Anesthesia in Laser Surgery

(1)

Anesthesia in

Laser Surgery

R1 Minghui Hung

(2)

“Never are

cooperation

and

communication

between surgeon

and anesthesiologist more important

than during head and neck surgery.”

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Physics of Laser light (I)



_L

_ight

_A

_{mplification by}

_S

_timulated

_E

_m

ission of

R

adiation



_{Electromagnetic radiation}



_Einstein:

_{all electromagnetic radiation consisted of wav}

elike quanta called photons →E (J) = h v

(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}

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Laser system components

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

_{Used as scalpels and electrocoagula}

tors



_{Dermatology, thoracic surgery, opht}

halmology, gynaecology, plastics, E

NT, 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

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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 Green 514 Vascular,

pigmented lesions Xenon fluoride Ultraviolet 351 Cornea, angioplasty

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

_{Atmospheric contamination}



_{Perforation of a vessels or structure}



_Embolism



_{Inappropriate energy transfer}

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 Plume of smoke and fine particulates (mean size 0.31 um)

 Efficiently transported and deposited in the alveoli

 Sensitive individuals: headaches, tearing, and nausea after inhalation

 Animal study: interstitial pneumonia, bronchiolitis, redu ced mucociliary clearance, inflammation, emphysema

 Prevention

→ smoke evacuator

→ high-efficiency masks

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

_{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

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

_{Venous gas embolism when laparoscopic}

or hysteroscopic laser surgery



_{At hysteroscopy, liquid (saline) coolant is t}

he only safe option



If coolant gas must be used, CO

2

should

be considered

→ Continuous airway CO

2

monitoring

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

_{Incidentally pressing the laser control trig}

ger



_{Tissue damage outside of surgical site}



_{Drape fire}



_{Eye (patient or other medical staff)}



_{Endotracheal tube fires}

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

_{Incidence: 0.5 – 1.5 %}



_Source:

– direct laser illumination – reflected laser light

– incandescent particles of tissue blown from the surgical site

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Approaches to reduce the

incidence of airway fire



_{Reduce the flammability of the endotrach}

eal tube



_{Use Venturi ventilation}

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Various endotracheal tubes for laser airway surgery Type of tube Advantages Disadvantages

Polyvinyl chloride

Inexpensive, nonrefl ective

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

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

_{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

Protection

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Cuff wrapping technique

methylene blue stained saline instead of air

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 _{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}

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

_{Oxygen and nitrous oxide are powerful}

oxidizers



_{Reduce FiO}

₂

_{to minimum concentration}



_{Helium may benefit as a diluent gas}



_{Volatile anesthetics currently used are n}

onflammable and nonexplosive



_{Pyrolized toxic compounds}

Effect of high oxygen and nitrous

oxide gas mixture

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 _{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 ste}

el spiral wound tube with two PVC cuffs

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 Barotrauma  Pneumothorax

 Restriction to only intravenous agents  Gastric distention

 Relative requirement for compliant lungs

Jet ventilation

Intermittent apnea technique

 Hypoventilation

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 _{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% O}₂_{, continue anaesth}

esia i.v.

 _{Direct laryngoscopy & rigid bronchoscopy for d}

amage and debris.

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

_{Reintubate if damage.}



_{Blowtorch fire may need distal fibreoptic br}

onchoscopy and lavage.



_{Severe damage may need low tracheosto}

my.



_{Assess oropharynx and face.}



_CXR.



_Steroids.

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I am a sheep. SHEEP

me 2.