Light Amplification by the Light Amplification by the Stimulation of Radiation Stimulation of Radiation

(LASER)(LASER)

James Ridgway, MDJames Ridgway, MD

3/22/073/22/07

Patient HistoryPatient History

Patient is a 18 week old male presenting to Patient is a 18 week old male presenting to pediatrics with a two week history of “noisy pediatrics with a two week history of “noisy breathing” that is worse with crying. This was breathing” that is worse with crying. This was noted when the child was with mother at work noted when the child was with mother at work (she works at a daycare facility). This has (she works at a daycare facility). This has worsened considerably over the last 5 days with worsened considerably over the last 5 days with difficulty in feeding and has created a difficulty in feeding and has created a considerable amount of parental concern. considerable amount of parental concern. Pediatrics has consulted you as med-nebs have Pediatrics has consulted you as med-nebs have had little effect over the last 4 hours.had little effect over the last 4 hours.

Patient HistoryPatient History

PMH: Uneventful full term delivery. Child PMH: Uneventful full term delivery. Child has had unremarkable history until current has had unremarkable history until current condition.condition.PSH: NonePSH: NoneMedications: NoneMedications: NoneAllergies: NKDAAllergies: NKDASH: Lives with parents, immunizations SH: Lives with parents, immunizations UTDUTDFH: Grandparents with DM, HTNFH: Grandparents with DM, HTN

Physical ExaminationPhysical Examination

General: Alert, but with nasal flaring General: Alert, but with nasal flaring and retractions. + biphasic stridorand retractions. + biphasic stridorEars: TM C/I/M AUEars: TM C/I/M AUNose: No evidence of polyp, septal Nose: No evidence of polyp, septal perforation or massperforation or massOC/OP: 2+ tonsils, no cleft or lesionOC/OP: 2+ tonsils, no cleft or lesionNeck: Soft, supple and without mass Neck: Soft, supple and without mass or LADor LADFace: Full facial motion and symmetry Face: Full facial motion and symmetry On examination of the left abdomen On examination of the left abdomen there is a red, slightly raised lesion there is a red, slightly raised lesion that has evolved rapidly over the last that has evolved rapidly over the last weekweek

Vascular: pulmonary artery sling, double aortic arch, anomalous innominate Vascular: pulmonary artery sling, double aortic arch, anomalous innominate artery, retroesophageal right subclavian artery, hemangioma.artery, retroesophageal right subclavian artery, hemangioma.Infection: bacterial tracheitis, laryngotracheobronchitis, abscess Infection: bacterial tracheitis, laryngotracheobronchitis, abscess (retropharyngeal/ parapharyngeal/ peritonsillar), croup, epiglottitis, (retropharyngeal/ parapharyngeal/ peritonsillar), croup, epiglottitis, tuberculosistuberculosisTrauma: intubation trauma, foreign body, laryngeal fracture, caustic and Trauma: intubation trauma, foreign body, laryngeal fracture, caustic and thermal burns thermal burns Autoimmune: ?Autoimmune: ?Metabolic: hypothyroidismMetabolic: hypothyroidismIatrogenic/idiopathic: vocal cord paralysis (unilateral or bilateral), localized Iatrogenic/idiopathic: vocal cord paralysis (unilateral or bilateral), localized malacia secondary to a tracheostomy or TEF repair, subglottic stenosis, malacia secondary to a tracheostomy or TEF repair, subglottic stenosis, arytenoid dislocation, trach obstruction, gastroesophageal reflux.arytenoid dislocation, trach obstruction, gastroesophageal reflux.Neoplasia: cystic hygroma, rhabdomyoma, neuroblastoma, bronchogenic Neoplasia: cystic hygroma, rhabdomyoma, neuroblastoma, bronchogenic cyst, teratoma, thymus cyst, teratoma, thymus Congenital: laryngomalacia, laryngotracheal stenosis, posterior laryngeal Congenital: laryngomalacia, laryngotracheal stenosis, posterior laryngeal cleft, vallecular cyst, laryngeal cysts, laryngeal webs, laryngocele, arytenoid cleft, vallecular cyst, laryngeal cysts, laryngeal webs, laryngocele, arytenoid fixation, complete cartilage rings, tracheobronchomalacia, choanal fixation, complete cartilage rings, tracheobronchomalacia, choanal atresia/stenosis, macroglossia, micrognathia, Arnold-Chiari malformation atresia/stenosis, macroglossia, micrognathia, Arnold-Chiari malformation

