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ATLS > Chapter 3- Shock > Flashcards

Chapter 3- Shock Flashcards

0
Q

Name the 5 types of shock.(p.63)

A

1/ Hypovolaemic (Most common) 2/ Cardiogenic 3/ Obstructive 4/ Neurogenic 5/ Septic

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1
Q

What is the definition of shock?

A

An abnormality of the circulatory system that results in inadequate organ perfusion and tissue oxygenation. (p.63)

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2
Q

Cardiac Output = (1) x (2)

A

1= Heart rate 2= Stroke volume

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4
Q

Preload (volume of blood flowing back to the heart) = (1)+(2)+(3)

A

1/ Venous capacitance 2/ Volume status 3/ The difference between mean venous systemic pressure and right atrial pressure.

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5
Q

Stroke Volume = (1) + (2) + (3)

A

1/ Preload 2/ Myocardial contractility 3/ Afterload

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6
Q

How does the body respond to blood loss?

A

1/ Vasoconstriction of cutaneous muscle and visceral circulation occurs to preserve blood flow to the kidneys, heart and brain. 2/ Increase in heart rate to preserve cardiac output.

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7
Q

What endogenous chemicals are released that cause vasoconstriction?

A

1/ Catecholamines 2/ bradykinin 3/ Histamin 4/ B-endorphins 5/ Cytokins 6/ Prostanoids.

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8
Q

What is the most effective way of restoring cardiac output and end organ perfusion?

A

Restore venous return by: 1/ Stopping the source of bleeding. 2/ Volume repletion

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9
Q

Inadequately oxygenated & perfused cells compensate by shifting to (BLANK) respiration which results in the formation of (BLANK) and the development of (BLANK).

A

1/Anaerobic respiration 2/ Lactic acid 3/ Metabolic acidosis

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10
Q

Name 2 proinflammatory mediators.

A

1/ Inducible nitric oxide synthase (INOS) 2/ TNF

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11
Q

Should vasopressors be given in shock?

A

No, they are contraindicated. Although they may increase BP. They worsen tissue perfusion by vasoconstriction.

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12
Q

Who should be called if there is shock in an injured patient?

A

A surgeon.

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13
Q

What should you assume if the patient is cool and has tachycardia?

A

They are in shock until proven otherwise.

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14
Q

How is tachycardia diagnosed in children?

A

Infants= >160bpm Preschoolers = >140bpm School age = >120bpm Adults = >100bpm

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15
Q

What may limited elderly patient’s compensatory response to blood loss? (and thus they may not show signs of tachycardia)

A

1/ Drugs - diuretics, Beta blockers, CCB

2/PPM

(Look for a narrow pulse pressure in elderly patients who may have these factors in order to diagnose shock.)

3/ Relative decrease in sympathetic activity.

4/ Catecholamine receptor deficit

5 Reduced cardiac compliance.

6/ Pre-existing volume depletion

7/ Malnutrition

8/ Renal glomerular and tubular senescence - reduced responsiveness to aldosterone, catecholamines, vasopressin and cortisol.

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16
Q

What should you not use to estimate blood loss? What should you use instead?

A

Do not use haemoglobin or haematocrit as they are unreliable in the acute setting. Use lactate and base excess.

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17
Q

What is the most common cause of shock?

A

Haemorrhagic shock (after injury)

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18
Q

Name the 4 types of non-haemorragic shock?

A

1/ Cardiogenic 2/ Neurogenic 3/ Obstructive 4/Septic

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19
Q

Name the causes of cardiogenic shock?

A

1/ MI 2/ Cardiac tamponade 3/ Air embolus 4/ Blunt cardiac injury

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20
Q

How do you identify and treat a cardiac tamponade?

A

1/ Identify -

  • Tachycardia
  • muffled heart sounds
  • Dilated neck veins
  • Hypotension resistant to fluid therapy.
  • Most commonly seen after thoracic penetrating injury.

2/ Treatment

  • Pericardiocentesis - temporarily
  • Thoracotomy (Definitive)
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21
Q

How do you identify and treat a tension pneumothorax?

A

1/ Identify

  • Absent breath sounds
  • Tracheal deviation
  • Hyperresonant percussion note over the affected hemithorax
  • Acute respiratory distress
  • Subcutaneous emphysema

2/ Treatment

  • Immediate thoracic decompression (See Chapter 4 for more details)
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22
Q

How does neurogenic shock cause hypotension?

A

Cervical or upper thoracic spinal cord injury can produce hypotension due to loss of sympathetic tone. This compounds the effects of hypovolaemia.

