Sympathomimetic agents

Question 1

Epinephrine receptors

Answer 1

Alpha-1 higher doses- associated with widening pulse pressure (DBP unchanged)
Beta-1 -increase chronotropy, inotropy, lusitropy and dromotropy
and Beta-2- low dose vasodilation helpful in acute RHF, 0.01-0.05 mcg/kg/min

Question 2

Epinephrine Indications

Answer 2

Anaphylaxis
ACLS
Hypotension w/bradycardia- or unresponsive to indirect acting
Refractory asthma

Question 3

Epinephrine Adverse

Answer 3

Hypokalemia- beta 2 stimulation causes uptake of K in skeletal muscle
Hyperglycemia- liver glycogenolysis- and inhibition of insulin secretion
Lactic acidosis
Myocardia ischemia- increases O2 utilization
Tachyarrhythmias
Severe hypertension with coadministration of B blocker

Question 4

Isoproterenol

Answer 4

Pure Beta (1&2)

Don’t forget about B-2 vasodilation!

Indication: high degree AV block prior to pacemaker

Question 5

Norepinephrine

Answer 5

Alpha-1 and Beta-1

-increased SVR can lead to lower CO despite B1- HR unchanged due to baroreceptor

-PVR increase- alpha-1

-Renal and splanchnic blood flow decrease

Question 6

Norepinephrine indication and adverse effects

Answer 6

Septic shock- lower incidence of arrhythmias than dopamine

Advers: myocardial ischemia (high afterload), organ hypoperfusion due to intense vasoconstriction- other impacts of high SVR

Question 7

Dopamine

Answer 7

Alpha-1 -high dosing
Beta-1 -moderate dosing
and
Dopamine-1=vasodilation with increased GFR and decreased SVR at low dose- no impact on AKI

We have better agents for septic and cardiogenic shock

Arrhythmias!!

Question 8

Dobutamine

Answer 8

Beta 1»»Beta 2- no alpha

Indications:
Low CO after CPB
RHF with elevated PVR- comparable to milrinone

Adverse: tachycardia, arrhythmias, myocardial ischemia

Question 9

LVOT (O)

Answer 9

Left Ventricular Outflow Tract Obstruction

Essentially obstruction of forward flow from a variety of causes placing strain on the ventricle and leading to hypertrophy from increased afterload

Question 10

Levosimendan

Answer 10

Calcium sensitizer

Increased inotropy and vasodilation- decreased preload and decreased afterload

Support of acutely decompensated CHF

Adverse: myocardial ischemia, hypokalemia

Question 11

Phenylephrine

Answer 11

Non-catecholamine!!

Pure alpha with reflex bradycardia

Treatment of mild hypotension during general surgery

Adverse:
LV dysfunction with increased afterload
RV dysfunction in setting of pulmonary hypertension
Severe hypertension

Question 12

Ephedrine

Answer 12

Long duration?

Causes release of endogenous catecholamines- which stimulate Alpha-1 Beta-1 and Beta-2

“Mild epinephrine”

Adverse: hypertension and tachycardia
Crosses BBB!! Insomnia and agitation
Urinary retention in patients with BPH

Question 13

Milrinone and other Inodilators

Answer 13

PDE 3 inhibitor

increased CO with decreased SVR and PVR

Indications: weaning CPB
RHF dependent on MAP- combined with vasopressin for decreased MAP
Many advantages over catecholamines after CPB

Can treat cerebral vasospasm

Adverse: increased O2 consumption, interferes with platelet aggregation
React in IV tubing with lasix

Question 14

Vasopressin

Answer 14

Antidiuretic hormone

V-1 receptors to stimulate vasoconstriction

Constricts renal efferent arterioles=increase in GFR

Indications:
Intraop hypotension for patients on ACE inhibitors or ARBs

Question 15

Non-hemodynamic uses for vasopressin & adverse

Answer 15

Anti-diuresis via V-2 in renal collecting duct: treatment of diabetes insipidus

Improved platelet function- von willebrand or antiplatelet agents

Control esophageal variceal bleeding

Adverse:
Mesenteric ischemia
Bradycardia, afib
Hyponatremia

Question 16

Digoxin

Answer 16

Cardiac Glycoside

Inhibits Na/K pump via ATPase
-Causing rise in intracellular Na- which is then exchanged for Ca
Ca is mainly pumped into SR during diastole- however this just leads to increased release during systole

Increases Vagal tone=bradycardia!!

Question 17

Digoxin adverse

Answer 17

Narrow therapeutic index: AV conduction block, Brady, ventricular arrhythmias, N/V, visual changes

Electrolyte imbalances:
Hypokalemia=increased dig toxicity
Hypercalcemia= increased dig toxicity

Multiple drug interactions: all increase risk of toxicity

Amiodarone
Verapamil
Itraconazole
Macrolide antibiotics
Quinidine

Question 18

Which receptor stimulation of Epi causes stabilization of mast cells and why is it important?

Answer 18

Beta

Decreases the release of histamine, and other inflammatory mediators that perpetuate the pathophysiology of anaphylaxis

Question 19

Epinephrine and Beta blockers

Answer 19

Alpha stimulation in the absence of Beta mediated vasodilation leads to severe hypertension and heart failure

Question 20

Why is vasopressin favored to counteract milrinone induced hypotension over norepinephrine

Answer 20

It decreases PVR

Norepi increases PVR!! Although it also increases right ventricular perfusion pressure…. Making it useful in RHF

Question 21

Treatment of phenylephrine induced hypertension

Answer 21

Alpha-1 antagonist (phentolamine)
Or
Direct vasodilator- hydralazine

NOT beta blockers or calcium channel blockers- cardiac depressants can result in acute HF

Question 22

What is vasopressin

Answer 22

Nonapeptide hormone synthesized in neurons of the hypothalamus

It is released by posterior pituitary

Question 23

Does of ephedrine

Answer 23

5-10mg

Tachyphylaxis with repeat dosing

Question 24

Neuro complications of ephedrine

Answer 24

Crosses the BBB causing agitation and insomnia