Hemangioma Hemangioma

A wait-and-see policy was recommended before laser developmentFunctional or structural complications should be treatedBatta et al. - first prospective and randomized controlled study in uncomplicated hemangiomas in 121 children

FPDL (585nm, 0.45ms, 3–5mm, 6–7.5 J/cm2)1 year: 30% in treatment group had resolved, 5% in controlResidual lesions in 42% of treated, 44% of controlHypopigmentations more frequent in treatment group (45% vs. 15%) and also slightly atrophic scars (28% v. 8%)Control group: hemangiomas increased by 160% compared to 61% in treatment group

Tanaka et al. supporting same level of intervention

Subglottic HemangiomaSubglottic Hemangioma

Sie et al. with 10 year experience with CO2 laser in SGH Serial procedures and 20% rate of post-treatment subglottic stenosis

Madgy et al. reviewed six cases of SGH managed with the KTP laser

Steroids after surgeryEnd point was to achieve 60 to 70% airway patency3 with mild post-procedural SGS

Barlow et al. - spastic diplegia in 20% of 26 children less than 2 years of age treated with IFN

Life threateningHemangiomas respond to steroids in 30 to 60% of cases – IFN administered in non-responders

TreatmentTreatment

Indicators for interventionIndicators for intervention– Compromised airwayCompromised airway– Deviation of visual axisDeviation of visual axis– Oral/digestive tract obstructionOral/digestive tract obstruction– Bilateral auditory obstructionBilateral auditory obstruction

– Relative: bleeding, ulceration and potential for Relative: bleeding, ulceration and potential for significant facial disfigurementssignificant facial disfigurements

Laser HistoryLaser History

1917: Einstein first discusses stimulated emissions1917: Einstein first discusses stimulated emissions1954: Townes & Gordon – maser1954: Townes & Gordon – maser1958: Townes & Schawlow (Bell Laboratories) publishes 1958: Townes & Schawlow (Bell Laboratories) publishes first theoretic calculations of then titled laserfirst theoretic calculations of then titled laser1960: Maimen (Hughes Aircraft) develops first laser 1960: Maimen (Hughes Aircraft) develops first laser (ruby with 694 nm wavelength)(ruby with 694 nm wavelength)1961: Neodymium-doped (Nd): glass laser1961: Neodymium-doped (Nd): glass laser1964: Nd:YAG and argon ion (Ar)1964: Nd:YAG and argon ion (Ar)1965: CO2 laser1965: CO2 laser1968: Polanyi develops articulating arm for CO2 laser 1968: Polanyi develops articulating arm for CO2 laser – Later works with Jako on the ablation of vocal fold papillomatosisLater works with Jako on the ablation of vocal fold papillomatosis

The LaserThe Laser

Three essential elementsThree essential elements– Lasing mediumLasing medium– Excitation sourceExcitation source– Two mirrors to provide optical feedbackTwo mirrors to provide optical feedback

The LaserThe Laser

Resonant Resonant CavityCavitySpontaneous Spontaneous emissionemissionStimulated Stimulated emissionemissionPopulation Population inversioninversionLaser outputLaser output

Laser PropertiesLaser Properties

MonochromaticMonochromatic

CoherentCoherent

CollimatedCollimated

High energy density (Power density)High energy density (Power density)– Irradiance = intensity / area = watts / cmIrradiance = intensity / area = watts / cm22

– Fluence = (intensity X time) / areaFluence = (intensity X time) / area

= watts X seconds / cm= watts X seconds / cm2 2 = J / cm= J / cm22

Laser DeliveryLaser Delivery

HandheldHandheld

Articulating armsArticulating arms

Optical fiberOptical fiber

Patient-to-laserPatient-to-laser

Beam CharacteristicsBeam Characteristics

Beam waist (d)Beam waist (d)– d = 2fd = 2fD (f = focal length, D = diameter) D (f = focal length, D = diameter)

Depth of focus (Df)Depth of focus (Df)– Df = Df = X d X d2 2 /2/2

Temporal ProfilesTemporal Profiles

Continuous or PulsedContinuous or Pulsed

Mechanical shutter (1ms – 1s)Mechanical shutter (1ms – 1s)

Flash-lamp-pumped lasers (1Flash-lamp-pumped lasers (1s – 1ms)s – 1ms)

Q-switched (10ns - 10Q-switched (10ns - 10s)s)

