Shock Flashcards
What does normal tisse perfusion rely on?
Cardiac function
Capacity of vascular bed
Circulating blood volume
What is used as a surrogate to measure normal perfusion?
Blood pressure/MAP
What are 5 classifications of shock?
Hypovolaemic Cardiogenic DIstributive Obstructive Endocrine
What can cause hypovolaemic shock?
Acute haemorrhage
Severe dehydration
Burns
What does hypovolaemic shock affect?
Volume depletion Decreased SVR Reduces CO (reduced preload)
What can cause cardiogenic shock?
Pump failure
Ichaemia induced myocardial dysfunction
Cardiomyopathies
Valvular problems
If cardiogenic shock is due to an MI what does that suggest?
> 40% of the Left ventricle is involved
What is obstructive shock?
Mechanical obstruction to normal cardiac output to an otherwise normal heart
What can cause obstructive shock?
PE
Air embolusm
Tamponade
Tension pneumothorax
What is distributive schocl caused by?
Disruption of normal vascular autoregulation and profound vasodilation
What are the causes of distributive shock?
Sepsis Anaphylaxis Acute liver failure Spinal cord injuries Poor perfusion
What are some endocrine causes of shock?
Severe hypothyroidism
Addisonian crisis
Thryotoxicosis
What is the main cause of shock/
Septic (62%)
What is the neuroendocrine response to shock?
Release f pituitary hormones
Release of cortison
Release of glucagon
What is a basic vibe of the pathophysiology of shock?
Poor perfusion
Inflammatory cascafe
Vicious cycle of vasoconstriction and oedema
What causes the inflammatory resooinse/
Pathological process (sepsis) Persistent hypoperfusion
What follows the inflammatory response?
Secondary immune suppression
What is involved in the inflammatory respinse?
Activation of leukocytes Cytokine release pAF Adhesion molecules etc
What haemodynamic changes occur in shock?
Vascular changers (Vaso-) Maldistibution of blood flow Microcirculatory abnormalities Innapropriate activation of coagulation system Reperfusion injuries
What are the clinical features of shock?
Hypotension Signs of myocardial failure Raised JVP Pulsus parodoxus Pyrexia Vasodilatation Rapid cap refill Erythema Bronchospasm Oedema
What is class one hypovolaemia?
<15% blood loss
What is class 2 hypovolaemia?
15-30%
What is class 3 hypovolaemia/
31-40% blood loss
What is class 4 hypovolaemia?
> 40% blood loss