Shock Flashcards
What are the 4 types of shock?
1) Hypovolaemic: haemorragic and non haemorhagic
2) Cardiogenic: damage to the heart
3) Obstructive: obstruction of the heart (tamponade, tension pneumothorax, PE, severe arotic stenosis)
4) Distributive: Neurogenic (spinal injury or vasoactive (septic shock or anaphalasis)
What is shock?
An abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation.
Inadequate tissue perfusion leads to…?
Inadequate tissue oxygenation
=> Anaerobic metabolism
=> Accumulation of metabolic waste products
=> Cell failure and death
What is needed fro adequate tissue perfection?
Blood pressure and cardiac output MAP = CO x SVR
What can effect the stroke volume?
Preload (venous return and end diastolic volume)
Myocardial contractility and afterload
What is the pathogenisis of hypovolaemic shock?
Decreased blood volume => Decreased venous return => decreased EDV => decreases SV => decreased CO and BP => inadequate tissue perfusion
What causes cardiogenic shock?
Decreased cardiac contractility.
The blood volume is okay but the heart cannot pump it.
Decreased cardiac contractility => decreased stroke volume => decreased CO and BP => inadequate tissue perfusion
What causes obstructive shock?
Increased intrathoracic pressure => increased atrial pressure => decreased venous return => decreased EDV => decreases SV => decreased CO and BP => inadequate tissue perfusion
What causes neurogenic/distributive shock?
Loss of sympathetic tone to the vasculature => massive arterial and venous dialitaition => decreased venous return and SVR => decreased EDV => decreases SV => decreased CO and BP => inadequate tissue perfusion
What causes vasoactive shock?
Release of vasoactive mediators => massive arterial and venous dialitaition => decreased venous return and SVR => decreased EDV => decreases SV => decreased CO and BP => inadequate tissue perfusion
Increased capillary permeability =>plasma volume moving to the extra cellular fluid and decrease in blood volume
How is shock treated?
1) ABCDE approach
2) High flow oxygen to improve tissue oxygenation
3) Volume replacement with fluid or blood (only if they are losing volume)
4) Treat the cause:
Ionotropes for cardiogenic shock
Chest drain for tension pneumothorax
Pericarial centesis for cardiac tamponade
Adrenaline for anaphylaxis => bronchodilation and systemic vasodilation
Vasopressors for septic shock in addition to colume replacement
** Although the presentation can be similar, shock has different causes and should be treated accordingly
What are the haemorrhagic and non haemorrhagic causes of hypovolaemic shock?
Haemorrhagic = trauma, surgery, GI bleed
Non haemorrhagic = vomiting, diarrhoea, excessive sweating (decrease in extracellular fluid volume and plasma volume)
What percentage of your blood volume is lost before compensatory mechanisms cannot maintain you BP?
30%
What is class 1 haemorrhagic shock?
Blood loss = <750ml Percentage blood loss = <15% Heart rate = <100 Blood pressure = normal Pulse pressure = normal Resp rate = <20 Urine output (ml/hour) = >30 Mental status = normal
What is class 2 haemorrhagic shock?
Blood loss = 750-1500ml Percentage blood loss = 15-30% Heart rate = 100-120 Blood pressure = normal Pulse pressure = decreased Resp rate = 20-30 Urine output (ml/hour) = 20-30 Mental status = anxious
