10: Edema, Congestion, Hyperemia

what maintain normal fluid homeostasis?

wall integrit, intravascular pressure, osmolarity

what is edema?

alterations in any factor that regulates normal fluid distribution, resulting in accumulation of that fluid in the interstitium

edema

increased fluid into interstitial/extracellular spaces

describe edema

clear to yellow gelatinous material or fluid

2 types of starling forces

hydrostatic and oncotic pressures

hydrostatic pressure

push pressure - pushes fluid in

oncotic pressure

pull pressure - pulls fluid out

gross appearance of edema

swelling/distension, usually sags ventrally, tissue pits and is cool to touch (if inflammation is present will be warm)

describe edema fluid IN TISSUE

clear, yellow-tinged fluid

color of effusion fluid

CLEAR/SEE THROUGH

edema on histology

separation of tissues by clear spaces

prefix used before location of body cavities when describing effusion

hydro

hydrocoele

fluid filled cyst anywhwere in body

anasarca

severe/generalized edema, with profound SQ tissue swelling, affects whole body

non-inflammatory effusion

transudate

describe transudate fluid

low protein levels, clear/colorless/slightly yellow

describe modified transudate fluid

moderately high protein levels, most common in FIP

inflammatory effusion

exudate

describe exudate fluid

high protein levels, OPAQUE (not-see through)

causes of intracellular edema

depression of metabolic systems, lack of nutrition to cells, inflammation

causes of extracellular edema

leaky capillaries, no lymphatic circulation, renal retention of salt/water

most common cause of intracellular edema

inflammation

4 MAJOR MECHANISMS OF EDEMA (VERY IMPORTANT, MUST KNOW)

increased microvascular permeability/intravascular hydrostatic pressure, decreased oncotic pressure/lymphatic drainage

2 of the 4 edema mechanisms are due to an INCREASE IN WHAT?

microvascular permeability (leaky vessels) and intravascular hydrostatic pressure (more fluid flowing out)

2 of the 4 edema mechanisms are due to a DECREASE in what?

oncotic pressure and lymphatic drainage

what causes increased microvascular permeability?

inflammation or endothelial damage

how does inflammation increase microvascular permeability?

causes vasodilation, widening gaps, fluid leaks out

what causes increased intravascular hydrostatic pressure?

venous obstruction or impaired venous outflow

hyperemia

increased blood flow

congestion

passive accumulation of blood

most common causes of increased intravascular hydrostatic pressure

congestive heart failure, liver cirrhosis, obstruction/vein narrowing

what causes decreased oncotic pressure?

loss of colloids in capillaries

main issues causing decrease in oncotic pressure

kidney disease, liver cirrhosis/failure, GI parasite, malnutrition, blood loss

hypoalbuminemia

cirrhosis of liver/liver failure

what causes decreased lymphatic drainage?

inflammation, lymphatic vessel compression/constriction/bloackage

what causes lymphatic vessel compression?

neoplasia or inflammation

what causes lymphatic vessel constriction?

fibrosis

what causes lymphatic vessel blockage?

thrombus/embolus

what causes hyperemia?

dilation of arterioles

color of hyperemia and WHY

red, oxygenated blood engorges area

is congestion active or passive?

PASSIVE

color of congestion and WHY

red-blue, deoxygenated blood engorges area

causes of congestion

heart failure, venous occlusion, hypostasis

true or false: active hyperemia is a NORMAL, PHYSIOLOGIC PROCESS

TRUE

what causes congestion?

impaired blood outflow from a tissue

3 types of passive congestion

hypostatic, chronic passive, chronic pulmonary

hypostatic congestion

living livor mortis - blood pools in organs/tissues on lower side of recumbent animal

chronic passive congestion

right heart failure

chronic pulmonary congestion

left heart failure