Laser Surgery

Question 1

What is a laser?

Answer 1

A laser is a device that amplifies a narrow, intense beam of light. The term laser is actually an acronym that stands for Light Amplification by Stimulated Emission of Radiation.

Question 2

How does a laser differ from ordinary light?

Answer 2

The three ways that laser light differs from that emitted from an ordinary light are 1) it is monochromatic (a single wavelength),
coherent (it oscillates in the same phase), and collimated (it is a narrow, parallel beam of light). Lasers can be both long (CO2 laser) and short (YAG laser) wavelengths.

Question 3

What are the three components of a laser?

Answer 3

A laser requires an energy source, an optical resonating cavity, and a laser medium.

Question 4

What types of energy sources do lasers use and

what do they do?

Answer 4

The energy source for a laser is used to excite the atoms of the laser medium. Energy sources include flash lamps, continuous light sources, diodes, high-voltage discharge, and in some circumstances, other lasers.

Question 5

What is the laser medium?

Answer 5

The laser medium is the substance whose atoms are energized by the energy source. It can be a solid, liquid, gas, or a semiconductor. Most lasers are named for the medium. Gas lasers can employ a variety of gas media including CO2, argon,
helium, and krypton. Solid-state lasers include the neodymium-Yag laser that is commonly used in surgery. Semiconductorlasers are typically used in electronic devices such as laser pointers, CD players, and laser printers. Liquid lasers usually
use a complex dye immersed in a liquid such as alcohol.

Question 6

What are the advantages of laser use in surgery over traditional scalpels?

Answer 6

Lasers offer easier access to the surgical site, better preservation of anatomic structures, precision, hemostasis, andimproved patient satisfaction

Question 7

What is the primary use of the Holmium laser?

Answer 7

The Holmium laser is often used to ablate and restructure avascular tissues. It is commonly used in endoscopic orthopedic procedures for bone and cartilage reshaping, stone removal in urology, and transurethral resection of the prostate.

Question 8

What does the optical resonating cavity in a laser do?

Answer 8

The optical resonating cavity is a tubelike structure in which the laser beam is amplified. The optical cavity contains the laser medium. The energy source excites the electrons to a higher energy state. Two mirrors on each end of the optical resonating cavity reflect the laser beam back and forth through the medium exciting the electrons of more atoms. One of the mirrors is semitransparent
and allows a part of the beam to exit the resonating
cavity as a narrow, intense beam.

Question 9

Why is a Helium-Neon laser incorporated into a CO2

laser?

Answer 9

A CO2 laser emits infrared light, which cannot be seen by humans. A low-energy helium-neon laser is combined with the CO2 laser so that the operator has a visible, red light with which the CO2 laser can be aimed.

Question 10

What is the depth of penetration of a Nd-YAG laser

and for what procedures is it most commonly used?

Answer 10

The Nd-YAG laser penetrates to a depth of 5-7 mm and can be used for debulking of tumors in the gastrointestinal tract, the tracheobronchial tree, and genitourinal lesions.

Question 11

What is the medium used in an excimer laser?

Answer 11

Excimer is an abbreviated term combining the words ‘excited’ and ‘dimer’ which refers to the excitation of a noble gas such as chlorine or fluorine and a halogen such as argon or krypton.

Question 12

How does the wavelength of a laser affect the

tissues it is applied to?

Answer 12

Laser light has to be absorbed for it to be effective. If the light is reflected or scattered, it will be ineffective. Different tissues are affected by different laser wavelengths. The wavelength of the
laser must match the absorptive characteristic of the tissue. Once absorbed, the laser light converts to heat within the tissue. If the the amount of heat generated reaches 100 degrees Celsius, the tissue will be vaporized.

Question 13

What regulatory body requires a Laser Safety Officer to be designated in facilities employing a class IIIB or class IV laser? What are the responsibilities of the Laser Safety Officer?

Answer 13

ANSI requires a Laser Safety Officer to be designated in all facilities that use a class IIIB or class IV laser. This person is responsible for overseeing the maintenance, operation, and
servicing of medical lasers used in the hospital.

Question 14

What governmental agency regulates the
manufacturing and marketing of medical lasers?
What agency regulates medical laser safety? What
agency developed the standards for laser safety in
medical personnel?

Answer 14

The US Food and Drug Administration regulates the manufacture and marketing of medical lasers. The American National Standards Institute regulation Z136.1-2007 is the most utilized standard for medical laser safety. The Occupational
Safety and Health Administration developed standards to protect patients and health care personnel when lasers are in use.

Question 15

How are lasers classed by the Bureau for

Radiological Health?

Answer 15

They are classed into four categories from I to IV. Class I lasers are incapable of producing damaging radiation and include supermarket scanners and compact disc player lasers. Class II
lasers include laser pointers. These are visible spectrum lasers that are not dangerous unless viewed directly for a long period of time. Class III lasers include spectroscopy and light show
lasers and can cause eye injury if viewed directly. Class IV lasers are hazardous and can result in fires and damage to the skin.

Question 16

What is the most common laser used in surgery?

Answer 16

The CO2 laser.

Question 17

Why are CO2 lasers so dangerous?

Answer 17

Because the CO2 laser is an infrared laser, it emits essentially as heat. A CO2 laser can melt almost any structure upon which it is focused including steel.

