Shock

Question 1

What is shock?

Answer 1

Clinical syndrome of tissue hypoperfusion due to circulatory failure

Question 2

How does the body keep organs perfused?

Answer 2

Global perfusion (MAP) leads to adequate perfusion of organs with oxygen-carrying nutrient rich borth and enables function of cells

Question 3

What is the pathological mechanism leading to hypoperfusion?

Answer 3

MAP falls below 50-60mmHg leading to slow flow, thrombus formation and inadequate perfusion

Question 4

List some consequences of tissue hypoperfusion

Answer 4

Systemic acidosis and lactic acid formation
Thrombosis
Necrosis

Question 5

What clinical sign is a very poor prognostic indicator and sign of circulatory failure?

Answer 5

Skin mottling

Question 6

What are the immediate signs of tissue hypoperfusion?

Answer 6

SKIN: Mottled, clammy skin
BRAIN: Acute confusional state (low GCS)
KIDNEYS: Reduced urine output (oliguria)

Question 7

What biochemical result is diagnostic of shock?

Answer 7

Blood lactate level at ABG >2mmol/l

Question 8

Why does hypotension not always lead to shock?

Answer 8

Physiological compensation of mean arterial pressure

Question 9

List the two cardiac mechanisms affecting mean arterial pressure

Answer 9

Cardiac output

Systemic vascular resistance

Question 10

What is the mechanism behind cardiogenic shock?

Answer 10

PUMP NOT WORKING

Reduced stroke volume + force of contraction, thus reduced cardiac output and mean arterial blood pressure

Question 11

How does the body try to compensate for cardiogenic shock?

Answer 11

Increase vascular resistance (vasoconstriction), resulting in cool clammy peripheries

Question 12

What is the mechanism behind obstructive shock?

Answer 12

OBSTRUCTION TO PUMP WORKING

Obstruction to cardiac outflow (otherwise similar to cardiogenic shock) leads to venous back pressure

Question 13

What clinical signs might be seen in obstructive shock?

Answer 13

Raised JVP

Distended neck veins

Question 14

List some causes of obstructive shock

Answer 14

Aneurysm
Pulmonary embolism
Tension pneumothorax
Cardiac tamponade

Question 15

What is the mechanism behind hypovolaemic shock?

Answer 15

Reduced blood volume/lower venous return to heart, causing decreased cardiac output and reduced force of contraction (Frank-Starling law)

Question 16

How is hypovolaemic shock differentiated from distributive shock?

Answer 16

Cool peripheries due to reduced cardiac output

Question 17

List some causes of hypovolaemic shock

Answer 17

Haemorrhage/bleeding
Dehydration
Trauma
Burns
Diabetic ketoacidosis

Question 18

What is the mechanism behind distributive shock?

Answer 18

BOUNDING CIRCULATION

Reduced systemic vascular resistance due to vasodilation, causing reduced mean arterial blood pressure

Question 19

How does the body try to compensate for distributive shock?

Answer 19

Increase in cardiac output

Vasodilation causes warm, red peripheries

Question 20

List some causes of distributive shock

Answer 20

Inflammation (infection, sepsis)
Anaphylaxis
Spinal cord injury

Question 21

What is the most common type of shock?

Answer 21

Distributive shock caused by sepsis

Question 22

Define massive haemorrhage in terms of clinical situation

Answer 22

Bleeding which leads to a heart rate ?110bpm +/- systolic BP <90 mmHg
Bleeding which has prompted use of emergency RhD- cells

Question 23

What is the initial management for massive haemorrhage?

Answer 23

ABCDE (IV access)
Stop bleeding
Call blood bank
Send blood samples (FBC,coag,crossmatch,U+E,Ca)

Question 24

What blood component support is given in massive haemorrhage?

Answer 24

Transfuse red cells (tissue oxygenation)
FFP (replace coagulation factors)
Platelets
Cryoprecipitate (replace fibrinogen)

Question 25

How is shock managed?

Answer 25

Get help
IV access
Fluid replacement
Oxygen
Treat cause