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, cuttingNd-YAG 2,930 Coag, fiberopticsRuby 694 Tattoos, neviOrganic dye 632 PhototherapyKTP-YAG 532 General, pig. lesionArgon 514 Vascular, pig. lesionXenon fluoride 351 Cornea, angioplastyKrypton 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

Advantages and Disadvantages of ET Tube Types

Type of tube Advantages Disadvantages

PVC Inexpensive, nonreflective

Low melting point, combustible

Red rubber Puncture resistant, nonreflective

Highly combustible

Silicone rubber Nonreflective Combustible, turns to toxic ash

Metal Combustion resistant

Reflects laser, flammable cuff, cumbersome

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