Physiology of shock

Question 1

define shock

Answer 1

condition of inadequate perfusion to sustain normal organ function

Question 2

what are the different types of shock

Answer 2

hypovolaemic 
cardiogenic 
obstructive 
distributive 
cytotoxic

Question 3

what is hypovolaemic shock

Answer 3

loss of circulating volume

insufficient circulating volume to fill circuit

Question 4

give examples of hypovolaemic shock

Answer 4

blood loss

fluid loss

Question 5

what are causes of cardiogenic shock

Answer 5

heart failure eg MI, papillary muscle rupture, acute valve dysfunction, myocarditis, cardiomyopathy
post surgery

Question 6

causes of obstructive shock

Answer 6

tension pneumothorax
cardiac tamponade
PE

Question 7

what happens in distributive shock

Answer 7

circuit becomes too big, fluid is insufficient to fill circuit

Question 8

what types of distributive shock are there

Answer 8

septic
anaphylactic
neurogenic

Question 9

what happens in cytotoxic shock

Answer 9

uncoupling of tissue oxygen delivery and mitochondrial uptake

Question 10

causes of cytotoxic shock

Answer 10

CO or cyanide poisoning

Question 11

what are compensatory mechanisms for hypovolaemic shock

Answer 11

baroreceptor reflex
sympathetic neurohormonal response
capillary absorption of interstitial fluid
hypothalamo-pituitary-adrenal response

Question 12

what are methods of increasing cardiac output

Answer 12

increase HR, SV or both

Question 13

increased baroreceptor firing increases/decreases sympathetic activity and increases/decreases parasympathetic activity

Answer 13

^BR firing results in
decreased sympathetic activity
increased parasympathetic activity

Question 14

what happens to baroreceptors in hypovolaemic shock

Answer 14

decreased BP results in decreased baroreceptor firing

this results in increased sympathetic activity and decreased parasympathetic activity to try and increase BP

Question 15

what is the hypothalamo-pituitary-adrenal response in hypovolaemic shock

Answer 15

enhances renal system to hold on to Na and water

Question 16

what is the Frank Starling mechanism

Answer 16

ability of the heart to change its contractility + stroke volume depending on venous return

Question 17

in which direction does decreased inotropy change the Frank Starling curve

Answer 17

shifts down and to the right

Question 18

in which direction does the Frank Starling curve shift with increased inotropy

Answer 18

up and to the left

Question 19

you should give lots of fluid in a failing heart, true or false

Answer 19

false, leads to congestion

give lower fluid challenge

Question 20

fluids are prescribed, true or false

Answer 20

true

according to weight in kg

Question 21

indications for IV fluids

Answer 21

cannot be taken orally
vomiting, diarrhoea
hypovolaemic shock eg haemorrhage

Question 22

list findings suggestive of hypovolaemia

Answer 22

tachycardic 
hypotensive
tachypnoeic 
reduced oxygen saturations 
bilateral crackles on auscultation 
prolonged CRT
absent JVP

Question 23

do you still need fluid challenge when you are normovolaemic

Answer 23

no

Question 24

what is cardiogenic shock

Answer 24

inability of heart to meet circulatory demands

Question 25

what are consequences of cardiogenic shock

Answer 25

poor forward flow --> hypotension, fatigue, syncope | back pressure --> pulmonary oedema, ^JVP, hepatic congestion

Question 26

how can you treat cardiogenic shock, what is their function

Answer 26

inotropic drugs increase contractility of the heart

Question 27

examples of inotropic drugs and their mechanism of action

Answer 27

B agonists - dobutamine, adrenaline | dopamine agonists - dopamine, dopexamine

Question 28

what kind of a device is an intra-aortic balloon pump

Answer 28

counterpulsation device inflates in diastole deflates in systole

Question 29

what happens when you increase diastole

Answer 29

increase coronary artery filling - perfuse the heart

Question 30

what happens when you decrease systole

Answer 30

decrease the force which the heart has to pump against

Question 31

pathology of obstructive shock

Answer 31

something in the great vessels or obstruction in venous filling of the heart

Question 32

inspiration decreases/increases venous return

Answer 32

increases venous return

Question 33

what is the mechanism behind distributive shock

Answer 33

inappropriate vasodilatation | BP is usually normal but circuit is too big then BP drops

Question 34

management of septic shock

Answer 34

sepsis 6 bundle and vasopressors in 1 hour

Question 35

what is the cause of anaphylactic shock

Answer 35

mast cells release histaminergic vasodilators in response to allergen

Question 36

in anaphylactic shock, there is uncontrolled widespread vasoconstriction/dilatation

Answer 36

vasodilatation

Question 37

why is adrenaline preferred over noradrenaline in treatment of anaphylactic shock

Answer 37

adrenaline is a vasoconstrictor AND a mast cell stabiliser

Question 38

what can be measured to confirm anaphylaxis

Answer 38

serum mast cell tryptase levels

Question 39

what is neurogenic shock

Answer 39

loss of sympathetic outflow following spinal injury

Question 40

there is constant sympathetic/parasympathetic tone exerted on blood vessels

Answer 40

natural vasodilatation (passive process), therefore there is sympathetic tone (active process) exerted on blood vessels

Question 41

what is the difference between neurogenic and spinal shock

Answer 41

neurogenic shock = loss of sympathetic tone | spinal shock = loss of spinal reflexes even though spinal cord at that level is intact

Question 42

hypo/hypertension occurs as a result of neurogenic shock and why

Answer 42

hypotension because there is no sympathetic tone

Question 43

in neurogenic shock there is brady/tachycardia

Answer 43

BRADYcardia

Question 44

in hypovolaemic shock there is brady/tachycardia

Answer 44

TACHYcardia

Question 45

what can cause cardiac arrest in neurogenic shock

Answer 45

suction in ET tube or PR exam | - stimulates vagus nerve with no sympathetic to compensate

Question 46

what are the 4Hs and 4Ts or reversible causes of cardiac arrest

Answer 46

``` Hypoxia Hypovolaemia Hypothermia Hypo/Hyperkalaemia Tension pneumothorax Tamponade Toxins Thrombosis ```

Question 47

what is the basis of CPR

Answer 47

cyclical changes in intrathoracic pressure to alternatively push and suck blood out of the chest

Question 48

if you were to shock someone with a defibrillator, should they have a pulse

Answer 48

NO

Question 49

what are the shockable rhythms

Answer 49

VF | Pulseless VT

Question 50

what are the non-shockable rhythms

Answer 50

PEA | asystole

Question 51

in PEA, there is a rhythm that could be associated with a pulse, true or false

Answer 51

true

Question 52

generally, which arrhythmia does hypovolaemia cause

Answer 52

PEA

Question 53

asystole has a good/bad prognosis

Answer 53

BAD | low chance of resuscitation