PPT flashcards Surgical methods
1
Q
What are 3 undesirable effects assoc w charred electrode during electroincision?
A
- Higher power req to incise tissues
- Current dispersed to larger area of tissue
- Thermal necrosis @ wound edges increased
2
Q
2 ways vessels can be electrocoagulated?
A
- Obliterative coagulation – direct contact; vessel wall shrinks & occludes
- Coaptive coagulation – vessel occluded by hemostats which conducts energy to vessel inducing occlusion
3
Q
What is flow rate of Veress needles when used for insufflation?
A
< 3L/min
4
Q
What is flow rate of teat cannulas when used for insufflation?
A
6-7 L/min
5
Q
What size vessels can be sealed w vessel sealing devices (eg. Ligasure)?
A
Up to 7 mm
6
Q
Prognosis for horses with aortic-iliac thrombosis w thrombectomy?
A
65% regained athletic activity & 53% performed @ previous level
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
8
Q
Which 5 tissues not ideal for cryosurgery?
A
- Dry tissues – eg. cornea
- Tissues near major blood vessels (difficult to ↓ temp & keep it low)
- Nerve epineurium not destroyed so maintains potential for regrowth
- Cortical bone - ↓ bone strength by 70%; bone tumors don’t respond well; fx have been reported
- Auricular cartilage – can result in ear deformity
9
Q
5 complications of cryosurgery?
A
- Swelling
- Necrosis
- Bleeding
- Depigmentation
- Odor
10
Q
What does LASER stand for?
A
Light Amplification by Stimulated Emission of Radiation
11
Q
What is principle of selective photothermolysis?
A
Interaction btw laser light & tissue that preferentially absorbs wavelength
12
Q
What is fluence?
A
Total amt of energy delivered per unit area of tissue
13
Q
What is nm energy of CO2 laser?
A
10,600 nm
14
Q
CO2 laser penetrates tissue to what depth?
A
0.03 mm
15
Q
CO2 laser can eliminate hemorrhage from vessels of what size?
A
Up to 0.5 mm
16
Q
Wavelength of Nd:YAG laser?
A
1064 nm
17
Q
Wavelength of GAL diode laser?
A
980 nm
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
19
Q
Wavelength of Ho:YAG laser?
A
2100 nm
20
Q
Ho:YAG laser absorption?
A
Substantially absorbed by water; effect enhanced in water medium
(Pulsed laser)
21
Q
Which laser will ablate bone?
A
Ho:YAG
Has been used to remove palmar/plantar OC frags of P1
22
Q
Wavelength of pulsed dye laser?
A
400-700 nm
23
Q
Absorption of pulsed dye laser?
A
Hgb & urinary calculi
Has been used in equine laser lithotripsy – combo of plasma formation & photoacoustic effect
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
25
Contact or noncontact excision preferred for laser ventriculocordectomy?
Contact
Obtains tight arytenoid-thyroid adhesion
No ventricular mucoceles reported w contact technique
26
Which portion of vocal fold should be left for last & why?
Ventral aspect
| Houses a vessel that can obscure vision
27
Dose/energy for laser ventriculocordectomy?
GAL laser
20 W
600 um fiber
~ 10,000 J
28
Define tensile strength for suture?
Force that suture strand can withstand before it breaks when force is applied in direction of length
29
Define knot holding capacity?
Maximum load to failure when tension applied to knotted suture material
30
Define relative knot security?
Knot holding capacity expressed as a percentage of the unknotted sutures tensile strength
RKS = (KHC/TS) x 100
31
Weakest part of suture?
Knot
32
Most reliable knot configuration?
Superimposition of square knots
33
What 4 things can affect knot security?
1. Memory
2. Coefficient of friction
3. Number of throws
4. Suture end length
34
What is min number of throws for knots of 2-0 suture for PG910, polyglycolic acid, & polypropylene?
3
35
What is min number of recommended throws for 2-0 nylon & PDS?
4
36
Min number of throws for large diameter suture knots?
5
37
Knots @ end of continuous suture line req how many more throws than single suture strands?
2-3
38
How many additional throws needed to achieve knot security w asymmetric knots (sliding half hitch)?
2
39
6 advantages of interrupted over continuous suture patterns?
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
5 advantages of continuous suture patterns over interrupted?
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
What is optimal ratio of suture to wound length for abdominal incisions?
4:1 to allow for incisional lengthening during periods of abdominal distention
42
GI incisions heal rapidly; what is critical time period when suture strength important?
4 days (lag phase)
43
Closing paramedian skin incision involves suturing ? of ? muscle?
