The document discusses lasers and their applications in anaesthesia and surgery. It provides a brief history of lasers, explaining their basic physics and properties. It describes different types of lasers used in medicine like CO2, Nd:YAG, and argon lasers. It discusses biological effects of laser light and various clinical applications of lasers. It also outlines safety considerations for lasers, including protection of the eyes, endotracheal tube fires, and protocols for managing laser-related hazards and emergencies.

1. LASERS AND ANAESTHESIA Dr.P.Narasimha Reddy, Professor, Dept of Anaesthesiology, Narayana medical college, Nellore.

2. Laser printer Laser pointer Laser: everywhere in your life

3. “ Never are cooperation and communication between surgeon and anaesthetist more impartant than during head and neck surgery.” - MORGAN Clinical anaesthesia

4. Introduction 1. history 2.properties of laser 3.basic physics 4.proreties of laser 5.laser hardware 6.biological effects 7.applications of laser 8.dangers of lasers 9.anaesthesia considerations 10.protection strategies

5. L - LIGHT A - AMPLIFICATION BY S - STIMULATED E - EMISSION OF R - RADIATION TRANSFER OF LARGE QUANTITIES OF ENERGY RAPIDLY TO REMOTE LOCATIONS LASER

6. VISUAL LIGHT IS ELECTROMAGNETIC RADIATION (RADIOWAVES,X- RAYS,GAMMA RAYS) 1864 – MAXWELL-ELECTRICAL,MAGNETIC OSCILLATIONS- 299,792,458 m/sec - MAX PLANCK-PHOTO ELECTRIC EFFECT-1 st STEP TOWARDS LASER PHYSICS PHYSICS

7. 1905 – EINSTEIN – THEORETICAL BASIS FOR LASER ACTION - ELECTROMAGNETIC RADIATION CONSISTS OF PHOTONS

8. PROPERTIES OF PHOTONS Properties consistent with both particles and waves. Propagate in vaccum with spreads of 299,792,458 m/sec. Energy proportional to their vibrational frequency E(joules) =n h v n -an integral number h – Planck constant 6.63 × 10¯ 24 j/sec v – photon frequency in hertz Their wave lenghts can be calculated as follows Λ (m)= 2.998×10 to the power of 8 m/sec V (hz) wave lenghts of visible light is 385 to 760 nm

11. Monochromatic Consists of photons-well defined very narrow band of wave lenghts. Coherent (electromagnetic fields of all photons oscillate synchronously in identical phase). Beams are collimated (minimal dispersion-parallel). Allow lasers to generate intense light beams to send such beams efficiently & accurately through lenses-deliver intense energy to small target sites Polychromatic Wide spectrum of wave lengths. Electromagnetic fields phased randomly. Spread out in all directions from a point of source. LASER LIGHT ORDINARY LIGHT

12. Basic concepts for a laser Absorption Spontaneous Emission Stimulated Emission Population inversion

13. Absorption Energy is absorbed by an atom, the electrons are excited into vacant energy shells.

14. Spontaneous Emission The atom decays from level 2 to level 1 through the emission of a photon with the energy hv . It is a completely random process.

15. Stimulated Emission atoms in an upper energy level can be triggered or stimulated in phase by an incoming photon of a specific energy .

16. Stimulated Emission The stimulated photons have unique properties: In phase with the incident photon Same wavelength as the incident photon Travel in same direction as incident photon

17. Population Inversion A state in which a substance has been energized, or excited to specific energy levels. More atoms or molecules are in a higher excited state. The process of producing a population inversion is called pumping . Examples: -> by lamps of appropriate intensity -> by electrical discharge

18. How a laser works?

19. 1. High-voltage electricity causes the quartz flash tube to emit an intense burst of light, exciting some of Cr 3+ in the ruby crystal to higher energy levels. 2. At a specific energy level, some Cr 3+ emit photons. At first the photons are emitted in all directions. Photons from one Cr 3+ stimulate emission of photons from other Cr 3+ and the light intensity is rapidly amplified.

20. 3. Mirrors at each end reflect the photons back and forth, continuing this process of stimulated emission and amplification. 4. The photons leave through the partially silvered mirror at one end. This is laser light.

21. Laser Construction A pump source A gain medium or laser medium. Mirrors forming an optical resonator.

22. Pump Source Provides energy to the laser system Examples: electrical discharges, flashlamps, arc lamps and chemical reactions. The type of pump source used depends on the gain medium. -> A helium-neon (HeNe) laser uses an electrical discharge in the helium-neon gas mixture. -> Excimer lasers use a chemical reaction.