Question 18

What type of laser produces the greatest amount of

toxic smoke when used?

Answer 18

The CO2 laser produces the greatest amount of smoke and thus presents the greatest potential for spread of toxic gases and vapors and infectious agents. Note that high-filtration masks (0.3 micrometer) should be worn by operating room staff
when exposure to these agents is likely.

Question 19

What is the usual depth of penetration of a CO2

laser used in surgery?

Answer 19

Because the CO2 laser is greatly absorbed by water, the vaporization of tissues usually occurs within the first 200 micrometers of tissue depth.

Question 20

For what surgeries is an excimer laser most suited?

Answer 20

Because an excimer laser has a very short wavelength and minimal thermal effect on surrounding tissues, it is suited for use in microsurgical procedures such as photorefractive
keratectomy and LASIK surgery.

Question 21

What precautions should be taken when
anesthetizing a patient undergoing CO2 laser
vaporization of condylomatous lesions?

Answer 21

When viral tumors such as condylomatous lesions are vaporized by laser, intact viral particles can be recovered from the plume which warrants the use of gloves, a smoke evacuation system, high-efficiency filter masks, and protective goggles.

Question 22

What safety precautions should be in place when

using a laser in an operating room?

Answer 22

Warning signs indicating that a laser is in use should be posted both inside and outside the operating room. Windows should be covered and all doors closed. Access to the operating room
should be limited and a safety interlock device should be employed that shuts off the laser if the door is opened unexpectedly. Appropriate laser protective goggles should be worn by all personnel and eye protection should be provided to
the patient. All exposed skin should be covered. Unnecessary shiny surfaces should be removed from the field to prevent reflections. The surgeon should be advised to announce when he is activating the laser. Avoid looking into the laser’s beam and never leave a laser unattended.

Question 23

What are the major risks due to the use of a laser in

the operating room?

Answer 23

Thermal injury, eye injuries, electrical hazards, fire,

transmission of viruses, and contaminants in the smoke plume.

Question 24

Why should operating room lights be turned as bright

as possible when a laser is in use?

Answer 24

The bright light contricts the pupils and creates a smaller aperture through which a stray laser beam could enter the eye and damage the retina.

Question 25

What does the term OD refer to when discussing

laser protective eyewear?

Answer 25

It refers to the optical density of the glass.

Question 26

What is the OD of most laser glasses used in the
operating room? What are the advantages and
disadvantages of higher OD levels?

Answer 26

The optical density of the glasses used in the operating room is typically between 4 and 7. The higher increase in optical density, the greater the protection from a laser beam, but the greater difficulty in seeing through the glasses. Eyewear with the markings OD5 or greater for 1,064 nm would be appropriate protection for potential exposure to a Nd:YAG laser. Note: although the lenses are often green for this type of lens, the
color cannot be relied upon as some Nd:YAG glasses are clear.

Question 27

For what type of laser would green-tinted laser

glasses protect you from?

Answer 27

Green-tinted glasses are designed to protect from Nd-YAG lasers. There are, however, some clear laser goggles that possess a special protective film that protects from Nd-YAG lasers as well. In either green or clear lenses, there should be markings indicating that the glasses are OD5 or greater for
1,064 nm, which indicates protection from the Nd-YAG laser.

Question 28

In what laser procedures should specialized masks
be employed for all personnel in the room?
Specifically, what type of masks should be used?

Answer 28

Laser vaporization of condylomatous lesions have been demonstrated to release toxic chemicals such as benzene and formaldehyde as well as viable viruses capable of transmitting the disease. A high-efficiency N-95 respirator should be worn
by all personnel in the room.

Question 29

What procedures involving lasers have the highest

incidence of fire?

Answer 29

Surgical fires are most common in airway surgery (34%) and surgery on the head or face (28%).

Question 30

What are the appropriate precautions to take to

prevent a fire during laser surgery?

Answer 30

Appropriate precautions for fire prevention during laser airway surgery include: reducing the FiO2 (as close to 0.21 as the patient will tolerate), replacement of nitrous oxide with air or helium, fill the tracheal balloon with saline that has been dyed
with methylene blue to signal cuff rupture and help dissipate heat, limit the laser intensity and duration as much as possible, place saline-saturated pledgets in the airway, keep a source of water on hand in case of fire. The addition of 2% lidocaine jelly in a 1:2 mixture with saline in the endotracheal tube cuff can help seal small cuff leaks from laser surgery and help prevent combustion.

Question 31

What are endotracheal tubes composed of and what type of laser has the greatest capability of ignitingthem?

Answer 31

Endotracheal tubes are composed of the flammable substance polyvinyl chloride and are most susceptible to ignition by CO2 lasers.

Question 32

What are the indications that an endotracheal fire is

occurring?

Answer 32

Darkening of the endotracheal tube or circuit with soot, an orange or red glow to the endotracheal tube, or the presence of flames

Question 33

What steps should be taken if an airway fire occurs?

Answer 33

Ventilation should be discontinued, the breathing circuit should be disconnected from the patient, all gases (oxygen, nitrous, and volatile agents) should be turned off, the endotracheal tube removed, saline poured into the airway, and the patient
ventilated by mask with air until the fire is extinguished, at which point, 100% O2 can be restarted.