2LASER Light Amplification of the Stimulated Emission of Radiation Intense controlled beam of lightCharacteristics :- coherence (one phase)- collimation ( parallel direction)- Monochromaticity (same wavelength)
3Apparatus Lasing medium External source of energy - Pumping Unstable potential energy – Population reversalRelease of quantum of energy – photons of lightReflected through a long resonatorExit through a mirror
5Effect of Laser Thermal effects depend on - Energy density - Flux Temperature
6Thermal effect on tissues Below 55ºc slight destructive shrinkingAbove 55ºc welding of cell walls60ºc early denaturation of cell protiens100ºc cell water boils and vaporises
7Types of Lasers Argon gas - ophthalmic photocoagulation, skin lesions, angioplasty, stapedectomyCO2 gas cutting & vaporisingLiquid dyes - angioplastyExcimer gas - angioplasty, radial keratotomyKrypton gas - photocoagulationNd-YAG solid – coagulation, heating of tissues forhaemostasiserbium:YAGThuliumHolmium:YAG (Ho:YAG)
8CO2 Lasers HeNe used as an aiming co-axial laser Laryngeal laser surgery (e.g., laryngeal condylomata, papilloma’s and tumors)Long wave length (10.6 um)Total absorption in the first few cell layersAccurate vaporization with minimal peripheral injuryBest precision (0.2mm)Cannot be used through a fiberoptic scopeErrant beams can result in corneal damageCan be stopped with any clear lens material
9Nd-YAG lasers Neodymium-yttrium aluminum garnet (Nd-YAG) Invisible Coagulation of hemorrhagic lesions (necrotic respiratory tumors and GI varices)Wave length of 1.06 umPenetrate tissues causing deep damage with more thermocoagulation and less vaporizationCan be used through a fiberoptic scopePenetration is variable with a greater potential for damage to normal tissue
10Holmium:YAG (Ho:YAG)Precise cutting with minimal damage to adjacent tissueFiberoptic delivery (which is ideal for endoscopic use)Treats tissue in a liquid-filled environment (e.g., saline, blood).
11Argon Laser Blue-green light Short wavelength of 0.6 um Primary use for pigmented structures (hemangiomas, port wine stains, retinal surgery)
12Diode laser 980-nm wavelength Fiberoptic delivery system Tissue-cutting effect comparable to CO2 laserCoagulation effect comparable argon laserHigher degree of absorption by tissue than Nd:YAG laserLarge (up to 10 mm) penetration depth in biologic tissueIdeal for photocoagulation
13Advantages of laser surgery PreciseSelective absorptionMinimal pain, scarring and edemaRemote alteration of tissuesEasy transmission through endoscopes
14Applications Laparoscopy Endoscopy Thoracic surgery Ophthalmology GynecologyPlastic surgeryUrologyNeurosurgeryENT
15Laser in Urology Nd:YAG, Ho:YAG, KTP, diode sources Lasers for benign and neoplastic tissue coagulation and vaporization- Prostatectomy- Transitional cell carcinoma of bladder,ureter, and renal pelvis- Renal, adrenal. genital and urethral tumorsLaser incision of ureteropelvic junction, ureter, and urethral stricturesLaser lithotripsy
16General safety considerations PatientProtection of eyes, nose, moustache/ beardNo eye ointments / No metal eye cupsNo plasticsCloth adhesive tape/ Wet with high porosityAvoid tincture benzoinTissue cleansing agents should be wiped off
17General safety considerations Operating RoomEye shields for OR personnelWave length specific glass inserts on windows and doorsSigns identifying laser useDrapes and towels – cloth with high porosity / wetFire extinguisher, water bucket
18Recommendations American National Standards for the Safe use of Lasers in Health Care Facilities I All persons should be aware of areas of laser use, and controlled access to these areas must be maintainedNominal hazard zone is identified to prevent unintentional exposure to the laser beamRegulation laser signs should be placed at all entrances to laser treatment areasDoors in the nominal hazard zone should remain closed and windows--including door windows--should be covered as appropriate to the laser usedThe nominal hazard zone should be occupied only by authorized persons (including patients) or health care personnel approved by the laser safety officer.
19II Everyone in the nominal hazard zone should wear appropriate eyewear All personnel in the nominal hazard zone should wear protective eyewear, labeled with the appropriate optical density and wavelength for the laser in useThe patient's eyes and eyelids should be protected from the laser (eg, wet eyepads, laser protective eyewear, laser specific eye shield)
20III All persons in the laser treatment area should be protected from laser beamexposures to their skin and othernontargeted tissuesExposed tissues around the operative site should be protected with saline-saturated or water-saturated fire/flame-retardant materials (eg, towels, sponges) when thermally intensive lasers are being used. These materials should be remoistened periodically to ensure proper protectionAnodized, dull, nonreflective, or matte-finished instruments should be used near the laser siteWhen a fiber is used to deliver laser energy through an endoscope, the end of the fiber must extend at least I cm past the end of the endoscope
21IV Exposure to smoke plume generated during laser surgery should be reduced by implementing avariety of engineering controlsSmoke plume inhalation should be reduced by implementing various controls that include but are not limited to the use of* high-filtration surgical masks,* wall suction units with in-line filters, and* smoke evacuator units.
