PPT flashcards Surgical methods
What are 3 undesirable effects assoc w charred electrode during electroincision?
- Higher power req to incise tissues
- Current dispersed to larger area of tissue
- Thermal necrosis @ wound edges increased
2 ways vessels can be electrocoagulated?
- Obliterative coagulation – direct contact; vessel wall shrinks & occludes
- Coaptive coagulation – vessel occluded by hemostats which conducts energy to vessel inducing occlusion
What is flow rate of Veress needles when used for insufflation?
< 3L/min
What is flow rate of teat cannulas when used for insufflation?
6-7 L/min
What size vessels can be sealed w vessel sealing devices (eg. Ligasure)?
Up to 7 mm
Prognosis for horses with aortic-iliac thrombosis w thrombectomy?
65% regained athletic activity & 53% performed @ previous level
Method of cell destruction with cryosurgery?
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
Which 5 tissues not ideal for cryosurgery?
- 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
5 complications of cryosurgery?
- Swelling
- Necrosis
- Bleeding
- Depigmentation
- Odor
What does LASER stand for?
Light Amplification by Stimulated Emission of Radiation
What is principle of selective photothermolysis?
Interaction btw laser light & tissue that preferentially absorbs wavelength
What is fluence?
Total amt of energy delivered per unit area of tissue
What is nm energy of CO2 laser?
10,600 nm
CO2 laser penetrates tissue to what depth?
0.03 mm
CO2 laser can eliminate hemorrhage from vessels of what size?
Up to 0.5 mm
Wavelength of Nd:YAG laser?
1064 nm
Wavelength of GAL diode laser?
980 nm
Nd:YAG & GAL laser absorption?
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
Wavelength of Ho:YAG laser?
2100 nm
Ho:YAG laser absorption?
Substantially absorbed by water; effect enhanced in water medium
(Pulsed laser)
Which laser will ablate bone?
Ho:YAG
Has been used to remove palmar/plantar OC frags of P1
Wavelength of pulsed dye laser?
400-700 nm
Absorption of pulsed dye laser?
Hgb & urinary calculi
Has been used in equine laser lithotripsy – combo of plasma formation & photoacoustic effect
Laser setting/dose for laser thermoplasty of soft palate?
GAL laser
20W w 600 um fiber applied in pin fire contact fashion
~ 1500J total
Contact or noncontact excision preferred for laser ventriculocordectomy?
Contact
Obtains tight arytenoid-thyroid adhesion
No ventricular mucoceles reported w contact technique
Which portion of vocal fold should be left for last & why?
Ventral aspect
Houses a vessel that can obscure vision
Dose/energy for laser ventriculocordectomy?
GAL laser
20 W
600 um fiber
~ 10,000 J
Define tensile strength for suture?
Force that suture strand can withstand before it breaks when force is applied in direction of length
Define knot holding capacity?
Maximum load to failure when tension applied to knotted suture material
Define relative knot security?
Knot holding capacity expressed as a percentage of the unknotted sutures tensile strength
RKS = (KHC/TS) x 100
Weakest part of suture?
Knot
Most reliable knot configuration?
Superimposition of square knots
What 4 things can affect knot security?
- Memory
- Coefficient of friction
- Number of throws
- Suture end length
What is min number of throws for knots of 2-0 suture for PG910, polyglycolic acid, & polypropylene?
3
What is min number of recommended throws for 2-0 nylon & PDS?
4
Min number of throws for large diameter suture knots?
5