Hypovolemic Shock

Question 1

What is haemodynamic shock?

Answer 1

Acute- inadequate blood flow throughout the body

Catastrophic fall in aBP

Question 2

What causes haemodynamic shock?

Answer 2

Fall in CO- mechanical (filling)

• pump
• volume loss

Fall in Peripheral resistance- vasodilation

Question 3

What are the types of shock due to reduced CO?

Answer 3

Cardiogenic
Mechanical
Hypovolaemic

Question 4

What are some causes of cardiogenic shock?

Answer 4

MI- damage to LV

Serious arrhythmias- bradycardia or tachycardia

Acute worsening of heart failure

Question 5

What occurs in cardiogenic shock?

Answer 5

• CVP raised/ normal
• Dramatic drop in arterial BP (pump failure)
• Tissues poorly perfused

Question 6

How does cardiac tamponade cause shock?

Answer 6

Restricts filling of heart (increased pressure in all chambers)
High central venous pressure (can’t get into heart)
Low arterial BP

Question 7

How does a pulmonary embolism cause shock?

Answer 7

Massive embolism occludes artery

• pul arterial pressure high
• RV can’t empty (CVP high as can’t fill RV)
• LA pressure low due to small return
• Arterial BP low

Question 8

How is cardiac tamponade treated?

Answer 8

Pericardiocentensis

Question 9

How does hypovolaemic shock occur?

Answer 9

Due to reduced blood volume

<20% fine
20-30% some shock
30-40% large decrease mean aBP= serious shock

Question 10

How does the body respond to hypovolaemic shock?

Answer 10

Fall in BP detected by baroreceptors
Increased sympa activity
(Increased contractility and hr)
Vaso and veno constriction (increase return to heart)

Reversal of fluid movement in capillaries

Question 11

How does fluid movement in capillaries change?

Answer 11

Net movement of fluid into caps
(Internal transfusion)

Increases PR= reduced cap hydrostatic pressure

Question 12

What signs does a patient with hypovolaemic shock show?

Answer 12

Tachycardia
Weak thready pulse
Pale skin
Cold and clammy extremities (sympa activation)

Question 13

How can prolonged vasoconstriction lead to decompensation?

Answer 13

Peripheral tissues experience hypoxia 
Release of chemical vasodilatory mediators 
TPR decreases 
Dramatic bp fall 
Organs not perfused 

The sympa system can’t overcome vasodilation

Question 14

What are long term responses to increasing mean aBP?

Answer 14

RAAS system
Anti-diuretic hormone

Several days to restore 20% blood loss

Question 15

How would you treat hypovolaemic shock?

Answer 15

IV fluids
Transfusion of blood products

Amount determined by CVP values (careful not to overperfuse)

Question 16

What is distributive shock?

Answer 16

Decrease in TPR

Profound peripheral vasodilation

Question 17

What are types of distributive shock?

Answer 17

Toxic (septic)

Anaphylactic

Question 18

How does sepsis cause shock?

Answer 18

Endotoxins releases by bacteria trigger excessive inflammatory response

Causes vasodilation, fall in TPR, fall in aBP
Impaired perfusion organs

Capillaries leaky= lose blood volume

Increased coagulation= local hypo perfusion

Question 19

What symptoms/ signs does septic shock cause?

Answer 19

Tachycardia (sympa trying maintain BP)

Initially warm red extremities 
Later vasoconstriction (syma)= hypoperfusion

Question 20

How does anaphylaxis cause shock?

Answer 20

Release of histamine from mast cells
(Powerful vasodilator that syma response can’t overcome) = fall in TPR

Drop in aBP
Impaired perfusion organs
Bronchoconstriction ect

Question 21

What signs/ symptoms will be present in anaphylactic shock?

Answer 21

Difficulty breathing
Rapid hr (syma trying to increase CO)
Red and warm extremities (vasodilation in peripheries)

Question 22

How is anaphylactic shock treated?

Answer 22

Pharmacological does of Adrenaline

Causes vasoconstriction of alpha 1 adrenoreceptors, increase TPR

Question 23

What are the general features of heaodynamic shock?

Answer 23

Fast pulse
Low aBP
Activation of sympa system and effects that come along with that