Shock

Question 1

define shock

Answer 1

this is a condition of inadequate perfusion to sustain normal organ function

Question 2

five classes of shock

Answer 2

1. hypovolaemia
2. cardiogenic
3. obstructive
4. distributive
5. endocrine

Question 3

what is hypovolavemic shock?

Answer 3

insufficient circulating volume to perfuse organs

Question 4

causes of hypovolaemic shock

Answer 4

blood loss
dehydration (skin losses, overuse diuretics, vomiting, diarrhoea)
third space losses (fluid moves into the interstitium?)

Question 5

most common hypovolaemic shock

Answer 5

haemorrhagic shock

Question 6

four compensatory mechanisms for hypovolaemic shock

Answer 6

1. baroreceptor reflexes
2. sympathetic mediated neurohormonal response
3. capillary absorption of interstitial fluid
4. hypothalamic-pituitary-adrenal response

Question 7

where are the baroreceptors located?

Answer 7

carotid sinus (CNIX)
aortic arch (CNX)

Question 8

what do the baroreceptors sense?

Answer 8

decreased stretch so transmit decreased afferent input to medulla

Question 9

action of baroreceptors

Answer 9

inhibit parasympathetics and enhance sympathetic output

Question 10

what is the sympathetic mediated neurohormonal response?

Answer 10

release of vasoconstrictors which redirects fluid from secondary and peripheral organs

Question 11

examples of vasoconstrictors released

Answer 11

adrenaline
angiotensin
NA
ADH

Question 12

what is the hypothalamic-pituitary-adrenal response to hypovolavemic shock?

Answer 12

intrarenal baroreceptors mediate renin release producing angiotensin II vasoconstriction and ADH reabsorption of Na+ and H2O

Question 13

how does a falling heart lead to pulmonary congestion?

Answer 13

decreased contractility so EDV increases to maintain SV which results in pulmonary congestion

Question 14

define cardiogenic shock

Answer 14

inability of the heart to meet circulatory demands

commonly a complication of acute MI

Question 15

what happens in cardiogenic shock

Answer 15

poor flow leads to hypotension, shock, fatigue with back pressure causing oedema and hepatic congestion

Question 16

response to cardiogenic shock

Answer 16

sympathetics increase inotropy which can be replicated pharmacologically with dobutamine, adrenaline, dopamine, dopexamine, etc.

Question 17

management of cardiogenic shock

Answer 17

pharmacological sympathetics

intra-aortic balloon pump

Question 18

define obstructive shock

Answer 18

physical obstruction to heart of great vessels affecting cardiac filling rather than ejection

Question 19

causes of obstructive shock

Answer 19

PE
cardiac tamponade
tension pneumothorax

Question 20

define distributive shock

Answer 20

vasodilatory

Question 21

three sub-types of distributive shock

Answer 21

1. septic
2. anaphylactic
3. neurogenic

Question 22

define septic shock

Answer 22

bacterial endotoxin mediated capillary dysfunction

Question 23

management of septic shock

Answer 23

vasopressors
fluids
broad spectrum antibiotics
minimise fluid overload

Question 24

define anaphylactic shock

Answer 24

uncontrolled activation and degranulation of mast cells, the release of histamine results in uncontrolled vasodilation

Question 25

diagnosis of anaphylactic shock

Answer 25

serum mast cell tryptase (protease stored in mast cells)

Question 26

management of anaphylactic shock

Answer 26

adrenaline acts as a vasoconstrictor and mast cell stabiliser

Question 27

define neurogenic shock

Answer 27

loss of thoracic sympathetic outflow following spine or central trauma so hypotension follows with inappropriate bradycardia due to unopposed vagal tone

Question 28

management of neurogenic shock

Answer 28

dopamine alongside vasopressors