Autonomic pharmacology V Flashcards
EPI is a potent stimulant of which receptors?
alpha and beta
why are the effects of EPI so complex?
dose dependent, route dependent
what are the cardiac effects of small IV doses of EPI?
B1 - increase PP, HR, SV, CO
B2 - decreased TPR
what are the cardiac effects of moderate IV doses of EPI?
B1 - increase PP, HR, SV, CO
B2 - decrease TPR, DBP
a1 - increase TPR, BP
what are the cardiac effects of high IV doses of EPI?
a1 - increase TPR, BP (potential reflex bradycardia)
B1 - increase PP, HR, SV, CO
B2 - decrease TPR, DBP
what is EPI reversal phenomenon?
because EPI activates both alpha and beta receptors, if you block either prior to EPI administration then the effect on remaining unblocked receptors will be much more pronounced
how does EPI reversal phenomenon affect the heart when alpha receptors are blocked?
- increased EPI induced vasodilation
- decrease TPR
- decrease MAP
how does EPI reversal phenomenon affect the heart when beta receptors are blocked?
- EPI induced vasoconstriction unmasked
2. LARGE increase in MAP
what is the main vascular site of action for EPI?
arterioles and precapillary sphincters
how does EPI affect cutaneous blood flow?
decrease (large)
how does EPI affect skeletal muscle blood flow?
increase
how does EPI affect renal blood flow? fractional flow?
- decrease
2. increase (large)
how does EPI affect the GFR?
no effect
how does EPI affect renin secretion? via what receptor?
increase (via B1)
how does EPI affect pulmonary blood flow?
- increase PAP
2. increase PVP
how does EPI affect coronary blood flow?
increase (relative diastole and aortic pressure and metabolic stimulation)
how does EPI affect inotropy, lusitropy, and chronotropy?
inotropy - increase
lusitropy - increase
chronotropy - increase
how does EPI affect overall cardiac oxygen consumption?
increase
the increase in BP by EPI is due to what mechanism?
a1 activation on vascular smooth muscle
which receptors are more important to pay attention to during shock - alpha or beta?
alpha - vascular effects
what are the adverse effects of EPI toxicity?
- throbbing headache, tremor, palpitations
- cerebral hemorrhage
- arryhthmias
- angina (CAD)
what are the contraindications to EPI use?
beta blockers
what are the therapeutic uses for EPI?
- hypersensitivity
- cardiac arrest
- local anesthetic
- post-extubation croup, viral croup
why doesn’t NE produce vasodilation?
no B2 activation
what receptors does NE stimulate?
B1 (same as EPI)
alpha (less than EPI)