23
Q

Do you get tachycardia in neurogenic shock?

A

No. Neurogenic shock is hypotension without tachycardia. A narrowed pulse pressure is not seen in neurogenic shock.

24
Q
A
25
Q

Describe the difference between rapid responders, Transient responders and Non responders?

A
26
Q

Describe the different classes of haemorrhage.

A
27
Q

What is the definition of haemorrhage?

A

An acute loss of circulating blood volume.

28
Q

What percentage of body weight is there of blood in a normal adult and in a normal child?

A

Adult = 7% (~5L in 70kg male)

Child 8-9% (80-90ml/kg)

29
Q

When should hemorrhage control and balanced fluid resuscitation be initiated?

A

When early signs and symptoms of blood loss are suspected NOT when blood pressure is falling or absent.

30
Q

Which patients will need pRBCs and blood products as an early part of resuscitation?

A

Class III and Class IV haemorrhage.

31
Q

What type of pRBC should females of childbearing age get and why? (p. 74)

A

Rh-negative cells in order to avoid sensitization and future complications.

32
Q

If someone has an exsanguinating haemorrhage, what type of blood should they get?

A

Type O.

33
Q

What temperature should we heat fluids to for hypotehermic patients in shock?

A

39C

This can be warmed in a microwave.

34
Q

Can we warm blood products?

A

NO! They can be heated by passage through IV fluid warmers.

35
Q

What is the definition of a massive transfusion?

A

The need for >10 units of pRBC in the first 24 hours of admission.

36
Q

What does “balanced, hemostatic resucitation” (a.k.a. Damage control resuscitation) mean?

A

Th early administration of pRBC, plasma and platelts in order to minimize crystalloid administration.

37
Q

Coagulopathy is present in up to (BLANK) severely injured patients on admission.

A

30%

38
Q

What coagulation parameters should be used when deciding on the use of platelets, FFP, & cryoprecipitate?

A

1/ PT (prothrombin time)

2/ PPT (partrial prothrombin time)

3/ Fibrinogen.

4/ Platelet count

39
Q

Do most patients that have blood transfusions require calcium supplementation?

A

NO

40
Q

In order to correct inadequate organ perfusion, what do we need to reverse?

A

We need to reverse shock.

(increase organ blood flow and tissue oxygenation.)

Remember the definition of shock is the opposite of the above.

41
Q

Who’s law do we use increase blood pressure?

A

Ohm’s law:

Blood pressure (V) = (I) Cardiac output x (R) Systemic vascular resistance.

REMEMBER: We care about in increase in cardiac output (I) NOT R.

We do this by increasing stroke volume not heart rate. (stroke volume=preload+contractility+afterload)

Vasopressors can increase R by vasoconstriction but with no improvement to end organ perfusion.

42
Q

How much may blood volume increase by in athletes?

A

15 to 20%

43
Q

How much can cardiac output increase by in athletes?

A

6 times.

44
Q

How much can stroke volume increase in athletes?

A

50%

45
Q

Who is more likely to suffer from hypothermia as a result of vasodilation?

A

A trauma victim under the influence of alcohol or exposed to the cold.

46
Q

In mild to moderate hypothermia, how do you rewarm a patient?

A

Heat lamps, external warming devices, thermal caps, warmed IV fluids and warmed blood.

47
Q

In severe hypothermia, how is a patient rewarmed?

A

Core rewarming. (Irrigation of the peritoneal or thoracic cavity with crystalloid solutions warmed to 39C

OR

Extracorporeal bypass.

48
Q

Why is CVP useful?

A

The CVP allows us to evaluate appropriate volume replacement.

49
Q

What can cause pronounced increases in CVP?

A
  1. Overtransfusion
  2. Cardiac dysfunction
  3. Cardiac tamponade
  4. Increased intrathoracic pressure from tension pneumothorax.
  5. Catheter malposition.
50
Q

What does a declining CVP suggest?

A

Fluid loss.

51
Q

In what scenarios can you have an initial high CVP but actually have significant volume loss?

A
  1. COPD
  2. Generalised vasoconstriction
  3. Rapid fluid replacement
52
Q

In what way can we misinterpret/over rely on CVP (central venous pressure)?

A

The precise measure of cardiac function is the relationship between ventricular end diastolic volume and stroke volume

NOT

Right atrial pressure (CVP) and cardiac output are insensitive measures.

CVP is just a guide.

53
Q

What are some complications of inserting a CVP line?

A
  1. Infections
  2. Vascular injury
  3. Nerve injury
  4. Embolization
  5. Thrombosis
  6. Pneumothorax

ATLS (7 decks)

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