laser, like the Nd:YAG laser, is differentially absorbed by darker pigments and blood. It does not have as much forward and/or back scatter as the Nd:YAG laser. A CO 2 jet must be present when the argon laser is used for bleeding disorders. The argon laser is probably the laser of choice for the treatment of pigmented lesions on the skin. Test areas should be treated and observed for up to 6 months prior to definitive therapy. Grid patterns and/or the use
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of the argon under ice water prevents unnecessary superficial burning. The lasing under ice water also prevent unwanted heat transfer to normal tissue. Here as well, the laser room should have limited access.": 5
REFERENCES 1. Andrews, A. H., Jr., and Horowitz, S. L.: Bronchoscopic CO 2 laser surgery. Lasers Surg. Med., 1:35-45, 1980. 2. Andrews, A. H., Jr., Polanyi, T., and Grybauskas, V. T.: General techniques and clinical considerations in laryngologic laser surgery. Otolaryngol. Clin. North Am. , 16(4):793-800, 1983. 3. Davis, R. K., and Simpson, G. T., II: Safety with the carbon dioxide laser. Otolaryngol. Clin. North Am., 16(4):801-814, 1983. 4. DiBartolomeo, J. R.: The argon and CO 2 lasers in otolaryngology: Which one, when and why? Laryngoscope, 51(9):1-16, 1981. 5. Dixon, J. A. (ed.): Surgical Applications of Lasers. Chicago, Year Book Medical Publishers, 1983. 6. Dumon, J.-F., Meric, B., Velardocchio, J.-M., et al.: Yag laser resection of tracheo bronchial lesions. Thorac. Cardiovasc. Surg., 14:28-31, 1982. 7. Gillis, T. M., and Strong, M. S.: Surgical lasers and soft tissue interactions. Otolaryngol. Clin. North Am., 16(4):778-784, 1983. 8. Healy, G. B.: Complications of laser surgery. Otolaryngol. Clin. North Am., 16(4):815-820, 1983. 9. Healy, G. B., McGill, T., and Strong, M. S.: Surgical advances in the treatment of lesions of the pediatric airway: The role of the carbon dioxide laser. Pediatrics, 61:380-383, 1978. 10. Healy, G. B., Strong, M. S., Shapshay, S., et al.: Complications of carbon dioxide laser surgery of the aerodigestive tract: Experience in 4,400 cases. Otolaryngol. Head Neck Surg., (in press). 11. Hermens, J. M., Bennett, M. J., and Hirshman, C. A.: Anesthesia for laser surgery. Anesth. Analg., 62:218-229, 1983. 12. Kaeder, C. S., and Hirshman, C. A.: Acute airway obstruction: A complication of aluminum tape wrapping of tracheal tubes in laser surgery. Can. Anaesth. Soc. J., 26(2):138-139, 1979. 13. Lejeune, F. E., Jr., and LeTard, F., et al.: Heat sink protection against lasering endotracheal cuffs. Ann. Otol. Rhinol. Laryngol., 91:606-607, 1982. 14. Mayer, T., and Matlak, M. E., et al.: Experimental subglottic stenosis: Histopathologic and bronchoscopic comparison and electrosurgical, cryosurgical, and laser resection. J. Pediatr. Surg., 16(8):944-952, 1980. 15. Meyers, A. D., and Kuzela, D. C.: Dose-response characteristics of the human larynx with carbon dioxide laser radiation. Am. J. Otolaryngol., 1(2):13&-140, 1980. 16. Ossoff, R. H., Eisenman, T. S., et al.: Comparison of tracheal damage from laser-ignited endotracheal tube fires. Ann. Otol. Rhinol., Laryngol., 92(4):~36, 1983. 17. Patel, K. F., and Hicks, J. N.: Prevention of fire hazards associated with use of carbon dioxide lasers. Anesth. Analg., 60(12):885-888, 1981. 18. Polanyi, T. G.: Laser physics. Otolaryngol. Clin. North Am., 16(4):753-754, 1983. 19. Rogers, P., and Schellhar, H. F.: Laser Safety in Surgery and Medicine. Vols. V and VI. Cincinnati, Rockwell Associates, 1983. 20. Ruder, C. B., Rapheal, N. L., et al.: Anesthesia for carbon dioxide laser microsurgery of the larynx. Otolaryngol. Head Neck Surg., 89:732-737, 1981. 21. Ryuichi, Y., Amemiya, R., et al.: Indications and complications of Nd-Yag laser surgery via the fiberoptic bronchoscope in cases involving the trachea and major bronchi. Head Neck Surg. Otorhinolaryngol. (Tokyo), 887-910, 1981. 22. Schramm, V. L., Jr., Mattox, D. E., and Stool, S. E.: Acute management of laser-ignited intratracheal explosion. Laryngoscope, 91:1417-1426, 1981. 23. Schwartz, D.: Expert legal comments on 13 clinical laser dilemmas. Clin. Laser Monthly, 1983.
