Shock and Hemodynamics

Question 1

Pt factors that impair recognition of shock

Answer 1

Elderly
Athletes
Pregnant - extra volume
Medications (beta blocker, Ca channel blocker)
Pacemaker
Sepsis

Question 2

What do you look for in clinical exam to recognize shock

Answer 2

• signs/sxs of hypoperfusion
• signs/sxs of catecholamine response
• baroreceptor reflex activation
  consider underlying
• Consider underlying scenario
• Be very suspicious

Ex: decreased consciousness/anxiety tachypnea, shallow respirations, cool/clammy skin**, prolonged capillary refill **, decreased urine output, JVD, in cardiogenic shock,
*** Or warm erythematous skin with nl cap refill in septic shock due to inflammatory mediators causing vasodilation

Question 3

Is it better to use MAP or systolic/diastolic to assess BP

Answer 3

MAP in most cases

Question 4

What is MAP

Answer 4

average pressure at arterial level

MAP= Systolic + (2/3)(Diastolic)

Question 5

Why is MAP better than systolic/diastolic for tissue perfusion…

Answer 5

2/3 cardiac cycle are diastole

• remains constant as pressure wave propagates distally in veseles
• less prone to waveform dignal distortions from monitoring systems (over/underdamping)

Question 6

Drawbacks to using MAP to assess tissue perfusion

Answer 6

less accurate as more time in dystole (tachycardia)

- variations in SVR may have acceptable MAP but CO2 too low

Question 7

What does lower pulse pressure indicate

Answer 7

suggests significant blood loss

• result of increasing diastolic pressure from compensatory

Question 8

If you can feel dorsalis pedis pulse, what is the rough BP

Answer 8

at least 80

Question 9

If you can feel femoral pulse, what is the rough BP

Answer 9

70

Question 10

If you can feel radial pulse, what is the rough BP

Answer 10

80

Question 11

If you can feel carotid pulse, what is the rough BP

Answer 11

60

Question 12

ATLS Classifications of hemorrhagic shock

Answer 12

Class I, II, III IV

Question 13

how much blood do you lose before hypotension occurs

Answer 13

Class III–lose about 40% of blood

• One of last sxs of shock
• BP responds to volume loss

Question 14

Consequences of hypoperfusion

Answer 14

tissue hypoxia -> anaerobic metabolism -> cell injury/death -> inflammatory cascade -> organ dysfunction

Question 15

What causes cardiogenic shock

Answer 15

you get a lower cardiac output due to a lower heart rate or contractility (heart can’t squeeze as well)

• Due to changes in HR and SV
  (bradycardia, tachyarrhythmias prevent filling–>decreased stroke volume, heart failure)

Question 16

What is distributive/Septic shock

Answer 16

decreased cardiac output due to combo of impaired preload and contractility (thus making stroke volume decrease)

Preload problems: lose vasomotor tone, capillary leak

Contractility issues: inflammatory mediators cause your heart not to work as well (myocardial depression)

Sepsis: get massive swelling/edema

Question 17

What is shock

Answer 17

inadequate tissue perfusion/cellular oxygenation

Question 18

What are the 3 main types of shock

Answer 18

Hypovolemic
Cardiogenic
Distributive/septic

Question 19

What is hypovolemic shock

Answer 19

Not enough preload, so the heart can’t pump as much out –> lower stroke volume

Subtypes:

• Hemorrhagic (trauma, GI bleed, maternal/fetal hemorrhage)
• Nonhemorrhagic (dehydration, gastroenteritis, infection)

Question 20

Compensatory physiology ni shock

Answer 20

lower preload –> message to shut down vagus nerve –> Tachycardia

catecholamines released for heart to pump harder/faster. We get vasoconstriction/narrowed pulse pressure (- Pale, purple– trying to redirect bloodflow to heart and brain)

** NOTE pulse pressure is increased in septic shock since you get vasodilation and decreased diastolic pressure)

RAAS– body tells kidneys to conserve water

Question 21

Tests/labs to assess for shock

Answer 21

Test: Serum lactic acid
Labs: ABG (pH/bicarb), lactate , CBC
- also procalcitonin–tells you if you should be concerned about microbial infection; virtual absence in health

Question 22

Most common type of shock in surgery

Answer 22

hypovolemic