1. Anesthesia in Laser Surgery
R1 Minghui Hung
Department of Anesthesiology, NTUH

2. “Never are cooperation and communication between surgeon and anesthesiologist more important than during head and neck surgery.”
Morgan, Clinical Anesthesiology

4. Physics of Laser light (I)
Light Amplification by Stimulated Emission of Radiation
Electromagnetic radiation
Einstein:
all electromagnetic radiation consisted of wavelike quanta called photons
→E (J) = h v
Wavelength for visible light ranges from 385nm to 760 nm

5. Physics of Laser light (II)
Characteristics:
Monochromatic (one wavelength)
Coherent (oscillates in the same phase)
Collimated (exists as a narrow, parallel beam)
Intense light beams, intense energy to small target sites

6. Laser system components

7. Laser system components Light guide

8. Clinical applications
Used as scalpels and electrocoagulators
Dermatology, thoracic surgery, ophthalmology, gynaecology, plastics, ENT, urology and neurosurgery

9. Laser interaction with tissue
Used as scalpels and
electrocoagulators
Precise microsurgery
Relative “dry”
Less damage to
adjunct tissue
Less postoperative
pain and edema

10. Common used Laser lights
Laser media
Color
Wavelength (nm)
Typical application
Carbon dioxide
Far infrared
10,600
General, cutting
Ruby
Red
694
Tattoos, nevi
KTP:YAG
Green
532
General,
pigmented lesions
Argon
514
Vascular,
Xenon fluoride
Ultraviolet
351
Cornea, angioplasty

11. Laser Hazards Atmospheric contamination
Perforation of a vessels or structure
Embolism
Inappropriate energy transfer

12. Atmospheric contamination
Plume of smoke and fine particulates (mean size 0.31um)
Efficiently transported and deposited in the alveoli
Sensitive individuals: headaches, tearing, and nausea after inhalation
Animal study: interstitial pneumonia, bronchiolitis, reduced mucociliary clearance, inflammation, emphysema
Prevention
→ smoke evacuator
→ high-efficiency masks

13. Perforation
Misdirected laser energy may perforate a viscus or a large blood vessel
Laser-induced pneumothorax
Perforation may occur several days later when edema and necrosis are maximal

14. Venous gas embolism
Venous gas embolism when laparoscopic or hysteroscopic laser surgery
At hysteroscopy, liquid (saline) coolant is the only safe option
If coolant gas must be used, CO2 should be considered
→ Continuous airway CO2 monitoring

15. Inappropriate energy transfer
Incidentally pressing the laser control trigger
Tissue damage outside of surgical site
Drape fire
Eye (patient or other medical staff)
Endotracheal tube fires

16. Endotracheal tube fires
Incidence: 0.5 – 1.5 %
Source:
direct laser illumination
reflected laser light
incandescent particles of tissue blown from the surgical site

17. Blowtorch ignition of an endotracheal tube.

18. Approaches to reduce the incidence of airway fire
Reduce the flammability of the endotracheal tube
Use Venturi ventilation
Use intermittent apnea technique

19. Various endotracheal tubes for laser airway surgery
Type of tube
Advantages
Disadvantages
Polyvinyl chloride
Inexpensive, nonreflective
Low melting point, highly combustible
Red rubber
Puncture-resistant, maintains structure, nonreflective
Highly combustible
Silicone rubber
Nonreflective
Combustible, turns to toxic ash
Metal
Combustion-resistant, kink-resistant
Thick-walled flammable cuff, transfers heat, reflects laser, cumbersome

20. of the endotracheal tubes
Protection
of the endotracheal tubes
wrapping with moistened muslin
coating with dental acrylic
wrapping with metallized foil tape
→ most popular approach
aluminum foil
copper foil
plastic tape thinly coated with metal

21. Cuff wrapping technique
methylene blue
stained saline
instead of air

22. Disadvantages of wrapping
No cuff protection
Adds thickness to tube
Not an FDA-approved device
Protection varies with type of metal foil
Adhesive backing may ignite
May reflect laser onto non-targeted tissue
Rough edges may damage mucosal surfacess

23. Effect of high oxygen and nitrous oxide gas mixture
Oxygen and nitrous oxide are powerful oxidizers
Reduce FiO2 to minimum concentration
Helium may benefit as a diluent gas
Volatile anesthetics currently used are nonflammable and nonexplosive
Pyrolized toxic compounds

24. Metal endotracheal tubes
Norton. spiral wound stainless steel ETT
Bivona Fome-Cuff. aluminium spiral tube with a silicone polyurethane foam cuff
Xomed Laser-Shield. silicone elastomer tube containing metallic powder
Mallinckrodt Laser-Flex. airtight stainless steel spiral wound tube with two PVC cuffs

25. Intermittent apnea technique
Jet ventilation
Barotrauma
Pneumothorax
Restriction to only intravenous agents
Gastric distention
Relative requirement for compliant lungs
Intermittent apnea technique
Hypoventilation
Pulmonary aspiration

26. Airway fires protocol (I)
Remove source of fire (the laser!).
Stop ventilating, disconnect circuit, extubate.
Extinguish fire in bucket of water (MUST have one ready!).
Mask ventilate with 100% O2, continue anaesthesia i.v.
Direct laryngoscopy & rigid bronchoscopy for damage and debris.

27. Airway fires protocol (II)
Reintubate if damage.
Blowtorch fire may need distal fibreoptic bronchoscopy and lavage.
Severe damage may need low tracheostomy.
Assess oropharynx and face.
CXR.
Steroids.

28. I am a sheep.
SHEEP me 2.
We wish you…
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