Shock Flashcards

1
Q

what is shock

A

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

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2
Q

how does shock lead to cellular failure

A

inadequate tissue perfusion= inadequate tissue oxygenation= anaerobic metabolism= accumulation of metabolic waste products

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3
Q

what does adequate tissue perfusion depend on

A

adequate blood pressure and adequate cardiac output

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4
Q

what affects stroke volume

A

preload (affected by venous return), myocardial contractility, afterload

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5
Q

what is afterload

A

resistance into which the heart is pumping

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6
Q

what is hypovolaemic shock

A

shock cause by loss of blood volume

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7
Q

how does hypovolaemic shock lead to inadequate tissue perfusion

A

decreased blood volume, decreased venous return, decreased EDV, decreased stroke volume, decreased cardiac CO and blood pressure= inadequate tissue perfusion

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8
Q

how is preload affected by end diastolic volume

A

as preload dependant on myocardial fibre length which is dependant on EDV

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9
Q

what is cardiogenic shock

A

sustained hypotension caused by decreased cardiac contractility (heart not capable)

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10
Q

what can cause cardiogenic shock

A

damage to the heart e.g. heart attack or severe arrhythmias

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11
Q

hows does cardiogenic shock lead to inadequate tissue perfusion

A

decreased cardiac contractility, decreased SV, decreased CO and blood pressure= inadequate tissue perfusion

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12
Q

how do heart failure and cardiogenic shock affect the frank-staling curve

A

shift it to the left (decreased SV)

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13
Q

what causes obstructive shock

A

tension pneumothorax

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14
Q

how does obstructive shock lead to inadequate tissue perfusion

A

increased intrathoracic pressure= decreased venous return= decreased EDV= decreased SV= decreased CO and BP= inadequate tissue perfusion

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15
Q

why does increased intrathoracic pressure decrease venous return

A

as pressure in right atrium increased, decreasing gradient for venous return

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16
Q

what is neurogenic shock

A

loss of sympathetic tone

17
Q

how does neurogenic shock lead to inadequate tissue perfusion

A

loss of sympathetic tone= massive venous and arterial vasodilatation= decreased venous return and decreased SVR (TPR)= decreased CO and BP = increased tissue perfusion

18
Q

what is vasoactive shock

A

septic shock= release of vasoactive mediators

19
Q

how does vasoactive shock lead to inadequate tissue perfusion

A

release of vasoactive mediators= massive venous and arterial vasodilatation (also increases capillary permeability)= decreased venous return and SVR (TPR)= decreased Co and BP= inadequate tissue perfusion

20
Q

how should all types of shock be treated

A

ABCDE approach and high flow oxygen

21
Q

what additional treatment should be used for hypovolaemic shock

A

volume replacement

22
Q

what additional treatment should be used for cardiogenic shock

A

inotropes (drugs that increase contractility of the heart)

23
Q

what additional treatment should be used for obstruction shock (tension pneumothorax)

A

immediate chest drain

24
Q

what additional treatment should be used for anaphylactic shock

A

adrenaline

25
Q

what additional treatment should be used for septic shock

A

vassopressors (induced vasoconstriction)

26
Q

what can lead to a decrease in blood volume

A

haemorrhage (trauma, surgery, GI haemorrhage (vomiting blood)),

vomiting, diarrheoa, excessive sweating (extracellular fluid volume decreased)

27
Q

what is the limit of compensatory mechanisms for haemorrhagic shock

A

can maintain blood pressure until more than 30% of blood volume is lost

28
Q

what do the compensatory mechanisms of haemorrhagic shock mostly consists of

A

baroreceptor reflex

29
Q

what effects are seen in the body during haemorragic shock

A

pulse rate increases, blood pressure decreases, pulse pressure decreases, resp rate increases, urine output decreases, mental state declines- anxious, confused, lethargic

30
Q

why are cold peripheries an effect of haemorrhagic shock

A

increased systemic vascular resistance via baroreceptor reflex

31
Q

when in cerebral blood flow affected by haemorrhagic shock

A

only if MAP dereases below 60 mmHg or over 160 mmHg

32
Q

what effect does a decrease in arterial blood pressure have on baroreceptor discharge

A

decreases baroreceptor discharge

33
Q

what are the two types of haemorrhagic shock

A

haemorrhagic and non-haemorrhagic

34
Q

what can cause obstructive shock

A

tension pneumothorax, cardiac tamponade, pulmonary embolism, severe aortic stenosis

35
Q

what are the two types of disruptive shock and their causes

A

neurogenic e.g. spinal chord injury

vasoactive e.g. septic shock, anaphylactic shock