SHOCK

Question 1

What is shock

Answer 1

life-threatening, generalised form of acute circulatory failure with inadequate oxygen delivery to, and consequently oxygen utilisation by, the cells

Question 2

Shock defined by:

Answer 2

Low BP
Tissue hypoperfusion
raised serum lactate

Question 3

Equations

Answer 3

BP = CO x Resistance to Blood flow
CO = SV X HR

Question 4

What is shock essentially

Answer 4

Ischaemia on global scale - circulatory failure of whole body

Question 5

What is hypovolaemic shock

Answer 5

induced by a low fluid volume of blood. A loss of around 20% of total blood volume can be enough to induce hypovolaemic shock

Question 6

2 types of hypovolaemic shock

Answer 6

• Non-haemorrhagic: the loss of fluid volume isn’t from bleeding e.g. dehydration, burns
• Haemorrhagic: loss of blood volume through ruptured blood vessels (i.e. loss of blood volume from bleeding) - e.g. GI bleeding, trauma, peri/post-operative

Question 7

What does hypovolaemia lead to

Answer 7

• Total volume filling of heart goes down > SV goes down > decreased CO > decreased BP
• When CO goes down > epi and norepinephrine, ADH, Ang II are released > cause vasoconstriction of BVs

Question 8

What does vasoconsctriction of BVs do?

Answer 8

increases vascular resistance and heart rate, and in turn, this increases cardiac output. These combined effects increase blood pressure.

Question 9

Indicator of hypovolaemic shock

Answer 9

Decreased mived venous oxygen (MVO2)

Question 10

What type of shock is hypovolaemic shock

Answer 10

Cold - BF also provides heat to the tissues, when it’s down, the skin starts to feel cool and clammy

Question 11

S + S of hypovolaemic shock

Answer 11

• Cold and clammy skin
• Confusion and drowsiness
• Increased sympathetic tone
• Tachycardia or bradycardia: depending on stage
  Initially narrow pulse pressure and weak pulse until there is compensation, and then again when there is failure of compensation

Question 12

What is cardiogenic shock

Answer 12

shock related to pathology of the heart, which prevents it from pumping enough blood to the tissues

Question 13

Causes of cardiogenic shock

Answer 13

• Acute MI - most common cause
• Pericardial effusion
• Cardiac tamponade
• arrhytmias
• Pulmonary embolus
• Pneumothorax

Question 14

Signs of cardiogenic shock

Answer 14

• HF
• Raise JVP
• Pulmonary oedema

Question 15

Cardiogenic shock pathophysiology

Answer 15

Same as hypovolaemic
Body release vasoconstrictors to increase vascular resistance to maintain BP
MVO2 down
Reduction in CO leads to lowered BF - Cold shock

Question 16

Distributive shock

Answer 16

• There is typically leakiness of blood vessels and an excessive amount of arteriole vasodilation.
• If arterioles dilate, vascular resistance to blood flow goes down, so blood pressure goes down, leading to less perfusion and distribution of blood to organs and tissues.

Question 17

What happens in septic shock

Answer 17

• Endotoxins on pathogens (gram - usually) cause cascade leading to lowered perfusion - damage endothelial cells releasing vasodilators
• Activate complement > activate mast cells + IM cell prod inflam cytokines > causes release of Platelet activating factor and ROS > Damage endothelial cells and increase vascular permeability so vesssels more leaky

Question 18

What do endothelial cells also express in septic shock?

Answer 18

• Procoagulant - TF - these combined with decrease of anti-coags leads to increase in coag + clotting - further blockages and adds to perfusion

Question 19

MVO2 and type of shock septic shock is

Answer 19

Warm due to increase in flow to peripheral BVs
MVO2 normal

Question 20

S + S of septic shock

Answer 20

• Warm and flushed skin
• Pyrexia and rigors
• Nausea and vomiting
• Bounding pulse

Question 21

What happens in an anaphylactic shock

Answer 21

• An allergic reaction that causes dangerously low blood pressure.
• Massive release of histamine and other vasoactive mediators causes hemodynamic collapse.

Question 22

S + S of anaphylactic shock

Answer 22

• Warm and flushed skin
• Itching
• Sweating
• May be breathlessness and wheeze
• Cyanosis
• Low BP
• Tachycardia

Question 23

What happens in neurogenic shock

Answer 23

The nervous system gets damaged and can’t control the body’s blood pressure.

e.g. spinal cord injury, epidural or spinal anaesthesia

Question 24

Anaemia + Cytotoxic shock

Answer 24

• Anaemic shockNot enough oxygen being carried in blood
• Cytotoxic shockCells are poisoned

Question 25

Treatment of shock

Answer 25

• ABC
  
  • Airways: intubation if necessary
  • Breathing: give O2
  • Circulation: establish IV access, raise legs if hypovolaemic, fluid resuscitation and blood transfusion if necessary, ensure haemostasis

Question 26

Septic shock treatment

Answer 26

Antibiotics

Question 27

Anaphylactic shock treatment

Answer 27

remove causative agent + adrenaline, chlorphenamine and hydrocortisone

Question 28

Cardiogenic shock treatment

Answer 28

may require revascularisation

Question 29

Complications of shock

Answer 29

• Organ failure: due to prolonged hypotension
  
  • Kidneys - acute tubular necrosis
  • Lung - Acute Respiratory Distress Syndrome (ARDs)
  • Heart - myocardial ischaemia and infarction
  • Brain - confusion, irritability and coma