23. Optical Resonator Two parallel mirrors placed around the gain medium. Light is reflected by the mirrors back into the medium and is amplified . The design and alignment of the mirrors with respect to the medium is crucial . Spinning mirrors, modulators, filters and absorbers may be added to produce a variety of effects on the laser output.

24. Laser medium containing the atoms whose electrons create the laser light Resonating mirrors - to boost laser efficiency Energy source- excite or pump the atoms of the laser medium into producing laser light. Gas lasers- co2 ,Argon, krypton, helium – neon LASER SYSTEM HARDWARE

25. Laser Types According to the active material : solid-state, liquid, gas, excimer or semiconductor lasers. According to the wavelength : infra-red, visible, ultra-violet (UV) or x-ray lasers.

26. Solid-state Laser Example: Ruby Laser Operation wavelength: 694.3 nm (IR) 3 level system: absorbs green/blue Gain Medium: crystal of aluminum oxide (Al 2 O 3 ) with small part of atoms of aluminum is replaced with Cr 3+ ions. Pump source: flash lamp The ends of ruby rod serve as laser mirrors.

27. Gas Laser Example: Helium-neon laser (He-Ne laser) Operation wavelength: 632.8 nm Pump source: electrical discharge Gain medium : ratio 5:1 mixture of helium and neon gases

28. Schematic diagram of a dye laser DYE LASER A dye laser can be considered to be basically a four-level system. The energy absorbed by the dye creates a population inversion, moving the electrons into an excited state.

29. SOLIDS- DOPANTS-CHROMIUM(AS IN RUBY LASER), NEODYMIUM(Nd),HOLMIUM (Ho), YAG(YTTRIUM,ALUMINIUM,GARNET-SYNTHETIC GEM CRYSTAL) -PUMPED BY HIGH ENERGY PHOTONS FROM XENON FLASH LAMP. LIQUIDS – YET TO APPEAR

33. BIOLOGIC EFFECTS OF LASER LIGHT

34. Biological effects of laser CRITICAL TEMP ( 0 C) BIOLOGICAL EVENT 42 Warmed 45 Cell death, edema, endothelial damage 60 Protein coagulation 80 Collagen denaturation 100 Tissue boils 210 Dehydrated tissue burns

35. Biological effects of laser Carbon dioxide Laser Completely absorbed by water in first few layers of cells – vaporization of surface tissue with little damage to underlying tissue. Nd-YAG Laser Less absorbed by water and beam diffuses through several millimeters – energy is disseminated producing less vaporization and more coagulation (Cooking Effect).

36. commonly used Laserlights Laser media Color Wavelength (nm) Typical application Carbon dioxide Far infrared 10,600 General, cutting Ruby Red 694 Tattoos, nevi KTP:YAG Green 532 General, pigmented lesions Argon Green 514 Vascular, pigmented lesions Xenon fluoride Ultraviolet 351 Cornea, angioplasty

37. LASERS ARE NOT VERY EFFICIENT AT CONVERTING ELECTRICITY INTO LIGHT,THEY REQUIRE A LARGE POWER SUPPLY. FREQENCY DOUBLES TO CONVERT LASER LIGHT TO DIFFERRENT WAVE LENGTH ENHANCING THERAUPETIC FLEXIBILITY

38. DR.GERRY ROSS CLINICAL APPLICATIONS PIONEER OF LASER THERAPY

39. CLINICAL APPLICATIONS Scalpels Electrocoagulation Highly precise micro surgery (confined or difficult to reach sites-percutaneous discectomy, endovascular angioplasty) Small target areas-concentrate intensity or power per area enormously. Precise rapid evoparisation of tissues

42. ARGON LASER

43. ARGON LASER PAN RETINAL

44. COSMETIC LASER SURGERY

45. LASER IRIDOTOMY

46. LASER REVASCULARISATION

47. LASER TO RESHAPE CORNEA

48. LASER SKIN RESURFACING

49. LASER LIPOSUCTION

51. HAIR REMOVAL

52. LASER PLASTIC SURGERY-SAGGING

53. LASER TO MAKE AN INCISION

54. LASER VISION CORRECTION

55. ADVANTAGES Laser surgery Relatively dry Near instantaneous ceiling of blood vessels, lymphatics even in presence of coagulation abnormalities Faster healing Lower infection rates

56. LASER HAZARDS

57. Safety Considerations

58. LASER HAZARDS Atmospheric contamination-laser plumes -Objectional odour,tears, headache, nausea. -Interstitial pneumonia, bronchiolitis,emphysema -Mutogenic & teratogenic

59. Laser plume Protection Efficient smoke evacuator at surgical site. Use of special high efficiency mask : Tex, protector II, Ango, Fort worth Ordinary surgical mask gives protection from molecules up to 3.0 µm size.

