Sympathomimetics Flashcards Preview

Anesthesia Pharmacology > Sympathomimetics > Flashcards

Flashcards in Sympathomimetics Deck (36)
1

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

pipe-vasopressor
pump-inotrope

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

2

what are the effects of inotropes?

Improve contractility
improve CO
treat pump problem

3

What are the effects of vasopressors?

INcrease vascular tone
Increase SVR
treat pipe problem

4

What role does calcium play in muscle contraction?

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.

5

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

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

6

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

cAMP

7

how do B agonists increase cAMP?

Indirectly by stimulating adenyl cyclase which converts ATP into cAMP

8

How do phosphodiesterase inhibits increase cAMP?

prevents breakdown of cAMP

9

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

Inotropy and chronotropy
ionotroy

10

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

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)

11

What are adverse effects of epi and norepi?

Epi-Arrythmogenic, can cause Vtach
Norepi--Intense SVR may decrease CO

12

What are adverse effects of dopamine, dobutamine and isoproteronol?

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

13

What are the effects of cyclic nucleotides as second messengers?

activate protein kinases
open ion channels

14

Which family of PDEs are used for CV system?

IIIA

15

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

Cardiac=increase cAMP->Ca++, increase Ca+++->contractility
Vascular tissue: INcrease cyclic nucleotide->smooth muscle relaxation. decreases PA pressures and SVR

16

What is loading dose and infusion rate for milrinone?

0.05mg/kg lasts 30 minutes
Infusion rate 0.5mcg/kg/min

17

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

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

18

The second messenger in vasculature is cAMP? t or f

f
The end result still comes from an increase in calcium

19

Increasing dose of catecholamines increase _______ effects.

alpha

20

What is onset and duration of phenylephrine?

Onset 30 seconds
duration 2-3 minutes

21

what is the dose for an infusion of phenylephrine?

25-100 mcg/min

22

what is methoxamine?

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

23

how is ephedrine metabolized and eliminated?

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

24

how does ephedrine affect uterine vascular resistance?

minimally

25

How does vasopressin exert its effect on SVR?

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

26

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

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

27

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

F

28

What are physiologic levels of vasopressin?

5-10 pmol/L

29

Onset of sepsis_____ AVP levels

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

30

Vasopressin replacement therapy may be needed after ______________

cardiopulmonary bypass
4-6 units/hour

31

What are side effects of vasopressin?

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

32

What are potential advantages of calcium sensitizers?

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

33

Primobendon and levosimendon are examples of _______ _________

calcium sensitizers

34

how does methyline blue affect vasodilation?

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

35

What is dose, of methylene blue for vasodilation?

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

36

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

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