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Laser Surgery of the Airway. Airway Issues, Anesthesia Choices and Ventilation. Disclosures/Conflicts. Vanderbilt Anesthesia Department Board of Trustees, MTSA Clinical Consultant, Organon-Schering Plough. Airway Surgery Issues. Stimulation of surgery Difficult intubation
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Laser Surgery of the Airway Airway Issues, Anesthesia Choices and Ventilation
Disclosures/Conflicts • Vanderbilt Anesthesia Department • Board of Trustees, MTSA • Clinical Consultant, Organon-Schering Plough
Airway Surgery Issues • Stimulation of surgery • Difficult intubation • Airway competition • Potential loss of airway • Positioning • Emergence timing issues
Difficult Airway Presentations • Anatomic • Narrowing of airway • Vocal cord dysfunction • Trauma • History of difficult intubation • Low threshold for FOI
Anesthesia Requirements • Light premedication with antisialagogue • Adequate intraop and postop analgesia • Quiet surgical field/paralysis • Smooth emergence • Anesthetic choices range from local to inhalation to TIVA
FiO2 Management • Maintain 100% FiO2, affording longer periods of apnea • For laser, use lowest FiO2, maintaining adequate oxygen saturation • Dilute oxygen with air • May use heliox (lower FiO2, improved flow/resistance)
Airway Management • Airway is shared continuously between the surgeon and the anesthetist • Small cuffed tube (effective in 95%) • Laser ET tube • Intermittent apnea (1-5 minutes) • Jet ventilation
Introduction to Lasers • CO2 is the most widely used laser (longer wavelength, less tissue penetration) • Absorbed by water contained in blood and tissues • Invisible beam offers unobstructed view of the lesion • Several applications with potential for rare severe complications
Laser Media Wavelengths Medium Wavelength Application (nm) CO2 10,600 General, cutting Nd-YAG 2,930 Coag, fiberoptics Ruby 694 Tattoos, nevi Organic dye 632 Phototherapy KTP-YAG 532 General, pig. lesion Argon 514 Vascular, pig. lesion Xenon fluoride 351 Cornea, angioplasty Krypton fluoride 248 Cornea, angioplasty
Laser Applications for ENT • Laryngeal or vocal cord papillomas • Laryngeal webs • Redundant subglottic tissues • Debulking of tumors
Advantages of Laser • Precise lesion targeting • Minimal bleeding • Minimal edema/tissue reaction • Preservation of surrounding structures and normal tissues • Rapid healing/less postop pain
Hazards of Laser • Eyes are vulnerable to misdirected beam • Fire hazard (up to 0.4%) • Damage by reflection of light by tube, instruments • Laser smoke may damage lungs • Hypoxic mixture of inhaled gases • Vaporization of cancers may aerosolize carcinogens (plume, fine particles)
Laser Plume • Viral DNA has been detected in plume from condylomas and warts but not from laryngeal papillomas • CO2 lasers produce the most smoke and Nd:YAG produces the least • Ordinary masks filter down to 3 micrometers so that special filter masks are required along with vacuum of field
Other Precautions for Laser Surgery • Eye goggles for OR staff (laser specific) • Warning sign outside OR • Wet towels for eyes of patient • Special ET tube vs. apneic ventilation vs. jet ventilation
Heliox • Combustion is more vigorous when excess oxidizer is used (e.g., oxygen) • Index of flammability is reduced only by 2% when helium is substituted for air • Helium lowers density and allows use of smaller ET tube without turbulence and high flow resistance
Endotracheal Tubes for Laser Surgery • Standard is 5.0 cuffed tube coming from left side of mouth • Saline-soaked gauze pads to limit risk of ignition • 60 ml bulb syringe with saline should be immediately available • Used with preexisting lung disease, long case
Laser Endotracheal Tubes • Standard polyvinyl chloride tubes (PVC) are flammable and can ignite, vaporize • Wrapped tubes still have a vulnerable cuff • Fill cuff with sterile saline and methylene blue for easy detection and fire dousing
Airway-Fire Protocol • Stop ventilation, remove endotracheal tube, submerge in water • Turn off O2 and disconnect circuit • Ventilate with face mask • Assess airway damage with bronchoscopy • Consider bronchial lavage and steroids
Apneic Ventilation • Usually used for infants, small children and short cases • Advantage is absence of ET tube • Anesthetized deep vs. muscle relaxant • Between laser applications the patients lungs are ventilated either by mask, jet or ETT ventilation • Debris may enter airway
Jet Ventilation • Main advantage is clear operating field for surgeon and laser safety • Operating laryngoscope is fitted with a side port • Oxygen is delivered under pressure through a reducing valve (20-30 torr) via a metal catheter
Jet Ventilation • 100% oxygen is used, rise and fall of chest as monitor • Surgeon will usually direct ventilations • TIVA necessary as vaporizers are bypassed
Complications of Jet Ventilation • Barotrauma (SQ emphysema, pneumothorax) • Gastric distention • Ball-valve distention from tumor • Blown debris down unprotected trachea • Dessicated vocal cord with long procedure • Hypoxia/hypercarbia
Total Intravenous Anesthesia (TIVA) • Useful when inhalation agent is unavailable or undesirable (jet vent, evoked potentials) • 100-300 mcg/kg/minute propofol • 0.1-0.5 mcg/kg/minute remifentanil • Remifentanil 0.1 mg/10 ml propofol • BIS used to monitor state of anesthetic
Jet Ventilation with TIVA • Standard induction with propofol, sevoflurane maintenance • Turn off sevoflurane, start propofol infusion @ 200 mcg/kg/minute with syringe pump • Maintain infusion while ventilating patient as per surgeon request, maintain BIS @ 40-60 • At completion of procedure, turn propofol off and ventilate by mask until awake
Laser Airway Surgery with ETT • Check helium tanks (max. 1600 psig) • Set up and test jet ventilation (adjust to 20-30 torr) • 5.0 laser ETT from core, 10 cc NS from blue cart, tape @ 20 cm (unmarked) • Narrow stylet for tube
Emergence Issues • “Rodeo” emergence • Must be able to maintain airway and deal with spasm/pain • Reversal must be complete, and easy-on, easy-off agents a necessity
Key Points • Airway issues include sharing and difficult intubation • Choice of anesthesia must be individualized after communication with surgeon • Emergence dependent upon control of analgesia and ability to protect airway