Editorial On the Development of a New Laser-Resistant Endotracheal Tube Mitchel B. Sosis, MD, PhD* Department of Anesthesiology, Chicago, IL.
Rush-Presbyterian-St.
Luke’s Medical Center,
Catastrophic endotracheal tube fires continue to be a serious hazard of laser airway surgery. prevention of these fires requires modified equipment and of the Xomed Laser-Shield II enanesthetic techniques. 1 The introduction
*Assistant Professor Address reprint requests to Dr. Sosis at the Department of Anesthesiology, Rush-Presbyterian-St. Luke’s Medical Center, 1653 W. Congress Pkwy., Chicago, IL 60612, USA. Received for publication December 2, 1991; revised manuscript accepted for publication December 3, 1991. 0 1992 Butterworth-Heinemann
J. Clin. Anesth. 4:87-W,
1992.
dotracheal tube (Xomed-Treace, Jacksonville, FL), coupled with the discontinuation of its predecessor, the original Xomed Laser-Shield endotracheal tube, is an important development in the quest for a safe endotracheal tube for laser airway surgery. The first Laser-Shield endotracheal tube was constructed from silicone with embedded metallic particles. The metallic particles were thought to provide protection comparable to foil wrapping, while affording a thin, smooth shaft. However, this endotracheal tube had a tendency to absorb much of the laser’s energy.* The resulting high temperature could ignite the metallic particles and lead to a blowtorch Iire that was difficult to extinguish. Its use resulted in severe patient injuries.3 The Xomed Laser-Shield II endotracheal tube retains the basic silicone design of the earlier model. Instead of having embedded metallic particles, however, its shaft is wrapped with aluminum foil, which is overwrapped with Teflon. As reported in this issue of the Journal of Clinical Anesthesia by Green et a1.,4 this technique affords good protection of the wrapped portion of the endotracheal tube’s shaft from the carbon dioxide (CO,) laser under the conditions of their experiments. Green’s group4 noted the same tendency of the unwrapped portions of the Xomed Laser-Shield II tube to disintegrate when ignited by the CO, laser as was seen with the earlier Xomed tube.5 This tendency is not shared to the same degree by either rubber or polyvinylchloride (PVC) endotracheal tubes. Also of note is the finding that PVC cannot be ignited in air, whereas silicone can be.6 These considerations raise the question of whether silicone is an appropriate material for the new endotracheal tube. Green et aL4 correctly raise the question of whether laser-induced pyrolysis of the Teflon overwrap on the Xomed Laser-Shield II might contribute to polymer fume fever in the patient or operating room (OR) personnel. This question calls for animal studies to determine the risks involved. Our group has advocated the use of metallic foil taping to protect the shafts of combustible endotracheal tubes from laser impact.’ The development of a commercially available foil-wrapped endotracheal tube would be welcome. However, the choice of silicone for the Xomed Laser-Shield II and the questions raised by the use of Teflon are troubling. We feel that the careful foil wrapping of PVC or rubber endotracheal tubes with the appropriate tape7 still represents a good technique for laser airway surgery. Whichever technique of endotracheal anesthesia is used for laser airway surgery, it is important that nitrous oxide be avoided during these cases, since J. Clin. Anesth.,
vol. 4, March/April
1992
87
Editorial
its exothermic decomposition supports combustion as readily as oxygen (0,). The fraction of 0, administered to the patient should be the minimum that will result in a satisfactory arterial oxyhemoglobin saturation. Protection of the endotracheal tube cuff can be afforded by filling it with saline* to which a dye such as methylene blue has been added and by packing it off with wet pledgets. The pledgets must be kept moist and carefully retrieved after surgery. The entire OR team should be well rehearsed in a protocol1 to follow if an airway fire occurs, since a completely safe anesthetic technique has not yet been achieved. The protocol includes the termination of all anesthetic gases, including 0,; the removal of the endotracheal tube; and the dousing of any flames with saline. The patient’s lungs are then ventilated by mask, and the airway is examined for burns.
References 1. Sosis MB: Anesthesia for laser surgery. Int Anesthesiol Clin 1990;28: 119-3 I. 2. Ossoff RA: Laser safety in otolaryngology-head and neck surgery: anesthetic and educational considerations for laryngeal surgery. Lqngoscope 1989;99(Suppl 48): l-26. 3. Sosis MB: Airway fire during CO, laser surgery using a Xomed laser endotracheal tube. Anesthesiology 1990;‘72:747-9. 4. Green JM, Gonzalez RM, Sonbolian N, Rehkopf P: The resistance to carbon dioxide laser ignition of a new endotracheaf tube: Xomed Laser-Shield II. J Clin An&h 1992;4: 89-92. 5. Sosis MB: Which is the safest endotracheal
tube for COP? A comparative
study. J Clzn
Anesth (in press, 1992). 6. Wolf CL, Simpson JI: Flammability of endotracheal tubes in oxygen and nitrous oxide enriched atmosphere. Anesthesiology 1987;67:236-9. 7. sosis MB: Evaluation of five metallic tapes for protection of endotracheal tubes during CO, laser surgery. An&h Analg 1989;68:392-3. 8. sosis MB, Dillon FX: Saline filled cuffs help prevent laser-induced polyvinyfchloride endotracheal tube fires. An&h An&g 1991;72:187-9.
