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24 terms

CV stimulants

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Small doses of Epi may do what?
decrease BP, because B2 vasodilator is more sensitive than the constrictor A receptors
Why is Epi coformulated with local anesthetics?
local vasoconstrictive effects slows absorption to keep injection where the dentist wants it to be
What does Epi do to heart?
powerful and direct cardiac stimulant, increases HR, shortens systole, increases CO, increases O2 consumption
Do catecholamines predispose to arrthymias?
yes they also predispose to sudden cardiac death
What does Epi do to coronary blood flow?
increases it, increases diastole duration and aortic pressure
What is epi good for in patients with cardiac arrest?
restoration of cardiac rhythm
what can be given if NE leaks out (would cause bad necrosis!)
phentolamine
what does NE do to CO, TPR, and SV?
decreases CO, increases TPR, increases SV
What is low dose dopa good for?
D1 action, vasodilates, good for improving GFR/renal perfusion/urine output
What does moderate dose dopa do?
D1 and B1 action, increases CO, and some D1 vasodilation
What does high dose dopa do?
Alpha agonist action, increases PVR and renal vasoconstriction
what receptor activity for Dobutamine
B agonist, enantiomers (+/-) A1 agonist (should cancel out)
what is T1/2 of dobutamine?
2 min
what does dobutamine do to CO, SV, and HR
increases CO
increases SV
does nothing to HR
What would dobutamine be used for?
short term treatment of cardiac decompensation (after cardiac surgery, CHF, acute MI)
What does isoproterenol do to CO and diastolic BP?
raises CO
lowers diastolic BP
when should isoproterenol be used?
in emergencies to stimulate HR in pts with heart block/bradycardia, esp before insertion of pacemaker, and in pts with torsades de pointes
What receptors does phenylephrine work on?
alpha
what does this do to arteries, BP, HR, CO
arterial vasoconstriction, raises BP, leading to a reflex drop in HR and CO
When might phenylephrine be useful?
control of hypotension associated with epidural (regional or spinal anesthesia)
where does ephedrine work?
direct agonist and alpha and beta receptors
enhances NE release
what does ephedrine do to HR, CO, TPR, BP
raises everything
what can ephedrine cause?
fatal arrhythmias, v fib
What ephedra containing herbs have been banned?
herbal products containing ephedra alkaloids, also ephedra is precursor of amphetamine and methamphetamine