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LASER

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LASER

  1. 1. Light Amplification by the Stimulation of Radiation (LASER) James Ridgway, MD 3/22/07
  2. 2. Patient History <ul><li>Patient is a 18 week old male presenting to pediatrics with a two week history of “noisy breathing” that is worse with crying. This was noted when the child was with mother at work (she works at a daycare facility). This has worsened considerably over the last 5 days with difficulty in feeding and has created a considerable amount of parental concern. Pediatrics has consulted you as med-nebs have had little effect over the last 4 hours. </li></ul>
  3. 3. Patient History <ul><li>PMH: Uneventful full term delivery. Child has had unremarkable history until current condition. </li></ul><ul><li>PSH: None </li></ul><ul><li>Medications: None </li></ul><ul><li>Allergies: NKDA </li></ul><ul><li>SH: Lives with parents, immunizations UTD </li></ul><ul><li>FH: Grandparents with DM, HTN </li></ul>
  4. 4. Physical Examination <ul><li>General: Alert, but with nasal flaring and retractions. + biphasic stridor </li></ul><ul><li>Ears: TM C/I/M AU </li></ul><ul><li>Nose: No evidence of polyp, septal perforation or mass </li></ul><ul><li>OC/OP: 2+ tonsils, no cleft or lesion </li></ul><ul><li>Neck: Soft, supple and without mass or LAD </li></ul><ul><li>Face: Full facial motion and symmetry </li></ul><ul><li>On examination of the left abdomen there is a red, slightly raised lesion that has evolved rapidly over the last week </li></ul>
  5. 5. <ul><li>Vascular: pulmonary artery sling, double aortic arch, anomalous innominate artery, retroesophageal right subclavian artery, hemangioma. </li></ul><ul><li>Infection: bacterial tracheitis, laryngotracheobronchitis, abscess (retropharyngeal/ parapharyngeal/ peritonsillar), croup, epiglottitis, tuberculosis </li></ul><ul><li>Trauma: intubation trauma, foreign body, laryngeal fracture, caustic and thermal burns </li></ul><ul><li>Autoimmune: ? </li></ul><ul><li>Metabolic: hypothyroidism </li></ul><ul><li>Iatrogenic/idiopathic: vocal cord paralysis (unilateral or bilateral), localized malacia secondary to a tracheostomy or TEF repair, subglottic stenosis, arytenoid dislocation, trach obstruction, gastroesophageal reflux. </li></ul><ul><li>Neoplasia: cystic hygroma, rhabdomyoma, neuroblastoma, bronchogenic cyst, teratoma, thymus </li></ul><ul><li>Congenital: laryngomalacia, laryngotracheal stenosis, posterior laryngeal cleft, vallecular cyst, laryngeal cysts, laryngeal webs, laryngocele, arytenoid fixation, complete cartilage rings, tracheobronchomalacia, choanal atresia/stenosis, macroglossia, micrognathia, Arnold-Chiari malformation </li></ul>
  6. 6. Hemangioma <ul><li>A wait-and-see policy was recommended before laser development </li></ul><ul><li>Functional or structural complications should be treated </li></ul><ul><li>Batta et al. - first prospective and randomized controlled study in uncomplicated hemangiomas in 121 children </li></ul><ul><ul><ul><li>FPDL (585nm, 0.45ms, 3–5mm, 6–7.5 J/cm2) </li></ul></ul></ul><ul><ul><ul><li>1 year: 30% in treatment group had resolved, 5% in control </li></ul></ul></ul><ul><ul><ul><li>Residual lesions in 42% of treated, 44% of control </li></ul></ul></ul><ul><ul><ul><li>Hypopigmentations more frequent in treatment group (45% vs. 15%) and also slightly atrophic scars (28% v. 8%) </li></ul></ul></ul><ul><ul><ul><li>Control group: hemangiomas increased by 160% compared to 61% in treatment group </li></ul></ul></ul><ul><li>Tanaka et al. supporting same level of intervention </li></ul>
