Vasopressors Flashcards
Phenylephrine agonizes what SNS receptor
Pure alpha 1
Is phenylephrine a catecholamine
No, it is a synthetic noncatecholamine
Phenylephrine produces profound
arterial vasoconstriction
What effect does phenylephrine have on SVR
Increased
What effect does phyenylephrine have on BP
Increased
What effect does phyenylephrine have on contractility
No direct effect
What effect does phyenylephrine have on HR
Reflexive decrease from elevation of SVR
What effect does phyenylephrine have on CO
Decreased
- from baroreceptor reflexive decrease of HR
- increased afterload
What effect does phyenylephrine have on PAP
Increased
-alpha 1 receptors dominant in pulmonary vasculature
What effect does phyenylephrine have on CNS
Minimal effects
Phenylephrine is metabolized rapidly by
MAO
-DOA= 5 minutes
Pheylephrine is indicated for
Hypotension
Hypovolemia (until fluid restored)
SVT
Acute cyanosis
Epinephrine is considered a direct
mixed agonist
Epi directly agonizes
a1, a2, b1, b2 receptors
Does epinephrine cause the release of endogenous NorEpi
No
Is tachyphylaxis not with Epi administration
No
What catecholamine is the most potent alpha-adrenergic receptor activator
Epi
B1 receptors stimulated by epi cause an increase in
Systolic BP
HR
Inotropy
CO
Epi cause a ——– in diastolic pressure
decrease
- due to stimulation of B2 receptors of skeletal muscle vessels
Epi cause a —–in pulse pressure
increase
*systolic increase>diastolic with minimal change in MAP
Epi ——- the rate of ventricular relaxation
increases
How is epi metabolized
MAO
COMT
What two respiratory effects does epi have
bronchodilation (B2)
Inhibits antigen-induced release of inflammatory mediators from mast cells (B2)
Epi related positive inotropy, tachycardia, and increased myocardial oxygen demand will have what effect on myocardial cells
May induce or worsen myocardial ischemia
If Epi can cause what effect on tissues
necrosis d/t extravasation
Epi stimulation on the pancreas exerts what effect, how?`
Glucagon release from alpha cells via stimulation of alpha 2 receptor»»increased plasma glucose
Subsequently, increased glucagon leads to inhibition of glucose
Is Epi lipid soluble
No
*No CNS effects
Epi can be used to treat hyperkalemia by what mechanism
activaton of sodium-potassium pump in skeletal muscles
What are the indications for epi
Cardiac arrest
anaphylaxis/ bronchospasm
cardiogenic shock
Reduced CO after coronary bypass
How is coronary perfusion pressure increased by Epi
increases rate of ventricular relaxation and enhances LV filling which improves diastolic function
Don’t give > how many mcgs of epi
10 mcg
What are the routes that epi can be administered
ETT
SQ
IV
*Don’t give PO bc rapidly metabolized by GI mucosa and liver
Norepi directly agonizes what receptors
a1
a2
b1
What effect does Norepi have on SVR
Profound increase
*decreases venous return to the heart
Norepi causes a decrease venous return to the heart b/c of SVR increases which does what to the HR
Decreases
Norepi does what to the PAP
increases
How is Norepi metabolized
MAO
COMT
Norepi can what effect on end-organ perfusion and cardiac cells
reduced perfusion and myocardial ischemia
What effect can Norepi have on skin in unsafe doses
skin necrosis
What is the treatment for Norepi induced extravasation
Phentolamine
*alpha antagonist
Norepi is indicated for
Peripheral vascular collapse
Refractory SVR decreases
Ephedrine’s primary effect is
indirect release of Norepinephrine from mobile pool 1
*adequate stores required to be effective
otherwise tachyphlaxis will develop
Epedrine’s hemodynamic profile resembles what other catecholamine
Epinephrine
- Increased CO, contractility, HR, SVR (slightly), BP ( systolic and diastolic)
- however, with epi, the diastolic bp decreases d/t b2 vasodilation
Can ephedrine stimulate the CNS
Yes, cross the BBB
Ephedrine should be avoided in
patient’s taking MAO inhibitors
Vasopressin can produce direct peripheral vasoconstriction via
activation of smooth muscle V1 receptors
Does vasopressin act on adrenergic receptors
No
What are the indications for Vasopressin
DI
hemorrhage from esophageal varices, sepsis, and catecholamine-resistant shock
refractory cardiac arrest
What is the distinction between vasopressin and epinephrine with regards to cardiac arrests
Vasopressin may increase coronary perfusion pressure without tachycardia as seen with epi
Adverse effects of vasopressing include
bronchoconstriction
uterine contractions
visceral hypoperfusion
thrombocytopenia
Dobutamine is a synthetic beta agonist catecholamine distributed as
a racemic mixture
- isomer = potent alpha 1 agonist
- isomer = potent 1 antagonist
Therefore, dobutamine is considered a Beta agonist
- isomer = potent 1 antagonist
Dobutamine primarily agonizes
beta 1 receptors
Dobutamine agonizes —- to a limited extent
B2
Dobutamine antagonizes —–at high doses
A1
Dobutamine causes what effects on SVR
decreased
Dobutamine causes what effects on BP
slight increase
Dobutamine causes what effects on HR
Dobutamine causes what effects
Dobutamine causes what effects on contractility
increased
Dobutamine causes what effects on CO
increased
Dobutamine causes what effects on LVEDP
decreased
Dobutamine causes what effects PAP
decreased via B2
How is dobutamine metabolized
COMT
What is the plasma half-life of dobutamine
2 minutes
Isoproterenol is a
direct acting b1, b2 catecholamine, agonist
Isoproterenol has what effect on SVR
Marked decrease via B2 stimulation of skeletal muscle, renal, and splanchnic vasculature
Isoproterenol has what effect on CO
Increased
Isoproterenol has what effecto on BP
variable
*Systolic increase only