Shock Flashcards
How do you calculate mABP?
COxTPR
SVxHRxTPR
diasBP+0.33 PulseP
0.33sysP+0.66 diasP
What can cause shock?
Fall in TPR
Fall in CO
What is shock?
Acute condition of inadequate blood flow through it body. A catastrophic drop in arterial pressure leads to circulatory shock.
What three things can cause a reduced CO leading to shock?
Mechanical failure- heart cannot fill
Pump fails
Low blood volume
Mechanical shock is also known as
obstructive
What is cardiogenic shock?
The pump is failing and the ventricle aren’t emptying properly.
What is hypovolaemic shock?
Reduced blood volume- poor venous return- can’t maintain arterial pressure
What conditions can lead to cariogenic shock?
MI
Serious arrhythmia (Tachy or Brady)
Sudden heart failure progression
How can tachycardia give a reduced CO?
Although HR increases the filling time in diastole is reduced. This decreases stroke volume.
Why is cardiogenic shock self propagating?
Coronoray artery perfusion drops- increasing the pump failure
A patient with chest pain and dyspnoea presents in shock. They have a visible IJP what do you think the cause of the shock is?
Pulmonary embolism
What are two causes of mechanical shock?
PE
Cardiac tamponade
Does cardiac tamponade effect one or two sides of the heart?
both
how does PE lead to shock?
High pulmonary artery pressure. Right heart fails to empty. Venous pressure rises. Low return to left heart Left trail pressure low Reduced filling of LV reduced CO SHOCK
What is oliguria and why would you get it in shock?
v little urine production
poor perfusion of kidney
What is a cardia arrest?
Pulseless unresponsiveness where the heart has either stopped or lost the ability to pump effectively.
What basic life support do you give in cardiac arrest?
Chest compressions and ventilation
What advanced life support is given in cardiac arrest?
Defibrillation- depolarise all cells of heart. Induce refractory period to allow coordinated beating to restart.
Adrenaline for non shockable rhythm- increase TPR and heart activity
Name 3 cardiac arrest rhythms
VF- most common
Asystole- flat line
Pulseless electrical activity - electric of heart are fine its the structural mechanics that aren’t.
How do you get a PE?
DVT embolising to the lungs through the right heart.
30-40% reduction in blood volume causes …
serious shock response
Some shock response is seen at a ….. drop in blood volume
20
How does hyopvolaemia give shock?
venous pressure drops
reduced return to hear
cardiac out put falls
arterial pressure drops
How do bro receptors attempt to help in hypovolaemia?
Detect low arterial pressure sympathetic trunk increases heart rate and force of contraction by stimulating Beta1 receptors. Alpha receptors in vascular smooth muscle increase TPR by vast constriction.
Veno constriction helps return blood to heart.
What is internal transfusion?
Increased TPR reduces the hydrostatic pressure so fluid moves in to capillary.
Tachycardia, weak pulse, pale skin with cold and sweaty extremities could all be signs of….
Hypovolaemic shock
Symapthtic system attempting to compensate.
What can cause hypovolaemia?
Severe burns Severe diarrhoea Severe Vomiting Loss of Na+ Haemorrhage
The body copes with hypovolaemia initially but what happens in decompensation?
Vasoconstriction reduces tissue perfusion.
Hypoxia results in local metabolites increasing.
Vasodialtion occurs
TPR falls
BP drops
Vital organs not perfused
Multi-system failure
List the long term responders to hypovolaemia?
RAAS
ADH
20% loss replaced in 3 days
What is distributive shock?
Adequate blood volume but TPR drops and gives low resistance shock -too much space in vessels for normal blood volume to give adequate pressure.
Toxic shock and anaphylactic shock can both cause…. shock
Distributive
What is toxic shock?
Endotoxins released in bacteraemia vasodilation and increase vascular permeability TPR drops and blood volume drops Fall in arterial pressure poor tissue perfusion DIC
This will lead to shock inspire of increase sympathetic activity attempting to compensate.
What is septic shock?
Persisting hypotension requiring treatment to maintain BP despite fluid rescussitation.
List features of patients in septic shock.
Tachycardia
Warm, red extremities initially
Late stages hypo perfusion of extremities
Outline the events of anaphylaxis
Exposure to allergen Histamine released from mast cells Vasodilation reduced TPR Sympathetic system attempts to compensate. CO increase inadequate Vital organs not perfused
Laryngeal oedema and bronchochonstriction from mediators cause difficulty breathing
Collapsed patient, difficulty breathing, rapid HR with red warm extremities presents what do you give for anaphylaxis?
Adrenaline- vasoconctricts to increase TPR, bronchodilates to aid breathing.
