Edema – excess fluid in the interstitial space, which is extracellular fluid (ECF); this is outside the vessel
Types of Edema
1. Non-Pitting edema – increased vessel permeability with pus in the interstial space
(pus=exudates). Lymphatic fluid is another type of non-pitting edema. Blockage of lymphatics
leads to lymphatic fluid in the interstial space. Pits early, but eventually becomes nonpitting.
Exudates and lymphatic fluid does not pit.
2. Pitting edema – transudate with right heart failure, swelling of the lower extremities, fluid in
the interstial space. Transudate does pit.
3. So there are three things that cause edema: exudates, lymphedema, and transudate, and
transudates are the only one that has pitting edema.
Transudate deals with starling forces:
1. What keeps fluid in our blood vessels? Albumin, and this is called oncotic pressure. 80% of
our oncotic pressure is related to the serum albumin levels. Anytime there is hypoalbuminemia
then we will have a leaking of a transudate (protein of less than 3 g/dL) leaking into interstial
space via capillaries and venules (pitting edema);
2. Normally, hydrostatic pressure is trying to push fluid out. Therefore, in a normal person,
oncotic pressure is winning. Therefore, a decrease in oncotic pressure and an increase in
hydrostatic pressure will lead to transudate (pitting edema).
3. Albumin is made in the liver. With chronic liver dz (cirrhosis), have a decreased albumin
level. Can you vomit it out? No. Can crap it out (malabsorption syndrome), or can pee it out
(nephrotic syndrome), can come off our skin (3 degree burn b/c losing plasma), another
possibility of low protein ct (low-intake) is seen in kids – Kwashiorkor – kid has fatty liver and
decreased protein intake, leading to low albumin level.
a. Person with MI 24 hrs ago and he died and he has fluid coming out– transudate b/c