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24. Shapshay, S. M., Strong, M. S., et al.: Removal of rhinophyma with the carbon dioxide laser. Arch. OtolaryngoI., 106:257-259, 1980. 25. Stellar, S., Polany, T. G., and Bredemeier, H. C.: Experimental studies with the carbon dioxide laser as a neurosurgical instrument. Med. Biol, Eng. Comput., 8:549-557, 1970. 26. Strong, M. S., Vaughan, C. W., et al.: Transoral resection of cancer of the oral cavity: The role of the CO 2 laser. Symposium on Malignant Disease of the Oral Cavity and Related Structures. Otocigna, 12(1):207-218, 1979. 27. Tamada, J., Ito, M., and Teramatsu, T.: Clinical study ofbronchofiberscopic Nd-Yag laser surgery. Thorac. Surg., 14:13-15, 1982. 28. Tomita, Y., Mihashi, S., Nagata, K., et al.: Mutagenicity of smoke condensates induced by CO 2 laser irradiation and electrocauterization. Mutat. Res., 89(2):14~149, 1981. 29. Wilpizeski, C., Maioriello, R. P., et al.: Otological applications of lasers: Basic background. Annual Meeting of the Pennsylvania Academy of Ophthalmology and Otolaryngology, Bedford, Pennsylvania, May 19, 1977. (Dr. Mohr) Department of Otorhinolaryngology and Bronchoesophagology Temple University Health Sciences Center 3400 North Broad Street Philadelphia, Pennsylvania 19140
Safety Considerations and Safety Protocol for Laser Surgery
Rose M. Mohr, M.D.,* Bernard C. McDonnell, D.O.,t Michael Unger, M.D.,:I: and Theodore P. Mauer, D.O.§
Laser safety depends on precise knowledge of the physics of each laser and tissue effects in a constantly changing environment. The minimum requirement for certification in laser usage at any hospital should include a "hands-on" course that includes basics in laser physics and usage of the laser in an animal laboratory. This usually means at least 5 hours of didactics and 5 hours of laboratory and observation of a few clinical cases performed by a trained physician. It is best to precept for some time, as understanding and using lasers depend on the amount of usage and quality of supervision. 19 In this article focusing on laser safety, the most common lasers used in surgery and medicine are used to illustrate safety principles: the CO 2 , Nd:YAG, and argon lasers.