Light and Tissue InteractionsLight and Tissue Interactions

AbsorptionAbsorption

ScatteringScattering

ReflectionReflection

TransmissionTransmission

Laser Materials/PropertiesLaser Materials/PropertiesInfrared light: primarily Infrared light: primarily absorbed by waterabsorbed by waterVisible and UV light are Visible and UV light are absorbed by hemoglobin absorbed by hemoglobin and melaninand melaninAs wavelength becomes As wavelength becomes shorter – scatter begins shorter – scatter begins to dominate the to dominate the penetration of lightpenetration of light

Tissue AblationTissue Ablation

10 C – 45 C: 10 C – 45 C: Conformation change of Conformation change of proteinsproteins50 C: Reduction of 50 C: Reduction of enzyme activityenzyme activity60 C: Denaturation 60 C: Denaturation 100 C: Water vaporizes100 C: Water vaporizes

Thermal damageThermal damage

CO2 LaserCO2 Laser

10,600 nm wavelength10,600 nm wavelength Water is target chromophoreWater is target chromophore Aiming helium-neon (HeNe) beamAiming helium-neon (HeNe) beam Highest power continuous-wave laserHighest power continuous-wave laser

Cutting or ablating toolCutting or ablating toolFocus to 200 Focus to 200 mmSeals blood vessels less than 0.5 mmSeals blood vessels less than 0.5 mmPulsed to accommodate thermal relaxation time, less pain Pulsed to accommodate thermal relaxation time, less pain and less edemaand less edemaPattern generatorsPattern generators

Work in distal airway in “hands off” fashionWork in distal airway in “hands off” fashionUsed in majority of procedures except those requiring Used in majority of procedures except those requiring coagulation of larger vesselscoagulation of larger vesselsNo current optical fiber to carry beamNo current optical fiber to carry beam

Nd: YAG LaserNd: YAG Laser

1064 nm wavelength (neodymium-doped yttrium aluminum garnet )1064 nm wavelength (neodymium-doped yttrium aluminum garnet ) Aiming helium-neon (HeNe) beamAiming helium-neon (HeNe) beam Wavelength is between minimal absorption of water and a small amount of Wavelength is between minimal absorption of water and a small amount of scatterscatter Solid state laserSolid state laser Fiberoptic carrierFiberoptic carrier

ApplicationApplicationDeeper penetration (up to 4 mm) for ablative therapy and hemostasisDeeper penetration (up to 4 mm) for ablative therapy and hemostasisPreferentially absorbed by pigmented tissuesPreferentially absorbed by pigmented tissuesVascular malformations amenable to treatmentVascular malformations amenable to treatmentUsed in a multitude of pulmonary, urology and gastroenterology proceduresUsed in a multitude of pulmonary, urology and gastroenterology proceduresMinimally invasive percutaneous laser disk decompressionMinimally invasive percutaneous laser disk decompression

LimitationsLimitationsGreater scatter than CO2Greater scatter than CO2Deep thermal injuryDeep thermal injuryRisk for transmural injuryRisk for transmural injury

Argon LaserArgon Laser

488 - 514 nm wavelength (ion laser)488 - 514 nm wavelength (ion laser) Oxyhemoglobin is target chromophoreOxyhemoglobin is target chromophore Small spot size (0.1 – 1 mm) – variable in size and intensitySmall spot size (0.1 – 1 mm) – variable in size and intensity Flexible delivery systemFlexible delivery system

ApplicationsApplicationsRetina or middle ear surgeryRetina or middle ear surgeryFacial spider veinsFacial spider veinsJunctional neviJunctional neviCherry hemangiomaCherry hemangiomaVascular birthmarksVascular birthmarks

LimitationsLimitationsAlso absorbed by epidermal and dermal tissues due to melaninAlso absorbed by epidermal and dermal tissues due to melaninContinuous mode of operationContinuous mode of operationHigher prevalence of postoperative pigmentary alteration and fibrosis Higher prevalence of postoperative pigmentary alteration and fibrosis Pulsed Dye Laser (PDL) – preferred for many roles Argon laser Pulsed Dye Laser (PDL) – preferred for many roles Argon laser originally used (treatment of vascular lesions, including spider veins, originally used (treatment of vascular lesions, including spider veins, strawberry birthmarks and port wine stains)strawberry birthmarks and port wine stains)

KTP LaserKTP Laser532 nm wavelength (potassium-titanyl-phosphate)532 nm wavelength (potassium-titanyl-phosphate)

Frequency doublingFrequency doublingNd: YAG laser passes through a KTP crystal – emission is ½ its wavelengthNd: YAG laser passes through a KTP crystal – emission is ½ its wavelengthOxyhemoglobin is primary chromophoreOxyhemoglobin is primary chromophoreFiberoptic carrierFiberoptic carrierContinuous wave (CW) mode to cut tissueContinuous wave (CW) mode to cut tissuePulsed mode for vascular lesionsPulsed mode for vascular lesionsQ-Switched mode for red/orange tattoo pigmentQ-Switched mode for red/orange tattoo pigment

