Shock (12)

Question 0

What is the equation for mean arterial bp?

Answer 0

• Mean arterial bp = CO x TPR

Question 1

What is generalised shock?

Answer 1

• Inadequate blood flow throughout body
• Poor perfusion
• Too low CO or TPR
• Decrease in arterial bp

Question 2

Why may CO fall?

Answer 2

• Mechanical: heart unable to fill
• Pump failure: cardiogenic shock
• Loos of blood volume: hypovolaemic shock

Question 3

What is cardiogenic shock?

Answer 3

• Damage to LV following MI
• Serious Arrhythmias
• Acute worsening of HF
• CVP normal/raised, heart fills effectively but can’t pump.
• Coronary and renal arteries become poorly perfumed

Question 4

What is mechanical shock and what is the main reason for this?

Answer 4

• Cardiac tamponade
• Blood fills in pericardial space
• Restricts filling of heart, limits end diastolic volume
• Heart attempts to beat due to continued electrical activity
• High CVP
• Low arterial bp

Question 5

What is a pulmonary embolism and why may this lead to shock?

Answer 5

• Embolus occludes PA
• PA pressure high
• RV can’t empty
• Increased CVP
• Decreased return of blood to left heart
• Arterial bp decreased

Question 6

What is distributive shock?

Answer 6

• Low resistance shock
• Decrease in TPR due to profound peripheral vasodilation
• Volume of circulation increases
• E.g: toxic/anaphalactic shock

Question 7

What is toxic shock?

Answer 7

• Leaky capillaries
• Septicaemia
• Tachycardia
• Warm, red extremities
• Endotoxins produced

Question 8

What are endotoxins and what do they do?

Answer 8

• Released by circulating bacteria
• Profound vasodilation
• Fall in TPR
• Decrease in arterial pressure
• Poor perfusion

Question 9

What is anaphylactic shock?

Answer 9

• Severe allergic reaction
• Release of histamine from mast cells
• Adrenaline in response to cause vasodilation
• Causing a decrease in TPR something the sympathetic response can’t overcome

Question 10

What are the symptoms of anaphylactic shock?

Answer 10

• Difficulty breathing
• Collapse
• Rapid hr
• Life threatening
• Red, warm extremities

Question 11

What is hypovolaemic shock and what does its severity depend on?

Answer 11

• Severe decrease in blood volume
• 30-40% decrease -> serious shock
• Severity depends on speed and amount of blood loss

Question 12

What are the symptoms of hypovolaemic shock?

Answer 12

• Cold and clammy extremities
• Tachycardia
• Weak pulse
• Pale skin

Question 13

Why does a haemorrhage lead to hypovolaemic shock?

Answer 13

• Blood loss
• Decreases venous pressure
• Decreases CO
• Decreases arterial pressure

Question 14

What is the body’s response to haemorrhage?

Answer 14

• Baroreceptors detect the decrease in arterial pressure
• Response from medulla of brain
• Increases sympathetic stimulation
• Tachycardia
• Increase in ionotropy
• Increase in peripheral resistanc, decreasing hydrostatic pressure, net movement -> capillaries
• Venoconstriction
• Peripheral vasoconstriction: impairs tissue perfusion