Shock

Question 1

Define shock

Answer 1

• “a momentary pause in the act of death”
• a syndrome: if we do nothing, the patient will die
• results from an reduced effective tissue perfusion; imbalance of cellular substrate supply & demand; inadequate cellular energy production

Question 2

4 classifications of shock

Answer 2

1. Hypovolemic (low circulating volume)
2. Cardiogenic (pump failure)
3. Obstructive (blocked venous return to heart)
4. Maldistributive (blood pooling in peripheral vasculature)

Question 3

3 subtypes of hypovolemic shock

Answer 3

hemorrhage, GI losses (d+/v+), severe dehydration

Question 4

2 subtypes of cardiogenic shock

Answer 4

structural failure (HCM, MVD); electrical failure (vtach, AV block)

Question 5

2 substypes of obstructive shock

Answer 5

Gastric dilatation volvulus (LDA in cattle); pericardial effusion

Question 6

2 subtypes of maldistributive shock

Answer 6

septic shock; anaphylactic shock

Question 7

Compensatory mechanisms of shock

4 ways the body compensates for shock

Answer 7

1. Maintains circulatory pressure (maintain volume, increase tone)
2. Optimizes cardiac performance
3. Redistributes perfusion to vital organs
4. Optimizes offloading of O2 at tissues

Question 8

Compensatory mechanisms of shock

How does body maintain circulatory pressure via maintaining volume?

Answer 8

• pulls blood from other spaces (interstitium and intracellular water) into IV space
• reduces urinary losses (reduce GFR; increase aldosterone; increase vasopressin)

Question 9

Compensatory mechanisms of shock

How does body maintain circulatory pressure via reducing venous capacitance?

Answer 9

• increase circulating epinephrine
• increase angiotensin
• increase vasopressin

Question 10

Compensatory mechanisms of shock

Boyle’s Law

Answer 10

P1V1 = P2V2 in a closed system

Question 11

Compensatory mechanisms of shock

How does body redistribute in compensation

Answer 11

via peripheral vasoconstriction (dominant autoregulation of heart & brain)

pale mm: two differentials = shock v. anemia

Question 12

Signs of shock

Answer 12

weakness; poor mentation; organ dysfunction; increased lactate

Lactate:
Normal conditions: Glucose => pyruvate => acetyl-CoA (via pyruvate dehydrogenase) => citric acid cycle => 32 ATP

Anaerobic conditions: pyruvate gets converted into lactate (via lactate dehydrogenase, reducing NAD+ into NADH, H+), and NO citric acid cycle occurs! Aka no ATP –> lactate +++ and tissues not getting the ATP they need!

Question 13

Exceptions of signs of shock

Answer 13

• cardiogenic shock caused by bradyarrhythmia
• shock caused by maldistribution of blood –> may see hyperthermia, bright, pink/red mm w/ overly quick CRT due to inappropriate vasodilation