Shock

Question 1

Shock definition

Answer 1

Abnormality in circulatory system that results in inadequate organ perfusion

Question 2

Types of shock

Answer 2

Hypovolaemic (Haemorrhagic)
Cardiogenic
Distributive (Septic, Anaphylactic)
Obstructive
Neurogenic

Question 3

Most common cause of shock in trauma patients

Answer 3

Haemorrhage

Question 4

Cardiac output equation

Answer 4

CO = Stroke volume x Heart rate

Question 5

Factors contributing to stroke volume

Answer 5

Preload
Myocardial contractility
Afterload

Question 6

Definition of preload

Answer 6

Volume of venous blood return to the left and right sides of the heart

Question 7

Effect of haemorrhage on preload

Answer 7

Haemorrhage reduces preload

Question 8

Starling’s law

Answer 8

Muscle fibre length of the myocardium is related to the myocardial muscle contractility

Question 9

Effect of preload on myocardial contractility

Answer 9

Volume of preload determines myocardial muscle fibre length after ventricular filling at the end of diastole

(Starling’s law)

Question 10

Afterload definition

Answer 10

Resistance to the forward flow of blood

Question 11

Early physiologic responses to blood loss

Answer 11

Release of catecholamines

Increase peripheral vascular resistance and diastolic BP

Progressive vasoconstriction to preserve blood flow to kidneys, heart and brain

Increased HR to preserve cardiac output

Shift from aerobic to anaerobic cellular metabolism

Question 12

Useful marker of severity of shock and to monitor response to treatment

Answer 12

Lactate
Base deficit

Question 13

Focus of management for haemorrhagic shock

Answer 13

Locate and stop haemorrhage

Question 14

Diagnostic adjuncts for identifying source of haemorrhage

Answer 14

CXR
Pelvic XR
FAST scan
Diagnostic Peritoneal Lavage
Bladder catheterisation

Question 15

4 views in FAST scan

Answer 15

Pericardial view
RUQ view
LUQ view
Suprapubic view

Question 16

RUQ view of fast scan

Answer 16

Liver
Interface between liver and diaphragm
Morrison’s pouch

Question 17

Morrison’s pouch

Answer 17

Interface between liver and right kidney

(Hepatorenal fossa)

Question 18

LUQ view of FAST scan

Answer 18

Spleen
Interface between spleen and diaphragm
Interface between spleen and left kidney

Question 19

Suprapubic view of FAST scan

Answer 19

Area behind bladder looking for fluid

Fluid posterior to the bladder is abnormal

Question 20

Pericardial view of FAST scan

Answer 20

Sub-xiphoid view
Parasternal view

Looking for tamponade

Question 21

Major haemorrhage protocol ratio to give products for major trauma initially

Answer 21

RBC : Platelets : FFP
1:1:1

Question 22

Major haemorrhage protocol ratio to give products for major trauma initially

Answer 22

RBC : Platelets : FFP
1:1:1

Question 23

What guides ongoing blood products to give by monitoring coagulation

Answer 23

Where available:

Thromboelastography (TEG)

or

Rotational Thromboelastometry (ROTEM)

Question 24

Consequence of massive crystalloid resuscitation in haemorrhagic shock

Answer 24

Coagulopathy due to dilution of platelets and clotting factors

Question 25

Poiseuille's law equation

Answer 25

Question 26

Interpretation of Poiseuille's law

Answer 26

Flow rate of IV fluids through a cannula / tube is: - Proportional to the Radius^4 - Inversely proportional to the length

Question 27

Ideal size and shape of a cannula according to Poiseuille's law

Answer 27

Short and large calibre (diameter)

Question 28

Normal adult blood volume in Litres

Answer 28

Approximately 7% body weight in Kg (ideal body weight in obese adults)

