Cardiogenic Shock

Question 1

What determines adequate tissue perfusion ?

Answer 1

Adequate blood pressure and adequate cardiac output

MAP= CO x SVR
CO=SVR x HR

Question 2

What is shock ?

Answer 2

Abnormality of circulatory system resulting in inadequate tissue perfusion and oxygenation
-Can have high mortality
-Early recognition and intervention can help

Question 3

How can shock lead to cellular failure ?

Answer 3

Question 4

What can cause inadequate tissue perfusion?

Answer 4

-Loss of blood volume
-Sudden severe impairment of heart function
-Physical obstruction to circulation
-Excessive vasodilation and abnormal distribution of blood flow

Question 5

What are the four types of shock ?

Answer 5

Hypovolaemic

Cardiogenic

Obstructive

Distributive

Question 6

What is hypovolemic shock ?

Answer 6

Loss of blood volume. Can be:

Haemorrhagic
-Trauma, GI bleed, ruptured aneurysm

Non-haemorrhagic
-Burns, GI losses, diabetic ketoacidosis, dehydration

Question 7

How does hypovolemic shock lead to poor tissue perfusion ?

Answer 7

Question 8

What is the Effect of EDV on SV- Frank Starling Curve ?

Answer 8

Question 9

What is cardiogenic shock ?

Answer 9

Sustained hypotension due to reduced cardiac function; reduced CO

Contractility
-MI, myocarditis, cardiomyopathy

Mechanical
-Papillary muscle rupture, severe aortic stenosis

Arrhythmia
-Heart block, VT, SVT, AF

Cardiotoxicity
-Medication overdose

acute heart failure can cause, MI most common cause

Question 10

How does cardiogenic shock lead to poor tissue perfusion ?

Answer 10

Also stimulates sympathetics to vasoconstrict to try and increase BP

Question 11

How can cardiogenic shock enter a worsening cycle ?

Answer 11

1) Reduced contratibility; decreases stoke volume so decreased CO; decreased BP; decreased coronary perfusion; cycle of ischaemia

2) Heart fails, low CO, less oxygen to organs , reflex vasoconstirction which increases afterload, more stress on heart, cycle of worsening perfusion

Question 12

What are symptoms of cardiogenic shock ?

Answer 12

Rapid breathing
Weak pulse
Sweaty skin
Less urinationa than normal
Nausea/vomiting
Swollen feat
Pale and/or cool skin
Low BP
Loss of consciousness
Chest pain (suggets MI, most common cause here)

Question 13

What is the first main indication of cardiogenic shock ?

Answer 13

Low urine output indicates poor tissue perfusion in cardiogenic shock;
-First signs organs have stopped working as kidenys are first to show signs of hypoperfusion here

Question 14

What is obstructive shock ?

Answer 14

Physical obstruction of flow outside of the heart

Outflow
-Massive PE, cardiac tamponade, tension pneumothorax

Venous Return
-Vena Cava syndrome, sickle cell splenic sequestration

Question 15

How does a tension pneumothroax lead to poor tissue perfusion ?

Answer 15

A type of obstructive shock (same general steps for all)

Question 16

Which ionotropes are used to treat cardiogenic shock ?

Answer 16

Positive ionotropes e.g. dobutamine, noradrenaline, dopamine
-↑ contractility
-↑ cardiac output
-Maintain perfusion

Question 17

What is distributive shock ?

Answer 17

Abnormal distribution of blood flow

Neurogenic
-Spinal cord injury

Vasoactive
-Sepsis (most common)
-Anaphylaxis

Question 18

How does neurogenic distributive shock cause poor tissue perfusion ?

Answer 18

Loss of sympathetic tone e.g. due to spinal anaesthesia mistakes/spinal injuries

Question 19

How does vasoactive distributive shock cause poor tissue perfusion ?

Answer 19

Reduced preload
TPR = total peripheral resistance

Question 20

What are causes of hypovolemic shock ?

Answer 20

ECFV = extraceullular fluid volume

Question 21

What is the role of compensatory mechanisms in haemorrhagic shock ?

Answer 21

Compensatory mechanisms can maintain blood pressure until about >30% of blood volume is lost

Question 22

E

Explain the The Baroreceptors Reflexes

Answer 22

Response to Decreased Arterial Blood Pressure

Question 23

How is shock managed ?

Answer 23

Call for help
Structured approach <C>ABCDE
High flow oxygen to keep oxygen sats >94%
iv access
Fluid resuscitation (most)
Specific treatments depending on cause</C>