Chapter 60 : Laser Surgery

Question 1

LASER is an acronym for __________________________

Answer 1

Light Amplification by the Stimulated Emission of Radiation

Question 2

Who postulated the theoretic foundation of laser action, stimulated emission of radiation, in 1917

Answer 2

Albert Einstein

Question 3

Excitation that comes from the electron interacting with light (a photon) is termed ______________________________

Answer 3

Absorption

Question 4

This term refers to the waves of light that oscillate in phase over a given time

Answer 4

Temporal Coherence

Question 5

This means that the photons are equal and parallel across the wave front

Answer 5

Spatial Coherence

Question 6

After the laser energy exits the optical cavity through the partially transmissive mirror, the radiant energy typically passes through a lens that focuses the laser beam to a very small diameter, or spot size, that ranges from

Answer 6

0.1 to 2 mm

Question 7

With most surgical lasers, the physician can control 3 variables

Answer 7

1. Power, 2. Spot size, 3. exposure time

Question 8

the least useful variable and may be kept constant with widely varying effects

Answer 8

Power

Question 9

________ is the most important operating parameter of a surgical laser at a given wavelength

Answer 9

Irradiance

Question 10

refers to the distribution of energy across the focal spot and determines the shape of the laser’s spot

Answer 10

Transverse Elecromagnetic Mode (TEM)

Question 11

The power density of the beam follows a _________ distribution: the greatest amount of energy is at the center of the beam and the amount of energy diminishes progressively toward the periphery

Answer 11

Gaussian

Question 12

The smallest beam diameter and highest power concentration occur at the focal plane, where much of the precise cutting and vaporization is carried out

Answer 12

TRUE

Question 13

________ refers to the amount of time (measured in seconds) that a laser beam irradi- ates a unit area of tissue at a constant irradiance

Answer 13

FLUENCE

Question 14

When the target absorbs a specific amount of radiant energy to increase its temperature to between ___° C and ___° C, protein denaturation occurs

Answer 14

60-65 deg C

Question 15

The minimal operative trauma, combined with the vascular seal, probably accounts for the absence of postoperative edema that is char- acteristic of laser wounds.

Answer 15

TRUE

Question 16

According to the study of Buell and Schuller, they compared the rate of tissue repair after CO2 laser and scalpel incisions on hogs. In this study, the tensile strength of the laser incisions was _______ compared to that of similar scalpel incisions during the first 3 weeks after surgery.

Answer 16

Less than

Question 17

This kind of laser produce blue-green light in the visible range of the electromagnetic spectrum, with primary wavelengths of 0.488 and 0.514 μm

Answer 17

Argon

Question 18

As part of eye protection for the OR staff, it is important to note that Laser radiation in the ultraviolet (<0.4 μm) or in the
infrared (>1.4 μm) range of the spectrum produces effects pri-
marily which part of the eye?

Answer 18

Cornea

Question 19

How many suction setups should be available for all laser
cases in the upper aerodigestive tract

Answer 19

Two

Question 20

Mixtures of helium, nitrogen, or air plus oxygen are commonly used to maintain the forced inspiratory oxygen less than ____ to ensure that the patient is adequately oxygenated.

Answer 20

40%