Shock

Question 1

Define Shock

Answer 1

A syndrome of inadequate tissue perfusion

Question 2

What is the pathogenesis of shock

Answer 2

Decreased perfusion leads to decreased O2 delivery

Tissue O2 requirements exceeds O2 delivery

Cellular hypoxia leads to cell dysfunction

Question 3

What are the two main determinants of tissue perfusion?

Answer 3

Cardiac Output
Peripheral Vascular Resistance

Question 4

What is the formula for Cardiac Output

Answer 4

Stroke volume x Heart Rate

Question 5

What are the three factors that affect cardiac output

Answer 5

Preload
Contractility
Afterload

Question 6

What are the two factors that affect Peripheral Vascular Resistance

Answer 6

Blood vessel diameter
Blood viscosity

Question 7

What are the 4 main types of shock

Answer 7

• Hypovolemic
• Cardiogenic
• Obstructive
• Distributive

Question 8

What is the etiology of a hypovolemic shock

Answer 8

Excess Fluid Loss

Question 9

What can cause a hypovolemic shock

Answer 9

Hypovolemic shock can be classified as Hemorrhagic or non-hemorrhagic

Question 10

List some causes of hemorrhagic Hypovolemic shock

Answer 10

Hemorrhagic:
- Post partum hemorrhage
- upper GI bleed
- penetrating trauma
- A/V fistula
-

Question 11

List some causes of non-hemorrhagic Hypovolemic shock

Answer 11

GI loss
Increased insensible fluid loss (burn)
Renal fluid loss (adrenal insufficiency, drug induced diuresis)
Third space fluid loss (SBO/LBO, pancreatitis)

Question 12

What is the pathophysiology of Hypovolemic Shock?

Answer 12

< intravascular volume = <preload + SV= < Cardiac Output= compensatory inc. in vascular resistance and heart rate

Question 13

What is the pathophysiology of cardiogenic shock?

Answer 13

An underlying pathology causes dysfunction of the heart =
< contractility/ <stroke volume leading to < cardiac output

Question 14

List 9 causes of cardiogenic shock

Answer 14

• MI
• Arrythmias
• HF
• Cardiomyopathy
• Myocarditis
• VSD
• Valve Defect (aortic/mitral regurgitation)
• blunt cardiac trauma
• drugs (Beta blockers, CCBs)

Question 15

What is the pathophysiology of obstructive shock

Answer 15

Obstruction of the heart and its Great Vessels> inability of the heart to circulate blood > dec. Cardiac Output > compensatory inc. in Systemic vascular resistance >

Question 16

What are 3 main causes of obstructive shock?

Answer 16

Dec. diastolic filling
Dec. venous return
Inc. Ventricular afterload

Question 17

List 3 pathologies that can lead to decreased diastolic filling and then obstructive shock

Answer 17

Cardiac Tamponade
Constrictive Pericarditis
Restrictive Cardiomyopathy

Question 18

List 3 pathologies that can lead to decreased venous return and then obstructive shock

Answer 18

Tension pneumothorax
Intrathoracic tumour

Question 19

List 3 pathologies that can lead to increased ventricular afterload and then obstructive shock

Answer 19

Massive PE
Aortic Dissection
Aortic Stenosis
Severe pulmonary hypertension

Question 20

List 4 types of Distributive Shock

Answer 20

• Septic Shock
• Anaphylactic Shock
• Neurogenic Shock
• Acute Adrenal insufficiency

Question 21

What is the classical presentation in neurogenic shock

Answer 21

• hypotension
• bradycardia
• vasodilation

Question 22

What is the main pathophysiology underlying Distributive Shock

Answer 22

Vasodilation (relative hypovolemic state)

Question 23

Define Neurogenic Shock

Answer 23

This is a type of shock that is caused by sudden loss of signals from the sympathetic system caused by upper spinal cord damage
(Leading to systemic vasodilation)

Question 24

What drug can be administered to correct bradycardia

Answer 24

Atropine

Question 25

List 3 vasopressors

Answer 25

Norepinephrine Epinephrine Phenylepinephrine

Question 26

What are the two specific mechanisms associated with septic shock

Answer 26

Dysregulated host response to infection leading to capillary leakage and systemic vasodilation leading to organ dysfunction Circulating inflammatory cytokines lead to myocardial depression

Question 27

Describe the pathophysiology of anaphylactic shock

Answer 27

Immunologic anaphylaxis leads to degranulation of mast cells > massive histamine release> systemic vasodilation and increased capillary leakage

Question 28

What are the two important parts of the history in diagnosing shock

Answer 28

- Initial/ Focus hx - hx of end organ function

Question 29

List 6 signs/ symptoms of shock

Answer 29

- tachycardia - tachypnoea - hypotension - altered mental status - decrease urine output - low output: cold clammy - high output: warm dry

Question 30

What determines the investigations done in shock patients

Answer 30

Determined by the possible cause

Question 31

What investigations should be done in the event of septic shock

Answer 31

Vitals CBC, UnEs Blood Culture sensitivity

Question 32

What investigations should be done in the event of cardiogenic shock

Answer 32

Vitals CBC UnEs Cardiac Enzymes ECG Echo CXR

Question 33

What general investigations should be done in the event of shock

Answer 33

Vital Signs CBC + UnEs Urine Output GCS CVP/PCWP Evaluation of tissue oxygenation

Question 34

How do you evaluate tissue oxygenation

Answer 34

Arterial Blood Gas

Question 35

Which drugs are useful in distributive shock

Answer 35

Vasopressors (to stimulate vasoconstriction) Noradrenaline, Vasopressin