Question 29

Normal paediatric blood volume in Litres

Answer 29

Approximately 8-9% body weight in Kg

Question 30

Classification of Haemorrhagic shock

Answer 30

Class I Class II Class III Class IV

Question 31

Class I Haemorrhagic shock definition

Answer 31

Blood volume loss <15% Eg someone who has donated 1 unit of blood

Question 32

Class I Haemorrhagic shock signs

Answer 32

Minimal tachycardia Normal BP, pulse pressure, RR Base deficit 0 to -2

Question 33

Class II Haemorrhagic shock definition

Answer 33

Blood volume loss 15 - 30% Uncomplicated haemorrhage Requires crystalloid fluid resuscitation

Question 34

Class II Haemorrhagic shock signs

Answer 34

Raised HR and RR Decreased pulse pressure Urine output 20 - 30 ml/hr Base deficit -2 to -6 Subtle central nervous system signs (anxiety, fear)

Question 35

Class III Haemorrhagic shock definition

Answer 35

Blood volume loss 30 - 40% Complicated haemorrhagic state Requires blood replacement often, but minimum crystalloids

Question 36

Class III Haemorrhagic shock signs

Answer 36

Marked increased HR and RR Changes in mental state Significant hypotension Inadequate perfusion Base deficit -6 to -10

Question 37

Class IV Haemorrhagic shock definition

Answer 37

Blood volume loss >40% Preterminal event Patient will die within minutes unless aggressive measures taken

Question 38

Class IV Haemorrhagic shock signs

Answer 38

Marked tachycardia Significant hypotension Very narrow pulse pressure Minimal Urine output Cold, pale skin Base deficit -10 or more

Question 39

Confounding factors that alter haemodynamic response

Answer 39

Age Injury severity Time lapse between injury and treatment Prehospital fluid resus Medications Implanted cardiac devices Athletes

Question 40

Causes of hypovolaemia with soft tissue injures

Answer 40

Blood loss at site of injury Oedema in injured soft tissue from fluid shifts

Question 41

Methods for haemorrhagic control

Answer 41

Direct pressure Splint fractures Pelvic binder Tourniquet Surgery Angio-embolisation

Question 42

Role of NG tube in trauma

Answer 42

For gastric decompression Gastric distention can cause hypotension, dysrhythmia and increase aspiration risk

Question 43

How to deliver fluid / blood

Answer 43

Warmed and high flow rates via Belmont

Question 44

Balanced / Controlled resuscitation

Answer 44

Aka permissive hypotension Refraining from aggressive fluid resuscitation until source is controlled to reduce further bleeding Not acceptable for suspected head injuries

Question 45

Minimum urine output indicating adequate perfusion in Adults

Answer 45

0.5 ml/kg/hr

Question 46

Minimum urine output indicating adequate perfusion in Children

Answer 46

1 ml/kg/hr

Question 47

Minimum urine output indicating adequate perfusion in Infants

Answer 47

2 ml/kg/hr

Question 48

Categories of response to initial fluid bolus

Answer 48

Rapid response Transient response Minimal / No response

Question 49

Ongoing management of rapid response

Answer 49

No further bolus needed but can switch to maintenance regime Have types and matched blood ready in case

Question 50

Ongoing management of transient response

Answer 50

Respond to initial bolus but then deteriorate again - Transfusion of blood and blood products - Consider major haemorrhage protocol - Obtain source control

Question 51

Ongoing management of minimal / no response

Answer 51

Massive haemorrhage protocol Immediate, definitive intervention

Question 52

Most common cause for a transient response to fluid bolus

Answer 52

Undiagnosed source on bleeding

Question 53

Definition of massive transfusion

Answer 53

> 10 units packed cells in first 24 hrs OR > 4 units packed cells in 1 hr

Question 54

When to use tranexamic acid

Answer 54

Within 3 hours of injury give 1g TXA stat Followed by 1g TXA infusion

Question 55

How common is coagulopathy in trauma patients

Answer 55

Occurs in 30% severely injured pts Baseline clotting studies and platelets are useful

Question 56

Calcium replacement target range

Answer 56

Free / Ionised Calcium > 1.0 This figure is obtained on a blood gas

Question 57

Consideration of pregnancy and haemorrhage

Answer 57

Normal hypervolaemia masks perfusion abnormalities Decreased foetal perfusion may indicate maternal hypovolaemia