Session 5-Haemodynamic Shock

Question 1

What are the equations for mean arterial blood pressure?

Answer 1

MABP = CO x TPR

MABP = SV x HR x TPR

MABP = diastolic pressure + 1/3 pulse pressure

Question 2

What is haemodynamic shock?

Answer 2

Acute condition of inadequate blood flow throughout the body

Question 3

True or false: shock can be due to fall in CO or fall in TPR beyond capacity of the heart to cope

Answer 3

TRUE

Question 4

How can shock lead to excessive vasodilation?

Answer 4

Fall in peripheral resistance

Question 5

What is cardiogenic shock?

Answer 5

Acute failure of the heart to maintain CO - pump failure

Question 6

What are the potential causes of cardiogenic shock? (3)

Answer 6

1) following MI
2) serious arrhythmias
3) acute worsening of heart failure

Question 7

True or false: central venous pressure may be normal or raised in cardiogenic shock

Answer 7

TRUE

Question 8

Which tissues may be poorly perfused in cardiogenic shock?

Answer 8

Coronary arteries

Kidneys

Question 9

What can poor perfusion of kidneys lead to?

Answer 9

Reduced urine production (oliguria)

Question 10

What is the definition of cardiac arrest?

Answer 10

Unresponsiveness associated with lack of pulse

Question 11

True or false: asystole is loss of electrical and mechanical activity

Answer 11

TRUE

Question 12

What is the most common form of cardiac arrest?

Answer 12

Ventricular fibrillation

Question 13

What are the two types of mechanical shock?

Answer 13

Cardiac tamponade

Pulmonary embolism

Question 14

Which side of the heart does cardiac tamponade affect?

Answer 14

BOTH

Question 15

True or false: cardiac tamponade leads to low central venous pressure but high arterial blood pressure

Answer 15

FALSE - high venous and low arterial

Question 16

Complete the sentences:

Pulmonary embolus occluded a large pulmonary artery, leading to _____ pulmonary artery pressure. The right ventricle cannot empty so central venous pressure is _____ and there is __________ return of blood to left heart. Left atrial pressure is _____, arterial blood pressure is ______ and this leads to shock, chest pain and dyspnoea.

Answer 16

High
High 
Reduced 
Low
Low

Question 17

How might an embolus reach the lungs?

Answer 17

Due to deep vein thrombosis, portion breaks off, travels in venous system to right side of the heart and is pumped out via pulmonary artery to lungs.

Question 18

What is hypovolaemic shock?

Answer 18

Reduced blood volume, most commonly due to haemorrhage

Question 19

What % of blood loss results in a serious shock response?

Answer 19

30-40%

Question 20

What is the severity of shock related to?

Answer 20

Amount and speed of blood loss

Question 21

What is the compensatory response for hypovolaemic shock? (5)

Answer 21

1) Increased sympathetic stimulation
2) Tachycardia
3) Increased force of contraction
4) Peripheral vasoconstriction
5) Venoconstriction

Question 22

In hypovolaemic shock, what dos increased peripheral resistance do to capillary hydrostatic pressure?

Answer 22

Reduces it

Question 23

What are the symptoms of hypovolaemic shock?

Answer 23

Tachycardia
Weak pulse
Pale skin
Cold, clammy extremities

Question 24

True or false: hypovolaemic shock can also result from burns and diarrhoea or vomiting (loss of Na+)

Answer 24

TRUE

Question 25

How can hypovolaemic shock lead to decompensation (organ failure)?

Answer 25

Peripheral vasoconstriction impairs tissue perfusion - 1) tissue damage due to hypoxia 2) release of vasodilators 3) TPR falls 4) BP falls 5) vital organs no longer perfused 6) multi system failure

Question 26

How many days does it take for blood fluid volume to be restored if there has been 20% blood volume loss?

Answer 26

About 3 days if salt and water intake are adequate

Question 27

What is distributive shock?

Answer 27

Low resistance shock (normovolaemic) due to profound peripheral vasodilation (decreased TPR)

Question 28

What are the two types of distributive shock?

Answer 28

Toxic (septic) shock | Anaphylactic shock

Question 29

What are the consequences of toxic/septic shock? (5)

Answer 29

1) vasodilation -> fall in TPR 2) fall in arterial pressure 3) impaired perfusion of vital organs 4) leaky capillaries 5) increased coagulation

Question 30

What are the symptoms of septic/toxic shock? (2)

Answer 30

1) tachycardia | 2) warm, red extremities initially

Question 31

What causes anaphylactic shock?

Answer 31

Severe allergic reaction

Question 32

What is released from mast cells during anaphylactic shock and what does this cause?

Answer 32

Histamine Vasodilator effect, fall in TPR Drop in arterial pressure Impaired perfusion of vital organs Bronchoconstriction and laryngeal oedema - difficulty breathing

Question 33

What are the symptoms of anaphylactic shock? (4)

Answer 33

1) Difficulty breathing 2) Collapsed 3) Rapid heart rate 4) Red, warm extremities

Question 34

What is given to patients suffering from anaphylactic shock?

Answer 34

Adrenaline -> vasoconstriction via action of alpha1-adrenoceptors

Question 35

How can anaphylactic and septic shock lead to multi-organ failure?

Answer 35

Distributive shock -> decreased TPR -> decreased BP -> decreased tissue perfusion OR Distributive shock -> decreased cardiac output due to leaky capillaries -> decreased blood pressure -> decreased tissue perfusion

Question 36

How can haemorrhage or severe burns lead to multi-organ failure?

Answer 36

Hypovolaemic shock -> decreased cardiac output -> decreased blood pressure -> decreased tissue perfusion

Question 37

How can MI or heart failures cause multi-organ failure?

Answer 37

Cardiogenic shock -> decreased cardiac output -> decreased blood pressure -> decreased tissue perfusion

Question 38

How can cardiac tamponade or pulmonary embolism lead to multi-organ failure?

Answer 38

Mechanical shock -> decreased cardiac output -> decreased blood pressure -> decreased tissue perfusion