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					          Laser

Dr Aidah Abu Elsoud Alkaissi
An-Najah National University
     Faculty of Nursing
                       Laser
•   Changing surgery by
•   developing less invasive procedures,
•   decreasing inpatient hospitalization,
•   diminishing postoperative complications and
•   saving health care dollars
               Tissue interaction
• When laser energy is delivered to the target
  area, four different interactions can occur
• Reflection
• Scattering
• Transmission
• Absorption
              Tissue interaction
• The extent of the reaction of the beam on the
  target depends upon:
• the laser wavelength,
• power settings,
• length of time the beam is in contact with the
  tissue
• And the X´s of the tissue
                      Reflection
• Reflection of the laser beam occurs when the
  direction of the beam is changed after it impacts an
  area
• Specular (an object that reflects light) reflection
  occurs when the angle of incoming light is equal to
  the angle of the reflected light
• Laser light can be intentionally reflected in this maner
  off a reflective mirror to impact hard-to-reach- areas
• This type of reflection can also pose (introduce)
safely problems if not controlled at all times
                 Scattering
• Occurs when the beam spreads over a large area as
  the tissue causes the beam to disperse (scatter:
  distribute loosely)
• The intensity of the beam is decreased as the
  waves travel in different directions
• The ND-YAG laser beam can backscatter up
  an endoscope and possibly cause damage to
  the end of the scope, the optics or the
  operator´s eye
                  Transmission
• Occurs when the beam passes through fluids or
  tissue withour thermally affecting the area
• For example the argon beam can be transmitted
  through the clear fluids and structures of the eye to
  impact the retina and cause a thermal
  photocoagulation
• The lens and vitreos are unaffected by the
  transmission of the beam
                     Absorption
• Absorption of the lazer light results when the tissue is
  altered from the impact of the beam
• This reaction is usually thermal but can sometimes be
  acoustic (pertaining to sound) in effect
• The consistency, color, and water content of the
  target tissue often determine the rate of absorption of
  the laser energy
• Specific laser light as argon laser is highly absorbed
  by pigmented tissues
• The cO2 laser is independent of clor-selective
  absorption
                      Absorption
• The CO2 laser light is absorbed superficially by tissue
  to a shallow depth of o.5 mm
• Argon laser light is absorbed by pigmented tissue to
  depth of 0.5 to 2mm. While that of the ND:YAG is
  more readily absorbed by darkened tissue to a depth of
  2-6 mm
• Tissue reaction becomes more pronounced as the
  temperature of the impact area increases
• During this thermal reaction the laser energy is
  absobed, causing the cellular water to be heated
                       Absorption
• Intracellulr protein is is destroyed as the temp rises, the
   water inside the cell turns to steam
• Teventually the membrane ruptures from increased
   pressure, spewing, cellular debris and plume (laser
   smoke) from the tissue
• The surrounding tissue is also heated because it borders
   (A part that forms the outer edge of something)
   the impact site
• The degree of adjacent (Close to; lying near )
tissue damage depends on the duration of the laser beam
   exposure that causes the thermal injury
             Common surgical laser
• CO2 is widely used. A visible helium neon laser beam is
  uaually transmitted coaxially (lateral (or spreading)
  directions) with CO2 energy to serve as an aiming beam
• It is characterized by its superficial tissue reaction as the
  beam is highly absorbed by water
• The degree of tissue response is related to the amount of
  heat build from the absorption
• Therefore the longer the CO2 beam impacts the tissue, the
  more destruction is noted
• The depth of penetration by the cO2 energy is very
  superficial and might be described as what you see is what
  you get
             Common surgical laser
• The CO2 beam is also absorbed by any color of tissue,
  theefore lighter tissue cn absorb the beam as readilly as
  darker tissue
• Two types of CO2 laser are available
• The free flowing system requires an external cylinder
  of a special gas mixture of carbon dioxide, helium, and
  nitrogen
• The concentration must be precise so that the laser
  operates properly
• The gas is pulled into the laser head by a vacuum
  pump, generates laser energy and then discharged as
  dissociated by products
• The cylinder is replaced when empty
          Common surgical laser
• The other type of CO2 laser is the sealed tube
  system which contains the special mixture of
  carbon dioxide, helium, and nitrogen within a
  tube that is sealed
• A catalyst (Substance that alters the
  velocity of a chemical reaction )is added to
  the tube and causes regeneration of the mixture
  so that lasing action is produced again
            Common surgical laser
• The neodymium: yttrium aluminum garnet (Nd:YAG)
  laser wavelength is the infrared region of the
  electromagnetic spectrum
• Visible wave is accompanied by a visible helium neon
  beam or white light to provide an aiming source
• The argon laser: produces an intense, visible blue
  )green light
• This light wavelength allows more complete tissue
  absorption
• The aiming system is low-power argon laser energy
  because the beam is visible
           Common surgical laser
• The argon energy is highly absorbed by HB,
  melanin or other pigmentation and is less
  absorbed by light tissue
• The absorbed laser energy is hen converted to
  heat to cause coagulation or vaporization
• Because of the high color selectivity of the
  beam adjacent tissue injury is reduced
  significantly
• The argon transmitted through clear fluids and
  structures
                     Safety
•   Lesd to:
•   Fire
•   Skin burns
•   Optical damage
             recommendation
• Protective goggles, glases and endoscope lens
  covers should be inscribed (printing)
with the appropriat filtering capabilities and
  adequate optical densities or the specific
  wavelength being used
A baseline eye examination, noting visual acuity and
  retinl health
Te patient´s eues must lso protected, wetgauze, eye
  pad or towel should be taped closed, if a wahe eye
  protection used for pat
• Read guide 182, 183, 184
• Laser comittee 186, 189 benifits of
  technology

				
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posted:1/23/2013
language:English
pages:18