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