CVS Shock

Question 1

How does shock come about?

Answer 1

Dramatic fall in arterial blood pressure due to either:
Fall in cardiac output
Fall in total peripheral resistance

Question 2

Give 3 types of shock due to a fall in cardiac output.

Answer 2

Hypovolaemic shock - fall in blood volume.
Cardiogenic shock - pump failure.
Mechanical shock - filling failure.

Question 3

What volume of blood must be lost for hypovolaemic shock to occur?

Question 4

What causes hypovolaemic shock and how?

Answer 4

Haemorrhage leads to reduced blood volume.
Venous pressure falls
Arterial pressure falls

Question 5

What is the compensatory response to hypolvolaemia?

Answer 5

Baroreceptors in carotid sinus/arch of aorta detect fall in arterial blood pressure.
This results in sympathetic activation resulting in peripheral vasoconstriction and positive inotropy and chronotropic to increase cardiac output.
Venoconstriction results in reduction of capillary hydrostatic pressure allowing a net movement of water into capillaries.

Question 6

How does a patient with hypovolaemic shock present?

Answer 6

Fast heart rate
Pale, cold, clammy hands
Weak pulse

Question 7

Describe decompensation in hypovolaemic shock.

Answer 7

Peripheral vasoconstriction results in hypoxia in peripheral tissues.
vasodilator metabolites result in a reduced total peripheral resistance resulting in a fall in blood pressure.
Vital organs cannot be perfumed leading to system failure.

Question 8

What can hypovolaemic shock result from?

Answer 8

Haemorrhage
Severe burns
Severe diarrhoea

Question 9

Describe the changes in cardiogenic shock.

Answer 9

Heart cannot pump effectively.
Venous pressure is normal so end diastolic volume is normal however this is not pumped.
Dramatic fall in arterial blood pressure.

Question 10

What can cardiogenic shock be due to?

Answer 10

Myocardial infarction.
Serious arrhythmia
Heart failure

Question 11

What can cardiogenic shock result in?

Answer 11

Coronary arteries poorly perfused, exacerbating problem.

Kidneys poorly perfused, less urine production.

Question 12

Describe what can cause mechanical shock.

Answer 12

Cardiac tamponade

Pulmonary embolism

Question 13

How does cardiac tamponade lead to mechanical shock?

Answer 13

Fluid accumulates in pericardial space.
Inelastic fibrous pericardium does not allow for expansion.
Heart is compressed so end diastolic volume is reduced.
Thus, venous pressure increases and arterial pressure falls.
There is a low stroke volume.

Question 14

How does pulmonary embolism result in mechanical shock?

Answer 14

Embolus occluded pulmonary artery.
This increases pulmonary artery pressure.
RV cannot empty.
Central venous pressure increases.
Less venous return to left atrium.
Limits filling of left heart, reducing stroke volume.
Arterial pressure is low.

Question 15

What is distributive normovolaemic shock. Give two types.

Answer 15

Due to a fall in TPR.
Blood volume is normal but volume of circulation increases.
Septic shock
Anaphylactic shock

Question 16

Describe anaphylactic shock.

Answer 16

Severe allergic reaction.
Mast cells release powerful vasodilator histamine.
Causes profound peripheral vasodilation.
TPr falls and so arterial pressure falls.
Baroreceptors in carotid sinus and arch of aorta detect fall but cannot compensate with SNS.
Mediators also cause bronchoconstriction and laryngeal oedema.

Question 17

How does a patient with anaphylactic shock present?

Answer 17

Difficulty breathing
Red, warm, clammy hands.
Tachycardia.
Collapse

Question 18

Describe septic shock.

Answer 18

Endotoxins cause peripheral vasodilation reducing TPR.
Arterial blood pressure falls.
Impaired perfusion.
Leaky capillaries reduces blood volume.
SNS is overridden by vasodilation.

Question 19

How does a septic shock patient present?

Answer 19

Tachycardia

Red, warm, clammy extremities.

Question 20

How do you treat hypovolaemic shock

Answer 20

Infuse colloid intravenous fluid. This raises arterial blood pressure.

Question 21

How do you treat cardiogenic shock

Answer 21

Positive ionotropic medication.

Anti arrhythmic agents.

Question 22

How do you treat cardiac tamponade.

Answer 22

Pericardiocentesis to drain fluid from pericardial space

Question 23

How do you treat pulmonary embolism?

Answer 23

Heparin

Thrombolytic drugs

Question 24

How do you treat anaphylactic shock

Answer 24

Adrenaline to act on alpha1 for vasoconstriction.

Question 25

How do you treat septic shock?

Answer 25

Adrenaline to act on alpha1 for vasoconstriction.

Antibiotics to kill bacteria producing toxin.

Question 26

Definition of hypertension

Answer 26

BP > 140/90

Normal is 120/80

Question 27

What are the treatments for hypertension?

Answer 27

ACE inhibitors alpha1 antagonists
Beta adrenoceptor antagonist
Calcium channel blockers
Diuretics

Question 28

What organs are involved in hypertension

Answer 28

Vasculature
Heart
Kidney

Question 29

Define shock

Answer 29

Circulatory failure leading to inadequate tissue perfusion, leading to generalised lack of oxygen.