Test 5: CV Drugs pt. 2 Flashcards
What is Ephedrine?
A synthetic non-catecholamine.
Mixed actions:
-Mild direct (A1, B1, B2). Weakly agonizes these receptors on the postsynaptic side.
-Mostly Indirect actions: Increases NE release to the post synaptic receptors. Relies on endogenous NE stores for results. Greater effect on venous side. Both Alpha and Beta.
-Increases CO and PL
-Not metabolized by MAO or COMT
-Renal elimination (mostly unchanged)
-Administered IV, IM, and PO
What is the dose of Ephedrine?
IVP: 5 - 10 mg
IM: 25 - 50 mg
What are the uses of Ephedrine?
-Can be given IM before placing a spinal to counteract hypotension
-Used in OB since it doesn’t compromise uterine blood flow
-Used post-induction to buy time to adequately fluid resuscitate
-Can use instead of Neo if pt is already bradycardic.
-Hypotension with low CO + HR
-Tx of Sympathectomy
-Temporary tx of hypovolemia
-Treat transient myocardial depression
What are the advantages of Ephedrine?
Similar to epinephrine:
-Epinephrine is 250X more potent
-Ephedrine 10X longer duration
SBP, DBP, HR and CO increase (inotrope and pressor)
What are the disadvantages of Ephedrine?
-Tachyphylaxis
-Reduced efficacy with depleted NE stores
-R/O malignant HTN with MAOIs (If pt is on MAOI anti-depressants, can lead to malignant HTN (nothing to get rid of it).
-Increased HR
Caution use in:
-Patients on NDRIs and MAOIs
-CV dz or HOCM
-Closed angle glaucoma
-Hyperthyroidism
What is Phenylephrine?
-Direct acting alpha adrenergic agonist
-Some indirect with NE release
-Mainly Alpha 1 stimulation (arterial > venous)
-Just vasoconstriction
-Metabolized by MAO (not COMT). Short DOA (<5 minutes)
What is the dose of Phenylephrine?
-40 to 80 to 160 mcg IV push
-Watch for reflex bradycardia
-Can be given as infusion: 20-200 mcg/min
What are the uses of Phenylephrine?
-Anesthesia-induced hypotension (Both GA and SAB)
-Nasal decongestant
-Hypotension with low SVR
-Temporary tx for hypovolemia
Decreased risk of fetal acidosis associated with phenylephrine when used for tx of hypotension r/t spinal
What are the effects of Phenylephrine?
CV effects:
-Reflexive DECREASE in HR
-↑ SVR, ↓ CO
-Short duration (quick on/off)
-During hypotension: will increase CBF without increase in CO
-MVO2 does not ↑↑ if hypertension is avoided
Disadvantages
-May ↓ SV and ↑ PVR
-May ↓↓ renal, peripheral, and mesenteric perfusion
-RARELY may induce vasospasm: IMA, radial, gastroepiploic artery
Metabolic effects:
-Can interfere with K+ loading
What is Vasopressin?
-Arginine vasopressin (AVP) also known as ADH
-Endogenous regulation of osmolality, cardiovascular stability, blood coagulability
-Intense peripheral vasoconstriction via V1 receptors in vascular smooth muscle (peripheral, mesenteric vasoconstriction)
-Can restore vasomotor tone in refractory arterial hypotension or relative AVP deficiency
-Refractory shock states/CPR
What are the clinical uses for Vasopressin?
Adjunct vasopressor in the perioperative setting.
-Vasoplegia (post bypass and ACE-I; septic shock)
-Sympathetic blunting by GA or high SAB
-Post-pheochromocytoma resection
-Post CPB vasodilatory shock
-Alternative to Epi in ACLS
-Concomitant use with corticosteroids in septic shock
-Adjunct to catecholamines in septic shock
What is vasoplegia?
When the post-synaptic receptors stop being receptive to Norepi/Epi.
-Occurs with patients on ACE-I therapy and post-CPB
What is the dosing for Vasopressin?
-2-4 units IVP
-10-20 unit bolus followed by infusion at 0.03- 0.1U/min
-Resuscitation dose 40 units
What are the cautions associated with Vasopressin?
-Withdrawal hypotension, DI after discontinuation
-Hyponatremia, pulmonary vasoconstriction
What is Digoxin?
-Cardiac glycoside
-Perioperative use for supraventricular tachydysrhythmias and last line in CHF
-Renal elimination
What is the MOA of Digoxin?
-Inhibition of Na/K ATPase
-Increased Ca2+ in myocardium increases inotropy without increasing HR
-Some negative chronotropic and dromotropic effects via parasympathetic enhancement
What are the cautions with the use of Digoxin?
-Narrow therapeutic index
Toxicity most common in setting of renal dysfunction and hypokalemia:
-Nausea, vomiting, arrhythmias
-Correct causes, administer antiarrhythmics, temporary pacer, digoxin antibodies
Many drug-drug interactions
-Amiodarone - MAJOR
What is Milrinone?
-Phosphodiesterase 3 Inhibitor
-Inodilator: Provides inotropy and vasodilation
-Non-catecholamine inotrope and relaxation of arterial and venous beds
-Increases contractility and CO
-Decreases LVEDP, CVP, and PCWP
-Adverse effects: hypotension, arrhythmias
-Uses: Heart failure (Low CO with high PVR and LVEDP), bridge to transplant
-Preferred over dobutamine in patients with high risk of arrhythmia, pulmonary hypotension, and those on chronic beta-blockade
What is the dose of Milrinone?
Titrate as IV infusion:
-0.2 to 0.75 mcg/kg/min
-Requires renal adjustment
-Can do loading dose of 50 mcg/kg TRO 10 minutes
What are the advantages to Milrinone?
Favorable myocardial profile:
-Decrease preload and afterload
-Minimal tachycardia
-Less arrhythmogenesis than Dopa or Epi
Retains efficacy when NE stores are depleted (chronic CHF)
No tachyphylaxis
What are the disadvantages to Milrinone?
Hypotension can occur with rapid IV bolus
What are the indications for the use of Milrinone?
-Low CO with high PVR and LVEDP
-Bridge to transplant
-Preferred over dobutamine in patients with high risk of arrhythmia, pulmonary hypotension, and those on chronic beta-blockade
What are Beta 2 Agonists used for?
-Relax bronchioles and uterine muscles without tachycardia
-Slowly metabolized = long duration
-Inhalation as well as IV
-Tolerance may develop
-Increase lactic acid levels
