Flashcards in Cardiovascular responses to shock Deck (12)
What is shock?
An abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation
What does shock cause?
inadequate tissue perfusion --> inadequate tissue oxygenation --> anaerobic metabolism -->accumulation of metabolic waste products -->cellular failure
What does adequate tissue perfusion depend on?
adequate blood pressure
adequate cardiac output
What happens in hypovolaemic shock?
decreased blood volume -->decreased venous return --> decreased EDV --> decreased SV -->Decreased CO and BP -->inadequate tissue perfusion
What is cardiogenic shock?
Sustained hypotension caused by decreased cardiac contractility --> decreased stroke volume --> decreased CO and BP -->inadequate tissue perfusion
What happens in tension pneumothorax : obstructive shock?
increased intrathoraic pressure-->decreased venous return --> decreased EDV --> decreased SV -->Decreased CO and BP -->inadequate tissue perfusion
Why does increased intrathoracic pressure cause decreased venous return?
Venous return is dependant on pressure gradient between thorax and big veins so if there is a high level in thorax, there is no pressure gradient
What happens in neurogenic shock?
loss of sympathetic tone --> massive venous and arterial vasodilation --> decreased venous return and decreased TPR --> decreased CO and BP--> inadequate tissue perfusion
What happens in vasoactive shock?
release of vasoactive mediators --> massive venous and arterial vasodilatation and increase capillary permeability --> decreased venous return and decreased TPR --> Decreased CO and BP --> inadequate tissue perfusion
What are the outlines for treatment of shock?
-high flow of oxygen
-inotropes for cardiogenic shock
-immediate chest drain for tension pneumothorax
-adrenaline for anaphylactic shock
-vassopressors for septic shock
What are the two causes of hypovolaemic shock?
-haemorrhage- trauma , surgery
-non haemorrhage - vomiting, diarrhoea, excessive sweating
-both cause loss of blood volume and so decrease in CO