Shock

Question 1

Define shock.

Answer 1

Shock = an imbalance between oxygen delivery to the tissues and oxygen consumption by the tissues.

Question 2

What are the four types of circulatory shock?

Answer 2

Hypovolaemic
Cardiogenic
Obstructive
Distributive

Question 3

Describe hypovolaemic shock.

Answer 3

Results in decreased blood volume
Result of fluid losses or decreased fluid intake
Losses may be haemorrhagic (internal/external) or non-haemorrhagic (internal/external)

Question 4

Describe cardiogenic shock and list some examples.

Answer 4

Forward/’pump’ failure i.e. reduced cardiac output

E.g. reduced systolic/diastolic funtion, bradyarrythmias, tachyarrythmias

Question 5

Describe obstructive shock and list some examples.

Answer 5

Due to physical obstructions - overlaps with cardiogenic shock

E.g. GDV, pericardial tamponade, pulmonary/aortic thromboembolism

Question 6

Describe distributive shock.

Answer 6

Maldistribution of blood flow
Inappropriate and widespread vasodilation
Due to histamine release or uncontrolled inflammatory responses (bacterial infection - sepsis / non-infectious insults)

Question 7

What is the physiological response to hypovolaemic shock?

Answer 7

Catecholamine release (increased HR, cardiac contractility, peripheral vasoconstriction)
Activation of renin-angiotensin-aldosterone system
ADH released (increased renal water retention)

Question 8

What is the difference between compensated and decompensated hypovolaemia?

Answer 8

Compensated = the homeostatic mechanisms are successfully maintaining tissue perfusion

Decompensated = the compensatory mechanisms are failing, and the patient is in danger of dying

Question 9

How does hypovolaemic shock differ in feline patients?

Answer 9

Less predictable

Bradycardia and hypothermia are common features

Question 10

Briefly outline the treatment of hypovolaemic shock.

Answer 10

Rapid admin of fluids
Treatment of underlying cause
Severe = transfusion therapy

Question 11

How are crystalloid fluids used to treat hypovolaemic shock?

Answer 11

Bolus - 10-20ml/kg in dogs / 5-10ml/kg in cats
Reassess
Bolus - same again
Reassess
Is there ongoing blood loss?
Concurrent anaemia (PCV <20%) - consider transfusion
Once stable move on to maintenance therapy

Question 12

How do we determine the efficacy of treatment for hypovolaemic shock?

Answer 12

Mentation, HR, pulse quality, MM colour, CRT, temp,
BP
Lactate
Urine output
ECG