Lecture 16 11/12/24 Flashcards
How does electrocautery work?
-vaporization of the cells
-thermal necrosis of the edges of the incision
-no bleeding
What are the characteristics of CUT electrocautery?
-constant impulse
-vaporization of the tissue
-minimal collateral damage
What are the characteristics of COAG electrocautery?
-intermittent impulse
-activates coagulation of the proteins to form blood clot
What are the components of the electric circuit on a monopolar handle electrocautery unit?
-active electrode
-patient
-plate
What are the characteristics of plate installation for monopolar handle electrocautery?
-close to surgical site
-adequate contact
-well vascularized area
-prevent burns
What should be done to ensure best outcome with electrocautery?
-surgical site must be somewhat dry
-electrode should be maintained clean
What are the characteristics of bipolar handle electrocautery?
-maximal distance between tips of 1 mm
-precise coagulation
-can be used in a wet wound
-limits thermal collateral damages
What are the principles of a bipolar radio-frequency energy device?
-high current with a low voltage in a bipolar circuit
-denaturation of collagen and elastin within vessel wall
-device detects changes of impedance of the tissue and automatically stops
-can seal veins up to 7mm in diameter
What are the characteristics of a harmonic scalpel?
-ultrasound device
-waves are transmitted to tip of blade
-energy is transferred to adjacent tissue
-denaturation of proteins
What is LASER?
Light Amplification by Stimulated Emission of Radiation
What is Class 1 LASER?
incapable of production of damaging radiation during operation
What is Class 2 LASER?
potential to cause optical damage if viewed directly during prolonged exposition
What is Class 3 LASER?
-potentially hazardous under some direct viewing conditions if the eye is appropriately focused and stable
-probability of actual injury is small
What is Class 4 LASER?
-hazardous to the skin by direct beam
-direct or indirect exposure of the eye to the beam causes injury to the eye
-produces air contaminant by vaporization of cellular debris
What are the characteristics of the LASER light?
-different sources of emission of light
-energy in joules
-power in watts
-density of power in watts/cm^2
How does the LASER work?
-absorption of light produces heat
-denaturation of proteins occurs at 65-90 deg. C
-dehydration occurs at 90-100 deg. C
-vaporization/carbonization occurs at greater than 100 deg. C
What are the safety steps taken when working with LASER?
-no attenuation of the signal
-wear protective glasses that match the LASER
-protect the endotracheal tubes and the high conc. of O2
-close doors and windows
-have indicators to the outside that say LASER is in use
-have a way to evacuate/filter the smoke
How does the focus of the laser beam impact its use?
-more focused laser beam is used for incision
-less focused laser beam is used for coagulation
What are the characteristics of photodynamic cells?
-dye is given that is only taken up by cancer cells
-a LASER is used in which the light produced can only be taken up by cells that also took up the dye
-very targeted treatment of cancer cells
What are the benefits of cryosurgery?
-limit inflammation
-lower pain
What are the characteristics of cold cytotoxicity?
-intracellular formation of ice crystals alters cellular membrane
-extracellular formation of ice crystals dehydrates and causes hyperosmolarity
What temperature must be reached to cause cold cytotoxicity?
-20 deg. C/-4 deg. F
What is used to freeze tissue in cryosurgery?
liquid nitrogen, which reaches temps of -196 deg. C/-320 deg. F
What are the indications for cryosurgery?
-cutaneous tumors
-ophthalmic surgeries
-dentistry
What is the primary damage that occurs in cryosurgery?
formation of ice crystals
What are the secondary damages that occur in cryosurgery?
-increase in vascular permeability
-local hemoconcentration
-damage to the endothelium of small vessels
-thrombus formation
-ischemia/infarction of tissue
Which materials are needed for cryosurgery?
-hollow probes
-solid probes
-freeze guns
What does cryosurgery consist of?
-two cycles each of fast freezing and slow thawing
-fast freezing increases the intracellular conc. of ice crystals
-slow thawing increases the size of ice crystals and increases cellular damage
What is electrochemotherapy?
application of an electrical current to a tumor to increase the conc. of chemotherapy in the tumor cells
Which tumors are electrochemotherapy used on in dogs and cats?
-mast cell tumors
-hemangioma
-perianal tumor
-squamous cell carcinoma
-Schwannoma
Which tumors are electrochemotherapy used on in horses?
-sarcoids
-fibrosarcomas
What are the indications for the use of a surgical stapler?
-skin closure
-intestinal resections and anastomosis
What are the benefits of surgical stapler use?
-reduction in surgery time
-less intra-operative contamination
What are the characteristics of a skin stapler?
-wounds not placed under tension
-excellent wound edge eversion
-no strangulation of tissue
-minimal tissue reaction
-associated with increased SSI in some procedures
Which staplers are used for resection-anastomosis?
-thoraco-abdominal stapler: 2 rows of staples
-gastrointestinal anastomosis stapler: 4 rows of staples and a blade
What are resection-anastomosis staplers used for?
-resection and biopsy
-functional end-to-end anastomosis
