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Flashcards in Cardiovascular responses to shock Deck (12)
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1

What is shock?

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

2

What does shock cause?

inadequate tissue perfusion --> inadequate tissue oxygenation --> anaerobic metabolism -->accumulation of metabolic waste products -->cellular failure

3

What does adequate tissue perfusion depend on?

adequate blood pressure
adequate cardiac output

4

What happens in hypovolaemic shock?

decreased blood volume -->decreased venous return --> decreased EDV --> decreased SV -->Decreased CO and BP -->inadequate tissue perfusion

5

What is cardiogenic shock?

Sustained hypotension caused by decreased cardiac contractility --> decreased stroke volume --> decreased CO and BP -->inadequate tissue perfusion

6

What happens in tension pneumothorax : obstructive shock?

increased intrathoraic pressure-->decreased venous return --> decreased EDV --> decreased SV -->Decreased CO and BP -->inadequate tissue perfusion

7

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

8

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

9

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

10

What are the outlines for treatment of shock?

-ABCDE
-high flow of oxygen
-volume replacement
-inotropes for cardiogenic shock
-immediate chest drain for tension pneumothorax
-adrenaline for anaphylactic shock
-vassopressors for septic shock

11

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

12

Up to what percentage can compensatory mechanisms maintain blood pressure?

until 30% of blood volume is lost