CV responses to shock

Question 1

What are the 4 different types of shock?

Answer 1

Hypovolaemic
Cardiogenic
Obstructive
Distributive

Question 2

What is the definition of shock?

Answer 2

An abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation

Question 3

What is the progression of shock?

Answer 3

inadequate tissue perfusion, inadequate tissue oxygenation, anaerobic metabolism, accumulation of metabolic waste products and ultimately cellular failure

Question 4

What is required for adequate tissue perfusion?

Answer 4

Adequate blood pressure (CO x SVR) and adequate cardiac output (SV x HR)
(the factors which influence SV are preload(venous return), myocardial contractility and afterload)

Question 5

What is the cause of Hypovolaemic shock?

Answer 5

LOSS OF BLOOD VOLUME,
decreased blood volume, decreased venous return, decreased EDV, decreased SV, decreased CO and MAP - inadequate tissue perfusion

Question 6

What is the cause of cardiogenic shock?

Answer 6

sustained hypotension caused by decreased cardiac contractility

decreased cardiac contractility, decreased stroke volume, decreased CO & MAP, inadequate tissue perfusion

Question 7

What are the types of hypovolaemic shock?

Answer 7

haemorrhagic

non-haemorrhagic

Question 8

What are some examples of causes of obstructive shock?

Answer 8

cardiac temponade
tension pneumothorax
pulmonary embolism
severe aortic stenosis

Question 9

What are the types of distributive shock?

Answer 9

neurogenic

vasoactive

Question 10

What are the causes of obstructive shock due to a tension pneumothorax?

Answer 10

increased intrathoracic pressure, decreased venous return, decreased EDV, decreased SV, decreased CO & decreased MAP and inadequate tissue perfusion

Question 11

What is the cause of neurogenic shock?

Answer 11

loss of sympathetic tone to blood vessels and heart,
massive venous and arterial vasodilatation
effect on HR (slows)
decreased venous return and SVR, decreased HR
decreased CO & MAP
inadequate tissue perfusion

Question 12

What are the causes of vasoactive shock?

Answer 12

release of vasoactive mediators
massive venous & arterial vasodilatation and increased capillary permeability
decreased venous return and decreased SVR
decreased CO & MAP
inadequate tissue perfusion

Question 13

What type of shock is a decreased HR unique to?

Answer 13

neurogenic shock

Question 14

How should shock be managed?

Answer 14

ABCDE
high flow oxygen 
volume replacement - unless cardiogenic shock
call early for help
inotropes for cardiogenic shock
adrenaline - anaphylactic shock
vasopressors - septic shock
treat cause

Question 15

Examples of causes of haemorrhage, hypovolaemic shock

Answer 15

trauma
surgery
GI bleed

Question 16

Examples of causes of non-haemorrhagic hypovolaemic shock

Answer 16

vomiting
diarrhoea
excessive sweating
- leads to a decrease in extracellular fluid volume including plasma leading to decreased blood volume

Question 17

What is the maximum volume of blood which can be lost and be compensated for?

Answer 17

Compensatory mechanisms can maintain blood pressure until >30% of blood volume is lost

Question 18

What are the clinical indications of haemorrhagic shock?

Answer 18

• Tachycardia - increased HR via baroreceptor reflex
• Small volume pulse - decreased stroke volume
• cool peripheries - CO may be decreased, and SVR increased via baroreceptor reflex
• decreased MAP if >30% blood loss