Kj Lee 10Th Ed - Chapter 35 - Laser And Radiofrequency Surgery

Front 1

What does "laser" stand for?

Back 1

LASER = light amplification by stimulated emission of radiation

Front 2

What is the process of spontaneous emission?

Back 2

photons being emitted after high energy electrons decay to their lower energy "ground state"
most of these spontaneously emitted photons are absorbed and decay, however, photons emitted in the direction of the long axis of the resonant cavity are retained as they bounce between the two mirrors of the laser.

Front 3

What is the process of stimulated emission?

Back 3

When photons encounter an atom in the excited state, they stimulate an excited electron to decay to its ground state, and emit another photon of the SAME wavelength in the SAME direction.
This amplifies the light.

Front 4

What is the process of population inversion?

Back 4

When more than half of the atoms in the active medium reach the high-energy state, population inversion occurs.
This is a necessary condition for a laser to start working.

Front 5

What are properties of laser light?

Back 5

Monochromatic
Unidirectional
Uniform in phase and polarization
Spreads over distances, and can be focused with lenses
Once laser light exits the main resonance chamber, it has to be delivered to tissue via optical fibers or waveguides.

Front 6

How does tissue interact with laser light?

Back 6

tissue interacts ONLY with laser light that is ABSORBED, not reflected, transmitted, or scattered

Front 7

Visible and infrared (IR) lasers used in ENT work by heating tissues, photodissociation of bonds, or both?

Back 7

heating tissues only; laser is absorbed and converted to heat

Front 8

What is thermal relaxation time?

Back 8

time needed for tissue to dissipate HALF of its heat.

Front 9

What are the layers of laser wounds?

Back 9

Tissue vaporization
Necrosis
Thermal conductivity and repair (reversible damage)

Front 10

What is done to minimize thermal injury?

Back 10

High laser energy is delivered in short pulses and by allowing time for heat to diffuse between pulses

Front 11

What are the laser parameters that are under surgeon's control?

Back 11

Power
Spot size
Exposure time

Front 12

What is the argon laser used for?

Back 12

Argon (514 nm - blue green) - transmits easily through clear tissues.
Light is absorbed by hemoglobin and pigment tissues.
Used for photocoagulation of pigmented lesions, port-wine stains, hemangiomas and telangiectasias, middle ear and STAPES surgery.

Front 13

What is the copper vapor laser used for?

Back 13

Copper vapor (511 nm--green, 578 nm--yellow)
The green 511 nm laser is best absorbed by melanin and is used to treat superficial pigmented lesions, cafe au lait spots, nevi and freckles.

The yellow 578 nm variety is better absorbed by hemoglobin and is used for vascular lesions.

Front 14

What is the KTP laser used for?

Back 14

KTP = potassium titanyl phosphate, 532nm - green
Absorbed by hemoglobin even better than argon gas. Used for pigmented dermal lesions, port-wine stains, middle ear, and stapes surgery.
Light can easily be delivered through a flexible fiberoptic bronchoscope for management of tracheobronchial lesions.
KTP laser has been used in endoscopic sinus surgery and management of sinonasal polyps.
Major advantage of the KTP laser in sinonasal surgery is excellent HEMOSTASIS!

Front 15

What is the tunable dye laser used for?

Back 15

Tunable dye laser (585 nm--yellow) - dye is chosen for best absorption by hemoglobin.
Used for treatment of vascular lesions such as hemangiomas and port-wine stains.

Front 16

What is the ruby laser used for?

Back 16

Ruby laser - 694 nm--red - absorbed by melanin
This laser was used for hair and tattoo removal, works best in patients with light skin complexion

Front 17

What is the alexandrite laser used for?

Back 17

Alexandrite laser - 755nm--red; absorbed by melanin
Frequently used for hair and tattoo removal in pts with a range of Fitzpatrick skin types

Front 18

What is the Nd:YAG laser used for?

Back 18

Nd:YAG = neodymium yttrium aluminum garnet, 1.06μm--near IR
Produces a layer of tissue coagulation and necrosis 4mm deep, but precise control is NOT possible
This laser allows good control of hemorrhage
Used for palliation of obstructive esophageal and tracheobronchial lesions, photocoagulation of vascular lesions, and lymphatic malformations.
Nd:YAG laser CAN be transmitted through optical fibers, allowing easy delivery via flexible endoscopes

Front 19

What is the Er:YAG laser used for?

