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2013-10-11 20:49:51

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  1. When operating lasers, what three variables are set by the physician?
    • power (measured in watts)
    • spot size (measured in millimeters)
    • exposure time (measured in seconds)
  2. How does scatter impact the effect of the laser?
    Scattering tends to spread the laser energy over a larger surface area of tissue, but it limits the penetration depth. Light of shorter wavelength has greater scatter.
  3. What is a strategy for minimizing thermal collateral damage?
    To minimize lateral thermal damage from thermal diffusion, the tissue should be ablated with a short laser pulse.
  4. Describe the properties of a Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) Laser.
    • wavelength of 1.064 µm in the near infrared range
    • can be transmitted through clear liquids, facilitating its use in the eye
    • Absorption is slightly color dependent, with increased absorption in darkly pigmented tissues and char
    • strong scattering and deep penetration makes precise control impossible.
    • Good for coagulationp
  5. Describe the properties of Carbon Dioxide (CO2) Laser.
    • wavelength of 10.6 µm in the infrared (invisible) range
    • strongly absorbed by pure, homogeneous water and by all biologic tissues high in water content.
    • The extinction length of this wavelength is about 0.03 mm in water and in soft tissue.
    • Reflection and scattering are negligible.
    • absorption of the radiant energy produced by the CO2 laser is independent of tissue color
    • the thermal effects produced by this wavelength on adjacent nontarget tissues are minimal
  6. Describe the properties of the Potassium-Titanyl-Phosphate (KTP) Laser
    • 532 nm comparable to Argon
    • scattering and absorption by skin pigments when using the KTP laser are nearly the same as for the Ar laser
    • the KTP laser light is more strongly absorbed by hemoglobin
  7. Describe the properties of 585-nm Pulsed Dye Laser
    • 585-nm pulsed dye laser (PDL)
    • used mainly as a photoangiolytic laser for laryngeal applications.
    • The targets oxyhemoglobin, which has an absorption peak of 571 nm.
    • absorbed by intraluminal blood of vascular lesions such as papilloma, vascular polyps, vocal fold ectasias and varices.
    • PDL causes involution of the lesion through disruption of the vascular supply rather than immediate removal of the lesion.
  8. Which protective glasses are worn with which laser?
    • CO2: clear lenses
    • Nd:YAG: blue/green
    • KTP, Ar: tinted
  9. What do you do In the event of tube ignition during a laser airway procedure?
    • ventilation must be stopped immediately and the tube withdrawn simultaneously as saline is flushed down the endotracheal tube.
    • reestablish airway immediately
    • bronchoscopy performed to assess the degree of injury.
    • Intravenous steroids may be delivered and the patient should remain intubated; repeat bronchoscopy should be performed daily until it is established that the airway is stable.