60. Plume of smoke and fine particulates (mean size 0.31um) Efficiently transported and deposited in the alveoli Sensitive individuals: headaches, tearing, and nausea after inhalation Animal study: interstitial pneumonia, bronchiolitis, reduced mucociliary clearance, inflammation, emphysema Prevention -> smoke evacuator -> high-efficiency masks Atmospheric contamination

61. LASER HAZARDS CONTD … 2.Tissue and vessel perforation(misdirected laser energy) -Viscous perforation -vessels more than 5 mm not coaguable by lasers -Pneumothorax(after laryngeal perforation) Perforational bleeding after several days post operatively with edema and necrosis. 3.Embolism- VAE 4.Energy transfer to an inappropriate location

62. Incidentally pressing the laser control trigger Tissue damage outside of surgical site Drape fire Eye (patient or other medical staff) Endotracheal tube fires Inappropriate energy transfer

63. EYE PROTECTION Operating room staff- goggles or lenses specific for specific laser wave length. Patient-non operated eye-taped, closed,covered with an opaque saline soaked knit or metal shields.

64. Eyes Protection Protection of OT staff eyes : Safety goggles or lenses specific for laser wave length in use. CO 2 Laser – any clear glass or plastic lenses. Nd:YAG Laser – green tinted or clear lenses. Argon & Krypton – Amber orange. KTP-Nd:YAG – Red.

65. E.T.T. FIRES Airway surgery-ignition of ETT, cuff, or cottonoids Most fires on external surface of ETT-because of O 2 .

66. Reduce the flammability of the endotracheal tube Use Venturi ventilation Use intermittent apnea technique Approaches to reduce the incidence of airway fire

67. Incidence: 0.5 – 1.5 % Source: direct laser illumination reflected laser light incandescent particles of tissue blown from the surgical site Endotracheal tube fires

68. E.T.T. FIRES (CONTD….) Reduction of flammability of ETT Choice of ETT. Extrinsic protection: - Moistened muslin (dry-fire) - Dental acrilic (trauma) 3. ETT taping-aluminium , copper foil with adhesive backing.Cuff is not protected- well supported by medical literature-no fda approval.Lead foil should not be used-toxic to airway

69. Various endotracheal tubes for laser airway surgery Type of tube Advantages Disadvantages Polyvinyl chloride Inexpensive, nonreflective Low melting point, highly combustible Red rubber Puncture-resistant, maintains structure, nonreflective Highly combustible Silicone rubber Nonreflective Combustible, turns to toxic ash Metal Combustion-resistant, kink-resistant Thick-walled flammable cuff, transfers heat, reflects laser, cumbersome

70. A clean tube wiped with alcohol later with mastisol or tincture benzion. The end of the tape cut at 60°- cut edge proximal end of cuff junction- rapped in spiral way with 30% overlap,to the exit point of cuff pilot tube

71. No cuff protection Adds thickness to tube Not an FDA-approved device Protection varies with type of metal foil Adhesive backing may ignite May reflect laser on to non-targeted tissue Rough edges may damage mucosal surfacess Disadvantages of wrapping

72. Oxygen and nitrous oxide are powerful oxidizers Reduce FiO 2 to minimum concentration Helium may benefit as a diluent gas Volatile anesthetics currently used are nonflammable and nonexplosive Pyrolized toxic compounds Effect of high oxygen and nitrous oxide gas mixture

73. FDA APPROVED ETT WRAPS Merocel laser guard - - Metal foil laminated to a synthetic sponge kept moist - protection against co2, argon, ktp:nd:yag (but not yag) lasers - ETT diameter increased by 2 mm. - No protection for the cuff.

74. FDA APPROVED ETT WRAPS CONTD … Integrated laser resistent coating in the manufacture of ett- CO 2 laser - Xomed laser shield tube (fabricated from silicon with an outer layer of aluminium powder with silicon-aluminised layer extends over inflatable cuff.)

75. FDA APPROVED ETT WRAPS CONTD… .Laser shield ii- CO 2 ,ktp laser -silicon based wrapped by a coated alluminium tape - The cuff-unshielded silicon elastoma-designed to be expanded with saline and methylene blue.

