Shock

Question 1

What is Shock?

Answer 1

An abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation

Question 2

How do you calculate Mean Arterial Pressure (MAP)?

Answer 2

Mean Arterial Pressure (MAP) = Cardiac Output (CO) x Systemic Vascular Resistance (SVR)

Question 3

What is Cardiac Output?

Answer 3

The volume of blood pumped by each ventricle of the heart per minute

Question 4

How is Cardiac Output calculated?

Answer 4

CO = Stroke Volume (SV) x Heart Rate (HR)

Question 5

What is Stroke Volume?

Answer 5

The volume of blood pumped by each ventricle of the heart per heart beat

Question 6

What does adequate tissue perfusion depend upon?

Answer 6

Adequate Blood Pressure

Adequate Cardiac Output

Question 7

What is Hypovolaemic shock due to?

Answer 7

Loss of blood volume

Question 8

Describe the process of hypovolaemic shock

Answer 8

Loss of blood volume –> decreased blood volume –> decreased venous return –> decreased end diastolic volume –> decreased stroke volume –> decreased cardiac output and decreased blood pressure –> inadequate tissue perfusion

Question 9

What is Cardiogenic shock due to?

Answer 9

Sustained hypotension caused by decreased cardiac contractility

Question 10

Describe the process of cardiogenic shock?

Answer 10

Decreased cardiac contractility –> decreased stroke volume –> decreased cardiac output and decreased blood pressure –> inadequate tissue perfusion

Question 11

Give and example of Obstructive shock

Answer 11

Tension Peumothorax

Question 12

Describe the process of obstructive shock

Answer 12

Increased intrathoracic pressure –> decreased venous return –> decreased end diastolic volume –> decreased stroke volume –> decreased cardiac output and decreased blood pressure –> inadequate tissue perfusion

Question 13

Give an example of Neurogenic shock

Answer 13

Spinal cord injury

Question 14

Describe the process of neurogenic shock

Answer 14

Loss of sympathetic tone –> Massive venous & Arterial vasodilatation –> Decreased venous return & decreased SVR (TPR) –> Decreased cardiac output & decreased blood pressure –> inadequate tissue perfusion

Question 15

Describe the process of Vasoactive shock

Answer 15

Release of vasoactive mediators –> Massive venous & Arterial vasodilatation - also increased capillary permeability –> Decreased venous return & decreased SVR (TPR) –> Decreased cardiac output & Decreased blood pressure –> Inadequate tissue perfusion

Question 16

Give the 4 most important steps in treating shock

Answer 16

1. ABCDE
2. High flow Oxygen
3. Replace volume
4. Call for help early

Question 17

How would you treat cardiogenic shock?

Answer 17

Inotropes (increases cardiac contractility)

Question 18

How would you treat obstructive shock caused by a tension pneumothorax?

Answer 18

Immediate chest drain

Question 19

How would you treat anaphylactic shock?

Answer 19

Adrenaline

Question 20

How would you treat septic shock?

Answer 20

Vasopressors

Question 21

Why don’t you replace volume in cardiogenic shock?

Answer 21

The pump itself is damaged so no point replacing the volume as it can’t be pumped anyway

Question 22

What percentage of blood volume lost can the body compensate for itself?

Answer 22

30%