Laser

1. Laser Dr Aidah Abu Elsoud Alkaissi An-Najah National University Faculty of Nursing

2. Laser • Changing surgery by • developing less invasive procedures, • decreasing inpatient hospitalization, • diminishing postoperative complications and • saving health care dollars

3. Tissue interaction • When laser energy is delivered to the target area, four different interactions can occur • Reflection • Scattering • Transmission • Absorption

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. Safety • Lesd to: • Fire • Skin burns • Optical damage

17. 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

18. Read guide 182, 183, 184 • Laser comittee 186, 189 benifits of technology