Dr. Krishna Koirala

LASERs in Otorhinolaryngol

ogy

• Acronym

• Light Amplification by Stimulated

Emission of Radiation

• Definition • Laser is a device that produces and

amplifies light by stimulated emission of radiation

• It can produce light in the ultraviolet, visible, and infrared region of the electromagnetic spectrum

HISTORY

• 1960: Ruby (first laser)

• 1961: Neodymium-doped (Nd): glass

laser

• 1964: Nd: YAG and Argon (Ar)

• 1965: CO2 laser

Ordinary light LASER

• Radiation from conventional light source is emitted over a wide range of wavelengths, or spectrum

• The light intensity decreases at the distance due to divergent nature of the conventional radiation

• Laser produces a beam with a very narrow divergence

• Light leaves the source with a high degree of collimation

• As the beam travels in space, the directionality is maintained over a long distance and high beam intensity is also maintained

Components of a LASER• A LASER consists of the lasing medium contained

in an optical cavity, and a pumping system provided by external energy

• The mirrors at each end ensure that the photons bounce back parallel to the axis, so that they in turn collide with excited atoms and stimulate further production of photons

Mechanism of production of LASER light• An atom consists of a dense nucleus around

which electrons move in orbit and they are free to change their orbit to a higher level by absorbing energy from an external source and thus acquire an excited unstable state

• The unstable electrons cannot stay in the higher unstable orbit and tend to decay to a lower more stable orbit

• In the process they lose extra energy of the higher level in the form of packets of energy or photons

• A photon released from an excited atom might

interact with another similarly excited atom which

results in the second atom releasing its photon

which is identical in every respect to the first photon

• This phenomenon is called stimulated emission of

radiation

• The two photons have the same direction of travel,

and are in phase

Properties of laser light• Monochromatic • A single pure color emitted by a single wavelength

• Collimated • A beam in which almost all the photons are

travelling in the same ‘parallel direction’

• Coherent• Waves produced by a laser travel through space in

phase which is responsible for the strength and intensity of the beam between different points in the field

Types of lasers acc. to materials used

• Solid : Nd: YAG laser

• Liquid : Organic dye laser.( rhodamin 6G , disodium fluorescein)

• Gas : Helium Neon (HeNe) laser, CO2,Argon and Krypton Gas laser.

• Semiconductors : Gallium-Arsenide -Diode laser

• Excited dimer (Eximer Laser) : Argon fluoride and Krypton fluoride

• Infrared light is primarily absorbed by water• Visible and UV light are absorbed by

hemoglobin and melanin• As wavelength becomes shorter – scatter

begins to dominate the penetration of light

Depth penetration of LASERs

Comparison of different types of laser

CO2 Nd: YAG

Argon KTP

Wavelength (nm)

10600 1060 488- 514 532

Tissue Absorption

High Low SelectiveHigh in Blood

Selective High in Blood

Tissue Penetration

0.1 4 1 1

Coagulation Low High Medium Medium

Cutting effect High Low Low Low

Laser reaction to tissues

• When laser radiation strikes a tissue, the temperature

begins to rise

• 10 0 C – 45 0 C : Conformation change of proteins

• 50 0 C : Reduction of enzyme activity

• 60 0 - 99°C : Coagulation begins

• 100°C and above : Vaporization starts

• 400 0 -500°C : Char starts to burn

Modes of laser• Continuous : continuously pumped ,emits

light continuously• Pulse: laser energy delivered with each peak

over an extremely short period of a few nanoseconds with rest period (allows time for tissues to cool down)

• Q-switched: Allows a high build-up of energy within the tube which is then released over a very short duration of a few nanoseconds

Different types of laser

CO2 Laser• 10,600 nm wavelength

• Highest power continuous wave laser used for cutting or ablating tool using water as target chromophore

• Focus to <500 mm and seals blood vessels less than 0.5 mm

• Pulsed to accommodate thermal relaxation time (less pain and less edema)

• Used in majority of procedures except those requiring coagulation of larger vessels

• Shallow thermal damage zone (≤ 500 μm)

• Comparatively a poor hemostat (not being

effective in controlling bleeding from vessels

greater than 0.5 mm in diameter)

