Shock

Question 1

What is a definition of shock?

Answer 1

An acute clinical syndrome initiated by ineffective perfusion and cellular hypoxia resulting in severe dysfunction of organs vital to survival

Question 2

What are the key features of shock, physiologically?

Answer 2

Acute hypoperfusion to tissues/organs
Impaired O2 delivery
Cellular hypoxia
Anaerobic respiration
Haemodynamic abnormalities
Oxygen utilisation may be abnormal, not just impaired

Question 3

Where in the blood is the oxygen?

Answer 3

Bound to haemoglobin as oxyhaemoglobin, small amount dissolved in plasma

Question 4

How are pressure, CO and vascular tone related?

Answer 4

Pressure = COxvascular tone

Question 5

What affects CO?

Answer 5

CO = SV x HR

Question 6

What can affect the stroke volume?

Answer 6

Preload
Contractility
Afterload

Question 7

What are the four types of shock?

Answer 7

Hypovolaemic
Cardiogenic
Distributive
Obstructive

Question 8

Whatever is the mechanism for the different types of shock?

Answer 8

Hypovolaemic - reduced intravascular tone
Distribution - vasodilatation and malperfusion
Cardiogenic - intrinsic cardiac failure
Obstructive - impairment of circulatory flow

Question 9

What are some clinical examples of hypovolaemic shock?

Answer 9

Haemorrhage
Burns
GI blood losses (D/V, fistulat)
Dehydration (heat exposure, polyuria)

Question 10

What are some clinical examples of distributive shock?

Answer 10

SIRS related -sepsis, pancreatitis, trauma, burns

Neurogenic - spinal cord injury

Anaphylaxis

Question 11

What are some clinical examples of cardiogenic shock?

Answer 11

MI/ischaemia
Arrhythmia
Acute valve pathology

Question 12

What are some clinical examples of obstructive shock?

Answer 12

Tension pneumothorax
Pericardial tamponade
PE

Question 13

How does hypovolaemia cause shock?

Answer 13

Reduction of venous return
Fall in SV and CO
Hypotension
Hypoperfusion of organs
Organ dysfunction

Question 14

What is starling’s law?

Answer 14

Contraction of the heart is directly related to stroke volume and preload

Question 15

What are the physiological responses of hypovolaemia?

Answer 15

SNS activation
Adrenal catecholamine release
NA and H2O retention due to renin-angiotensin system
Coagulation system activation
Cortisol release

Question 16

What does the SNS system activate to compensate for CO?

Answer 16

Tachycardia
Vascular tone increase
Contractility of heart increases (>SV)

Question 17

What are the signs of organ hypoperfusion?

Answer 17

Oliguria
Cognitive changes
Metabolic acidosis
Skin changes (blue and cool >CRT)

Question 18

What are the management principles of shock?

Answer 18

Restore tissue perfusion and O2 delivery to cells
Administer O2
Increase BP with IV fluids
Treat the cause

Question 19

Which size cannulas would you insert?

Answer 19

14G/16G

Question 20

Which bloods do you take in shock?

Answer 20

Cross match
Haemotology - FBC, cloting
Biochemistry - UE, glucose, liver, bone, lactate
ABG

Question 21

Which investigations can you do super quickly?

Answer 21

ECG
US abdo
ALL OBS

Question 22

How does hypothermia affect blood loss?

Answer 22

It has adverse affects on clotting so BEWARE

Question 23

What must you do if the patient isn’t responding to fluids as you had expected?

Answer 23

THINK AGAIN
Is the bleeding too rapid?
Are we missing something important? e.g. MI, sepsis, PE
Is there something specific they need urgently?

Question 24

Which conditions need a specific therapy and therefore must be ruled out?
How do you rule them out?

Answer 24

Tension pneumothorax
Pericardial tamponade
Pulmonary embolism
Acute MI

ECG
CXR

Question 25

What suggests other types of shock to hypovolaemic?

Answer 25

Cardiogenic:
History of CV
Signs of CCF
ECG evidence

Obstructive:
Impaired cardiac filling (cardiac tamponade/tension pneumo)
Obstructive forward flow
Specific symptoms and signs

Distributive (can masquerade as

Question 26

What is further management of shock post-stabilisation?

Answer 26

Surgery to control bleeding
Drugs (inotropes to increase contractility)
Invasive lines
Monitoring
ICU

Question 27

What are the mortality rates of shock?

Answer 27

Septic: 30-50%
Cardiogenic: 60-80%

Question 28

What are the consequences of shock?

Answer 28

Death
Cellular injury and death
Multiple organ dysfunction and failure

Question 29

Which is the best marker for improved tissue perfusion?

Answer 29

Urine output increase

Question 30

What does lactate returning to less than 2 indicate?

Answer 30

Indicates that the tissues are aerobically respiring and that the risk of cardiac arrest is reducing