ApplicationsApplicationsGranuloma excision of the respiratory tractSubglottic/tracheal stenosisSubglottic/supraglottic cyst excisionInferior turbinate reductionNasal papilloma excisionNasopharyngeal stenosisSupraglottoplastyLaryngeal papilloma excisionMiddle ear surgery (Cholesteatoma excision, stapes surgery)

DeliveryDeliveryCW/pulsed mode: insulated fiber, fiber handpiece, scanner, or microscope CW/pulsed mode: insulated fiber, fiber handpiece, scanner, or microscope Q-Switched mode: articulating arm Q-Switched mode: articulating arm

Laser SafetyLaser SafetyEducation: attendance at a "hands-on" laser surgery course that Education: attendance at a "hands-on" laser surgery course that stresses safety precautions –proven reduction of laser-related stresses safety precautions –proven reduction of laser-related complications complications Development of protocol for safe laser use (credentials, continued Development of protocol for safe laser use (credentials, continued education, ect.)education, ect.)Dedicated laser technician/ nurse/ engineerDedicated laser technician/ nurse/ engineerTeam approach in fire prevention and anesthetic managementTeam approach in fire prevention and anesthetic management

Safest anesthetic gas mixture is 30% oxygen in helium Posting of “Laser in Safest anesthetic gas mixture is 30% oxygen in helium Posting of “Laser in use” signsuse” signsLaser specific endotracheal tubeLaser specific endotracheal tube

Eye protection (medical personnel & patient)Eye protection (medical personnel & patient)Saline moistened eye padsSaline moistened eye pads

Skin protection: saline-saturated surgical towelsSkin protection: saline-saturated surgical towelsSmoke evacuation: two separate suction set-upsSmoke evacuation: two separate suction set-upsEbonized surgical instrumentsEbonized surgical instrumentsPlacement of signs and additional eye protection outside operative Placement of signs and additional eye protection outside operative roomroom

While using the CO2 laser in the ablation of laryngeal While using the CO2 laser in the ablation of laryngeal papillomatosis the ET tube catches fire. What do you do?papillomatosis the ET tube catches fire. What do you do?

A: stop inflammable anestheticsB: remove ET tubeC: pour water down the ET tubeD: OCT

Time to initiation of fire and burn through the lumen of ET tube:Time to initiation of fire and burn through the lumen of ET tube:0.3 second for T-tube (silicone)0.3 second for T-tube (silicone)0.5 s for jet ventilation tube0.5 s for jet ventilation tube0.8 s for PVC endotracheal tube0.8 s for PVC endotracheal tube5 s for Xomed laser shield endotracheal tube5 s for Xomed laser shield endotracheal tubeLaser-Flex tracheal tube (stainless) and aluminum foil wrapped PVC Laser-Flex tracheal tube (stainless) and aluminum foil wrapped PVC endotracheal tube did not catch fire after 30 s of CO2 laser irradiationendotracheal tube did not catch fire after 30 s of CO2 laser irradiation

In short, the stainless endotracheal tube is the safest tube during In short, the stainless endotracheal tube is the safest tube during CO2 laser surgery.CO2 laser surgery.

Patient presents with lesion of Patient presents with lesion of the tongue. Which laser is the the tongue. Which laser is the best choice?best choice?

Patient has a predominantly green tattoo that they want to Patient has a predominantly green tattoo that they want to have removed. Which of the following is the best answer?have removed. Which of the following is the best answer?

A. A. Frequency doubling

BB. Q-switched Nd: YAG

C. Q-switched alexandriteQ-switched alexandrite

D. Q-bertD. Q-bert

Ossicular SurgeryOssicular SurgeryCO2CO2

Pros: absorbed by water, no deep Pros: absorbed by water, no deep penetration into the inner earpenetration into the inner ear

Cons: invisible (requires separate aiming Cons: invisible (requires separate aiming beam), alignment of mirrors can be beam), alignment of mirrors can be problematicproblematic

KTP, ArgonKTP, ArgonPros: Aiming beam is attenuated, Pros: Aiming beam is attenuated, treatment beam can pass through treatment beam can pass through fiberoptic cablefiberoptic cable

Cons: Requires pigment for absorption, Cons: Requires pigment for absorption, can pass through clear fluids and can pass through clear fluids and potentially damage the inner earpotentially damage the inner ear

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