  7. 7. Subglottic Hemangioma <ul><li>Sie et al. with 10 year experience with CO2 laser in SGH </li></ul><ul><ul><ul><li>Serial procedures and 20% rate of post-treatment subglottic stenosis </li></ul></ul></ul><ul><li>Madgy et al. reviewed six cases of SGH managed with the KTP laser </li></ul><ul><ul><ul><li>Steroids after surgery </li></ul></ul></ul><ul><ul><ul><li>End point was to achieve 60 to 70% airway patency </li></ul></ul></ul><ul><ul><ul><li>3 with mild post-procedural SGS </li></ul></ul></ul><ul><li>Barlow et al. - spastic diplegia in 20% of 26 children less than 2 years of age treated with IFN </li></ul><ul><ul><ul><li>Life threatening </li></ul></ul></ul><ul><ul><ul><li>Hemangiomas respond to steroids in 30 to 60% of cases – IFN administered in non-responders </li></ul></ul></ul>
  8. 8. Treatment <ul><li>Indicators for intervention </li></ul><ul><ul><li>Compromised airway </li></ul></ul><ul><ul><li>Deviation of visual axis </li></ul></ul><ul><ul><li>Oral/digestive tract obstruction </li></ul></ul><ul><ul><li>Bilateral auditory obstruction </li></ul></ul><ul><ul><li>Relative: bleeding, ulceration and potential for significant facial disfigurements </li></ul></ul>
  9. 9. Laser History <ul><li>1917: Einstein first discusses stimulated emissions </li></ul><ul><li>1954: Townes & Gordon – maser </li></ul><ul><li>1958: Townes & Schawlow (Bell Laboratories) publishes first theoretic calculations of then titled laser </li></ul><ul><li>1960: Maimen (Hughes Aircraft) develops first laser (ruby with 694 nm wavelength) </li></ul><ul><li>1961: Neodymium-doped (Nd): glass laser </li></ul><ul><li>1964: Nd:YAG and argon ion (Ar) </li></ul><ul><li>1965: CO2 laser </li></ul><ul><li>1968: Polanyi develops articulating arm for CO2 laser </li></ul><ul><ul><li>Later works with Jako on the ablation of vocal fold papillomatosis </li></ul></ul>
  10. 10. The Laser <ul><li>Three essential elements </li></ul><ul><ul><li>Lasing medium </li></ul></ul><ul><ul><li>Excitation source </li></ul></ul><ul><ul><li>Two mirrors to provide optical feedback </li></ul></ul>
  11. 11. The Laser <ul><li>Resonant Cavity </li></ul><ul><li>Spontaneous emission </li></ul><ul><li>Stimulated emission </li></ul><ul><li>Population inversion </li></ul><ul><li>Laser output </li></ul>
  12. 12. Laser Properties <ul><li>Monochromatic </li></ul><ul><li>Coherent </li></ul><ul><li>Collimated </li></ul><ul><li>High energy density (Power density) </li></ul><ul><ul><li>Irradiance = intensity / area = watts / cm 2 </li></ul></ul><ul><ul><li>Fluence = (intensity X time) / area </li></ul></ul><ul><ul><li>= watts X seconds / cm 2 = J / cm 2 </li></ul></ul>
  13. 13. Laser Delivery <ul><li>Handheld </li></ul><ul><li>Articulating arms </li></ul><ul><li>Optical fiber </li></ul><ul><li>Patient-to-laser </li></ul>
  14. 14. Beam Characteristics <ul><li>Beam waist (d) </li></ul><ul><ul><li>d = 2f  D (f = focal length, D = diameter) </li></ul></ul><ul><li>Depth of focus (Df) </li></ul><ul><ul><li>Df =  X d 2 /2  </li></ul></ul>
  15. 15. Temporal Profiles <ul><li>Continuous or Pulsed </li></ul><ul><li>Mechanical shutter (1ms – 1s) </li></ul><ul><li>Flash-lamp-pumped lasers (1  s – 1ms) </li></ul><ul><li>Q-switched (10ns - 10  s) </li></ul>
  16. 16. Light and Tissue Interactions <ul><li>Absorption </li></ul><ul><li>Scattering </li></ul><ul><li>Reflection </li></ul><ul><li>Transmission </li></ul>
