Vasoactive Pharmacology

Question 0

Volatile anesthetics also depress ______ reflex control of arterial pressure to varying degrees.

Answer 0

• Baroreceptor reflex

* Isoflurane has the least effect

Question 1

In a normal heart, volatile anesthetics produce dose related: ?

Answer 1

1. Depression in myocardial contractility
2. Left ventricular diastolic function decreases
3. Decrease left ventricular afterload
4. Left ventricular -arterial coupling
5. Depression of the SA node (Direct negative chronotrope)
   * Desflurane exception - tachycardia with rapid increase in dose

Question 2

Nitrous oxide causes direct negative inotropic effects, but also produces…?

Answer 2

• modest increases in pulmonary and systemic arterial pressure via a sympathomimetic effect

Question 3

All drugs used in anesthesia cause hypotension except…?

Answer 3

• Ketamine and Etomidate

Question 4

What is our goal during anesthesia?

Answer 4

• Goal is to maintain organ and tissue perfusion and avoid hypertensive crisis.
• Brain, Heart, Lungs, and Kidneys are the organs we are most concerned about.

Question 5

What is autoregulation?

Answer 5

• the intrinsic ability of a circulation to maintain a constant blood flow despite changes in perfusion pressure

Question 6

In anesthesia, where do we try to maintain patients hemodynamically?

Answer 6

• within 20% of baseline

Question 7

What are the intrinsic factors of blood pressure control?

Answer 7

1. Frank-Starling Mechanism (Stroke Volume)

2. SA and AV node (HR and A-V synchronization)

Question 8

What are the nervous system factors for blood pressure control?

Answer 8

1. Sympathetic

2. Parasympathetic

Question 9

What are the reflexes of blood pressure control?

Answer 9

1. Baroreceptor Chemoreceptor

2. Atrial receptor (Bainbridge)

Question 10

What are the humoral factors that affect blood pressure control?

Answer 10

• Renin-Angiotensin-Aldosterone System

Question 11

What is vasopressin (ADH)?

Answer 11

• Potent vasoconstrictor

Question 12

Where is vasopressin produced?

Answer 12

• Posterior pituitary gland, the heart, and adrenal gland

Question 13

What is the infusion rate of vasopressin (ADH)?

Answer 13

• 0.01 to 0.04

Question 14

When is vasopressin used?

Answer 14

• Considered in refractory hypotension (shock, hemorrhage) and patient who are on ACE inhibitors

Question 15

When alpha 2 receptors are activated on presynaptic neurons, what happens?

Answer 15

• They inhibit neurotransmitter release from presynaptic neurons

Question 16

Where are alpha 1 receptors found and what is their effect?

Answer 16

• Location: Vascular smooth muscle (peripheral, renal and coronary circulation)
• Effect: Vasoconstriction (increase SVR)

Question 17

Where are Beta 1 receptors found and what is their effect when stimulated?

Answer 17

• Location: Heart

- Effect: Increased heart rate and increased contractility (increasing cardiac output)

Question 18

Where are Beta 2 receptors located and what is their effect?

Answer 18

• Location: Vascular smooth muscle (peripheral and renal circulation)
• Effect: Vasodilation (reducing systemic vascular resistance)

Question 19

Where are Beta 3 receptors found and what are their effects?

Answer 19

• Location: Gall Bladder and adipose tissue

- Effect: May play a role in lypolysis and brown fat thermogenesis

Question 20

What receptors does Phenylephrine work on?

Answer 20

• Mainly Alpha 1

Question 21

What receptors does Epinephrine work on?

Answer 21

• Alpha 1, Alpha 2, Beta 1, Beta 2

Question 22

What receptors does Ephedrine work on?

Answer 22

• Alpha 1, Beta 1, mild Beta 2

Question 23

What receptors does Norepinephrine work on?

Answer 23

• Alpha 1, Alpha 2, Beta 1

Question 24

What receptors does Dopamine work on?

Answer 24

- Mainly DA 1 and DA 2 | - Alpha 1, Alpha 2, Beta 1, mild Beta 2,

Question 25

Phenylephrine

Answer 25

- Non-catecholamine with predominately Alpha 1 agonist activity - Primarily a vasoconstrictor used to increase blood pressure due to vasodilator effects of anesthesia agents. - Reflex bradycardia

Question 26

Phenylephrine: What is the dose for small intravenous boluses?