PROTOCOL FOR LASER USERS AND INFORMED CONSENT General Guidelines Laser safety begins with multiple in-services, both for the user and the assistants. Resident physicians should be required to complete a course just as their teachers and/or precept and show knowledge of laser use to be *Associate Professor of Otorhinolaryngology and Bronchoesophagology, and Director, Chevalier Jackson Center, Temple University Health Sciences Center, Philadelphia, Pennsylvania tVice-Chairman, Otorhinolaryngology, Suburban General Hospital, Norristown, and Clinical Instructor of Otorhinolaryngology, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania :l:Associate Chief, Pulmonary Section, Presbyterian-University of Pennsylvania Medical Center, and Clinical Assistant Professor of Medicine, University of Pennsylvania School of Medicine, Philadelphia; and Co-Director, Institute for Applied Laser Surgery, Bala Cynwyd, Pennsylvania § Professor and Chairman, Otorhinolaryngology, Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania
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safe assistants. Laser use by a resident should always be supervised through direct observation. Teaching attachments (such as observer tubes) are requisite. 19 Laser Operator Only extremely well instructed personnel should manage the controls of the laser. Some 80-W CO 2 lasers have more than one scale. No one should operate the CO 2 laser if the scale usage on the laser is not understood. The surgeon using the instrument is the individual who must test the instrument prior to its application to a patient. The setting used should be set by the surgeon and double-checked prior to the first lasing. Most Nd:YAG lasers must be calibrated before each use.!" It is recommended that lasers be used in areas in which a distinct advantage has been shown to exist for the treatment of a patient's condition. When the use of the laser offers no advantage over routine techniques, the laser should not and/or does not have to be utilized. When scheduling, patients should be told that either routine methods or laser methods would be used, depending on findings at the time of the procedure. If the laser is a requisite for the performance of a particular procedure or the patient wants only laser treatment then the patient should be cancelled if the laser is out of order. 23 Special permits are required for the use of the Nd:YAG laser; special permits are not currently required for use of the CO 2 laser. Informed consent is required for both, however, and a careful explanation of the reason for usage and any additional hazards that might be added because of the use of the laser should be carefully explained to the patient and documented on the chart. 19, 23 Laser maintenance should be recorded. If a laser fire and/or any other complication occurs, proper repair records are essential. 19 A laser safety comittee should be established and a laser safety officer appointed. Laser accreditation and quality control groups must be organized. 19
SAFETY AND THE CO 2 LASER CO 2 laser safety measures are the most elaborate because the laser is used in open-field surgery, as well as in the upper respiratory tract, with the route of administration of anesthesia In the field. Combustible gas mixtures and endotracheal tubes must be avoided. The CO 2 laser is absorbed by most surfaces but reflected by shiny ones; it is almost completely absorbed by water. Eye Protection All personnel should wear glass, transparent plastic, or quartz glasses with side protectors when working in a CO 2 laser (10,600 nm) environment. Regular glasses and/or contact lenses protect only the area covered by the lens. The patient, should also have protective eyewear if the laser is tested during the preinduction phase. The operator behind a binocular microscope need not wear protective eyewear. The aiming light on the CO 2 laser allows determination of the direction
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of the laser beam. A helium-neon laser (630 nm) is the most frequently used aiming guide and can cause photochemical effects in the eye and skin. When a CO 2 laser is in use for any purpose, the doors to the room should be locked. Laser caution signs should be posted, and only personnel familiar with laser safety or usage should be allowed into the treatment area. 19 Prevention of Fires If the treatment area is within the patient's airway, or the endotracheal tube will in any way be exposed or could potentially be exposed to the laser beam, the anesthesiologist is required to take specific precautions to prevent a fire. An endotracheal tube, preferably a red rubber Rusch tube or a Silastic reinforced endotracheal tube that is wrapped with overlapped (V3 to V2 in.) aluminum tape must be used for intubation. The tube can be cleaned with acetone, and benzoin applied before wrapping to prevent dislodging of the tape. Both the surgeon and anesthesiologist should check the tube before use." 10 The tube wrap can cause tube kinking and become a foreign body if dislodged. The cuff should be inflated with sterile saline and be protected with wet neurosurgical cottonoids. The cottonoid strings should also be wet or replaced with wire. If the cuff is perforated with saline in it, it acts as a heat sink and prevents combustion;" If methylene blue is added to the cuff solution, it will stain the cottonoids, thus allowing earlier recognition of cuff perforation. The use of a polyvinyl chloride (PVC) endotracheal tube is not recommended. Fire-breakdown products and tissue destruction associated with combustion of this tube are quite severe. Breakdown products from the red rubber tube are intermediate between those of PVC and Silastic. The Silastic tube, if it does combust, forms silica ash. The tissue effects from the silicone tube are minimal, but the effects of silica ash are unknown. 