  17. 17. Laser Materials/Properties <ul><li>Infrared light: primarily absorbed by water </li></ul><ul><li>Visible and UV light are absorbed by hemoglobin and melanin </li></ul><ul><li>As wavelength becomes shorter – scatter begins to dominate the penetration of light </li></ul>
  18. 18. Tissue Ablation <ul><li>10 C – 45 C: Conformation change of proteins </li></ul><ul><li>50 C: Reduction of enzyme activity </li></ul><ul><li>60 C: Denaturation </li></ul><ul><li>100 C: Water vaporizes </li></ul><ul><li>Thermal damage </li></ul>
  19. 19. CO2 Laser <ul><li>10,600 nm wavelength </li></ul><ul><ul><ul><li>Water is target chromophore </li></ul></ul></ul><ul><ul><ul><li>Aiming helium-neon (HeNe) beam </li></ul></ul></ul><ul><ul><ul><li>Highest power continuous-wave laser </li></ul></ul></ul><ul><li>Cutting or ablating tool </li></ul><ul><ul><ul><li>Focus to 200  m </li></ul></ul></ul><ul><ul><ul><li>Seals blood vessels less than 0.5 mm </li></ul></ul></ul><ul><ul><ul><li>Pulsed to accommodate thermal relaxation time, less pain and less edema </li></ul></ul></ul><ul><ul><ul><li>Pattern generators </li></ul></ul></ul><ul><li>Work in distal airway in “hands off” fashion </li></ul><ul><ul><ul><li>Used in majority of procedures except those requiring coagulation of larger vessels </li></ul></ul></ul><ul><ul><ul><li>No current optical fiber to carry beam </li></ul></ul></ul>
  20. 20. Nd: YAG Laser <ul><li>1064 nm wavelength (neodymium-doped yttrium aluminum garnet ) </li></ul><ul><ul><ul><li>Aiming helium-neon (HeNe) beam </li></ul></ul></ul><ul><ul><ul><li>Wavelength is between minimal absorption of water and a small amount of scatter </li></ul></ul></ul><ul><ul><ul><li>Solid state laser </li></ul></ul></ul><ul><ul><ul><li>Fiberoptic carrier </li></ul></ul></ul><ul><li>Application </li></ul><ul><ul><ul><li>Deeper penetration (up to 4 mm) for ablative therapy and hemostasis </li></ul></ul></ul><ul><ul><ul><li>Preferentially absorbed by pigmented tissues </li></ul></ul></ul><ul><ul><ul><li>Vascular malformations amenable to treatment </li></ul></ul></ul><ul><ul><ul><li>Used in a multitude of pulmonary, urology and gastroenterology procedures </li></ul></ul></ul><ul><ul><ul><li>Minimally invasive percutaneous laser disk decompression </li></ul></ul></ul><ul><li>Limitations </li></ul><ul><ul><ul><li>Greater scatter than CO2 </li></ul></ul></ul><ul><ul><ul><li>Deep thermal injury </li></ul></ul></ul><ul><ul><ul><li>Risk for transmural injury </li></ul></ul></ul>
  21. 21. Argon Laser <ul><li>488 - 514 nm wavelength (ion laser) </li></ul><ul><ul><ul><li>Oxyhemoglobin is target chromophore </li></ul></ul></ul><ul><ul><ul><li>Small spot size (0.1 – 1 mm) – variable in size and intensity </li></ul></ul></ul><ul><ul><ul><li>Flexible delivery system </li></ul></ul></ul><ul><li>Applications </li></ul><ul><ul><ul><li>Retina or middle ear surgery </li></ul></ul></ul><ul><ul><ul><li>Facial spider veins </li></ul></ul></ul><ul><ul><ul><li>Junctional nevi </li></ul></ul></ul><ul><ul><ul><li>Cherry hemangioma </li></ul></ul></ul><ul><ul><ul><li>Vascular birthmarks </li></ul></ul></ul><ul><li>Limitations </li></ul><ul><ul><ul><li>Also absorbed by epidermal and dermal tissues due to melanin </li></ul></ul></ul><ul><ul><ul><li>Continuous mode of operation </li></ul></ul></ul><ul><ul><ul><li>Higher prevalence of postoperative pigmentary alteration and fibrosis </li></ul></ul></ul><ul><ul><ul><li>Pulsed Dye Laser (PDL) – preferred for many roles Argon laser originally used (treatment of vascular lesions, including spider veins, strawberry birthmarks and port wine stains) </li></ul></ul></ul>