Back 19

Erbium yttrium aluminum garnet - 2.94μm--near IR
This laser wavelength is near the peak of water absorption, resulting in very shallow tissue penetration.
It produces a clean incision with minimal thermal damage to adjacent tissue.
Because of shallow penetration, hemostasis is difficult.
Used for facial skin resurfacing and epidermal lesions.

Front 20

What is the CO2 laser used for?

Back 20

CO2 laser -- 10.6μm - IR - this wavelength is invisible and needs a coaxial helium-neon (He-Ne) red laser as an aiming beam.
**CO2 laser is strongly absorbed by tissues with high water content. Tissue penetration is shallow.
Advantages include precision and good hemostasis of small vessels.
This wavelength cannot be delivered via optical fiber, however specialized flexible waveguides (OmniGuide; image) have been developed that allow delivery of this infrared wavelength directly to the tissues through a handpiece.
The CO2 laser is the most widely used laser in ENT.

Front 21

What are the semiconductor (diode) laser used for?

Back 21

Semiconductor (diode) lasers are available in several wavelengths.
Advantage = compact size (ie..think of the laser used to read CD's/DVD's)
Used in variety of ENT procedures.

Front 22

Lasers targeting hemoglobin and vascular lesions generally have short wavelengths of less than _________

Back 22

700nm

Front 23

List which lasers are used in the middle ear and stapes surgery.

Back 23

Argon
KTP
CO2 (less popular now)

Front 24

What are the properties of lasers used for facial skin resurfacing?

Back 24

Operate in the infrared range (Er:YAG - 2.94μm, CO2 - 10.6μm)
Well absorbed by water
Shallow tissue penetration

Front 25

What's the difference between CO2 and Er:YAG lasers in skin resurfacing?

Back 25

CO2 laser removes 50-100μm of surface tissue in one pass
- allows for "bloodless" skin resurfacing because small blood vessels in target skin are coagulated.
- skin reepithelializes within 2 weeks

Er:YAG is superbly absorbed by water, resulting in very shallow tissue penetration depth. Energy is absorbed in the epithelium, therefore this lase is used for skin with mild to moderate signs of aging, predominantly in the epidermis. Removes 25-30μm of surface tissue. Some bleeding occurs with this laser, as the light is unable to coagulate the small vessels within the targe skin. Skin reepithelializes in 5-7 days.

Front 26

Which two lasers are best for tattoo removal?

Back 26

Ruby
Alexandrite

Front 27

What are some preop considerations for laser skin rejuvenation?

Back 27

herpes prophylaxis started 24hrs prior to procedure and continues until 10th POD.
pseudomonas coverage with ciprofloxacin

Front 28

List the complications of laser skin resurfacing

Back 28

prolonged erythema
scarring
hyperpigmentation
(Fitpatrick skin types III and greater have a higher risk of pigmentary changes)

Front 29

What are contraindications of laser skin resurfacing?

Back 29

Isotretinoin (accutane) in the past 1-2yrs, as this could impair re-epithelialization
Scleroderma
active acne
Hx of facial burns
H&N radiation therapy

Front 30

What are some anesthesia precautions that are important while using lasers in the OR?

Back 30

Reducing partial pressure of O2 in the inhaled gas mixture to a minimum when lasing in the airway
Wavelengths-specific endotracheal tubes
Nitrous oxide should be avoided durnig laser surgery (may use halothane, enflurane, and isoflurane)

Front 31

What is radiofrequecy surgery? Explain radiofrequency energy.

Back 31

Radiofrequency energy is delivered to tissue where particles are IONIZED and a layer of plasma develops.
The high-energy plasma particles are capable of causing bond dissociation in tissue at relatively low temps (40-70*C). This allows tissue removal, tissue shrinkage, or vessel coagulation without significant thermal damage

Front 32

When was radiofrequency ablation tonsillectomy introduced?

Back 32

Radiofreq ablation tonsillectomy = coblation, was introduced in 2001.

Front 33

A 2008 meta-analysis found that radiofrequency surgery at the tongue base and palate in OSA pts results in ___% reduction in long-term (>24 months) respiratory distress index (RDI).

Back 33

45%

Front 34

Where is the neurovascular bundle in relation to the foramen cecum?

Back 34

2.7cm deep and 1.6cm lateral to foramen cecum

Front 35

In general, lasers with longer wavelengths have shorter or deeper tissue penetration?

What laser is an exception to this rule?

Back 35

Longer wavelength = deeper penetration

Exception is CO2 laser (10.6 μm)