16, 22 There has been no laser fire associated with the combustion of a Silastic tube. Continuous lasing for several seconds without protection on the Silastic tube finally perforates the tube, and if an oxygen-rich environment is within the tube, it will combust and form silica ash. The level of combustion for a PVC tube is somewhere around 149°F; for a Silastic tube, 700°F; and for a red rubber tube, somewhere inbetween. 3, 5, 9, 16, 22 Tubes with "laser guard and/or nonreinforced Silastic tubes should be used with caution as they have not had much clinical usage. Silastic tubes without reinforcement are extremely soft, and when inflating the cuff with saline, the lumen of the endotracheal tube can be reduced. Metal Norton endotracheal tubes are available; however, they " have a small inner diameter and no cuff. The anesthetic mixture should be carefully controlled. Oxygen percentage should remain below 40 per cent. Nitrous oxide is contraindicated, as it is combustible. Combining nitrogen, oxygen, and compressed air with an inhalation agent or using neuroleptic agents and monitoring the oxygen input continuously during the procedure is the safest method. Blenders incorporated within anesthesis machines are available to control the percentage of oxygen intake. Continuous oxygen-monitoring during the proH
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cedure with ear oximetry or percutaneous oximeters in addition to arterial blood gases is recommended. Other Necessary Precautions Wet towels should be placed around any surgical field associated wih a CO 2 laser. Paper drapes do not wet and can be ignited with a stray laser beam. 26 Blackened Instruments. The use of blackened instruments or glassbead-dusted instruments is recommended to prevent full reflection of the laser beam, should it accidentally strike the instruments. Blackened laser platforms below the area being lased prevent accidental lasing of normal tissue. Lubricants. During the intubation, the use of any oil-containing compound should be avoided. Oil-base anesthetic lubricants on endotracheal tube tips may be combustible. Noncombustible lubricants should also be avoided. Water-soluble lubricants may be used to coat the structures the surgeon wishes to lase. The CO 2 laser is almost entirely absorbed by water and water-soluble compounds. The effectiveness of the surgery might be altered. Instrument Off. The laser should always be on stand-by or off when lasing is not in progress. The operator's foot should be off the foot pedal when the laser is not in use, to prevent accidental discharge. Smoke Clearance. Constant suctioning should be used to remove the smoke from the environment so that it is not inhaled by the patient and/or operating room personnel. The smoke is probably mutagenic and/or carcinogenic.:" Smoke particles heat suction lines and can cause costly repairs; filters in suction lines are mandatory. Smoke impairs the vision of the surgeon and is potentially composed of flammable particles; it can reflect the laser beam. Safest Anesthesia Methods. The use of Venturi or rapid ventilation techniques during laser surgery works for selected patients. We helieve that the safest method is a wrapped, noncollapsible endotracheal tube with routine ventilation methods with control of the oxygen environment. The patients should be instructed to breathe on their own when the tracheobronchial tree is to be lased with a local stand-by technique that monitors the oxygen-nitrogen inhalation concentrations being administered through a ventilating rigid bronchoscope. Laryngeal surgery requires complete relaxation for precise work. 1, 3, 5, 11, 20 User Knowledge ofTissue Effects. Safety of surgical procedures utilizing the laser depends on the user's knowledge of the effects on the tissue. The laser is safe when used in short spurts; the surgeon should use the highest power and the lowest time setting that is comfortable. Continuous lasing should be avoided, and rest periods should be used; skip areas should be left. 2 , 14, 15, Intermittent iced saline irrigation should be used to prevent heat transfer to surrounding tissues. Drapes and cottonoids should be periodically rewet.P Constantly Changing Effects. The laser user has to be aware that tissue effects change as the distance of the lesion changes in relation to the laser beam. 24 When lasing in the lung, the operator should preferably lase during
