Shock Flashcards
Define haemodynamic shock
Acute condition of inadequete blood flow throughout body; the catastrophic fall in blood pressure leads to circulatory shock
Describe possible causes of haemodynamic shock
State, and describe, the 3 types of shock due to fall in CO
- Cardiogenic shock: pump failure in which ventricle cannot empty properly
- Mechanical shock: obstruction meaning that ventricle cannot fill properly
- Hypovolaemic shock: reduced blood volume leads to poor venous return
State, and describe, the one type of shock due to fall in TPR
Distributive shock: excessive vasodilation causing decrease in TPR
For cardiogenic shock, state:
- Causes
- Effect on CVP and BP
- Effects of poorly perfused tissues, e.g. kidneys
- Treatment
- Post MI (damage), serious arrhythmias, acute worsening of heart failure, acute valve failure, aortic dissection
- CVP normal or raised, BP low
- Poorly perfused kidneys leads to oliguria
- Treat underlying cause (may give fluids whilst treating cause)
Give 2 possible causes of mechanical shock
- Cardiac tamponade
- Pulmonary embolism
Describe how cardiac tamponade can lead to mechanical shock
How is it treated
Fluid in pericardium limits how much heart can expand so EDV limited- both sides of heart affected. High CVP (hard to fill heart as blood not moving out), low BP, rapid HR to compesnate
Treat: pericardiocentesis
Describe how pulmonary embolism can cause mechanical shock
How do you treat it
If PE occludes pulmonary artery right ventricle can’t empty properly leading to:
- High pressure in pulmonary artery
- High CVP
- Limited filling of L & R ventricle (right limited by pressure, left limited by small return of blood)
- BP low
Treatment: anticoagulants (heparin initially as it breaks down & prevents formation of more) then warfarin
State commonest cause of hypovolaemic shock (also list some other possible causes)
- Haemorrhage
- Severe burns
- Severe diarrhoea and vomitting
In hypovolaemic shock, severity of shock is related to…?
State what happens if have a 20-30% and a 30-40% decrease in blood volume
Amount and speed of blood loss
- 20-30%: some signs of shock
- 30-40%: serious shock
What happens to the net movement of fluid between capillaries and interstitium in hypovolaemic shock?
Why is this beneficial?
Net movement is reversed; so now moves from interstitium to capillaries. Usually, small net movement in to interstitium and this is removed by lymphatic drainage. In hypovolaemic shock, arterioles constrict to try and increase BP but this decreases capillary hydrostatic pressure which reverses net movement of fluid. Called ‘internal transfusion’.
Attempt to increase blood volume
State signs of hypovolaemic shock
- Tachycardia
- Weak pulse
- Paleskin
- Cold, clammy extremities
- Low CVP
- Low arterial BP
With hypovolaemic shock, there is a risk of decompensation; explain this
- Peripheral vasoconstriction in attempt to increase blood pressure can impair tissue perfusion
- Tissue damage occurs due to hypoxia
- Organs release signals to say they aren’t being perfused
- Vasodilators released
- TPR falls
- Blood pressure dramatically falls
- Vital organs not perfused which can cause multi-organ failure
State 2 long term responses to hypovolaemia
- Renin-angiotensin-aldosterone system activation
- ADH release
State three possible causes of distributive shock
- Toxic/septic shock
- Anaphalytic shock
- Neurogenic shock
Give a summary of effects of all types of shock
Discuss the management of cardiogenic shock
Remind yourself of the different clases of shock and for each state:
- % blood lost
- Effect on BP
- Effect on cerebral function