76. PROTECTION OF ETT CUFF standard hi-lo cuff -colored saline. Cuff-placed as far distal in the trachea as possible. Surgeon should cover the visible cuff with moistened cotton pledges-cotton strings attached to pledges replaced by wire- pledges re moistened as needed.

77. METAL ETT NORTON DE VOS(1978 ) - Interlocking stainless spiral coil (resembling electrical cable armour)-no cuff. - Difficult ventillation-non compliance

78. 2 . LASER FLEX TUBE : - Air tight stainless spiral -Two distal saline inflatable pvc cuffs -resistent to CO 2 :ktp but not nd:yag 6mm size

79. THE BIVONA FOAM CUFF: - Aluminium spiral tube -Outer covering of silicon -Unique self inflating foam sponge filled cuff which prevents deflation after puncture.

80. Precautions to prevent fire Low FiO 2. Avoid nitrous oxide. Cuff should be filled with saline with methylene blue. Addition of 2% lignocaine jelly in water for filling of cuff. Limit laser density and duration. Laser resistant tubes. Saline soaked swabs in airway. Availability of source of water.

81. Regional anesthesia-best topical to nerve blocks with proper sedation especially for airway surgery . LOCAL TOPICAL CREAM TOPICAL ANAESTHETIC CONSIDERATIONS

82. 2. GENERAL ANESTHESIA-LARGE BORE IV NEEDLE - MAC - TIVA - G.A.

83. G.A. Premedication :-sedation,analgesia, Parasympatholytics must(vagal hyperactivity-for airway surgery). Induction:- i.V.,Inhalational better avoided. ETT :relaxant Maintainance :no N 2 O, inhalational anaesthetic, FIO 2 should be less than 40%. Spontaneous ventilation :(TIVA) Controlled ventilation Jet ventilation( close or remote) -Endolaryngeal surgery -Complications:barotrauma,pneumothorax,co poisoning,hypoxia.

84. Barotrauma Pneumothorax Restriction to only intravenous agents Gastric distention Relative requirement for compliant lungs Jet ventilation Intermittent apnea technique Hypoventilation Pulmonary aspiration

85. Monitoring Mandatory - pulse oximetry - ETCO2 - Temparature - TEE(VAE) Routine:-ECG/IBP/NIBP/CVP/ABG

86. AIRWAY FIRE CONTROL PROTOCOL Surgeon & anaesthesiologist-act qiuckly,decisively& in a coordinated fashion. Surgeon:qiuckly to remove the source. Anaesthetist:stop ventilation,disconnect the breathing circiut (temporarily) Flame extinguished with a bucket of water(available) Then ventilation with 100% O 2 , anaesthesia must be continued.

87. Remove source of fire (the laser!). Stop ventilating, disconnect circuit, extubate. Extinguish fire in bucket of water (must have one ready!). Mask ventilate with 100% O 2 , continue anaesthesia i.v. Direct laryngoscopy & rigid bronchoscopy for damage and debris. Airway fires protocol ( I)

88. Reintubate if damage. Blowtorch fire may need distal fibreoptic bronchoscopy and lavage. Severe damage may need low tracheostomy. Assess oropharynx and face. CXR. Steroids. Airway fires protocol (II)

89. AIRWAY FIRE CONTROL PROTOCOL Direct laryngoscopy-survey damage, remove debris,gentle bronchial lavage. Fibre optic assessment of most distal airways If pulmonary damage prolonged intubation & mechanical ventilation,brief course of high dose steroids

90. Applications of laser 1. Scientific a. Spectroscopy b. Lunar laser ranging c. Photochemistry d. Laser cooling e. Nuclear fusion

91. 2 Military a. Death ray b. Defensive applications c. Strategic defense initiative d. Laser sight e. Illuminator f. Rangefinder g. Target designator Applications of laser

92. 3. Medical a. eye surgery b. cosmetic surgery c. many more Applications of laser

93. 4. Industry & Commercial a. cutting, welding, marking b. CD player, DVD player c. Laser printers, laser pointers d. Photolithography e. Laser light display Applications of laser

94. CONCLUSIONS Stimulation emission is the basis of laser phenomenon CO 2 laser high risk of remote fires-invisible infrared –transmitted to surgical site in a beam through free air

95. CONCLUSIONS (CONTD….) Different laser sources – different eye protection - Co2 any glass / plastic -Others-type specific protection

96. CONCLUSIONS (CONTD..) SPECIAL ETT N 2 0,FIO 2 ,inhalational anaesthetics support combustion Special anaesthetic techniques Careful monitoring. Effective prevention,management of complications

97. THANK YOU THANK Q

98. Any questions?