Cardiovascular Response to Shock Flashcards
What is shock?
An abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation
Results of shock?
Inadequate tissue perfusion Inadequate oxygenation Anaerobic metabolism Accumulation of metabolic waste products Cellular failure
MAP equation
Cardiac Output (CO) x Systemic Vascular Resistance (SVR)
What does adequate tissue diffusion depend on?
Adequate BP
Adequate Cardiac output
Cardiac output equation?
SV x HR
Things that affect Stroke volume?
Myocardial contractility - how strong heart contracts
Afterload - resistance
Preload-venous return
Different types of shock?
Cardiogenic
Obstructive
Hypovolaemic
Distributive
Patients can have different types of shock at the same time. True or False?
True
Hypovolaemic shock? Flow diagram
Loss of blood volume
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Decreased blood volume
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Decreased venous return
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End diastolic volume
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Decreased Stroke volume
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Decreased CO and Decreased BPWhat is cardiogenic shock?
Sustained hypotension caused by decreased cardiac contractility
Cardiogenic shock flow diagram?
Decreased cardiac contractility | Decreased stroke volume | Decreased cardiac output | Inadequate tissue perfusion
Flow diagram of tension pneumothorax (obstructive shock?
Increased intrathoracic pressure (in pleural cavity) | Decreased venous return (pressure gradient has changed) | Decreased EDV | Decreased SV | Decreased CO and decreased BP | Inadequate tissue perfusion
Neurogenic shock flow diagram?
Loss of sympathetic tone to blood vessels and heart
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Massive venous and arterial vasodilation- affects heart rate
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Decreased venous return & decreased SVR (TPR)
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Decreased HR (UNLIKE other types of shock)
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Decreased CO & decreased BP
Why is neurogenic shock unique?
It causes a decreased HR which is unlike other types of shock. This is because there is loss of sympathetic tone to blood vessels and heart
Vasogenic shock flow diagram?
Release of vasoactive mediators | Massive venous & arterial vasodilation- also increased capillary permeability | Decreased venous return & decreased SVR (TPR) | Decreased CO & decreased BP | Inadequate tissue perfusion
4 general steps to treatment of shock?
1) ABCDE approach
2) High flow Oxygen
3) Volume replacement - EXCEPT cardiogenic
4) Call for help early
Treatment of cardiogenic shock?
Inotropes
Treatment for tension pneumothorax?
Immediate chest drain
Treatment for anaphylactic shock?
Adrenaline
Treatment for septic shock?
Vasopressers
Causes of hypovolaemic shock?
Haemorrhage- trauma, surgery, GI haemorrhage
What does haemorrhage result in?
Decrease in blood volume, decreased Cardiac output, circulatory shock (reduced MAP)
haemorrhage shock response?
Compensatory mechanisms can maintain BP until more than 30% of blood volume is lost
What is observed in haemorrhagic shock?
Tachycardia
Small volume pulse
Cool peripheries
Decreased MAP (if blood loss is more that 30%)
Types of hypovolaemic shock?
Haemorrhagic and non-haemorrhagic
Types of cardiogenic shock?
Acute myocardial infarction
Types of obstructuve shock?
Cardiac temponade
Tension pneumothorax
Pulmonary embolism
Severe aortic stenosis
Types of distributive shock?
Neurogenic- eg spinal cord injury
Vasoactive- eg septic shock, anaphylactic shock
Caused of decreased blood volume?
Haemorrhage
vomiting
Diarrheoa
Excessive sweating
Why does tachycardia occur?
Increased HR due to baroreceptor reflex
What could happen when there is small volume pulse and tachycardia?
Cardiac output could be decreased
What causes cool peripheries?
Increased systemic vascular resistance via baroreceptor reflex
