Sympathomimetics

Question 1

which type of drug should you give if the pt has a “pipe” problem? Pump?

Answer 1

pipe-vasopressor
pump-inotrope

Before deciding ask yoursef Is there a perfusing rhythm and does the pt have adequate volume

Question 2

what are the effects of inotropes?

Answer 2

Improve contractility
improve CO
treat pump problem

Question 3

What are the effects of vasopressors?

Answer 3

INcrease vascular tone
Increase SVR
treat pipe problem

Question 4

What role does calcium play in muscle contraction?

Answer 4

Actin wants to interact with myosin, but tropomysin is blocking it. Calcium binds to troponin which moves tropomysin out of the way so actin and myosin can form cross bridges.

Question 5

define the following in terms of calcium: inotropy, chronotropy, and lusitropy

Answer 5

ionotropy–quantity of Ca in cell, maximum tension developed
Chronotropy-Rate of Ca delivery, rate of contraction
Lusitropy–removal of Ca, rate of relaxation

Question 6

_______ is an important second messenger. By increasing it in the cardiac myocyte, you will increase Ca++ which will increase contractiliy

Answer 6

cAMP

Question 7

how do B agonists increase cAMP?

Answer 7

Indirectly by stimulating adenyl cyclase which converts ATP into cAMP

Question 8

How do phosphodiesterase inhibits increase cAMP?

Answer 8

prevents breakdown of cAMP

Question 9

B1 receptors increase _______ and _______. B2 receptors increase _____________.

Answer 9

Inotropy and chronotropy

ionotroy

Question 10

HOw do norepi, epi, dopamine, dobutamine and isoproteranol affect a, B1 and B2?

Answer 10

NOrepi, B1 with even stronger a
Epi- equal a, B@ and B2
Dopamine a is strongest , B1 and 2 are equal
Dobutamine-mostly B1 with some B2. + or - with a
Iso pure B (strong on both)

Question 11

What are adverse effects of epi and norepi?

Answer 11

Epi-Arrythmogenic, can cause Vtach

Norepi–Intense SVR may decrease CO

Question 12

What are adverse effects of dopamine, dobutamine and isoproteronol?

Answer 12

Dopamine–largely indirect acting
Dobutamine–tachycardia
Isopro–significant tachycardia, arrhythmias and and decreased SVR

Question 13

What are the effects of cyclic nucleotides as second messengers?

Answer 13

activate protein kinases

open ion channels

Question 14

Which family of PDEs are used for CV system?

Answer 14

IIIA

Question 15

What are the actions of PDEIII in cardiac myocytes and vasculature?

Answer 15

Cardiac=increase cAMP->Ca++, increase Ca+++->contractility

Vascular tissue: INcrease cyclic nucleotide->smooth muscle relaxation. decreases PA pressures and SVR

Question 16

What is loading dose and infusion rate for milrinone?

Answer 16

0.05mg/kg lasts 30 minutes

Infusion rate 0.5mcg/kg/min

Question 17

Why is norepi the first line inotrope? What would you add if you had poor systolic function?

Answer 17

NOrepi provides positive inotropy (B1) and maintains perfusion pressure (a1). If systolic function is poor add dobutamine, epi or a PDE3 inhibitor

Question 18

The second messenger in vasculature is cAMP? t or f

Answer 18

f

The end result still comes from an increase in calcium

Question 19

Increasing dose of catecholamines increase _______ effects.

Answer 19

alpha

Question 20

What is onset and duration of phenylephrine?

Answer 20

Onset 30 seconds

duration 2-3 minutes

Question 21

what is the dose for an infusion of phenylephrine?

Answer 21

25-100 mcg/min

Question 22

what is methoxamine?

Answer 22

a pure direct a1 agonist.
bolus 5-10 mg
onset 1 min
duration 5-10 min

Question 23

how is ephedrine metabolized and eliminated?

Answer 23

Inactivated by MAO in liver (if pt is on MAOIs duration may be prolonged to 20-30 min)
40% is exreted unchanged in urine

Question 24

how does ephedrine affect uterine vascular resistance?

Answer 24

minimally

Question 25

How does vasopressin exert its effect on SVR?

Answer 25

Activates V1 receptor which utilizes the same second messenger system as alpha agonists. Ca++ is increased and muscular contraction happens

Question 26

Name 2 other vasopressin receptors (besides V1) and give their function

Answer 26

V2-kidney
Dilation of renal endothelium, increases water permeability
V3-pituitary
Neurotransmitter that increases ACTH release

Question 27

The principle role of vasopressin is regulating vascular tone. T/F

Answer 27

F

Question 28

What are physiologic levels of vasopressin?

Answer 28

5-10 pmol/L

Question 29

Onset of sepsis_____ AVP levels

Answer 29

increases, but in time it will decrease these levels to 1/3 of normal

Question 30

Vasopressin replacement therapy may be needed after ______________

Answer 30

cardiopulmonary bypass

4-6 units/hour

Question 31

What are side effects of vasopressin?

Answer 31

Intense vasoconstriction
-Myocardial ischemia
-decreased CO
-Mesenteric ischemia
-Digital necrosis
However it may be beneficial for pulmonary HTN

Question 32

What are potential advantages of calcium sensitizers?

Answer 32

Less arrhythmogenic
Do not increase O2 consumption
Since they use a different mechanism of action they may be synergist with conventional inotropes

Question 33

Primobendon and levosimendon are examples of _______ _________

Answer 33

calcium sensitizers

Question 34

how does methyline blue affect vasodilation?

Answer 34

blocks activation of guanlylate cyclase by NO.-> less cGMP = less vasodilation
Should only be used as a rescue drug in refractory vasodilation when MAP < 50 mmHg and Norepi>35mcg/min

Question 35

What is dose, of methylene blue for vasodilation?

Answer 35

1.5-2mcg/kg over 10-60 min. Repeat doses have been given

Question 36

What side effect may methyline blue have in doses >2mg/kg?

Answer 36

hyperbilirubinemia and hemolytic anemia

under 2-transient decrease in spo2 and discoloration of skin and urine