  22. 22. KTP Laser <ul><li>532 nm wavelength (potassium-titanyl-phosphate) </li></ul><ul><ul><ul><li>Frequency doubling </li></ul></ul></ul><ul><ul><ul><li>Nd: YAG laser passes through a KTP crystal – emission is ½ its wavelength </li></ul></ul></ul><ul><ul><ul><li>Oxyhemoglobin is primary chromophore </li></ul></ul></ul><ul><ul><ul><li>Fiberoptic carrier </li></ul></ul></ul><ul><ul><ul><li>Continuous wave (CW) mode to cut tissue </li></ul></ul></ul><ul><ul><ul><li>Pulsed mode for vascular lesions </li></ul></ul></ul><ul><ul><ul><li>Q-Switched mode for red/orange tattoo pigment </li></ul></ul></ul><ul><li>Applications </li></ul><ul><ul><ul><li>Granuloma excision of the respiratory tract </li></ul></ul></ul><ul><ul><ul><li>Subglottic/tracheal stenosis </li></ul></ul></ul><ul><ul><ul><li>Subglottic/supraglottic cyst excision </li></ul></ul></ul><ul><ul><ul><li>Inferior turbinate reduction </li></ul></ul></ul><ul><ul><ul><li>Nasal papilloma excision </li></ul></ul></ul><ul><ul><ul><li>Nasopharyngeal stenosis </li></ul></ul></ul><ul><ul><ul><li>Supraglottoplasty </li></ul></ul></ul><ul><ul><ul><li>Laryngeal papilloma excision </li></ul></ul></ul><ul><ul><ul><li>Middle ear surgery (Cholesteatoma excision, stapes surgery) </li></ul></ul></ul><ul><li>Delivery </li></ul><ul><ul><ul><li>CW/pulsed mode: insulated fiber, fiber handpiece, scanner, or microscope </li></ul></ul></ul><ul><ul><ul><li>Q-Switched mode: articulating arm </li></ul></ul></ul>
  23. 23. Laser Safety <ul><li>Education: attendance at a &quot;hands-on&quot; laser surgery course that stresses safety precautions –proven reduction of laser-related complications </li></ul><ul><li>Development of protocol for safe laser use (credentials, continued education, ect.) </li></ul><ul><li>Dedicated laser technician/ nurse/ engineer </li></ul><ul><li>Team approach in fire prevention and anesthetic management </li></ul><ul><ul><ul><li>Safest anesthetic gas mixture is 30% oxygen in helium Posting of “Laser in use” signs </li></ul></ul></ul><ul><ul><ul><li>Laser specific endotracheal tube </li></ul></ul></ul><ul><li>Eye protection (medical personnel & patient) </li></ul><ul><ul><ul><li>Saline moistened eye pads </li></ul></ul></ul><ul><li>Skin protection: saline-saturated surgical towels </li></ul><ul><li>Smoke evacuation: two separate suction set-ups </li></ul><ul><li>Ebonized surgical instruments </li></ul><ul><li>Placement of signs and additional eye protection outside operative room </li></ul>
  24. 24. While using the CO2 laser in the ablation of laryngeal papillomatosis the ET tube catches fire. What do you do? <ul><li>A: stop inflammable anesthetics </li></ul><ul><li>B: remove ET tube </li></ul><ul><li>C: pour water down the ET tube </li></ul><ul><li>D: OCT </li></ul><ul><li>Time to initiation of fire and burn through the lumen of ET tube: </li></ul><ul><ul><ul><li>0.3 second for T-tube (silicone) </li></ul></ul></ul><ul><ul><ul><li>0.5 s for jet ventilation tube </li></ul></ul></ul><ul><ul><ul><li>0.8 s for PVC endotracheal tube </li></ul></ul></ul><ul><ul><ul><li>5 s for Xomed laser shield endotracheal tube </li></ul></ul></ul><ul><ul><ul><li>Laser-Flex tracheal tube (stainless) and aluminum foil wrapped PVC endotracheal tube did not catch fire after 30 s of CO2 laser irradiation </li></ul></ul></ul><ul><li>In short, the stainless endotracheal tube is the safest tube during CO2 laser surgery. </li></ul>
  25. 25. Patient presents with lesion of the tongue. Which laser is the best choice?