22Laser Plumes Carbonised tissue,blood and virus(0.1-0.8µm) Occupational Hazard (National Institute for Occupational Safety and Health)Hydrocarbons, including acetone, isopropanol, toluene, formaldehyde, and cyanideSmoke plume- respiratory irritation- viral infection- mutagenic and carcinogenic potential.
23V All persons in the laser treatment area should be protected from flammability hazards associated with laser usage.Personnel using lasers should be aware of the fire hazards associated with laser use. Items with the potential for causing fire, bums, or explosions include* flammable liquids or combustible ointments (eg, skin prep solutions, oil-based lubricants),* gases (eg, oxygen, methane, anesthetic agents),* plastics,* electrical failures,* paper or gauze materials,* surgical drapes,* adhesive or plastic tapes, and endotracheal tubes
24Fire extinguishers and water/saline should be immediately available where lasers are used. Special fire/flame-retardant drapes or moistened, reusable fabrics should be used to drape around areas that are close to the laser treatment siteAn endotracheal tube used during laser procedures in the patient's airway or aerodigestive tract should have protection or be specially designed to minimize the potential for fire.
25VI All persons in the laser treatment area should be protected from electrical hazards associated with laser useVisual inspection of laser equipment should be performed by the laser operator after setupLaser service and preventive maintenance should be documented
26VII Personnel working in the nominal hazard zone should demonstrate competency commensuratewith their responsibilitiesLaser safety programs should include but not be limited* to delegation of authority and responsibility for the supervision of laser safety to a laser safety officer or his/her designee;* criteria and authorized procedures for all health care personnel working in nominal hazard zones;* identification of laser hazards and appropriate control measures;* management and reporting of accidents or incidents related to laser procedures, including action plans to prevent reoccurrences; and* fundamentals of laser physics, tissue interaction, instrumentation, and delivery systems
27VIII Policies and procedures for laser safety should be developed with regard toindividual practice settings, applicablestandards, and federal and stateregulations. They should be reviewedperiodically, revised as necessary, andreadily available to all personnel.
28Laser airway surgery Endotracheal intubation Advantages Disadvantages secured airwayability to monitor ETCO2 and O2 conc.decreased risk of soiling the distal airway with debris,blood, or gastric contents.Disadvantagesrisk of an ETT fire,high AWPhigh resistance with spontaneous ventilationdifficulty in suction
29Special ETTs for use in laser surgery Red rubber and PVC tubes are at risk of burningPVC tubes seconds / red rubber tubes secondsLow cost alternative– aluminium foil wrap- cover cuff with moist gauze- methylene blue in saline for cuff inflation
30Special ETT’s Norton - coiled metal rings without cuff Bivona Fome-Cuff - aluminum tube coated with silicone with polyurethane foam cuffXomed Laser-Shield - silicone and non-reflecting metal particlesMalinckrodt Laser-Flex - coiled and flexible metal rings with two distal plastic cuffsSheridan Laser-Trach - red latex covered with atraumatic screen with latex distal cuffRusch Lasertubus – porous sponge coating and doublee cuff (one inside other)
31Laser airway surgery Without Endotracheal intubation Ventilating bronchoscopeJet ventilation- Sander’s injectorAdvantagesSurgical convenienceNo risk of ETT fire
32Laser airway surgery Disadvantages Unable to monitor pCO2 Contamination of lower resp. tractIntermittent endotracheal intubation
33Airway Fire Combustion Flammable substrate Oxidant Speed of combustion Incidence – 1.5%
34Airway Fire Prevention Non flammable substrate / jet ventilation Reducing O2 (30%)Avoid N2OHelium (high thermal conductivity)Avoid Flash point(below critical temp.)
35Airway Fire Management of an airway fire: Plan ahead, review plan with team.Immediately stop ventilation.Disconnect circuit (blow torch effect with flaming ETT and 02 flow).Remove and extinguished flaming ETT in a bucket of water.Extinguish any flaming debris in pharynx with water or saline.
36Reintubate, ventilate with 100% O2, flush pharynx with cold water. Flexible and rigid bronchoscopy to assess damage and remove debris.consider steroids, humidified gases, and prolonged ventilation in ICU.Consider tracheostomy if severe lower airway burn.Monitor CXR, ECG, and ABG's.
37Anesthetic considerations surgical procedurePatient’s pre-existing conditionsHazards of laser surgery to the patient, OR personnel and equipment
38Anesthesiologist must be aware of Laser mediumPhysical propertiesVital structures around the point of focusIceberg effect
39Anesthetic planPreoperative evaluation of the airway (stridor, voice quality, ventilation pattern, flow volume loops, CT, MRI, or fiberoptic airway evaluation)Mutual planning with the surgeon.Aspiration prophylaxisTotal iv anesthesia (propofol, remifentanil, short acting relaxant)Xylocaine spray
40Tooth guard.Methylene blue in ETT cuff.Saline gauze protection of face and airway and keep mucosal surfaces moistLaser should be used in short repeated bursts (pulse), rather than in a prolonged continuous mode.Communicate and monitor video camera for signs of airway fire.O2 < 30% using an air-oxygen mixture, avoid N2O and volatile anesthetic agents.
41Transcutaneous CO2 monitoring if available may be helpful. Esmolol and NTG immediately available for patients with CAD risk factors.smooth emergence with minimal bleeding, coughing or laryngeal spasm