PPT flashcards Surgical methods

1
Q

What are 3 undesirable effects assoc w charred electrode during electroincision?

A
  1. Higher power req to incise tissues
  2. Current dispersed to larger area of tissue
  3. Thermal necrosis @ wound edges increased
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2
Q

2 ways vessels can be electrocoagulated?

A
  1. Obliterative coagulation – direct contact; vessel wall shrinks & occludes
  2. Coaptive coagulation – vessel occluded by hemostats which conducts energy to vessel inducing occlusion
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3
Q

What is flow rate of Veress needles when used for insufflation?

A

< 3L/min

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4
Q

What is flow rate of teat cannulas when used for insufflation?

A

6-7 L/min

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5
Q

What size vessels can be sealed w vessel sealing devices (eg. Ligasure)?

A

Up to 7 mm

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6
Q

Prognosis for horses with aortic-iliac thrombosis w thrombectomy?

A

65% regained athletic activity & 53% performed @ previous level

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7
Q

Method of cell destruction with cryosurgery?

A

Formation of ice crystals in cell during freeze causes cell memb to rupture
Formation of ice crystals outside cell dehydrates cell & causes lethal electrolyte conc & pH changes
During thaw recrystalization causes more cell dmg

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8
Q

Which 5 tissues not ideal for cryosurgery?

A
  1. Dry tissues – eg. cornea
  2. Tissues near major blood vessels (difficult to ↓ temp & keep it low)
  3. Nerve epineurium not destroyed so maintains potential for regrowth
  4. Cortical bone - ↓ bone strength by 70%; bone tumors don’t respond well; fx have been reported
  5. Auricular cartilage – can result in ear deformity
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9
Q

5 complications of cryosurgery?

A
  1. Swelling
  2. Necrosis
  3. Bleeding
  4. Depigmentation
  5. Odor
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10
Q

What does LASER stand for?

A

Light Amplification by Stimulated Emission of Radiation

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11
Q

What is principle of selective photothermolysis?

A

Interaction btw laser light & tissue that preferentially absorbs wavelength

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12
Q

What is fluence?

A

Total amt of energy delivered per unit area of tissue

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13
Q

What is nm energy of CO2 laser?

A

10,600 nm

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14
Q

CO2 laser penetrates tissue to what depth?

A

0.03 mm

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15
Q

CO2 laser can eliminate hemorrhage from vessels of what size?

A

Up to 0.5 mm

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16
Q

Wavelength of Nd:YAG laser?

A

1064 nm

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17
Q

Wavelength of GAL diode laser?

A

980 nm

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18
Q

Nd:YAG & GAL laser absorption?

A

Absorbed by dark pigment (melanin & Hgb); poorly absorbed by water
GAL absorbed by water more than Nd:YAG – allows more efficient contact incision in URT

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19
Q

Wavelength of Ho:YAG laser?

A

2100 nm

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20
Q

Ho:YAG laser absorption?

A

Substantially absorbed by water; effect enhanced in water medium
(Pulsed laser)

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21
Q

Which laser will ablate bone?

A

Ho:YAG

Has been used to remove palmar/plantar OC frags of P1

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22
Q

Wavelength of pulsed dye laser?

A

400-700 nm

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23
Q

Absorption of pulsed dye laser?

A

Hgb & urinary calculi

Has been used in equine laser lithotripsy – combo of plasma formation & photoacoustic effect

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24
Q

Laser setting/dose for laser thermoplasty of soft palate?

A

GAL laser
20W w 600 um fiber applied in pin fire contact fashion
~ 1500J total

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25
Q

Contact or noncontact excision preferred for laser ventriculocordectomy?

A

Contact
Obtains tight arytenoid-thyroid adhesion
No ventricular mucoceles reported w contact technique

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26
Q

Which portion of vocal fold should be left for last & why?

A

Ventral aspect

Houses a vessel that can obscure vision

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27
Q

Dose/energy for laser ventriculocordectomy?

A

GAL laser
20 W
600 um fiber
~ 10,000 J

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28
Q

Define tensile strength for suture?

