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?
What is surgicel?
An oxidized cellulose that acts as a physical matrix for clotting
Why is surgicel antimicrobial?
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)
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