Pulmonary and systemic oedema

Question 1

What are the 2 classes of fluid within the body?

Answer 1

Interstitial - Bathes cells
Intravascular - In the blood stream

Question 2

What law does movement of gasses and solutes across the capillary walls follow?

Answer 2

Fick’s law of diffusion

Question 3

How do lipid soluble molecules pass through the capillary walls?

Answer 3

They diffuse through the epithelial cells

Question 4

How do water soluble molecules pass through the capillary walls?

Answer 4

They pass through pores in the capillary walls

Question 5

What is the net filtration pressure across the capillary walls equal to?

Answer 5

(Forces favouring filtration - Forces opposing filtration) multiplied by a filtration constant

Question 6

Which forces favour filtration across the capillary walls?

Answer 6

Capillary hydrostatic force (Pc) (Force due to blood flow) - 35mmHg at arteriole end, 17mmHg at venule end
Interstitial fluid osmotic pressure (πi)

Question 7

Which forces oppose filtration across the capillary walls?

Answer 7

capillary osmotic (Oncotic) pressure (πc) (Forces due to proteins in blood decreasing WP)
Interstitial fluid hydrostatic pressure (Pi)

Question 8

What happens to excess interstitial fluid?

Answer 8

It moves into the lymphatic system as lymph

Question 9

What is oedema?

Answer 9

the accumulation of fluid in the interstitial space

Question 10

What are the main causes of oedema?

Answer 10

Raised capillary hydrostatic pressure
Reduced plasma osmotic pressure
Lymphatic insufficiency
Changes to capillary permeability

Question 11

What can cause raised capillary hydrostatic pressure?

Answer 11

Arteriolar dilation - Less blood flow into capillaries
Raised venous pressure - Increases pressure at venule end, so less moves back into blood:
Left ventricular failure => Pulmonary oedema (Left = Lungs)
Right ventricular failure => Peripheral oedema (Right = Rest of body)

Question 12

What can cause reduced plasma osmotic pressure?

Answer 12

Malnutrition
Protein malabsorption
Excessive renal excretion of protein
Hepatic failure

Question 13

What is the normal plasma protein concentration?

Answer 13

65-80 g/l

Question 14

At what plasma protein concentration can oedema occur?

Answer 14

<30 g/l

Question 15

What are some causes of lymphatic insufficiency?

Answer 15

Lymph node damage
Filariasis - elephantiasis (Worm in lymphatic system)

Question 16

What are some causes of increased capillary permeability?

Answer 16

Inflammation
Histamine

Question 17

What is pulmonary oedema?

Answer 17

An accumulation of fluid in the interstitial fluid and intraalverolar spaces of the lungs

Question 18

What are some manifestations of pulmonary oedema?

Answer 18

varying degrees of shortness of breath (Orthopnoea, PND)
Crepitations upon lung auscultation
Haziness in perihilar regions on Chest X-Ray