Fascia
| Rectus abdominus muscle
44
Major holding layers within the walls of large vessels?
Tunica adventitia & tunica media
45
5 advantages of surgical staplers?
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
Dimensions for TA green cartridge staples?
Leg length 4.8 mm
Crown width 4.0 mm
Closed height 2.0 mm
47
Staple size for reusable GIA-90?
3.8 mm leg length
4.0 mm wide
1.5 mm final height
Staples B shaped when closed – permits blood flow
48
7 benefits of fiberglass for cast material?
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
Fiberglass cast should be how thick?
7-8 mm
50
By end of sx what percent of single gloves have punctures?
31%
51
Bacilus stearothermophilus used for which sterilization technique?
Steam, formaldehyde, hydrogen peroxide
52
Bacilus subtilus used for which sterilization technique?
Ethylene oxide & dry heat
53
Bacilus pumulis used for which sterilization process?
Radiation
54
What is Young’s modulus?
Measure of stiffness
55
What is MAC?
Alveolar conc of inhalation anesthetic that prevents movement in 50% of subjects in response to noxious stimulus
56
What is MAC of halothane, isoflurane, desflurane, & sevoflurane?
Halo - 0.88%
Iso - 1.31%
Des - 7.6%
Sevo - 2.31%
57
Alpha-2 agonists reduce MAC by how much?
30%
58
MOA of ketamine?
Dissociative agent
Induces analgesia, amnesia, immobility w/o depressing CV fun
Analgesia - NMDA receptor antagonist, high conc may partially block sodium channels
59
MOA of morphine?
mu agonist
60
What complication can occur w IV infusion of > 20% guaifenesin?
Thrombophlebitis
| IV hemolysis
61
What is maintenance rate of fluids for neonates?
As much as 120 ml/kg/day up to 1 mo
62
How much does Xylazine ↓ HR in healthy 10-28 d foals?
20-30%
63
Recommended O2 flow meter setting in neonates?
4-10 ml/kg
64
Circle rebreathing system suitable for foals of what weight?
< 150 kg
65
ETCO2 > 45 mmHg indicates? ETCO2 < 35 mmHg indicates?
> 45 hypoventilation
| < 35 hyperventilation
66
Dose of hetastarch for foals?
3 ml/kg @ 10 ml/kg/hr
67
What are typical ventilatory settings for neonate?
```
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
Diff in butorphanol metabolism for neonates vs adults?
Longer half-life (2.1 hrs after IV)
Incr bioavailability (12%)
Both half-life & bioavailability 2x adults
69
What % of foals develop hypoventilation under GA?
20%
70
What rate of chest compressions recommended when doing CPR on foal?
100 per min
71
What % of CO maintained w chest compressions?
No more than 25-30%
72
Complications of epinephrine administration?
Ventricular fibrillation
Pulseless ventricular tachycardia
Incr systemic vascular response
(all ↑ myocardial O2 demand & workload)
73
MOA of vasopressin?
Potent peripheral vasoconstrictor w high pressor activity via activation of vasopressin-1 receptors
74
What is MOA of lidocaine?
Sodium channel blocker
| Raises depolarization threshold making heart less likely to initiate or conduct early APs that cause arrhythmias
75
At what Na concentration do seizures commonly occur?
< 110 Meq/L
76
Options for decreasing potassium?
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
Most common life threatening arrhythmia in foals w uremia & hyperkalemia?
3rd degree AV block
78
Rib fx account for what % of life threatening injuries in young foals?
37%
79
Which ribs most commonly affected in foals w rib fx?
L side 3rd-8th
80
What % of anesthetic fatalities d/t inoperable orthopedic lesions sustained during recovery?
23%
81
Possible causes of URT obstruction during recovery/after sx?
```
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
Side effects of phenothiazines?
```
Arterial hypotension
Decr PCV
Priapism
Decr GI motility
Loss of thermoregulatory control
May reduce seizure threshold
```
83
Percent drop in PCV that can be caused by acepromazine?
~ 20%
84
MOA of benzodiazepines?
GABA agonist
85
Antagonists for benzodiazepines?
Fumazenil
| Sarmazenil
86
What should rate of blood transfusion be?
0.3 ml/kg over first 10-20 min
87
What does phenylephrine do to heart rate?
Reflex bradycardia
88
How does metabolic acidosis affect potassium?
K often elevated; potassium excretion can occur after correction of acidemia
89
Metabolic alkalosis commonly assoc w disproportionate loss of what ions?
Chloride
90
Which suture material’s degradation product act as antimicrobials?
Nylon
91
How deep is tissue penetration in a Nd:YAG laser?
5 mm