A

Force that suture strand can withstand before it breaks when force is applied in direction of length

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29
Q

Define knot holding capacity?

A

Maximum load to failure when tension applied to knotted suture material

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30
Q

Define relative knot security?

A

Knot holding capacity expressed as a percentage of the unknotted sutures tensile strength
RKS = (KHC/TS) x 100

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31
Q

Weakest part of suture?

A

Knot

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32
Q

Most reliable knot configuration?

A

Superimposition of square knots

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33
Q

What 4 things can affect knot security?

A
  1. Memory
  2. Coefficient of friction
  3. Number of throws
  4. Suture end length
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34
Q

What is min number of throws for knots of 2-0 suture for PG910, polyglycolic acid, & polypropylene?

A

3

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35
Q

What is min number of recommended throws for 2-0 nylon & PDS?

A

4

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36
Q

Min number of throws for large diameter suture knots?

A

5

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37
Q

Knots @ end of continuous suture line req how many more throws than single suture strands?

A

2-3

38
Q

How many additional throws needed to achieve knot security w asymmetric knots (sliding half hitch)?

A

2

39
Q

6 advantages of interrupted over continuous suture patterns?

A
  1. Inc knot security; failure of 1 suture does not jeopardize entire line
  2. Precise reconstruction
  3. Precise control of tension
  4. Less interference w blood supply of wound margins
  5. No purse string like effect in viscera
  6. Part of suture line can be opened
40
Q

5 advantages of continuous suture patterns over interrupted?

A
  1. Smaller volume of suture material
  2. Decr sx time
  3. More even distribution of tension
  4. Better holding power against stress
  5. Tighter seal of skin & hollow viscera
41
Q

What is optimal ratio of suture to wound length for abdominal incisions?

A

4:1 to allow for incisional lengthening during periods of abdominal distention

42
Q

GI incisions heal rapidly; what is critical time period when suture strength important?

A

4 days (lag phase)

43
Q

Closing paramedian skin incision involves suturing ? of ? muscle?

A

Fascia

Rectus abdominus muscle

44
Q

Major holding layers within the walls of large vessels?

A

Tunica adventitia & tunica media

45
Q

5 advantages of surgical staplers?

A
  1. Reduced sx time
  2. Less tissue trauma
  3. Less intraoperative contamination
  4. Preservation of blood supply
  5. Able to be used in hard to reach places
46
Q

Dimensions for TA green cartridge staples?

A

Leg length 4.8 mm
Crown width 4.0 mm
Closed height 2.0 mm

47
Q

Staple size for reusable GIA-90?

A

3.8 mm leg length
4.0 mm wide
1.5 mm final height
Staples B shaped when closed – permits blood flow

48
Q

7 benefits of fiberglass for cast material?

A
  1. Lightweight
  2. Strong
  3. Radiolucent
  4. Excellent molding capability
  5. Allows air through
  6. More durable
  7. Less material needed for adequate strength
49
Q

Fiberglass cast should be how thick?

A

7-8 mm

50
Q

By end of sx what percent of single gloves have punctures?

A

31%

51
Q

Bacilus stearothermophilus used for which sterilization technique?

A

Steam, formaldehyde, hydrogen peroxide

52
Q

Bacilus subtilus used for which sterilization technique?

A

Ethylene oxide & dry heat

53
Q

Bacilus pumulis used for which sterilization process?

A

Radiation

54
Q

What is Young’s modulus?

A

Measure of stiffness

55
Q

What is MAC?

A

Alveolar conc of inhalation anesthetic that prevents movement in 50% of subjects in response to noxious stimulus

56
Q

What is MAC of halothane, isoflurane, desflurane, & sevoflurane?

A

Halo - 0.88%
Iso - 1.31%
Des - 7.6%
Sevo - 2.31%

57
Q

Alpha-2 agonists reduce MAC by how much?

A

30%

58
Q

MOA of ketamine?

A

Dissociative agent
Induces analgesia, amnesia, immobility w/o depressing CV fun
Analgesia - NMDA receptor antagonist, high conc may partially block sodium channels

59
Q

MOA of morphine?