88
J. Clin. Anesth.,
vol. 4, March/April
1992
Rush-Presbyterian-St.
Luke’s Medical Center,
Catastrophic endotracheal tube fires continue to be a serious hazard of laser airway surgery. prevention of these fires requires modified equipment and of the Xomed Laser-Shield II enanesthetic techniques. 1 The introduction
*Assistant Professor Address reprint requests to Dr. Sosis at the Department of Anesthesiology, Rush-Presbyterian-St. Luke’s Medical Center, 1653 W. Congress Pkwy., Chicago, IL 60612, USA. Received for publication December 2, 1991; revised manuscript accepted for publication December 3, 1991. 0 1992 Butterworth-Heinemann
J. Clin. Anesth. 4:87-W,
1992.
dotracheal tube (Xomed-Treace, Jacksonville, FL), coupled with the discontinuation of its predecessor, the original Xomed Laser-Shield endotracheal tube, is an important development in the quest for a safe endotracheal tube for laser airway surgery. The first Laser-Shield endotracheal tube was constructed from silicone with embedded metallic particles. The metallic particles were thought to provide protection comparable to foil wrapping, while affording a thin, smooth shaft. However, this endotracheal tube had a tendency to absorb much of the laser’s energy.* The resulting high temperature could ignite the metallic particles and lead to a blowtorch Iire that was difficult to extinguish. Its use resulted in severe patient injuries.3 The Xomed Laser-Shield II endotracheal tube retains the basic silicone design of the earlier model. Instead of having embedded metallic particles, however, its shaft is wrapped with aluminum foil, which is overwrapped with Teflon. As reported in this issue of the Journal of Clinical Anesthesia by Green et a1.,4 this technique affords good protection of the wrapped portion of the endotracheal tube’s shaft from the carbon dioxide (CO,) laser under the conditions of their experiments. Green’s group4 noted the same tendency of the unwrapped portions of the Xomed Laser-Shield II tube to disintegrate when ignited by the CO, laser as was seen with the earlier Xomed tube.5 This tendency is not shared to the same degree by either rubber or polyvinylchloride (PVC) endotracheal tubes. Also of note is the finding that PVC cannot be ignited in air, whereas silicone can be.6 These considerations raise the question of whether silicone is an appropriate material for the new endotracheal tube. Green et aL4 correctly raise the question of whether laser-induced pyrolysis of the Teflon overwrap on the Xomed Laser-Shield II might contribute to polymer fume fever in the patient or operating room (OR) personnel. This question calls for animal studies to determine the risks involved. Our group has advocated the use of metallic foil taping to protect the shafts of combustible endotracheal tubes from laser impact.’ The development of a commercially available foil-wrapped endotracheal tube would be welcome. However, the choice of silicone for the Xomed Laser-Shield II and the questions raised by the use of Teflon are troubling. We feel that the careful foil wrapping of PVC or rubber endotracheal tubes with the appropriate tape7 still represents a good technique for laser airway surgery. Whichever technique of endotracheal anesthesia is used for laser airway surgery, it is important that nitrous oxide be avoided during these cases, since J. Clin. Anesth.,
vol. 4, March/April
1992
87
Editorial
its exothermic decomposition supports combustion as readily as oxygen (0,). The fraction of 0, administered to the patient should be the minimum that will result in a satisfactory arterial oxyhemoglobin saturation. Protection of the endotracheal tube cuff can be afforded by filling it with saline* to which a dye such as methylene blue has been added and by packing it off with wet pledgets. The pledgets must be kept moist and carefully retrieved after surgery. The entire OR team should be well rehearsed in a protocol1 to follow if an airway fire occurs, since a completely safe anesthetic technique has not yet been achieved. The protocol includes the termination of all anesthetic gases, including 0,; the removal of the endotracheal tube; and the dousing of any flames with saline. The patient’s lungs are then ventilated by mask, and the airway is examined for burns.
References 1. Sosis MB: Anesthesia for laser surgery. Int Anesthesiol Clin 1990;28: 119-3 I. 2. Ossoff RA: Laser safety in otolaryngology-head and neck surgery: anesthetic and educational considerations for laryngeal surgery. Lqngoscope 1989;99(Suppl 48): l-26. 3. Sosis MB: Airway fire during CO, laser surgery using a Xomed laser endotracheal tube. Anesthesiology 1990;‘72:747-9. 4. Green JM, Gonzalez RM, Sonbolian N, Rehkopf P: The resistance to carbon dioxide laser ignition of a new endotracheaf tube: Xomed Laser-Shield II. J Clin An&h 1992;4: 89-92. 5. Sosis MB: Which is the safest endotracheal
tube for COP? A comparative
study. J Clzn
Anesth (in press, 1992). 6. Wolf CL, Simpson JI: Flammability of endotracheal tubes in oxygen and nitrous oxide enriched atmosphere. Anesthesiology 1987;67:236-9. 7. sosis MB: Evaluation of five metallic tapes for protection of endotracheal tubes during CO, laser surgery. An&h Analg 1989;68:392-3. 8. sosis MB, Dillon FX: Saline filled cuffs help prevent laser-induced polyvinyfchloride endotracheal tube fires. An&h An&g 1991;72:187-9.
88
J. Clin. Anesth.,
vol. 4, March/April
1992
