Lecture 8: Shock

Question 1

How many liters of blood is in the body on average?

Answer 1

5L

Question 2

What is the most common cause of death?

Answer 2

insufficient early resuscitation

Question 3

The lack of perfusion to cells of the body can produce what?

Answer 3

anaerobic metabolism

Question 4

Give an overview of shock.

Answer 4

Condition resulting from lack of adequate perfusion at cellular level
most commonly occurs due to circulatory failure
during compensatory phase, body attempts to maintain perfusion using its available compensation mechanism
during decompensation phase, body can’t keep up with demands
systems are sacrificed to maintain O2 supply to brain
initially reversible if treatment provided rapidly to prevent progression to irreversible organ dysfunction

Question 5

What is the aerobic metabolism?

Answer 5

O2+Glucose ==> energy+ CO2+O2
Principle combustion process is the Krebs cycle (32ATP)

Question 6

What is the anaerobic metabolism?

Answer 6

energy+ lactic acid + pyruvic acid
short duration/ less efficient

Question 7

What is Fick’s Principle?

Answer 7

description of components necessary for adequate oxygenation of body cells (perfusion)
1. on-loading of O2 to RBC in the lung
2. Delivery of RBC to tissue cells
3. Off-loading of O2 from RBC to tissue cells

Question 8

What is the importance of adequate oxygenation?

Answer 8

oxygen required for the majority of cellular energy production derived from krebs cycle and electron transport chain
metabolism with O2 = aerobic metabolism
metabolism without O2 = anaerobic metabolism

Question 9

What are factors that can affect O2 delivery to tissues?

Answer 9

Cardiac output
available hemoglobin
O2 saturation (SpO2)

Question 10

What is the metabolic rate of O2 (MRO2)?

Answer 10

Sum total of O2 needed to drive various tissue metabolic processes
metabolic O2 delivery

Question 11

What is the arterial O2 delivery (DO2)?

Answer 11

Sum total of available oxygen delivery to the tissues
body approx 20-30% effective in extracting circulating O2
Comprised of 2 variables: cardiac output (CO) and arterial oxygen content (CaO2)

Question 12

What are things that can adversely effect oxygen delivery?

Answer 12

Hypoxia
inadequate circulation
inadequate transport medium
cellular toxins

Question 13

What leads to shock?

Answer 13

if the metabolic oxygen demands > metabolic oxygen supply = shock

Question 14

What are the different organs tolerance ot ischemia?

Answer 14

Heart, brain, lungs 4-6minutes
Kidney, liver, GI tract 45-90min
Muscle, bone, skin 4-6hours

Question 15

What is the progression of shock?

Answer 15

Compensatory defenses work well to a point
when defense mechanism can no longer overcome volume reduction BP decreases, going into decompensation

a patient with signs of compensation is already in shock not going into shock
Next stage after decompensated shock is death (irreversible shock)

Question 16

What are the different types of shock?

Answer 16

Hemorrhagic
respiratory
neurogenic
psychogenic
cardiogenic
septic
anaphylactic
metabolic

Question 17

What are the 4 ways that shock can occur in associated with failure of one or more components of the cardio-vascular system?

Answer 17

Hypovolemic (absolute hypovolemia)
Distributive shock (relative hypovolemia)
obstructive shock
cardiogenic shock

Question 18

What causes hypovolemic shock?

Answer 18

external hemorrhage controlled or uncontrolled
internal hemorrhage
other cause of intravascular volume loss (diarrhea, vomiting, etc…)
Blood loss most common cause of shock in trauma patients

Question 19

What are the characteristics of hypovolemic shock?

Answer 19

characterized by reduced intravascular volume
may occur with acute blood volume loss due to dehydration (loss of plasma)
Hemorrhage (loss plasma+ RBC), upsets the relationship of fluid volume to size of container balance

Question 20

What is the difference between absolute hypovolemia and relative hypovolemia?

Answer 20

absolute= hemorrhagic cause, loss of blood
relative= non-hemorrhagic cause, blood volume intact but all vessels dilate so not enough blood to sustain them

Question 21

What happens to the body with blood loss?

Answer 21

heart is stimulated, increased CO through release of epinephrine from adrenal glands
sympathetic system releases norepinephrine to decrease blood vessel size
this closes peripheral capillaries leading to anaerobic metabolism at cellular level

Question 22

What can cause distributive shock (relative hypovolemia)?