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the same phase of respiration throughout the entire procedure. 1, 6,7 It is always wise to lase along the margins of the tracheobronchial tree with the incident beam parallel to the wall; this prevents accidental deep penetration. Do not lase spurs, as they often harbor vessels underneath. Only luminal extensions of tumors or scars should be lased in the tracheobronchial tree. 1, 3, 6 Control of Bleeding. The CO 2 laser is predominantly a vaporizer, not a coagulator. Bleeding is best controlled when defocused. It may be necessary to switch to another laser, such as a Nd:YAG or argon laser to better coagulate the bleeding tissue. At present, the CO 2 laser is not transmittable through flexible cables, and thus rigid bronchoscopy is mandatory for its use. The requisite for rigid bronchoscopy affords better suction capabilities and better control of bleeding and tumor removal. 1, 3, ,5, 6 CO2 Laser Fire Management Fires can occur with rigid bronchoscopes because added cuffs or endotracheal tubes used along side are ignited by flaming tissue; the flame is perpetuated by an oxygen-enriched environment.P" Such fires should not occur to either the experienced laser operator or anesthesiologist. Everyone in the room must be oriented toward laser knowledge and safety; a laser fire is inexcusable. 22 If a laser fire should occur, the oxygen must be turned off within 1 second, as the patient is extubated to get rid of the flame and/or offending burning endotracheal tube or hot bronchoscope. 22 The patient should then be bagged with oxygen and reendoscoped to assess the damage and then reintubated. Any debris in the larynx and tracheobronchial tree should be removed and the area irrigated. If severe damage occurs, it is usually at the tip where the airway was lying. In this case, a tracheotomy might have to be performed below the injury. Ventilatory support is then most likely necessary for a period of time. Stenosis and permanent tracheobronchial damage can occur if the fire is allowed to smolder. Antibiotics should be given, along with steroids. 22 Special Precautions Outside the Airway CO 2 laser usage anywhere in the body requires the use of the same basic principles as those described for use in the tracheobronchial tree, although they are not quite as elaborate. If the airway is not in the field, the operator should protect areas from damage with water, and from materials such as moistened neurosurgical cottonoids, wet lap pads, or vaginal gauze. Paper drapes should be protected or not used. Smoke control and suction filters are more important with nonairway procedures because of the increased volume of smoke. When the CO 2 laser is used in the colon or in the area of any other flammable gas, a noncombustible gas (most likely CO 2) must be insufflated into the environment to prevent an explosion. Meticulous care of the CO 2 laser system and avoidance of disruption of the mirror system is essential in safety for all personnel. If mirror alignment is disrupted, the aiming and precision of the laser are impaired. 23
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SAFETY AND THE Nd:YAG LASER The Nd:YAG laser is more difficult to learn to use because of its .differential absorption characteristics and forward and backward scatter. This laser has multidisciplinary use, although it is currently approved for clinical usage only in gastrointestinal bleeding, esophageal tumors, and the tracheobronchial tree. All other uses are considered investigational. This laser offers coagulation capabilities and can be used through a flexible fiberoptic system. Eye Protection All personnel should have protective glasses in the blue/green spectrum (ANSI Standard 2136.1), which protects the entire globe. Special filters can be obtained for flexible endoscopes that will prevent the operator from eye damage. If the special filter is not utilized in the endoscope, the operator must wear the protective eye equipment described above. 23 Limited Access Windows in doors and/or scrub areas should be covered. Doors should be locked to prevent accidental entry into the room during laser procedures. Warning signs should be posted, and devices can be installed to automatically turn off the laser when the doors open. Prevention of Fires In the tracheobronchial tree, the same anesthetic precautions as described with the CO 2 should be used. The use of a flexible bronchoscope adds a risk for fire if the tip becomes coated with black debris, as the bronchoscope tip can beome heated and the surface of the bronchoscope may flame. 6, 21, 27, 29 If present within the gastrointestinal tract, methane gas may undergo combustion. Therefore, CO 2 installation is mandatory for visualization as well as prevention of combustion. Safe Anesthesia The precautions described in the section on CO2 lasers apply here, too; also that nitrous oxide should not be used because it can accumulate in the gastrointestinal tract. It is unfortunate that the safety glasses used for the Nd:YAG laser inhibit the anesthesiologist's ability to monitor the patient, in that it is difficult to evaluate the patient's color. Moreso than with a CO 2 laser, we urge the use of constant oxygen monitoring with transcutaneous oximetry and arterial blood gases to assess the patient's status." 11 Laser Fire Management If a fire occurs within the tracheobronchial tree when using an Nd:YAG laser, the same guidelines used with the CO 2 laser should be followed. If a fire occurs within the abdomen it would be unlikely that the patient would survive, as the fire would probably be associated with an explosion.
