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Flashcards in Surgical Principals/Instruments Deck (15):

What is the difference between cut and coag cautery?

Recall - Power = Current x Voltage

Cut - for a given power setting minimizes voltage but increases current and continuous so that you heat tissue rapidly and vaporize

Coag - for given power setting minimizes/pulsed current and increases voltage for deeper tissue penetration with lower current density. Pulsed - means you produce less heat and can produce a coagulum


What is Ohm's law?

Voltage = current x resistance


What is Joule's law?

Energy = current density (current/cross sectional area) squared x time x resistance.

If you want to high heat - increase continuous current (cut mode) vs decrease/pulse current (coag mode)


What is the difference between monopolar and bipolar?

Monopolar - current goes through tissue to the grounding pad

Bipolar - current just between the tines


How does spray work?

Argon gas passes over the electrocautery tip. Disperses pooled blood from the target area, and 


How does Gelfoam work?

Physical matrix for clotting initiation. Swells and can double volume so can be compressive for hemostasis but be wary of compressing adjacent structure/nerves. 


How long does gelfoam last in the body?

4-6 weeks


What is surgicel?

An oxidized cellulose that acts as a physical matrix for clotting


Why is surgicel antimicrobial?

Lowers pH


What are 2 limitations of surgicel?

Not as effective when wet, lowers pH so can't be used with thrombin


How does collagen products (e.g. microfibrillar collagen) aid hemostasis?

Platelets adhere to the fibrils on collagen surface. Also stimulates the release of platelet granules. Expected hemostasis in 2-5 mins. Can work with heparin on board but needs functional platelets so wont work with thrombocytopenia. 


How do polysaccharide spheres aid hemostasis?

Absorbs plasma or blood to concentrate platelet/clotting factors and forms a matrix for the formation of clot


Name 4 classes of hemostatic agents that act via mechanical means


Oxidized cellulose (ie surgicel)

Collagen (ie microfibrillar collagen)

Polysaccharide spheres


How does Floseal work?

Mechanical strength - Gelatin matrix of bovine collagen

Clot formation - mixed with microgranules human thrombin and glutaraldehyde. The crosslinked gelatin granules swell on contact with blood and offer an additive tamponade effect


How do chitins work as a hemostatic agent?

Rapid hemostatic bandage - rapidly binds and absorbs plasma proteins and coated nanofibers activate coagulation