8. Vascular Disorders & Thrombosis: Mechanisms of Edema

What is an important key to life?

water

What percent of body weight does water constitute?

60%

What amount of water is intracellular?

2/3

What amount of water is extracellular?

1/3

What compartments is extracellular water broken down into?

I
P

• interstitium

• plasma

What percent of water is extracellular in the interstitium?

80%

What percent of water is intravascular in the plasma?

20%

how water shifts from the different compartments and into and out of the cell

concentration gradient

What is water distribution between plasma and the interstitium determined mainly by?

osmotic and hydrostatic pressure differentials between the compartments

difference between the pressure within the capillaries and the pressure within the interstitium

hydrostatic pressure

Electrolytes make up roughly what percent of plasma osmolality? What can be said about their concentration between the intravascular compartment and the interstitium?

84%; due to their relatively free movements through the pores in the endothelium, their concentration remains relatively even

Plasma proteins make up roughly what percent of the osmolality? What do they represent the majority of? Why?

1%; oncotic pressure gradient; there is a vast difference in the concentration of these proteins between the interstitium and plasma

most important plasma protein responsible for the oncotic pressure gradient

albumin

The concentration of albumin is much greater in ________ than in the ________, typically which helps to pull fluid from the ________ into the ________ compartment.

plasma; interstitium; interstitium; intravascular

major oncotic protein within the interstitium

glycoproteins

What will alterations in any of the factors which regulate normal fluid distribution resulting in fluid accumulation in the interstitium result in?

edema

What are the mechanisms of edema?

I
I
D
D

• increased microvascular permeability

• increased intravascular hydrostatic pressure

• decreased oncotic pressure (or osmotic pressure)

• decreased lymphatic drainage

With increased microvascular permeability, ________ results in the release of ________ to cause ________. This results in the ________ of the interendothelial gaps. Water moves from the ________ ________ into the ________. This is the tissue ________ often seen in ________.

inflammation; mediators; vasodilation; widening; intravascular space; interstitium; swelling; inflammation

What is this an example of?

increased microvascular permeability (atopic dermatitis)

The edema due to increased microvascular permeability can be ________ or ________.

localized; systemic

What is this showing?

generalized edema due to septicemia

What are the mechanisms involved in increased intravascular hydrostatic pressure?

I
P
I

• increased blood flow (hyperemia)

• passive accumulation of blood (congestion)

• increased blood volume

How does an increase in blood flow lead to edema?

pressure within the capillary is higher, so the fluid will move out

How does passive accumulation of blood lead to edema?

more blood pooling means more fluid will move out

How does increased blood volume lead to edema?

more blood means more distended which means more pressure and more ability for fluid to move out

What is this an example of?

increased intravascular hydrostatic pressure

What is this an example of?

increased intravascular hydrostatic pressure (atrial septal defect causes dilation of the right side)

What does tracheal froth tell you?

that the lungs are edematous (indicative of pulmonary edema)

Which side of the heart with heart failure causes this?

left sided heart failure

What is this showing?

tracheal froth

What will chronic passive hepatic congestion cause?

yellow tinged fluid found in the abdominal cavity

Which sided heart failure causes chronic passive hepatic congestion?

right sided heart failure

With a liver suffering from chronic passive hepatic congestion, what will it look like on a cut surface? How would it feel?

reticular pattern and “Nutmeg” liver; firm

What is this showing?

chronic passive hepatic congestion

What is decreased oncotic pressure (or osmotic pressure) overwhelmingly most often due to? Which one specifically?

decreased plasma proteins; hypoalbuminemia

What are mechanisms of hypoalbuminemia that result in edema?

S
P
P
S
L
P

• severe blood loss

• protein losing enteropathy

• protein losing nephropathy

• severe burns

• loss of hepatic functional mass

• profound malnutrition (emaciation)

What is this an example of?

decreased oncotic pressure

Which mechanism of edema is responsible from bottle jaw caused by the barber pole worm?

decreased oncotic pressure

What is this image showing?

pulmonary edema

What is this image showing?

intestinal edema of the submucosa

What is this an image of?

equine GI lymphoma

What is the effect of hepatic cirrhosis in equines? What about in dogs and cats? What about in all 3?

liver gets giant; gets smaller; gets fibrous

What is this showing?

equine hepatic cirrhosis

reduced ability of the lymphatic system to remove excess fluid

decreased lymphatic drainage

What are causes of decreased lymphatic drainage?

L
L
L

• lymphatic vessel compression (neoplasia or inflammation)

• lymph vessel constriction (from fibrosis)

• lymph vessel blockage (thrombus or embolus)

What is this showing?

puppy with congenital lymphedema

In congenital lymphoma, the lymphatic vessels are either ________ or ________.

hypoplastic; aplastic

condition in which all tissues are edematous

anasarca

What is this showing?

fetal congenital edema (anasarca)

when fluid accumulates in a body cavity (abdomen, thorax, pericardial sac)

effusion

What are different examples of effusion>

A
T
P

• abdominal effusion

• thoracic effusion

• pericardial effusion

What are the three categories of effusions?

• pure transudate

• modified transudate

• exudate

type of effusion with low protein and low cellularity

pure transudate

Pure Transudate:

• protein = ________

• cellularity = ________

• ________ fibrinogen

• generally ________, ________, to ________ colored fluid

• < 2.5 g/dL

• < 1500 cells/uL

• low

• translucent; clear; straw

type of effusion that is high protein and high cellularity

exudate

Exudate:

• protein = ________

• cellularity = ________

• ________ therefore ________ fibrinogen

• generally ________ or ________

• > 2.5 g/dL

• > 5000 cells/uL

• inflammatory; high

• cloudy; opaque

type of effusion that does not fit into the other categories

modified transudate

Modified Transudate:

• category in between which is either ________ protein or ________ cellularity or a ________ thereof

• protein = ________

• cellularity = ________

• low; low; combination

• > 2.5 g/dL

• < 5000 cells/uL

Transudative effusions are generally a result of one of which two mechanisms?

I
D

• increased intravascular hydrostatic pressure

• decreased oncotic pressure (or osmotic pressure)

What is this an image of?

ascites

thoracic transudative effusion

hydrothorax

pericardial transudative effusion

hydropericardium

abdominal transudative effusion

hydroperitoneum or ascites

True or false: “Hydro” is not used for modified transudate or exudate.

true

What is this showing?

ascites

What are exudative effusions generally a result of?

increased vascular permeability due to inflammation

What is this showing?

exudative effusions due to FIP

specific type of effusion (typically thoracic) due to obstruction of the thoracic duct where there is lymph in the thoracic cavity itself that is an opaque white to pink tinged fluid

chylous effusions

What is the protein level in chylous effusions? What can be significant about the protein?

> 2.5 g/dL; may be artifactually increased due to large lipoproteins int he sample increasing the refractive index

What is the cellularity level of chylous effusions?

variable, but usually > 3000 cells/uL

What is this showing?

chylous effusions