12 - Shock

Question 0

What types of shock are the result of a drop in cardiac output?

Answer 0

Cardiogenic
Mechanical
Hypovalaemic

Question 1

What is Shock?

Answer 1

Catastrophic drop in mean arterial BP
Mean Arterial BP = CO x TPR
So shock is the result in a drop in CO or in TPR that the system cannot cope with

Question 2

What types of shock are the result of changes to total peripheral resistance?

Answer 2

Septic

Anaphylactic

Question 3

What is Cardiogenic shock?

Answer 3

acute failure of the heart to maintain cardiac output

Question 4

When can Cardiogenic shock occur?

Answer 4

Following an MI
As a result of a serious arrhythmias
Acute worsening of heart failure

Question 5

Describe what happens in Cardiogenic shock

Answer 5

CVP is normal or raised so the heart is able to fill properly but it does not pump effectively
Decreased Arterial Blood Pressure
Tissues are poorly perfumed, particularly the coronary arteries and kidney

Question 6

What is oliguria?

Answer 6

Reduced urine production as a result of Cardiogenic shock

Question 7

What is mechanical shock?

Answer 7

When there is an obstruction that prevents the ventricle from filling properly

Question 8

What are the two situations in which mechanical shock can occur?

Answer 8

Cardiac Tamponade

Pulmonary Embolism

Question 9

Describe how cardiac Tamponade causes mechanical shock

Answer 9

Fluid in the pericardial sac reduces filling of the heart
Reduced end diastolic volume
Increase CVP and decreased ABP
Electrical activity is normal

Question 10

Describe how a pulmonary embolism can cause mechanical schock

Answer 10

Only occurs if massive PE and occlusion of a large pulmonary artery
Increased pulmonary artery pressure
RV doesn’t empty properly so increased CVP
Decreased blood return to the heart so limited filling = lower LV pressure
Reduced AP

Question 11

What are some signs of mechanical shock as the result of pulmonary embolism

Answer 11

Chest pain

Dyspnoea

Question 12

What is hypovalaemic shock?

Answer 12

Shock caused by as severe loss to blood volume (>20%)

Question 13

What are some causes of hypovalaemic shock?

Answer 13

Haemorrhage
Severe burns
Severe diarrhoea or vomiting

Question 14

Describe hypovalaemic shock as the result of haemorrhage

Answer 14

Reduced VP = reduced CO = reduced AP which is detected by Baroreceptors = increased sympathetic drive
Leads to increased force of contraction, peripheral vasoconstriction and venoconstriction

Question 15

What are some signs of hypovalaemic shock?

Answer 15

Tachycardia
Weak pulse
Pale skin
Cold, clammy extremities

Question 16

How do you treat hypovalaemic shock?

Answer 16

Treat with internal transfusion

- increased peripheral resistance = decreased hydrostatic pressure = net movement of water into the capillaries

Question 17

What is decompression?

Answer 17

Peripheral vasoconstriction = tissue damage by hypoxia = release of chemical mediators = decreased TPR = decreased BP = multi-system failure

Question 18

What is septic shock?

Answer 18

Shock that occurs due to the release of endotoxins by circulating bacteria

Question 19

Describe what happens in septic shock

Answer 19

Release of endotoxins = profound vasodilation = decreased TPR = reduce AP = impaired perfusion and leaky blood vessels so reduced blood volume
Baroreceptors detect drop in AP so stimulate sympathetic NS = increased heart rate and stroke volume

Question 20

Despite the activation of the sympathetic nervous system there is still vasodilation, why?

Answer 20

The vasoconstriction effects of the sympathetic NS are overridden by the vasodilator mediators released by the bacteria

Question 21

What are some signs of septic shock?

Answer 21

Tachycardia

Warm, red extremities

Question 22

What is anaphylactic shock?

Answer 22

Shock that is the result of a severe allergic reaction

Question 23

Describe what happens in anaphylactic shock

Answer 23

Release of histamines = profound vasodilation = reduced TPR = reduced AP = stimulation of sympathetic NS = increased CO

• impaired perfusion
• brochoconstriction and laryngeal odema

Question 24

What are some signs of anaphylactic shock?

Answer 24

Difficulty breathing
Collapsed pulse
Red, clammy extremities
Treat with adrenaline