  26. 26. Patient has a predominantly green tattoo that they want to have removed. Which of the following is the best answer? <ul><li>A. Frequency doubling </li></ul><ul><li>B . Q-switched Nd: YAG </li></ul><ul><li>C. Q-switched alexandrite </li></ul><ul><li>D. Q-bert </li></ul>
  27. 27. Ossicular Surgery <ul><li>CO2 </li></ul><ul><ul><ul><li>Pros: absorbed by water, no deep penetration into the inner ear </li></ul></ul></ul><ul><ul><ul><li>Cons: invisible (requires separate aiming beam), alignment of mirrors can be problematic </li></ul></ul></ul><ul><li>KTP, Argon </li></ul><ul><ul><ul><li>Pros: Aiming beam is attenuated, treatment beam can pass through fiberoptic cable </li></ul></ul></ul><ul><ul><ul><li>Cons: Requires pigment for absorption, can pass through clear fluids and potentially damage the inner ear </li></ul></ul></ul>
  28. 28. References <ul><li>Einstein, A. On the quantum theory of radiation. Physikal Zeitschr 1917; 18:121. </li></ul><ul><li>Reinisch L. Laser physics and tissue interactions. Otolaryngol Clin North Am 1996;29(6): 893–912. </li></ul><ul><li>Lai HC, et al. Fires of endotracheal tubes of three different materials during carbon dioxide laser surgery. Acta Anaesthesiol Sin. 2002 Mar;40(1):47-51. </li></ul><ul><li>Batta K, Goodyear HM, Moss C, Williams HC, Hiller L, Waters R. Randomised controlled study of early pulsed dye laser treatment of uncomplicated childhood hemangiomas: results of a 1-year analysis. Lancet 2002; 360: 521–527. </li></ul><ul><li>Ossoff RH:  The co2 laser in otolaryngology-head and neck surgery: a retrospective analysis of complications.   Laryngoscope  1983; 93:1287. </li></ul><ul><li>Abramson AL, DiLorenzo TP, Steinberg BM:  Is papillomavirus detectable in the plume of laser-treated laryngeal papilloma?.   Arch Otolaryngol Head Neck Surg  1990; 116:604. </li></ul><ul><li>Tanaka R, Miyasaka M, Taira H, Tanino R. Comparison of pulsed dye laser and wait and see policy in treatment of childhood hemangioma. Lasers Surg Med 2005; 17: 35. </li></ul><ul><li>Barlow CF, Priebe CJ, Mulliken JB, et al.: Spastic diplegia as a complication of interferon Alpha-2a treatment of hemangiomas of infancy. J Pediatr 1998, 132:527–530. </li></ul><ul><li>Sie KC, McGill T, Healy GB: Subglottic hemangioma: ten years’ experience with the carbon dioxide laser. Ann Otol Rhinol Laryngol 1994, 103:167–172. </li></ul><ul><li>Madgy D, Ahsan SF, Kest D, Stein I: The application of the Potassium-Titanyl- Phosphate (KTP) laser in the management of subglottic hemangioma. Arch Otolaryngol Head Neck Surg 2001, 127:47–50. </li></ul><ul><li>American National Standards Institute :  American national standard for the safe use of lasers, Z136.1,   New York, American National Standards Institute, 1996. </li></ul><ul><li>Shah H:  Benign tumors of the tracheobronchial tree. Endoscopic characteristics and role of laser resection.   Chest  1995; 107:1744. </li></ul><ul><li>Karamzadeh, AM, et al. Lasers in pediatric airway surgery: current and future clinical applications. Lasers Surg Med. 2004;35(2):128-34. </li></ul><ul><li>Strunk Jr CL, Quinn Jr FB:  Stapedectomy surgery in residency: KTP-532 laser versus argon laser.   Am J Otolaryngol  1993; 14:113. </li></ul><ul><li>Cummings: Otolaryngology: Head & Neck Surgery, 4 th ed. 2005 Mosby, Inc. </li></ul><ul><li>Landthaler, M, Hohenleutner, U. Laser therapy of vascular lesions. Photodermatol Photoimmunol Photomed 2006; 22: 324–332 </li></ul><ul><li>Brown, DH. The Versatile Contact Nd:YAG Laser in Head and Neck Surgery: An in Vivo and Clinical Analysis. Laryngoscope 110: May 2000. 854-867. </li></ul><ul><li>Pransky, SM, Canto, C. Management of subglottic hemangioma. Curr Opin Otolaryngol Head Neck Surg. 2004 Dec;12(6):509-12. </li></ul>

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