Shock Flashcards
What is shock?
A syndrome in which tissue perfusion is inadequate for the tissues metabolic requirement
What does perfusion depend on?
Cardiac function
Capacity of vasculature
Circulating blood volume
How do you calculate MAP?
CO x SVR
Name the five types of shock
Hypovolaemic Cardiogenic Obstructive Distributive Endocrine
Describe hypovolaemic shock
Acute haemorrhage
Fluid depeltion - severe dehydration/burns
Describe cardiogenic shock
Pump failure, reduced cardiac output
Primarily due to ischaemia induced myocardial dysfunction
Describe obstructive shock
Mechanical obstruction
Direct - PE, air/fat/amniotic fluid embolism
Restriction - tamponade, tension pneumothorax
Describe distributive shock
Septic, anaphylaxis, acute liver failure, spinal cord injuries
Disruption of normal vascular autoregulation and profound vasodilation
Describe endocrine shock
Severe hypothyroidism, addisonian crisis, thyrotoxicosis causes reduced cardiac output and vasodilation
What is the sympathy-adrenal response to shock?
Baroreceptors and chemoreceptors
Sympathetic release of noradrenaline/adrenaline
RAAS
Aims to maintain BP and Cardiac output
What is the neuroendocrine response to shock?
Release of pituitary hormones - ACTH, ADH, Opioids
Release of cortisol - fluid retention, insulin antagonist
Release of glucagon
What makes up the inflammatory response?
Activation of complement
Cytokines - IL/TNF alpha
Platelet activating factor
Lysosomal enzyme - myocardial depression
Adhesion molecules - damage to vessels
Endothelium derived mediators - NO
Imbalance between oxidants and anti-oxidants
What haemodynamic changes occur as a result of shock?
Vasodilation –> vasoconstriction
Maldistribution
Microcirculatory abnormalities
Abnormal coagulation (DIC)
What is the main clinical feature of shock?
Hypotension
What are the clinical features of cardiogenic shock?
Myocardial failure - chest pain, cold/clammy, oedema
What are the clinical features of obstructive shock?
Raised JVP, pulses paradoxes, signs of cause
What are the clinical features of distributive shock?
Pyrexia, vasodilation, rapid capillary refill, anaphylaxis
Describe class I hypovolaemia
<15% blood loss
Base deficit 0 to -2
Monitor for blood requirement
Describe class II hypovolaemia
15-30% blood loss
Increased heart rate and reduced pulse pressure
Base deficit -2 to -6
Possible need for blood
Describe class III hypovolaemia
31-40% blood loss
Increased heart rate, reduced BP, reduced pulse pressure, increased resp rate, reduced urine output and GCS
Base deficit -6 to -10
Need blood
Describe class IV hypovolaemia
> 40% blood loss
Increased heart rate, reduced BP, reduced pulse pressure, increased resp rate, decreased urine output and GCS
Base deficit -10 or less
Massive transfusion protocol
Name the way in which a patient with shock can be monitored
Examination Urine Output Neurological Biochemical BP Central venous pressure Pulmonary artery monitoring Pulse contour analysis Doppler ultrasound
How is all shock managed initially?
ABCDE
Wide bore access
How is oxygen delivery managed?
15 litre non-rebreather initially and then whatever level required for normal SpO2
What is the risk of fluids?
Fluid overload and pulmonary oedema
What is fluid challenge?
Assessment of response, not too fast that it causes stress response
300-500ml over 10-20 minutes
What are the three main types of fluid?
Crystalloid
Colloid
Blood
What are examples and issues with crystalloid?
Saline, hartmann’s
Rapid loss from circulation to extracellular fluid, requires 3-4 times more than blood lost
What are examples and issues with colloids?
Gelatines, albumin
Can cause anaphylaxis, reduced volumes but no evidence of benefit
What pharmacological treatments can be used in shock?
Adrenaline Noradrenaline Vasopressin Dopamine Dobutamine
Name the mechanical support that can be used in shock
Balloon pump
L/R VAD
VA Echo
