02/23f Hemodynamics

Question 1

What is edema?

Answer 1

Increased tissue water content

Can be intracellular or extracellular

Question 2

Where in the body can extracellular edema occur?

Answer 2

Interstitial locations - within tissues

Body cavities - present spaces (pleural, peritoneal, pericardial) and potential spaces

Question 3

What are the two general mechanisms that lead to interstitial edema?

Answer 3

1) Increased hydrostatic pressure across the capillary bed

2) Decreased osmotic pressure gradient

Question 4

What can cause increased hydrostatic pressure across the capillary bed?

Answer 4

Chronic dependency or gravity (sitting or standing for long periods)
Congestive heart failure
Venous obstruction (deep vein thrombosis, cirrhosis, constrictive pericarditis)
Marked arterial vasodilation

Question 5

What substance is the main determinant of the osmotic pressure gradient across capillaries?

Answer 5

Plasma proteins, primarily albumin

Question 6

What can cause a decrease in the osmotic pressure gradient between interstitial compartments?

Answer 6

Hypoalbuminemia/hypoproteinemia (less osmotic pull)

Increased vascular permeability due to inflammation, trauma, burn, etc. (proteins leak out)

Question 7

What can cause hypoalbuminemia?

Answer 7

Inadequate synthesis of albumin due to liver failure or protein malnutrition
Excessive loss of albumin due to nephrotic syndrome or protein losing enteropathy

Question 8

Is edema resulting from hypoalbuminemia localized, or generalized?

Answer 8

Generalized, including all soft tissues and viscera (anasarca)

Question 9

What are the symptoms of nephrotic syndrome?

Answer 9

Proteinuria
Hypoalbuminemia
Generalized edema (anasarca)
Hyperlipidemia and hyperlipiduria

Question 10

What is the difference between edema caused by hypoalbuminemia or increased venous pressure, and edema caused by inflammation?

Answer 10

Edema caused by low albumin or high venous pressure is a transudate (fluid with low protein content)
Edema caused by inflammation is an exudate (fluid with high protein content)

Question 11

What are the causes of lymphatic obstruction?

Answer 11

Obstruction secondary to malignancy - hematologic "sludging" in leukemia and lymphoma patients
Iatrogenic - surgical interruption and post radiation therapy
Parasitic invasion (filiariasis/elephantiasis)

Question 12

What is a common consequence of increased venous pressure?

Answer 12

Congestive heart failure

Question 13

What are the major characteristics and manifestations of congestive heart failure?

Answer 13

Backward failure - increased atrial pressure
Forward failure - diminished cardiac output
Results in renal hypoperfusion and decreased effective blood volume, which causes decreased excretion of sodium and water

Question 14

What are the manifestations of left-sided heart failure?

Answer 14

Increase in left atrial pressure
Increase in pulmonary venous pressure
Pulmonary congestion and chief complaint of respiratory distress

Question 15

What are the manifestations of right-sided heart failure?

Answer 15

Increase in right atrial pressure
Increase in systemic venous pressure
Systemic congestion, particularly in the liver and lower extremities

Question 16

What is shock?

Answer 16

Syndrome resulting from generalized decrease in tissue perfusion

Question 17

What are the three types of shock?

Answer 17

Cardiogenic
Hypovolemic
Neurogenic/vasodilatory

Question 18

What is cardiogenic shock? What can cause it?

Answer 18

Marked decrease in cardiac output due to inadequate cardiac function
Can be caused by myocardial infarct, myocarditis, or toxic injury such as chemotherapy

Question 19

What is hypovolemic shock? What can cause it?

Answer 19

Significant loss of blood volume

Can be caused by blood loss (hemorrhagic shock), loss of plasma (severe thermal burns), or severe diarrhea/dehydration

Question 20

What are two types of vasodilatory shock?

Answer 20

Septic shock - bacterial endotoxin causes increased vascular permeability and depression of cardiac function
Anaphylactic shock - massive histamine release causes marked vasodilation

Question 21

What four compensatory mechanisms does the body use to deal with shock?

Answer 21

1) Vascular autoregulation to maintain blood flow to the heart and brain
2) Sympathetic activation to increase heart rate, cardiac contractility, and vasoconstriction
3) Shifts water from the interstitial to the intravascular space (hemodilution)
4) Increases renal sodium and water reabsorption

Question 22

What are some complications that can result from shock?

Answer 22

Acute tubular necrosis
Pancreatitis
GI mucosal hemorrhage and necrosis
Centrilobular liver necrosis
Watershed infarcts in the brain
Hemorrhagic necrosis of the adrenals
Pulmonary edema in cardiogenic and septic shock