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Tracheobronchial Tree The use of a rigid bronchoscope is recommended, as it allows the safest management of the airway and provides suction channels that allow for better control of smoke, bleeding, or both. When using the Nd:YAG laser, the incident beam should be parallel to the wall of the trachea or bronchus. The distance from the area being lased is critical in terms of beam penetration; 30 to 50 W with 0.5-second bursts are the safest. Care must be taken to lase in the same phase of the respiratory cycle to prevent unwanted depth or ineffectual lasing. 5, 6, 18 When using a flexible bronchoscope, a 2.6-mm suction channel should be used, which will allow passage of the laser cable as well as provide suction. Lasing in the Esophagus Lasing in the esophagus can be performed with either a rigid or a flexible esophagoscope. Most flexible esophagoscopes have black tips. These tips should be replaced with metal or whitened to prevent heating or combustion of the tip of the endoscope. The same technique as used in the lungs should be used in the esophagus. The operator should always, lase parallel to the wall of the esophagus in the direction of the distal lumen; when a lumen cannot be observed, lasing is not recommended. 5 Lasing in the Gastrointestinal Tract
A CO 2 jet is mandatory when using the Nd:YAG laser in the gastrointestinal tract, as it keeps the field dry and provides a noncombustible environment. Be aware that the CO 2 jet can cause accumulation of gas in the distal GI tract. Abdominal distension should be monitored during these procedures. Margins around bleeding areas should be lased to constrict the blood supply, rather than lasing the center of an ulcer. Repeat lasings have a higher incidence of complications associated with them." Lasing Pigmented Lesions A test area should be lased and observed for up to 6 months before definitive therapy is considered. 4, 5
SAFETY AND THE ARGON LASER The argon laser requires colored eye protection in the orange/yellow range. The anesthesiologist must be aware that this can affect the ability to monitor the patient. The argon laser, like the Nd:YAG laser, is differentially absorbed by darker pigments and blood. It does not have as much forward and/or back scatter as the Nd:YAG laser. A CO 2 jet must be present when the argon laser is used for bleeding disorders. The argon laser is probably the laser of choice for the treatment of pigmented lesions on the skin. Test areas should be treated and observed for up to 6 months prior to definitive therapy. Grid patterns and/or the use
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of the argon under ice water prevents unnecessary superficial burning. The lasing under ice water also prevent unwanted heat transfer to normal tissue. Here as well, the laser room should have limited access.": 5
REFERENCES 1. Andrews, A. H., Jr., and Horowitz, S. L.: Bronchoscopic CO 2 laser surgery. Lasers Surg. Med., 1:35-45, 1980. 2. Andrews, A. H., Jr., Polanyi, T., and Grybauskas, V. T.: General techniques and clinical considerations in laryngologic laser surgery. Otolaryngol. Clin. North Am. , 16(4):793-800, 1983. 3. Davis, R. K., and Simpson, G. T., II: Safety with the carbon dioxide laser. Otolaryngol. Clin. North Am., 16(4):801-814, 1983. 4. DiBartolomeo, J. R.: The argon and CO 2 lasers in otolaryngology: Which one, when and why? Laryngoscope, 51(9):1-16, 1981. 5. Dixon, J. A. (ed.): Surgical Applications of Lasers. Chicago, Year Book Medical Publishers, 1983. 6. Dumon, J.-F., Meric, B., Velardocchio, J.-M., et al.: Yag laser resection of tracheo bronchial lesions. Thorac. Cardiovasc. Surg., 14:28-31, 1982. 7. Gillis, T. M., and Strong, M. S.: Surgical lasers and soft tissue interactions. Otolaryngol. Clin. North Am., 16(4):778-784, 1983. 