• Not transmissible through the common optical

fibre

• Its use on the cords has the advantage of

producing minimal scarring therefore glottic

competency is rarely jeopardized

Nd: YAG Laser (Neodymium-doped Yttrium Aluminum

Garnet)• 1064 nm wavelength with Helium-Neon (He-Ne) beam

• Solid state laser with fiberoptic carrier

• Deeper penetration (up to 4 mm)

• Ideal laser for ablation, coagulation and hemostasis in vascular malformations

• Limitations• Greater scatter than CO2• Deep thermal injury• Risk for transmural injury

KTP Laser ( Potassium - Titanyl -Phosphate)• 532 nm wavelength with Oxyhemoglobin as

primary chromophore

• Continuous wave (CW) mode to cut tissue

• Pulsed mode for vascular lesions and

• Q-Switched mode for red/orange tattoo pigment

• Delivery• Insulated fiber, fiber handpiece, scanner, or

microscope for CW/pulsed mode• Articulating arm for Q-Switched mode

Helium –Neon LASER

• He-Ne laser emits at 633 nm in the

visible spectrum

• Low power laser mainly used as an

aiming beam superimposed on the path

of invisible lasers such as the CO2 or

ND:YAG

• Has also been used in wound healing

and pain treatment

Argon Laser• 488 - 514 nm wavelength (Blue green spectrum) • Oxyhemoglobin is target chromophore• Small spot size (0 . 1 – 1 mm) , variable in size

and intensity• Flexible delivery system• Mainly used in ophthalmological procedures

• Limitations• Also absorbed by epidermal and dermal tissues

due to melanin• Continuous mode of operation• Higher prevalence of postoperative pigmentary

alteration and fibrosis

Anaesthesia for laser airway surgery• Three major considerations

• Combustion, Airway, Anaesthetic risk

• Combustion • Risk is greater with a collimated beam such as

CO2 laser and less in lasers that operate in a pulsed mode, as heat can dissipate between bursts

• Commonly used tubes such as red rubber, latex, and plastics such as PVC, are easily ignited in a typical anaesthetic gas mixture, burning with a blowtorch-like flame

Management during Anesthesia• Intubation anaesthesia

• Water is fire retardant as well as being a heat sink, all swabs and fabric should be wet

• Protection of standard tracheal tubes• Jet ventilation anaesthesia• Intermittent apnoeic technique• Tubeless anaesthesia

Indications for LASER In larynx

• Congenital Disorders : Laryngomalacia,

laryngeal web, subglottic hemangioma,

mucous cysts

• Functional dysphonia : plica ventricularis

• Chronic inflammatory conditions

• Exudative lesions in Reinke’s space –

nodules, polyps, Reinke’s edema,

epidermoid cysts

• Chronic trauma • Hematoma• Ulceration and granuloma• Scarring• Subluxation of the arytenoid cartilage

• Neuromuscular disorders• Bilateral vocal cord paralysis , arytenoid

fixation• Recurrent respiratory papillomatosis

• Benign laryngeal tumors : Cysts( Intracordal

epidermoid mucous retention cysts) ,

laryngocoele

• Acquired webs and synechiae : Laryngo -

tracheal synechiae, anterior synechiae and

fibrous bands

• Chronic hyperplastic laryngitis : Leukoplakia ,

erythroplakia, speckled erythroplakia

• Excisions for malignancy : Carcinoma in situ (CIS) , micro - invasive carcinoma , verrucous carcinoma ,management of TIS, T1 and some early T2 glottic, supraglottic carcinoma

Lasers for nasal surgery

• Create relatively bloodless field in endonasal

surgery of the middle meatus complex (MMC) -

( surgical field becomes more clear)

• CO2 laser is not commonly used in endonasal

laser surgery because of• Lack of fibre transmissibility• Poor coagulation• Poor haemostasis• Increased risk of synechiae formation post

operatively

• KTP laser is better in Nasal surgery because• Fibre transmissible• Has a high affinity of absorption for

pigmented tissue (hemoglobin)• Energy conducted into the tissue is well

absorbed by the sinusoidal blood vessels of the turbinate and results in a coagulation zone with very little intraoperative bleeding

