20. Shock

Question 1

What is shock?

Answer 1

Acute failure of the cardiovascular system to adequately supply the tissues with nutrients and gases

Question 2

What are the 3 types of shock?

Answer 2

Cardiogenic
Distributive
Hypovolaemic

Question 3

Why might cardiac output be decreased in cardiogenic shock?

Answer 3

Decreased contractility of heart
Arrhythmias
Restriction of cardiac filling
Obstruction to outflow

Question 4

What are the two types of distributive shock?

Answer 4

Vasogenic (allergic reaction of sepsis)

Neurogenic (loss of sympathetic control)

Question 5

What is distributive shock characterised by?

Answer 5

Vasodilation

Low blood pressure

Question 6

Give three reasons for hypovolaemic shock?

Answer 6

Haemorrhage
Burns
Dehydration

Question 7

What is compensated shock?

Answer 7

1. Decreased blood pressure causes baroreflex activation
2. Low blood volume activates volume reflexes
3. Low BP mobilises blood from capillaries
4. Very low BP activates CNS ischaemic reflex

Question 8

What are symptoms of shock?

Answer 8

Cold, clammy skin
Tachycardia
Rapid respiration

Question 9

What does the sympathetic activation of cardiac beta-adrenoceptors do?

Answer 9

Increases force of ventricular contraction

Increases heart rate

Question 10

What effects does vasoconstriction have?

Answer 10

Mobilises blood reservoir from veins
Decreased glomerular filtration rate
Both increase blood volume

Question 11

What effect does the release of rennin have?

Answer 11

Activates angiotensin
Causes further renal arteriole constriction
Aldosterone causes Na+ and water reabsorption

Question 12

What happens to capillaries in hypovolaemia?

Answer 12

Arterioles are constricted which decreases capillary BP
Re-absorption of interstitial fluid (due to Starling forces)
Increased blood volume

Question 13

What is the general treatment of shock?

Answer 13

Fluids
Vasopressor drugs
Cardiac stimulant drugs
Antibiotics if septic
Antihistamines if anaphylactic

Question 14

What happens in irreversible shock?

Answer 14

1. Reflexes fail to restore BP and coronary blood flow falls
2. Vasomotor failure
3. Slow movement in vessels leads to thrombosis
4. Increased capillary permeability
5. Release of toxic by ischaemic tissue