Shock

Question 1

What is hypovolaemic shock?

Answer 1

insufficient circulating volume to fill the circut

Question 2

What can cause hypovolaemic shock?

Answer 2

blood loss
interstitial fluid deficit
pure water deficit

Question 3

What are the different compensatory mechanisms?

Answer 3

baroreceptor reflexes
sympathetic mediated hormonal response
capillary absorption of interstitial fluid
hypothalamo-adrenal-pituitary response

Question 4

What is the baroreceptor reflex to hypovolaemic shock?

Answer 4

decreased stretch causes decreased afferent input to the medullary CV centre

Question 5

What is the sympathetic mediated hormonal response to hypovolaemic shock?

Answer 5

releases circulating vasodilators redirecting fluid from peripheral + secondary organs

Question 6

How does capillary absorption of interstitial fluid change due to hypovolaemic shock?

Answer 6

causes reduced capillary hydrostatic pressure which causes inward net filtration

Question 7

How does the hypothalamo-adrenal-pituitary response change in relation to hypovolaemic shock?

Answer 7

intra renal baroreceptors mediate renin release from JGA this results in Ang 2 which enhances vasoconstriction + ADH secretion
which enhances renal absorption of Na + H20

Question 8

What happens if you increase fluids in hypovolaemia?

Answer 8

increase stroke volume

Question 9

What happens if you give fluids to a hypovolaemic patient with heart failure?

Answer 9

get an increase in end diastolic volume which causes pulmonary congestion

Question 10

What is cardiogenic shock?

Answer 10

inability of the heart as a pump to meet circulatory demands

Question 11

What causes cardiogenic shock?

Answer 11

acute MIs
valve dysfunction - acute mitral prolapse
myocarditis, cardiomyopathy, myocardial contusion

Question 12

How does cardiogenic shock present?

Answer 12

hypotension due to poor forward flow
fatigue
syncope
backpressure causing pulmonary oedema
elevated JVP
hepatic congestion

Question 13

How can you treat cardiogenic shock?

Answer 13

inotropes - dopaminergic and beta stimulation

dopamine, dopexamine, dopabutamine, adrenaline

Question 14

What is the next step if the heart cannot be helped by inotropy?

Answer 14

intra-aortic balloon pump - provides counter perfusion

Question 15

What is obstructive shock?

Answer 15

physical obstruction to either the heart or the great vessels

Question 16

How do you treat obstructive shock?

Answer 16

REMOVE UNDERLYING CAUSE

Question 17

What can cause obstructive shock?

Answer 17

PE - hyperkinetic apex
cardiac tamponade
tension pneumothorax

Question 18

What is distributive shock?

Answer 18

circut becomes too big so there is vasodilation and the pressure decreases causing decreased BP
still high cardiac output but insufficient to maintain forward perfusion

Question 19

What are the 3 types of distributive shock?

Answer 19

septic shock
anaphylactic shock
neurogenic shock

Question 20

What is septic shock?

Answer 20

bacterial endotoxin mediated capillary dysfunction - early use of vasopressors improves function

Question 21

What is anaphylactic shock?

Answer 21

mast cell release of histaminergic vasodilators

Question 22

How is anaphylactic shock confirmed?

Answer 22

serum mast cell tryptase - confirms the diagnosis of mast cell degranulation

Question 23

How is anaphylactic shock treated?

Answer 23

adrenaline which is a vasoconstrictor and mast cell stabaliser

Question 24

What is neurogenic shock?

Answer 24

loss of thoracic sympathetic outflow following spinal cord or central cord trauma
causes hypotension due to loss of descending sympathetic tone + innapropriate bradycardia due to unopposed vagal tone

Question 25

How is neurogenic shock treated?

Answer 25

dopamine and vasopressors