• Has adequate power for ablation of the bony framework of the MMC

Benefits to the patient from laser technology in Nose

• Minimally invasive surgery• Minimal bleeding• Minimal postoperative edema and

crusting• Ambulatory surgery• Cost effective

Indications of Laser surgery in Nose• Reduction of turbinates

• Nasal polyps removal

• Dacryocystorhinostomy

• Laser-assisted septoplasty

• FESS• Removal of polyps as a preliminary

procedure to FESS• Manipulation of middle turbinate• Solitary sphenoid or frontal sinus disease• Good intraoperative haemostasis• Excision of the uncinate process, removal of

bulla ethmoidalis, creation of middle meatal antrostomy

• Miscellaneous• Rhinophyma• Recurrent epistaxis• Telengiectatic, cavernous or pyogenic septal

granuloma• Hereditary haemorrhagic telangiectasia (HHT)• Choanal atresia or stenosis, nasopharyngeal

stenosis, polyps, adenoid hypertrophy• Juvenile angiofibroma ,nasopharyngeal cancer

• Any suspicion of orbital, facial, or intracranial extension of the disease is a contraindication for laser use!!!

Laser selection in otology• CO2, KTP , Argon , Nd: YAG lasers • In vascular lesions of ear - The Nd: YAG

laser, with its deep scatter, is the laser of choice

• For debulking of tissue : CO2 laser are used

• The visible KTP laser light is well suited for undertaking temporal bone surgery• Fibre transmissibility of the KTP beam

gives an added dimension to guide the light around corners

Use of Laser in otology• External auditory canal

• Vascular lesions –

haemangiomas ,telangiectasias

• Aural polyps and granulations

• Stenosis of the external auditory canal

• Debulking of large, inoperable EAC

carcinoma

• Laser reshaping of cartilage

• Tympanic membrane lesions : Epidermoid

cysts

• Middle ear cleft• Laser - assisted myringoplasty • Graft - welding of tympanic membrane

defects• Laser - assisted ossicular surgery• Cholesteatoma surgery• Vascular lesions of the middle ear• Laser-assisted, totally implantable

hearing aids

• Inner ear : Cochleostomy ,

labyrinthectomy

Orofacial Surgery : laser preference

• For vaporisation and cutting in soft tissue, a

wavelength such as carbon dioxide (CO2) modality

at 10.6 μm is indicated

• For coagulation in soft tissue, a wavelength which

is poorly absorbed by water but is maximally

penetrative is required (near infrared modality of

the Nd: YAG at 1.06 μm)

• For hard tissue such as bone, dentine or enamel, hydroxyapatite is the chromophore of importance (Erbium: YAG at 2.9 μm )

Use of lasers in Orofacial surgery• High intensity laser treatment (HILT)• Oral mucosal premalignant leucoplakia• Mucosal haemangiomatous lesions of the mouth• Temporomandibular joint : Division of adhesions,

coagulation of redundant capsule in recurrent dislocation, for pain relief

• Laser hemiglossectomy• Low intensity laser therapy (LILT)• Post-herpetic neuralgia , Idiopathic neuralgia,• Intractable ulcerations :Pemphigus vulgaris, Crohn’s

disease

• Surgery for snoring and obstructive sleep

apnea

• Uvulopalatoplasty

• Midline glossectomy

• Linguloplasty

• Laser palatine tonsillectomy

• Laser lingual tonsillectomy

• Cryptolysis for halitosis

Laser selection in lower airways• Most common lasers used : CO2 , Nd:YAG

• CO2 laser beam is directed towards the lesion through articulated arm, limiting its use to rigid bronchoscopy, presently used more for lesions involving the larynx and proximal trachea

• Nd:YAG laser beam can be passed through a flexible endoscope , which affords deeper penetration, better coagulation and produces better haemostasis• Its main disadvantage is the unpredictable

interaction of the laser beam with the tissue, making it difficult to determine the depth of penetration

Lower airway indications• Laser photoresection of obstructive airway lesions• Subglottic and tracheal stenosis• Granulation tissues, broncholith, foreign body,

benign tumours, congenital tracheo- esophageal fistula

• Photodynamic therapy• Curative therapy for carcinoma in situ, juvenile

laryngotracheobronchial papillomatosis, unresectable early stage lung cancer palliative treatment for advanced obstructive lung cancer

Hazards of laser• Damage to biological non-target tissue • Corneal or retinal eye injuries, skin and

mucosal burns• Damage to non-biological material• Anaesthetic tube and draping material

• Side-effects due to laser by-products• Laser-generated smoke

• Laser malfunction such as electric shock