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
