Auer Ch 14 15 Cryosurgery Lasers

Front 1

Temperature at which mammalian cells are destroyed at:

Back 1

-20C (-4F)

Front 2

How are cells destroyed with cryosurgery?

Back 2

Formation of intra- and extracellular ice crystals, outer cell membrane is ruptured by intracellular crystals, extracellular crystals dehydrate cells

Front 3

How does secondary injury occur with cryosurgery?

Back 3

Vascular stasis, thrombus formation, infarction of frozen tissue

Front 4

What produces the greatest concentration of intracellular ice?

Back 4

Rapid freezing

Front 5

What is the benefit of freeze-thaw cycles?

Back 5

Slow thawing causes recrystallization and more cellular damage, refreezing ensures all tissues receive a lethal cold dose

Front 6

Why do tissues respond differently to cryosurgery?

Back 6

Variations in vascularity, noncellular structure, water content

Front 7

Cryogens in veterinary medicine:

Back 7

liquid nitrogen, nitrous oxide, carbon dioxide

Front 8

Most common cryogen:

Back 8

liquid nitrogen

Front 9

Boiling point of liquid nitrogen:

Back 9

-195.8C (-320.4F)

Front 10

How can cryogens be delivered?

Back 10

Sprays, probes

Front 11

Types of cryogen probes:

Back 11

hollow, solid

Front 12

How do sprays deliver liquid nitrogen?

Back 12

As a vapor and droplets of liquid

Front 13

Advantage of sprays vs probes:

Back 13

remove a greater amount of heat from tissue

Front 14

Disadvantage of sprays:

Back 14

liquid runoff can damage unaffected tissues

Front 15

How are hollow probes cooled?

Back 15

Circulation of liquid cryogen through them

Front 16

How are solid probes cooled?

Back 16

Immersion in liquid cryogen

Front 17

Advantages of hollow probes:

Back 17

freezing is easy to control

Front 18

Disadvantage of hollow probes:

Back 18

rate of cool is slower than spray or solid probes

Front 19

Advantage of solid probes:

Back 19

using various sizes of probes, multiple probes can be used rapidly

Front 20

How is depth of freezing monitored?

Back 20

Subjective assessment, objective measurement of temperature changes

Front 21

How is subjective assessment of freezing performed?

Back 21

Visual inspection, palpation of ice ball

Front 22

What % of tissue in ice ball is destroyed?

Back 22

75%

Front 23

Normal biologic reaction to freezing:

Back 23

swelling (edema), bleeding, necrosis, depigmentation, odor

Front 24

When does edema develop & subside after cryosurgery?

Back 24

Occurs within hours and subsides within 48 hours

Front 25

When does necrosis occur after cryotherapy?

Back 25

14-21 days

Front 26

Effect of cryosurgery on bone:

Back 26

reduces strength of bone by 70%

Front 27

Laser acronym:

Back 27

light amplification by stimulated emission of radiation

Front 28

Describe laser emission:

Back 28

excitation of a contained medium produces electromagnetic radiation (light)

Front 29

Define monochromatic:

Back 29

a single wavelength (or color)

Front 30

What predicts laser effects on tissues?

Back 30

Wavelength

Front 31

What is the relationship between energy absorption and tissue penetration?

Back 31

More energy absorbed, less penetration

Front 32

Define selective photothermolysis:

Back 32

interaction between laser light and tissue that preferentially absorbs that wavelength

Front 33

What type of interactions do lasers have with tissue?

Back 33

Optical, thermal

Front 34

Define optical interaction:

Back 34

true result of absorption or lack of absorption of electromagnetic energy which usually results in thermal interaction

Front 35

What occurs if optical interaction cannot achieve desired effect?

Back 35

Irradiation is converted to heat before it is applied to tissue which causes energy to be absorbed at tip of laser

Front 36

Unit of energy measurement:

Back 36

joule or calorie

Front 37

Relationship of joules to calories:

Back 37

1 J = 0.24 cal

Front 38

How are lasers rates?

Back 38

Power (or rate of energy delivery)

Front 39

Unit of power (rate of energy delivery):

Back 39

watt (1 J/ sec)

Front 40

Unit of energy per unit area:

Back 40

fluence (J/cm2)

Front 41

What does fluence depend on?