8. Healy, G. B.: Complications of laser surgery. Otolaryngol. Clin. North Am., 16(4):815-820, 1983. 9. Healy, G. B., McGill, T., and Strong, M. S.: Surgical advances in the treatment of lesions of the pediatric airway: The role of the carbon dioxide laser. Pediatrics, 61:380-383, 1978. 10. Healy, G. B., Strong, M. S., Shapshay, S., et al.: Complications of carbon dioxide laser surgery of the aerodigestive tract: Experience in 4,400 cases. Otolaryngol. Head Neck Surg., (in press). 11. Hermens, J. M., Bennett, M. J., and Hirshman, C. A.: Anesthesia for laser surgery. Anesth. Analg., 62:218-229, 1983. 12. Kaeder, C. S., and Hirshman, C. A.: Acute airway obstruction: A complication of aluminum tape wrapping of tracheal tubes in laser surgery. Can. Anaesth. Soc. J., 26(2):138-139, 1979. 13. Lejeune, F. E., Jr., and LeTard, F., et al.: Heat sink protection against lasering endotracheal cuffs. Ann. Otol. Rhinol. Laryngol., 91:606-607, 1982. 14. Mayer, T., and Matlak, M. E., et al.: Experimental subglottic stenosis: Histopathologic and bronchoscopic comparison and electrosurgical, cryosurgical, and laser resection. J. Pediatr. Surg., 16(8):944-952, 1980. 15. Meyers, A. D., and Kuzela, D. C.: Dose-response characteristics of the human larynx with carbon dioxide laser radiation. Am. J. Otolaryngol., 1(2):13&-140, 1980. 16. Ossoff, R. H., Eisenman, T. S., et al.: Comparison of tracheal damage from laser-ignited endotracheal tube fires. Ann. Otol. Rhinol., Laryngol., 92(4):~36, 1983. 17. Patel, K. F., and Hicks, J. N.: Prevention of fire hazards associated with use of carbon dioxide lasers. Anesth. Analg., 60(12):885-888, 1981. 18. Polanyi, T. G.: Laser physics. Otolaryngol. Clin. North Am., 16(4):753-754, 1983. 19. Rogers, P., and Schellhar, H. F.: Laser Safety in Surgery and Medicine. Vols. V and VI. Cincinnati, Rockwell Associates, 1983. 20. Ruder, C. B., Rapheal, N. L., et al.: Anesthesia for carbon dioxide laser microsurgery of the larynx. Otolaryngol. Head Neck Surg., 89:732-737, 1981. 21. Ryuichi, Y., Amemiya, R., et al.: Indications and complications of Nd-Yag laser surgery via the fiberoptic bronchoscope in cases involving the trachea and major bronchi. Head Neck Surg. Otorhinolaryngol. (Tokyo), 887-910, 1981. 22. Schramm, V. L., Jr., Mattox, D. E., and Stool, S. E.: Acute management of laser-ignited intratracheal explosion. Laryngoscope, 91:1417-1426, 1981. 23. Schwartz, D.: Expert legal comments on 13 clinical laser dilemmas. Clin. Laser Monthly, 1983.
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24. Shapshay, S. M., Strong, M. S., et al.: Removal of rhinophyma with the carbon dioxide laser. Arch. OtolaryngoI., 106:257-259, 1980. 25. Stellar, S., Polany, T. G., and Bredemeier, H. C.: Experimental studies with the carbon dioxide laser as a neurosurgical instrument. Med. Biol, Eng. Comput., 8:549-557, 1970. 26. Strong, M. S., Vaughan, C. W., et al.: Transoral resection of cancer of the oral cavity: The role of the CO 2 laser. Symposium on Malignant Disease of the Oral Cavity and Related Structures. Otocigna, 12(1):207-218, 1979. 27. Tamada, J., Ito, M., and Teramatsu, T.: Clinical study ofbronchofiberscopic Nd-Yag laser surgery. Thorac. Surg., 14:13-15, 1982. 28. Tomita, Y., Mihashi, S., Nagata, K., et al.: Mutagenicity of smoke condensates induced by CO 2 laser irradiation and electrocauterization. Mutat. Res., 89(2):14~149, 1981. 29. Wilpizeski, C., Maioriello, R. P., et al.: Otological applications of lasers: Basic background. Annual Meeting of the Pennsylvania Academy of Ophthalmology and Otolaryngology, Bedford, Pennsylvania, May 19, 1977. (Dr. Mohr) Department of Otorhinolaryngology and Bronchoesophagology Temple University Health Sciences Center 3400 North Broad Street Philadelphia, Pennsylvania 19140