Oedema & Heart Failure

Question 1

What is the purpose of interstitial fluid?

Answer 1

Acts as a go between blood and body cells

Question 2

Describe capillaries

Answer 2

• single layer endothelial cells
• allow rapid exchange of gases, water & solutes
• allow nutrients & oxygen to be delivered & metabolites to be removed

Question 3

What do terminal arterioles & pre capillary sphincters do?

Answer 3

Regulate regional blood flow, pre capillary sphincters regulate flow in few tissues e.g. mesentery

Question 4

Why is blood flow slow?

Answer 4

To allow adequate exchange time

Question 5

How do small soluble substances pass across capillary walls?

Answer 5

Through pores e.g. sodium, potassium, glucose

Question 6

How do lipid soluble substances pass across capillary walls?

Answer 6

Through endothelial cells e.g. oxygen & carbon dioxide

Question 7

Can plasma proteins pass through capillary walls?

Answer 7

NO - they stay inside

Question 8

Is transcapillary flow passive or active?

Answer 8

passive by pressure gradients

Question 9

net filtration = ?

Answer 9

forces favouring filtration - forces opposing filtration

Question 10

Name the three major forces affecting net filtration

Answer 10

Pc - capillary hydrostatic pressure

∏c - capillary osmotic pressure

Question 11

What other forces act on filtration?

Answer 11

∏i - interstitial fluid osmotic pressure

Pi - interstitial fluid hydrostatic pressure

Question 12

What is the effect of starling forces?

Answer 12

Favour filtration at the arteriolar end and reabsorption at the venular end

Question 13

How is the pulmonary circulation different from the systemic?

Answer 13

The hydrostatic pressure is much lower than the systemic circulation. Resistance is only 10% of the systemic circulation

Question 14

Define oedema

Answer 14

accumulation of fluid in the interstitial space

Question 15

In terms of gas exchange what is the effect of oedema?

Answer 15

This increases distance of gas exchange in pulmonary oedema

Question 16

State four things that can cause oedema

Answer 16

1. Raised Capillary Pressure
2. Reduced Plasma Osmotic Pressure
3. Lymphatic Insufficiency
4. Changes in capillary permeability

Question 17

What is the effect of raised capillary pressure?

Answer 17

arteriolar dilatation and raised venous pressure

Question 18

What does pulmonary oedema indicate?

Answer 18

Left Ventricular Failure

Question 19

What does ankle/sacral oedema indicate?

Answer 19

Right Ventricular Failure

Question 20

Is the oedema pitting or non-pitting in heart failure?

Answer 20

Pitting

Question 21

State the normal plasma protein level

Answer 21

65-80g/l

Question 22

State the plasma protein level in oedema what causes this?

Answer 22

<30g/l

• malnutrition
• protein malabsorption
• excessive renal protein excretion
• hepatic failure

Question 23

Will lymphatic insufficiency cause pitting or non-pitting oedema?

Answer 23

Non-pitting

Question 24

State two causes of lymphatic insufficiency

Answer 24

• lymph node damage

- filariasis (infection blocks lymphatics)

Question 25

What causes changes in capillary permeability?

Answer 25

- inflammation | - histamine increases leakage of protein

Question 26

Where does fluid build up in pulmonary oedema?

Answer 26

Interstitial & intraalveolar spaces

Question 27

What are the signs/symptoms of pulmonary oedema?

Answer 27

- SOB - Crepitations at the lung bases - Haziness on CXR at perihilar region

Question 28

Where will pitting oedema be evident?

Answer 28

Ankles & Sacrum

Question 29

How does heart failure occur?

Answer 29

When cardiac output is low the body thinks fluid level is low so retains fluid. This causes fluid overload meaning the heart has to work harder

Question 30

Name three causes of left sided heart failure

Answer 30

- ischaemic heart disease e.g MI - cardiomyopathies - valvular disease

Question 31

How can an MI cause heart failure?

Answer 31

scar tissue reduced contractility & cardiac output

Question 32

State four symptoms of left sided heart failure

Answer 32

- dyspnoea on exertion/at rest - orthopnoea - Paroxysmal Nocturnal Dypnoea - Pink, frothy sputum (pulmonary oedema)

Question 33

State six signs of left sided heart failure

Answer 33

- tachycardia - crepitations - pleural effusion - S3 - cardiomegaly

Question 34

How can left sided heart failure cause pulmonary oedema?

Answer 34

left ventricular failure causes LA pressure to rise causing back pressure on the lungs which increases pulmonary capillary hydrostatic pressure

Question 35

What does an increase in pulmonary capillary hydrostatic pressure cause?

Answer 35

Accumulation of fluid in pleural space

Question 36

Name three causes of right sided heart failure

Answer 36

- secondary to LHF - cor pulmonale - congenital defects

Question 37

How does cor pulmonale result in right sided heart failure?

Answer 37

lung disease causes hypoxia resulting in pulmonary vasoconstriction, leading to increased back pressure so the right side has to work harder and often fails

Question 38

Name four signs/symptoms of right sided heart failure

Answer 38

- ankle/sacral oedema - raised JVP - hepatomegaly - ascites

Question 39

What drugs can be given in heart failure to prolong life?

Answer 39

Loop diuretics, ACE inhibitors, beta blockers, spironolactone

Question 40

What drugs can be given in heart failure to improve symptoms?

Answer 40

Digoxin & Furosemide

Question 41

Name two invasive treatments of heart failure

Answer 41

implantable defibrillator & cardiac resynch therapy

Question 42

Describe cardiac resynch therapy

Answer 42

Improves efficiency by making sure both sides of the heart contract at the same time

Question 43

What is the danger of furosemide & how can this be overcome?

Answer 43

It can cause hypokalaemia but ACEi and spironolactone cause hyperkalaemia so can be used in conjunction