Back 41

Time of exposure, power density

Front 42

Define power density:

Back 42

W/cm2

Front 43

How is power density changed?

Back 43

Changing output of laser, spot size of laser beam, distance from delivery device to tissue, or delivery device

Front 44

What are the broad categories of objectives of laser surgery?

Back 44

Incision/excision, ablation, coagulation

Front 45

What affect does laser incision/excision or ablation have on cells?

Back 45

Cell disruption and vaporization of tissue into smoke

Front 46

What affect does laser coagulation have on cells?

Back 46

Denaturation of proteins

Front 47

What is necessary to incise tissue with little collateral damage to nearby tissue?

Back 47

Highly concentrated laser energy

Front 48

What is the minimal power density with a small spot size for single pass incision for minimal collateral thermal damage?

Back 48

5000 W/cm2

Front 49

Define laser continuous mode:

Back 49

energy delivered uniformly throughout application to tissues

Front 50

Define laser pulsed mode:

Back 50

spikes of energy at 200 Hz or more increase power density while interruptions allow tissues to cool

Front 51

Advantage of laser pulsed mode:

Back 51

increase efficiency, minimize collateral thermal damage

Front 52

Laser tip types for application in contact manner:

Back 52

sapphire, quartz

Front 53

Wavelength of CO2 laser:

Back 53

10,600 nm

Front 54

Spectrum of CO2 laser:

Back 54

far infra-red

Front 55

Penetration depth of CO2 laser:

Back 55

0.03mm (due to water absorption)

Front 56

Relationship of power density to spot size:

Back 56

larger spot size (square) decrease power density

Front 57

How is CO2 laser energy transmitted?

Back 57

Through mirrors and a lens to focus beam

Front 58

Wavelength of Nd:YAG laser:

Back 58

1064 nm

Front 59

Wavelength of GAL diode laser:

Back 59

980 nm

Front 60

Advantages of GAL diode vs ND:YAG in upper respiratory surgery:

Back 60

GAL absorbed by water 3 times more than the Nd:YAG so there is more efficient contact incision with the GAL

Front 61

2 types of quartz fibers:

Back 61

bare, gas-cooled coaxial fibers

Front 62

wavelength of the Ho:YAG laser:

Back 62

2100 nm (near infra-red)

Front 63

Wavelength of pulsed dye laser:

Back 63

400-700 nm

Front 64

Applications of Ho:YAG laser:

Back 64

ablation of cortical bone, removal of palmar/ planter P1 chip fractures

Front 65

Application of pulsed dye laser:

Back 65

lithotripsy

Front 66

Lasers used for general surgery:

Back 66

CO2, Nd:YAG, GAL diode

Front 67

Lasers used for endoscopic laser surgery:

Back 67

Nd:YAG, GAL diode

Front 68

What procedure is commonly combines with laser thermoplasty for DDSP?

Back 68

Bilateral sternothyoideus tenectomy

Front 69

what is the advantage of laser treatment of epiglottic entrapment?

Back 69

No GA, no laryngotomy

Front 70

What are the laser options for guttural pouch tympany?

Back 70

Perforation of the median septum or creation of a new salipingopharyngeal opening

Front 71

Laser used for ethmoid hematoma ablation:

Back 71

NdYAG

Front 72

Therapeutic options for subepiglottic cysts:

Back 72

contact laser decompression, contact laser excision, OB wire amputation, electrosurgical loop amputation

Front 73

Complications of laser for treatment of subepiglottic cysts:

Back 73

DDSP, subepiglottic scar formation

Front 74

Laser used for endometrial cyst coagulation:

Back 74

NdYAG

Front 75

What effect do pulsed dye lasers have during lithotripsy?

Back 75

Vaporized mineral to plasma, and pulsed hydraulic pressure fragments stone

Front 76

What laser is used for distal tarsal fusion?

Back 76

NdYAG, GAL diode

Front 77

MOA of laser distal tarsal fusion:

Back 77

desensitization of capsular sensory nerves

Front 78

How is distal tarsal fusion performed?

Back 78

Needles placed in joint, lavaged during application of laser through needle