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LASER.pptx
- 1. Universal Precautions • Wash hands before and after patient or specimen contact • Wear gloves for potential contact with blood and body fluids • DO NOT recap or manipulate the needles • Discard used syringes and needles immediately • Wear protective eyewear if splatter of blood is expected • Handle all linen soiled with blood or body secretions as potentially infectious • Process all lab specimens considering infectious
- 2. Antiretroviral Treatment Nucleoside reverse transcriptase inhibitors Zidovudine (AZT) Didanoside Zalcitabine Stavudine Lamivudine Nonnucleoside reverse transcriptase inhibitors Nevirapine Delavirdine Protease Inhibitors Indinavir Sequinavir Ritonavir
- 4. LASER • ACRONYM FOR Light Amplification by Stimulated Emission of Radiation • A laser is a device that produces and amplifies light by stimulated emission. It can produce light in the ultraviolet, visible, and infrared region of the electromagnetic spectrum.
- 5. Laser History • 1917: Einstein first discussed stimulated emissions • 1960: Maimen (Hughes Aircraft) develops first laser (ruby with 694 nm wavelength) • 1961: Neodymium-doped (Nd): glass laser • 1964: Nd:YAG and argon ion (Ar) • 1965: CO2 laser
- 6. Stimulated Emission- Laser empowers atoms to store and emit light External energy source will energize the electrons in the atom to an excited state In Excited state the electron will emit one photon Light Amplification- These photons will move back and forth between two parallel mirrors triggering further stimulated emission
- 8. Laser Properties • Monochromatic- A single pure colour emitted by a single wavelength • Coherent- Waves produced by a laser travel through space in phase. coherence is responsible for the strength and intensity of the beam between different points in the field. • Collimated- A beam in which all the photons are travelling in the same ‘parallel direction’
- 9. Different types of lasers Solid -- Nd:YAG laser, Gas – Helium Neon, CO2,Argon and Krypton Gas laser. Liquid —Organic dye laser.( rhodamin 6G , disodium fluorescein ) Semiconductors – Gallium-Arsenide-Diode laser Excited dimer ( Eximer Laser) -- Argon fluoride (193 nm) , Krypton fluoride (248 nm)
- 11. Infrared light : primarily absorbed by water. Visible and UV light : absorbed by hemoglobin and melanin As wavelength becomes shorter – scatter begins to dominate the penetration of light
- 12. MODES OF LASER • CONTINUOUS :The laser is continuously pumped and emits light continuously • PULSE : In the superpulse mode, laser energy is delivered with each peak over an extremely short period of a few nanoseconds. The peaks are interspersed with rest periods when no exposure occurs, allowing time for tissues to cool down • Q-SWITCHED : Allows a high build-up of energy within the tube. This is then released over a very short duration of a few nanoseconds, reaching an enormous peak power.
- 13. Light and Tissue Interactions • Absorption • Scattering • Reflection • Transmission
- 14. Tissue Ablation • 10 C – 45 C: Conformation change of proteins • 50 C: Reduction of enzyme activity • 60 C: Denaturation • 100 C: Water vaporizes causing thermal damage
- 15. CO2 Laser • 10,600 nm wavelength • Water is target chromophore • Aiming helium-neon (HeNe) beam • Highest power continuous-wave laser • Cutting or ablating tool • Focus to 200 mm • Seals blood vessels less than 0.5 mm • Pulsed to accommodate thermal relaxation time, less pain and less edema • Pattern generators • Work in distal airway in “hands off” fashion • Used in majority of procedures except those requiring coagulation of larger vessels • No current optical fiber to carry beam
- 16. Nd: YAG Laser • 1064 nm wavelength (neodymium-doped yttrium aluminum garnet ) • Aiming helium-neon (HeNe) beam • Wavelength is between minimal absorption of water and a small amount of scatter • Solid state laser • Fiberoptic carrier • Application • Deeper penetration (up to 4 mm) for ablative therapy and hemostasis • Preferentially absorbed by pigmented tissues • Vascular malformations amenable to treatment • Used in a multitude of pulmonary, urology and gastroenterology procedures • Minimally invasive percutaneous laser disk decompression • Limitations • Greater scatter than CO2 • Deep thermal injury • Risk for transmural injury
- 17. Argon Laser • 488 - 514 nm wavelength (ion laser) • Oxyhemoglobin is target chromophore • Small spot size (0.1 – 1 mm) – variable in size and intensity • Flexible delivery system • Applications • Retina or middle ear surgery • Facial spider veins • Junctional nevi • Cherry hemangioma • Vascular birthmarks • Limitations • Also absorbed by epidermal and dermal tissues due to melanin • Continuous mode of operation • Higher prevalence of postoperative pigmentary alteration and fibrosis
- 18. KTP Laser • 532 nm wavelength (potassium-titanyl-phosphate) • Nd: YAG laser passes through a KTP crystal – emission is ½ its wavelength • Oxyhemoglobin is primary chromophore • Fiberoptic carrier • Continuous wave (CW) mode to cut tissue • Pulsed mode for vascular lesions • Q-Switched mode for red/orange tattoo pigment • Applications • Granuloma excision of the respiratory tract • Subglottic/tracheal stenosis • Subglottic/supraglottic cyst excision • Inferior turbinate reduction • Nasal papilloma excision • Nasopharyngeal stenosis • Supraglottoplasty • Laryngeal papilloma excision • Middle ear surgery (Cholesteatoma excision, stapes surgery) • Delivery • CW/pulsed mode: insulated fiber, fiber handpiece, scanner, or microscope • Q-Switched mode: articulating arm
- 19. Laser Safety • Education: reduction of laser-related complications • Development of protocol for safe laser use (credentials, continued education, ect.) • Dedicated laser technician/ nurse/ engineer • Team approach in fire prevention and anesthetic management • Safest anesthetic gas mixture is 30% oxygen in helium • Laser compatible endotracheal tube • Eye protection (medical personnel & patient) • Saline moistened eye pads • Skin protection: saline-saturated surgical towels • Smoke evacuation: two separate suction set-ups • Placement of signs and additional eye protection outside operative room
- 20. THANK YOU