Ch.14 Cryosurgery

Question 1

What are the 2 main mechanisms of tissue injury from freezing

Answer 1

Immediate
Delayed

Question 2

What ocurs in the immediate mechanism

Answer 2

1. Direct injury to cells caused by ice crystal formation
2. Hyperosmotic environment
3. Dehydrates cells
4. Increased electrolyte conc
5. pH changes
6. Crystals disrupt organelles & cell membranes
   immediate cell death

Thawing at -20 -25c ice crystals fuse - *recrystallization * - disrupt cell membranes
With thawing water enters cells - burst

Question 3

What occurs in the delayed mechanism

Answer 3

After thawing
Progressive microcirculation failure and vascular stasis
increased permeability of cell wall, edema, platelt aggregation, microthrombus

Question 4

Temps req for cell death

Answer 4

-20c for 1 min
-30 -40 for 1 min for cancer cells

Question 5

Temp of N2O gas

Answer 5

-89 C / -127 F

Question 6

Temp of liquid nitrogen

Answer 6

-196 C /-320.4 f