BY Azza Lotfy Ass. Lect. Of Anesthesia & ICU LASER Light Amplification of Stimulated Emission of Radiation Physical principles of laser Production of laser (Laser system hardware): Physical principles of laser Characters of Laser beam : Monochromatic: one wave length) Coherent: (oscillate in the same phase) Collimated: (exist as a narrow, parallel beam) Effect of Laser on tissues: Laser factors: Wavelength Power density Duration Tissue factors: Absorption Thermal conductivity Local circulation Scatter Types of medical Laser: Laser media Color Wavelength (nm) Typical application Carbon dioxide Far infrared 10.600 General, cutting Nd: YAG Near infrared 1.064 General, coagulation KTP:YAG Green 532 General, pigmented lesions Argon Green 514 Vascular, pigmented lesions Xenon fluoride Ultraviolet 351 Cornea, angioplasty Advantage and clinical uses of laser: Scalpel and electro coagulator. Allow precise microsurgery. Relatively dry field. Less postoperative edema and pain with lower infection rate. Disadvantages of laser (hazard of laser) Atmospheric contamination ” laser plume” Misdirection of laser energy Gas embolism Energy transfer to an inappropriate location Fire and explosion Disadvantages of laser (hazard of laser) Atmospheric contamination ” laser plume”: 1. 2. 3. 4. 5. Interstitial pneumonia. Bronchiolitis. Reduced mucociliary clearance, inflammation. Emphysema. Plume can be mutagenic, teratogenic or vector of viral infection. Disadvantages of laser (hazard of laser) Misdirection of laser energy: perforation of viscous or large blood vessels. Gas embolism: Venous gas embolism when laparoscopic or hysteroscopic laser surgery are reported. Energy transfer to an inappropriate location: Eye damage (corneal opacities, retinal damage); Skin damage (from erythema to blisters or charring). Fire and explosion: Laser contact with flammable material such as rubber or plastic may cause fire and explosion. Airway Fire 1. 2. 3. Incidence; 0.5% - 1.5% Predisposing factors; Flammable materials (ETT). Source of ignition (Laser beam). Gas support combustion (O2). Airway Fire Fire may be: On external surface of ETT cause local thermal destruction. Blowtorch like fire.