Endogenous Catecholamines

Question 1

How do the mechanisms of epinephrine and norepinephrine differ?

Answer 1

EPI: Agonist for alpha/beta receptors
NE: Does not act on B2 receptors much

Question 2

How does epinephrine act on blood pressure? How does NE act on blood pressure?

Answer 2

EPI: Decrease systolic, increase diastolic (MAP = no change)
NE: Increases BOTH systolic/diastolic (compensatory baroreflex response initiated)

Question 3

How does epinephrine act on the heart? How does NE act on the heart?

Answer 3

EPI: Increases (CO, HR, Contractility)
NE: Decrease CO/HR, increases contractility

Question 4

Although both EPI and NE cause vascular beds to constrict, they differ in what two ways?

Answer 4

EPI: dilates skeletal muscle blood vessels and has NET decreased in peripheral vascular resistance (PVR)
NE: increase PVR

Question 5

How does EPI affect metabolism? respiration?

Answer 5

1) Hyperglycemia (increased gluconeogenesis and glycogenolysis)
2) Inhibit insulin secretion
3) Lipolysis

Respiration: Dilation

Question 6

Minor vs. Serious Effects of EPI?

Answer 6

Minor: Headache, palps, tremors, restless
Serious: *Cerebral Hemorrhage, Cardiac Arrhythmia, Angina

Question 7

Adverse side effects of NE? (3)

Answer 7

1) Necrosis at injection site (tx: phenolamine)
2) Hypertension
3) Peripheral Vascular Insufficiency

Question 8

What is the single contraindication for EPI? Why?

Answer 8

Patients on non-selective beta-blockers
(unopposed activation of vascular a1 receptors could lead to vasoconstriction then hypertension then cerebral hemorrhage

Question 9

Clinical uses of NE? (4)

Answer 9

1) Elevate BP
2) Septic Shock
3) Spinal Anesthesia
4) Cardiogenic Shock (hemodynamic instability)

Question 10

Clinical uses of EPI? (5)

Answer 10

1) Anaphylaxis
2) Bradyarrhythmia
3) Asystole/pulseless CA
4) Mydriatic agent
5) Co-admin with local anesthesia

Question 11

___ is a metabolic precursor of NE and EPI

Answer 11

Dopamine

Question 12

What receptor is activated at low dopamine concentrations, intermediate concentrations, and high?

Answer 12

Low: D1
Int: B1
High: A1

Question 13

At low dopamine concentrations, dopamine is an ____ of D1. At high dopamine concentrations, dopamine is a ___/___ agonist

Answer 13

agonist; B1/A1

Question 14

What occurs at low dopamine concentrations?

Answer 14

1) Increased GFR and renal blood flow
2) Vasodil of renal, mesentery, coronary vasculature

Question 15

What occurs to dopamine at intermediate concentrations?

Answer 15

1) Increase HR/contractility
2) Increase systolic pressure
*Minimal effect on disastolic

Question 16

What occurs to dopamine at high concentrations?

Answer 16

1) Vasconstriction
2) Increase in peripheral vascular resistance

Question 17

Adverse Dopamine Effects - Minor vs. Serious

Answer 17

Minor: Anxiety, headache, palps
Serious: Angina pectoralis, arrhythmias

Question 18

Clinical uses of dopamine?

Answer 18

1) Severe decomp heart failure
2) Sepsis/Septic shock (alt to NE)
3) Cardiogenic shock

Question 19

If given the choice between NE or Dopamine to treat cardiogenic shock, which would you pick and why?

Answer 19

NE - Dopamine is more likely to cause arrhythmias

Question 20

Under what condition would you use dopamine to treat cardiogenic shock?

Answer 20

If the cardiogenic shock was associated with aortic regurgitation or bradycardia