Answer 22

neurogenic shock
medical causes (anaphylaxis, sepsis, overdose)

Question 23

What are the characteristics of distributive shock?

Answer 23

vascular container enlarges without proportional increase in fluid volume
relatively less fluid will be available for size of container
the amount of fluid available to the heart as preload decreases and cardiac output falls
resistance to flow is decreased because of increased vessel size leading to decreased diastolic BP, net effect is decreased systolic and diastolic BP

Question 24

What are the different kinds of distributive shock?

Answer 24

neurogenic shock
septic shock
systemic inflammatory response syndrome (SIRS)
anaphylactic shock
drug and toxin-induced shock
endocrine shock
psychogenic shock

Question 25

What is neurogenic shock?

Answer 25

can occur when a cervical spine injury damages the spinal cord above where the nerves of the sympathetic nervous system exit
because of loss of sympathetic control vessels dilate below level of injury

Question 26

What is spinal shock?

Answer 26

injury to the spinal cord that results in temporary loss of sensory and motor function
both neurogenic and spinal shock can happen at the same time

Question 27

What is septic shock?

Answer 27

exhibits vascular dilation
cytokines, which are locally active hormones produced by WBC responding to infection cause damage to the wall of blood vessels, causing peripheral vasodilation and a leakage of fluid from the capillaries into the interstitial space

Question 28

What is psychogenic shock?

Answer 28

Mediated through parasympathetic
Nervous system vagal nerve stimulation produces bradycardia
can also lead to transient peripheral vasodilation and hypotension
if severe enough: decrease cardiac output and then vasovagal syncope

Question 29

What is a mechanical obstructive shock?

Answer 29

valvular disruption from a sudden forceful abdominal blow

Question 30

What is pericardial tamponade?

Answer 30

fluid in pericardial sac will prevent heart from refilling completely during diastolic phase

Question 31

What is a tension pneumothorax?

Answer 31

shifting of mediastinum away from injury compresses/kinks superior and inferior vena cava
decreased venous return to the heart
preload pumping efficiency decreases and shock is rapid

Question 32

What is cardiogenic shock?

Answer 32

intracardiac cause of cardiac pump failure
intrinsic:
- problem within the heart
-cardiomyopathic (MI
- arrhythmic (efficiency of contractions)
- Contusion that may lead to cardiac muscle dysfunction

Question 33

What are the stages of shock?

Answer 33

Pre-shock (compensated): body’s compensatory mechanisms are able to maintain some degree of tissue perfusion

Shock (decompensated): body’s compensatory mechanisms fail to maintain tissue perfusion (blood pressure falls)

End-organ dysfunction (irreversible): tissue and cellular damage is so massive that the organism dies even if perfusion is restored

Question 34

What are the S/S you would expect to see when compensatory mechanisms fully engage?

Answer 34

Tachycardia
tachypnea
pupillary dilation
decreased capillary refill
pale cool skin

Question 35

What S/S would you expect to see when compensatory mechanism fail?

Answer 35

Hypotension
Falling SpO2
Bradycardia
Loss of consciousness
Dysrhythmias
Death

Question 36

What are complications of Shock?

Answer 36

Acute Respiratory distress syndrome (lung lining damage)
Acute renal failure (ischemic reaction)
Hematologic failure (coagulopathy)
Hepatic failure (liver ischemic reaction)
Multiple organ failure
Failure of 1 major body system
This leads to more shock
if all fail 100% mortality

Question 37

What are the first symptoms of shock?

Answer 37

Increased heart rate
Increased respiratory rate

Question 38

What should you do in pre-hospital management of shock?

Answer 38

deliver adequate O2 to produce enough energy to prevent or reverse anaerobic metabolism, thereby avoiding cellular death and ultimately patient death

Question 39

How should trauma patients in shock be transported?

Answer 39

supine and neutral

Question 40

Is elevation of feet recommended?

Answer 40

It is contraindicated for many reasons for example it may aggravate impaired ventilatory function by placing weight of abdominal organs on the diaphragm

Question 41

Summarize Shock Treatment.

Answer 41

treat the underlying cause
establish and maintain airway
ensure adequate breathing
ensure adequate oxygenation
ensure adequate circulation and severe bleeding is stopped
reassure patient and provide warmth
minimize the pain
monitor vital signs
nothing by mouth
arrange rapid transport