A

mu agonist

60
Q

What complication can occur w IV infusion of > 20% guaifenesin?

A

Thrombophlebitis

IV hemolysis

61
Q

What is maintenance rate of fluids for neonates?

A

As much as 120 ml/kg/day up to 1 mo

62
Q

How much does Xylazine ↓ HR in healthy 10-28 d foals?

A

20-30%

63
Q

Recommended O2 flow meter setting in neonates?

A

4-10 ml/kg

64
Q

Circle rebreathing system suitable for foals of what weight?

A

< 150 kg

65
Q

ETCO2 > 45 mmHg indicates? ETCO2 < 35 mmHg indicates?

A

> 45 hypoventilation

< 35 hyperventilation

66
Q

Dose of hetastarch for foals?

A

3 ml/kg @ 10 ml/kg/hr

67
Q

What are typical ventilatory settings for neonate?

A
Tidal vol – 6-10 ml/kg
Resp rate – 20-30/min
Peak flow – 60-90 ml/min
I:E ratio – 1:2
Peak insp pressure – 8-12 cm H2O
68
Q

Diff in butorphanol metabolism for neonates vs adults?

A

Longer half-life (2.1 hrs after IV)
Incr bioavailability (12%)
Both half-life & bioavailability 2x adults

69
Q

What % of foals develop hypoventilation under GA?

A

20%

70
Q

What rate of chest compressions recommended when doing CPR on foal?

A

100 per min

71
Q

What % of CO maintained w chest compressions?

A

No more than 25-30%

72
Q

Complications of epinephrine administration?

A

Ventricular fibrillation
Pulseless ventricular tachycardia
Incr systemic vascular response
(all ↑ myocardial O2 demand & workload)

73
Q

MOA of vasopressin?

A

Potent peripheral vasoconstrictor w high pressor activity via activation of vasopressin-1 receptors

74
Q

What is MOA of lidocaine?

A

Sodium channel blocker

Raises depolarization threshold making heart less likely to initiate or conduct early APs that cause arrhythmias

75
Q

At what Na concentration do seizures commonly occur?

A

< 110 Meq/L

76
Q

Options for decreasing potassium?

A

Sodium bicarb - incr pH which incr K/H cellular exchange (H out & K in)
Dextrose - incr insulin levels to drive K into cells
Insulin - as above
Furosemide - non-K sparing loop diuretic
Albuterol - B-2 agonist that drives K into cells

77
Q

Most common life threatening arrhythmia in foals w uremia & hyperkalemia?

A

3rd degree AV block

78
Q

Rib fx account for what % of life threatening injuries in young foals?

A

37%

79
Q

Which ribs most commonly affected in foals w rib fx?

A

L side 3rd-8th

80
Q

What % of anesthetic fatalities d/t inoperable orthopedic lesions sustained during recovery?

A

23%

81
Q

Possible causes of URT obstruction during recovery/after sx?

A
Pre-existing hemiplegia
Trauma
Hyperextension of neck
Prolonged duration of recovery
Sx of URT
Nasal edema d/t recumbency
Laryngospasm
DDSP
Kinking of head
82
Q

Side effects of phenothiazines?

A
Arterial hypotension
Decr PCV
Priapism
Decr GI motility
Loss of thermoregulatory control
May reduce seizure threshold
83
Q

Percent drop in PCV that can be caused by acepromazine?

A

~ 20%

84
Q

MOA of benzodiazepines?

A

GABA agonist

85
Q

Antagonists for benzodiazepines?

A

Fumazenil

Sarmazenil

86
Q

What should rate of blood transfusion be?

A

0.3 ml/kg over first 10-20 min

87
Q

What does phenylephrine do to heart rate?

A

Reflex bradycardia

88
Q

How does metabolic acidosis affect potassium?

A

K often elevated; potassium excretion can occur after correction of acidemia

89
Q

Metabolic alkalosis commonly assoc w disproportionate loss of what ions?

A

Chloride

90
Q

Which suture material’s degradation product act as antimicrobials?

A

Nylon

91
Q

How deep is tissue penetration in a Nd:YAG laser?

A

5 mm