Answer 26

- 50-100 mcg (0.5-1.0 mcg/kg)

Question 27

What is the infusion rate for phenylephrine?

Answer 27

- 0.25 to 1.0 mcg/kg/min

Question 28

Ephedrine

Answer 28

- Non-catecholamine indirect and direct acting Alpha and Beta agonist - Works by increasing the release of NE at the synaptic junction and similar direct Alpha and Beta effects as epinephrine * Increase BP, HR, contractility, CO, and bronchodilator - Longer duration of action and less potent than epinephrine - Direct stimulation of the CNS (may increase MAC) - Tachyphylaxis b/c you deplete NE stores

Question 29

Ephedrine: What is the IV bolus dose?

Answer 29

- 2.5 to 10 mg (pediatric 0.1 mg/kg) | * Dilute for IV administration

Question 30

Ephedrine: What is the IM/SQ dose?

Answer 30

- 25-50 mg (Onset may be 10-20 min)

Question 31

Epinephrine

Answer 31

- Endogenous catecholamine synthesized in adrenal medulla - Alpha 1 = Alpha 2 ; Beta 1 = Beta 2 - Peripherally vasoconstricts, inotrope, chronotrope, relaxation of peripheral vessels may lead to decrease in diastolic pressure (overall increases MAP) - Increased oxygen demand on the heart - Principle treatment in anaphylaxis

Question 32

Epinephrine: What is the dose in a code?

Answer 32

- 1 mg IV

Question 33

Epinephrine: What is the IV anaphylaxis dose?

Answer 33

- 0.3 - 0.5 mg IV

Question 34

Epinephrine: What is the IV gtt dose?

Answer 34

- 0.1 to 1.0 mcg/kg/min | * 1 mg/250 (4mcg/ml)

Question 35

Norepinephrine

Answer 35

- Direct Alpha 1 stimulation with little Beta 2 activity produces intense vasoconstriction - Alpha 1 = Alpha 2 ; Beta 1>>>>Beta 2 - Increased contractility. Increased afterload and some reflective bradycardia - Does not have the advantages of Beta 2 stimulation (renal and GI blood dilation) - Extravasation can cause tissue necrosis

Question 36

Norepinephrine: What is the bolus dose?

Answer 36

- 0.1 mcg/kg (short duration)

Question 37

Norepinephrine: What is the infusion dose?

Answer 37

- 2-20 mcg/min, or 0.01 to 3 mcg/kg/min (higher rates in septic shock)

Question 38

Dopamine

Answer 38

- Endogenous non-selective direct and indirect adrenergic and dopaminergic agonist which varies with dosage

Question 39

Dopamine: What is the Beta 1 dose?

Answer 39

- 2-10 mcg/kg/min

Question 40

Dopamine: What is the Alpha effects dose?

Answer 40

- > 10 mcg/kg/min

Question 41

Dopamine: What is the Dopaminergic effects dose?

Answer 41

- 0.5-2 mcg/kg/min

Question 42

Activation of Alpha 1 and Beta 2 increase....?

Answer 42

- Glucose release into the circulation

Question 43

Beta 2 activation also...?

Answer 43

- Promotes the uptake of potassium into cells

Question 44

What are the two Beta selective inotropes?

Answer 44

- Isoproterenol | - Dobutamine

Question 45

Isoproterenol

Answer 45

- Potent Beta 1 agonist, little effect on Alpha | - Positive chronotrope and inotrope

Question 46

Dobutamine

Answer 46

- Initially considered as Beta 1 selective, but more complicated than that - Positive inotrope over chronotrope when compared to isuprel - Some Alpha 1

Question 47

Esmolol

Answer 47

- Beta 1 blocker

Question 48

Esmolol: What is the intermittent dose?

Answer 48

- Up to 1 mg/kg

Question 49

Hydralazine

Answer 49

- Direct arteriole vasodilation

Question 50

Hydralazine: What is the intermittent dose?

Answer 50

- 10-40mg IV q4

Question 51

Labetalol

Answer 51

- Alpha 1 blocker (primarily) - Beta 1 blocker - Beta 2 blocker

Question 52

Labetalol: What is the intermittent dose?

Answer 52

- 10-40 mg IV q4

Question 53

Metoprolol

Answer 53

- Beta 1 blocker

Question 54

Metoprolol: What is the intermittent dose?

Answer 54

- 1.25-5 mg IV q6