Lasers: Safety and Anesthetic Implications

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Lasers Safety and Anesthetic Implications
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Agenda

• What is a laser
• Physiologic Principles
• Types of lasers
• Clinical uses of lasers
• Hazards of the laser environment
• patient
• provider

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What is a Laser?

• Light Amplification of the Stimulated Emission of
  Radiation

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Stimulated Emission

• Electrons usually at ground state can jump to
  higher energy level by absorbing outside energy
  from either light or electrical discharge.
• Excited atoms tend to revert to the ground state
  and release photons in the process

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Stimulated Emission

• Emitted photons have energy equal to the
  difference between the ground and excited state.
• The change in energy is responsible for the
  frequency of the emitted photons.

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Stimulated Emission

• Since the energy emitted is exactly the same, the
  frequency of the emitted energy is exactly the
  same for all photons.

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3 Characteristics of Laser light

• Monochromatic means that all waves are exactly
  the same wavelength or color
• Collimation means that all waves are parallel and
  do not diverge
• Coherence means that all waves travel in phase in
  the same direction and are of the same wavelength

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Components of a Laser

• Energy source
• Laser Medium
• Optical Cavity

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Laser Energy Source

• Source induces excitation of electrons
• Source could be electrical, chemical or other

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Laser Medium

• Population of molecules used to produce the
  photons
• Lasers are named after the type of laser medium

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Optical Cavity

• Chamber with mirror at each end
• Photons bounce back and forth
• As photons bounce, beam grows in strength
• Beam passes through shutter at one end

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Types of Lasers

• Carbon Dioxide
• NdYAG (neodynium-doped yttrium-aluminum-garnet)
• KTP (Potassium titanyl phosphate)
• Argon
• Helium-neon

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Carbon Dioxide Laser

• wavelength 10,600
• Absorbed by all tissues that contain water
• Shallow thermal penetration
• Eye considerations
• absorbed by lens of the eye
• any lens will stop this laser

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Carbon Dioxide Laser

• Common uses
• ENT surgery
• neurosurgery
• gynecology
• plastic surgery
• Used when precision is needed

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NdYAG Laser

• Wavelength 1064
• Transmitted through clear substance
• Absorbed by pigments
• May be transmitted through fiber optic cables

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NdYAG Laser

• Eye care
• passes through the lens and is absorbed by the
  retina
• Colored eye protection required

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NdYAG Laser

• Common uses
• trachea
• bronchi
• Penetrates 2-6 mm

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KTP Laser

• Wavelength 532 (1/2 of NdYAG)
• Appears green
• Produced by passing NdYAG laser through KTP
  medium
• More precise than the NdYAG and deeper
  penetration than the CO2

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KTP Laser

• Eye precautions
• passes through clear tissue and is readily
  absorbed by pigmented tissue
• will damage the retina of the eye
• colored eye protection required

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KTP Laser

• Common uses
• airway operations
• neurosurgery

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Argon Laser

• Wavelength 488-515
• Appears blue/green
• Passes through clear substances
• Absorbed by pigments
• Eye precautions
• colored eye protection required

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Argon Laser

• Common uses
• eye procedures of the retina
• plastic surgery
• dermatology
• photocoagulation

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Helium - Neon Lasers

• Wavelength 632
• Appears red
• Has no significant effect on tissues
• Incorporated in other lasers and is used to aim
  the more powerful laser beam

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Concept for eye protection

• Shorter wavelengths pass through the lens and
  damage the retina. Colored lenses are needed for
  shorter wavelengths.

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Thermal Damage

• Determined by the power density of the laser
• Power density watts
• spot size (cm2)
• Thermal damage modified by heat dissipation

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What types of damage can be done by the laser?
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Damage by Lasers

• Eye damage
• Skin injury
• Produce airborne contaminants
• Cause fire
• Cause explosion
• Potential danger classified by ANSI

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Minimizing Damage

• Laser safety committee / officer
• Credentialing
• Written policies and procedures
• Wear eye protection
• Skin protection
• Flame retardant drapes

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Eye Injuries

• Hazard to patient and providers
• Damage depends upon the wavelength of the laser
• Appropriate eye protection needed
• glasses for the providers
• wet sponge and towel for patient

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Skin Injuries

• Skin Burn (thermal)
• Provider hit with stray beam
• Patient tissue surrounding desired area may be hit

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Smoke Inhalation

• Laser plume may contain
• virus DNA
• viral particles
• Smoke may cause
• watery eyes
• nausea
• breathing difficulty

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Smoke Inhalation

• Smoke from burning endotracheal tube may be
  inhaled by the patient
• toxic plastic fumes
• thermal injury from hot smoke
• carbon monoxide

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Name the three elements required for a fire to
occur
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Fire / Explosion

• Fuel source
• Oxygen
• Combustible material
• endotracheal tube
• drapes

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Your patient is receiving laser surgery on
papillomas of the vocal cords and flames start to
shoot from the mouth. What do you do?
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An airway fire is an immediate life threatening
condition
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Airway Fire Protocol

• 1. Disconnect the tube at the Y-piece and remove
  the tube immediately
• 2. Turn off the oxygen
• 3. Irrigate the site with water if it is still
  smoldering
• 4. Ventilate the patient by mask or reintubate if
  possible

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Airway Fire Protocol

• 5. Attempt to maintain oxygenation and vital
  signs
• 6. Perform laryngoscopy and/or bronchoscopy to
  evaluate extent of injury
• 7. Secure the airway either by reintubation or
  tracheosteomy

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Airway Fire Protocol

• 8. Admit to the intensive care unit and monitor
  (including ABGs) for at least 24 hours.
• 9. Use ventilators, steroids and antibiotics as
  indicated

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Prevention is the best approach to fire safety
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What can you do to help prevent airway fires?
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Fire Prevention

• Protect the Endotracheal tube from laser beam
• laser tubes
• metal wrap
• wet gauze
• saline for the cuff

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Fire Prevention

• Consider apneic laser surgery
• Consider jet ventilator

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Fire Prevention

• Lower the inspired oxygen concentration (remove
  the oxidizer)
• Helium / oxygen 7030