Shock

Question 1

Define shock

Answer 1

When the metabolic demand exceeds the body’s ability to deliver oxygen and nutrients

Question 2

What are the clinical manifestations of shock?

Answer 2

Inadequate perfusion and compensation

Inadequate perfusion:

• BRAIN –> altered LOC
• kidneys –> decreased U/O

Compensatory mechanisms

• Tachycardia (out of proportion to fever, distress etc.)
• Peripheral vasoconstriction –> pale, mottling, cool extremities, delayed cap refill
• Increased RR
• BP changes
  
  • -> higher diastolic pressure = narrow pulse pressure
  • -> systolic falls - LATE sign

Question 3

2 stages of shock

Answer 3

Compensated

Uncompensated

Question 4

What is the exception to normal compensatory mechanisms?

Answer 4

Septic - warm shock
Warm distributive shock

Flushed skin, bounding pulses, hyperdynamic precordium, flash CR

Due to a cascade of inflammatory mediators

Neurogenic shock –> can cause bradycardia in the face of significant hypotension

Question 5

Markers of uncompensated shock

Answer 5

Acidosis
High lactate
Altered LOC
Oliguria/Anuric
Ileus - constipation, decreased GI motility, distention, edema of bowel wall
BP falls
Multiorgan failure
ARDS

Question 6

Mechanisms of Shock

Answer 6

Hypovolemic Shock
Distributive/Vasodilatory Shock
Cardiogenic Shock
Septic Shock

Hypovolemic Shock
- hemorrhage, V/D

Distributive/Vasodilatory Shock
- Neurogenic, Ingestion, Anaphylaxis, Septic shock

Cardiogenic Shock
- Viral myocarditis, hypertrophic cardiomyopathy, myocardial depressant drugs

Septic Shock
- can have features of both distributive and cardiogenic

Question 7

Most common potent initiator of shock

Answer 7

Endotoxin - lipopolysaccharide coat of a Gram neg bacteria
Viral proteins
Teichoic acid

Question 8

Which bacteria causes more severe septic shock?

Answer 8

Gram NEG - 20-50% mortality

Gram pos - 10-20%

Question 9

Describe the cascade of septic shock?

Answer 9

Endotoxin (LPS) is bound to a plasma protein (LBP) –> complex binds to CD14 receptor on macrophages
This stimulates the formation of tumor necrosis factor (TNF) and interleukin which begin the inflammatory cascade

Question 10

What needs to happen in the golden hour of septic shock?

Answer 10

Aggressive fluid resuscitation
Ionotropic therapy
Antibiotics

Question 11

Most common mechanism of shock in kids?

Answer 11

Hypovolemia

- due to diarrheal illness

Question 12

How does trauma cause shock?

Answer 12

Post-traumatic hemorrhage
- kids at high risk of blunt abdo trauma with weak abdo wall
Tension pneumonthorax
- from blunt chest trauma - reduces venous return to cause shock
Cervical spine injury
- can cause neurogenic shock

Question 13

Does isolated head trauma cause shock?

Answer 13

No

Not unless there is a large scale scalp laceration

Question 14

Classes of hemorrhage

Answer 14

Class I - IV

Class I - 15% loss of blood volume
- minimal tachycardia, Axmtc, no treatment

Class II - 15-30% loss

• tachycardia, tachypnic, narrowed pulse pressure
• U/O maintained, may have slight altered LOC - fright/anxiety

Class III - 30-40% loss
- compensated signs above +/- uncompensated signs (drop in BP, decreased U/O, confusion)

Class IV - > 40% loss

• Fatal if untreated
• may be irreversible shock
• markedly decreased BP, severe uncompensated shock - extreme tachycardia, complete peripheral vasoconstriction, anuric, altered LOC/unconscious

Question 15

How can you differentiate between neurogenic and hemorrhagic shock?

Answer 15

Hemorrhagic - rapid and possibly irregular pulse

Neurogenic - slow and regular pulse

Question 16

Priorities in treatment of shock

Answer 16

Supportive therapy - supplemental oxygen, assisted ventilation
Fluids - try crystalloid in any shock , blood for hemorrhagic (crystalloids can cause metabolic acidosis, hypothermia etc.), not too much for cardiogenic
Pressors - after fluids - can be dangerous in hypovolemia without giving fluids first

Question 17

What are the 4 common pressors and their actions?

Answer 17

Epinephrine
Norepinephrine
Dopamine
Dobutamine

Epinephrine (Alpha-1, Alpha-2, Beta-1, Beta-2)

• Inotrope (contractility) - Beta-1 / Alpha-1
• Chronotrope (increases HR) - Beta-1
• Vasodilation (low dose) - Beta-2
• Vasoconstriction (high dose)- Alpha-1

Norepinephrine (Alpha 1, Beta 1)

• Inotrope - Beta-1
• Vasoconstriction - Alpha-1

Dopamine (Alpha-1, Alpha-2, Beta-1, Beta-2, DA)

• Inotrope - Beta-1
• Chronotrop - Beta-1
• Vasodilation (low dose) - Beta-2
• Vasoconstriction (high dose) - Alpha-1

Dobutamine (Beta-1, Beta-2)

• Inotrope - Beta-1
• Vasodilation - Beta-2

Question 18

How should hypovolemic shock be treated?

Answer 18

Replace the volume
NS - 20 cc/kg boluses for fluid loss

Hemorrhagic - 10-15 cc/kg of RBCs - Type O or correct Type after type and screen, massive transfusion (platelets, cryo, FFP etc.)

Question 19

How should cardiogenic shock be treated?

Answer 19

Afterload reduction with inotropic support
Low dose epi infusion (0.05 -0.3 mcg/kg/min)
Inodilators (milrinone or amrinone)

Question 20

How should neurogenic shock be treated?

Answer 20

Can try fluids initially
But ultimately need pressors - Norepi or Phenyephrine
- powerful alpha agonists
If cardiac output/rate are inadequate (not usually) - try dopamine
If profound bradycardia - use atropine

Question 21

How should septic shock be treated?

Answer 21

Fluid resuscitation
Pressors if needed - ie refractory to fluid resuscitation
- Epi –> NE
Antibiotics

Question 22

What is the mechanism and use of phenylephrine?

Answer 22

Peripheral vasoconstriction
Causes vasoconstriction without excessive tachycardia
Useful for those whose shock state is caused by vasodilation primarily
Neurogenic shock

Question 23

What is early, goal-directed therapy?

Answer 23

Aggressive approach to target indicators of perfusion and vital organ function in the first 6 hours:
- BP: minimal systolic BP:
< 1 mo = 60
1 mo - 10 yr = 70 + 2(age in yrs)
> 10 years = 90
- Strong, distal pulses = to central pulses
- Skin perfusion (warm , CR <2 secs)
- Normal mental status
- U/O > or = 1 ml/kg/hr, once effective circulating volume restored

Question 24

How should anphylactic shock be treated?

Answer 24

IM Epineprhine

Question 25

What is Toxic shock syndrome (TSS)?

Answer 25

Fever
Erythroderma
Hypotension
Involvement of several other organ systems

Caused by Staph Aureus strains that produce an exotoxin - TSST-1, enterotoxin B and C
Secondary to prolonged tampon use or open skin wounds/abrasions

Exotoxins are profound vasodilators –> cause distributive shock
leaky tissues - loss of intravascular volume
myocardial depression

Can also be due to GAS - Streptococcal pyogenes -associated with scarlet fever