Shock Flashcards
what is shock
An abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation
how does shock lead to cellular failure
inadequate tissue perfusion= inadequate tissue oxygenation= anaerobic metabolism= accumulation of metabolic waste products
what does adequate tissue perfusion depend on
adequate blood pressure and adequate cardiac output
what affects stroke volume
preload (affected by venous return), myocardial contractility, afterload
what is afterload
resistance into which the heart is pumping
what is hypovolaemic shock
shock cause by loss of blood volume
how does hypovolaemic shock lead to inadequate tissue perfusion
decreased blood volume, decreased venous return, decreased EDV, decreased stroke volume, decreased cardiac CO and blood pressure= inadequate tissue perfusion
how is preload affected by end diastolic volume
as preload dependant on myocardial fibre length which is dependant on EDV
what is cardiogenic shock
sustained hypotension caused by decreased cardiac contractility (heart not capable)
what can cause cardiogenic shock
damage to the heart e.g. heart attack or severe arrhythmias
hows does cardiogenic shock lead to inadequate tissue perfusion
decreased cardiac contractility, decreased SV, decreased CO and blood pressure= inadequate tissue perfusion
how do heart failure and cardiogenic shock affect the frank-staling curve
shift it to the left (decreased SV)
what causes obstructive shock
tension pneumothorax
how does obstructive shock lead to inadequate tissue perfusion
increased intrathoracic pressure= decreased venous return= decreased EDV= decreased SV= decreased CO and BP= inadequate tissue perfusion
why does increased intrathoracic pressure decrease venous return
as pressure in right atrium increased, decreasing gradient for venous return
what is neurogenic shock
loss of sympathetic tone
how does neurogenic shock lead to inadequate tissue perfusion
loss of sympathetic tone= massive venous and arterial vasodilatation= decreased venous return and decreased SVR (TPR)= decreased CO and BP = increased tissue perfusion
what is vasoactive shock
septic shock= release of vasoactive mediators
how does vasoactive shock lead to inadequate tissue perfusion
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
how should all types of shock be treated
ABCDE approach and high flow oxygen
what additional treatment should be used for hypovolaemic shock
volume replacement
what additional treatment should be used for cardiogenic shock
inotropes (drugs that increase contractility of the heart)
what additional treatment should be used for obstruction shock (tension pneumothorax)
immediate chest drain
what additional treatment should be used for anaphylactic shock
adrenaline
what additional treatment should be used for septic shock
vassopressors (induced vasoconstriction)
what can lead to a decrease in blood volume
haemorrhage (trauma, surgery, GI haemorrhage (vomiting blood)),
vomiting, diarrheoa, excessive sweating (extracellular fluid volume decreased)
what is the limit of compensatory mechanisms for haemorrhagic shock
can maintain blood pressure until more than 30% of blood volume is lost
what do the compensatory mechanisms of haemorrhagic shock mostly consists of
baroreceptor reflex
what effects are seen in the body during haemorragic shock
pulse rate increases, blood pressure decreases, pulse pressure decreases, resp rate increases, urine output decreases, mental state declines- anxious, confused, lethargic
why are cold peripheries an effect of haemorrhagic shock
increased systemic vascular resistance via baroreceptor reflex
when in cerebral blood flow affected by haemorrhagic shock
only if MAP dereases below 60 mmHg or over 160 mmHg
what effect does a decrease in arterial blood pressure have on baroreceptor discharge
decreases baroreceptor discharge
what are the two types of haemorrhagic shock
haemorrhagic and non-haemorrhagic
what can cause obstructive shock
tension pneumothorax, cardiac tamponade, pulmonary embolism, severe aortic stenosis
what are the two types of disruptive shock and their causes
neurogenic e.g. spinal chord injury
vasoactive e.g. septic shock, anaphylactic shock
