12.6 A

Question 1

What are the three types of shock?

Answer 1

hypovolemic, cardiogenic, and distributive

Question 2

What are some conditions that cause hypovolemic shock?

Answer 2

• hemorrhage
• dehydration
• burns

Question 3

What are some conditions that cause distributive shock?

Answer 3

• sepsis

- anaphylaxis

Question 4

What are some conditions that cause cardiogenic shock?

Answer 4

• cardiac tamponade
• heart failure
• myocardial infarction

Question 5

Hypovolemic shock is a problem with _____ while distributive shock is a problem with _____ and cardiogenic shock is an issue with _____.

Answer 5

• blood volume
• arterioles
• pump

Question 6

What is the inciting event for distributive shock?

Answer 6

generalized systemic vasodilation

Question 7

Central venous pressure is high in what kind of shock?

Answer 7

cardiogenic

Question 8

Central venous pressure is low in what kind of shock?

Answer 8

hypovolemic

Question 9

Which type of shock is characterized by warm skin?

Answer 9

distributive

Question 10

How can you distinguish hypovolemic shock due to hemorrhage from that due to dehydration?

Answer 10

in hemorrhagic shock, plasma osmolality will be nearly normal, it won’t be in dehydration shock

Question 11

Why is someone’s pulse typically weak or thready when experiencing hypovolemic shock?

Answer 11

because stroke volume is reduced and stroke volume is directly proportional to pulse pressure

Question 12

Arterial pressure doesn’t significantly drop until CO drops by how much?

Answer 12

roughly 20%

Question 13

Describe the changes seen on a Starling curve beginning at the onset of hypovolemic shock.

Answer 13

• first EDV will decrease along the curve

- then baroreflex will kick in and increase inotropic state, shifting the curve upward a little

Question 14

Why does sympathetic firing not increase EDV despite triggering venoconstriction and thus increases venous return?

Answer 14

because it also increases heart rate, decreasing filling time

Question 15

Describe the steps that put one in a state of distributive shock.

Answer 15

• systemic release of inflammatory mediators
• increased iNOS expression by endothelial cells
• excessive NO production
• generalized arteriolar vasodilation

Question 16

What happens to arterial diastolic pressure in those with distributive shock?

Answer 16

it decreases because vasodilation allows for increased runoff into the venous system

Question 17

Why do vasoconstrictors not effectively treat distributive shock?

Answer 17

because there is so much NO that the vascular smooth muscle does not contract normally

Question 18

How can leukocyte adherence occur during septic shock with so much NO in the circulation?

Answer 18

because NO is a single anti-adherence molecule and the overall balance is still towards an inflammatory response and leukocyte adherence

Question 19

Neurogenic shock is what type of shock?

Answer 19

distributive

Question 20

What are some possible causes of neurogenic shock?

Answer 20

• deep anesthesia
• pain reflex from deep trauma
• vasovagal syncope

Question 21

How does neurogenic shock occur?

Answer 21

one of the triggers like deep anesthesia results in decreased sympathetic activity and thus arteries are allowed to vasodilate

Question 22

CO is decreased in what types of shock?

Answer 22

• hypovolemic

- cardiogenic

Question 23

How does cardiac tamponade result in cardiogenic shock?

Answer 23

the fluid accumulation in the pericardial sac impairs heart filling, decreasing stroke volume, decreasing cardiac output, decreasing MAP

Question 24

What happens to the passive filling curve (ventricular pressure v. ventricular volume) in someone experiencing cardiac tamponade-related cardiogenic shock?

Answer 24

the curve is shifted upward given that less volume is needed to increase the pressure within the ventricle since it is having a hard time relaxing

Question 25

What is a paradoxical pulse?

Answer 25

a greater than normal decline in systolic arterial pressure during inspiration

Question 26

Why does someone experiencing cardiac tamponade experience a paradoxical pulse?

Answer 26

- upon inspiration, the right ventricle fills more than it otherwise would - this causes the interventricular septum to bulge into the left ventricle - this limits filling even more than would be expected, reducing stroke volume and systolic arterial pressure

Question 27

What is the major change seen on an EKG in someone with cardiac tamponade?

Answer 27

the magnitude of the electrical events would be reduced

Question 28

Beta-1 receptors have what cardiovascular effects?

Answer 28

increase heart rate and inotropic state

Question 29

Alpha-1 receptors have what cardiovascular effects?

Answer 29

they vasoconstrict systemic arteries (except in skeletal muscle)

Question 30

Beta-2 receptors have what cardiovascular effects?

Answer 30

they vasodilate arteries in skeletal muscle and in the lungs

Question 31

If reduced CO is the cause of shock, the baroreflex will work to increase what?

Answer 31

TPR

Question 32

If reduced TPR is the cause of shock, the baroreflex will mainly work by trying to increase what?

Answer 32

CO

Question 33

What is the most significant secondary complication of cardiogenic shock?

Answer 33

pulmonary edema

Question 34

What is the most significant secondary complication of hypovolemic shock?

Answer 34

the increase in vascular permeability

Question 35

What is the most significant secondary complication of distributive shock?

Answer 35

the increase in vascular permeability

Question 36

Why is distributive shock life threatening?

Answer 36

- because although some organs are now getting higher than normal blood flow, others are getting less and there is no distributive regulation - one of these is the heart which is also working harder during shock to maintain CO

Question 37

How does microcirculation change to compensate for shock?

Answer 37

with hypotension there is less filtration and more resorption than normal so there is a net increase in plasma volume

Question 38

What happens to hematocrit during shock?

Answer 38

with increased resorption and decreased filtration in the capillaries, RBC concentration falls

Question 39

How is hypovolemic shock best treated?

Answer 39

with volume resuscitation

Question 40

How is cardiogenic shock best treated?

Answer 40

with treatment of the underlying condition (e.g. removal of blood from the pericardial sac)

Question 41

How is distributive shock best treated?

Answer 41

with alpha-1 agonists and antihistamines for anaphylaxis or with antibiotics and fluid for sepsis

Question 42

Why can't we give L-NAME to treat distributive shock?

Answer 42

because it will block iNOS and NO synthase, leading to massive leukocyte adhesion and microvascular injury

Question 43

What changes occur to induce the transition to irreversible shock?

Answer 43

- impaired organ blood flow leads to cell injury and therefore the release of toxic factors which impair heart contractility - local accumulation of vasodilator metabolites increase lactic acid production, impairing cell function - the vasodilator metabolites overcome the sympathetic NS response, leading to widespread vasodilation

Question 44

What is myocardial depressant factor?

Answer 44

a toxic factor released by injured cells during shock which reduce cardiac contractility

Question 45

Why is a blood transfusion often harmful in the case of prolonged hemorrhagic shock?

Answer 45

because it is like a reperfusion injury and factors are produced that increase vascular permeability