⭐ Hemodynamics / Pressors / Cardiac

Phenylephrine class

Phenylephrine class:

• Vasopressor

• Selective α1 agonist

Phenylephrine MOA

Phenylephrine MOA:

• Direct α1 agonist → venous > arterial vasoconstriction → ↑ SVR/MAP

• Reflex bradycardia → may ↓ HR/CO

Phenylephrine onset

Phenylephrine onset:

• Rapid

Phenylephrine duration

Phenylephrine duration:

• 5-20 min

Phenylephrine half-life

Phenylephrine half-life:

• ~2.5 hr

Phenylephrine metabolism

Phenylephrine metabolism:

• Hepatic metabolism via MAO

Phenylephrine elimination

Phenylephrine elimination:

• Renal elimination; mostly urine

Phenylephrine cardiac side effects

Phenylephrine cardiac side effects:

• Reflex bradycardia → from ↑ SVR/MAP

• ↓ CO possible → increased afterload + lower HR

Phenylephrine respiratory side effects

Phenylephrine respiratory side effects:

• Minimal direct respiratory effect

Phenylephrine other side effects

Phenylephrine other side effects:

• Peripheral/organ ischemia possible with excessive vasoconstriction

Phenylephrine contraindications/cautions

Phenylephrine contraindications/cautions:

• Low CO state → may worsen forward flow

• Bradycardia → reflex bradycardia can worsen

• Severe PVD/ischemia → vasoconstriction concern

Phenylephrine dose

Phenylephrine dose:

• Bolus: 50-200 mcg IV

• Infusion: 0.1-1 mcg/kg/min or titrate to MAP

Phenylephrine oral exam pearl

Phenylephrine oral exam pearl:

• "Phenylephrine is a pure α1 pressor, so it is great for vasodilatory hypotension with normal/high HR, but it can cause reflex bradycardia and reduce CO."

Ephedrine class

Ephedrine class:

• Vasopressor

• Mixed indirect/direct sympathomimetic

Ephedrine MOA

Ephedrine MOA:

• Releases endogenous norepinephrine + direct α/β agonism → ↑ MAP, HR, and contractility

Ephedrine onset

Ephedrine onset:

• Immediate

Ephedrine duration

Ephedrine duration:

• ~1 hr

Ephedrine half-life

Ephedrine half-life:

• ~3 hr

Ephedrine metabolism

Ephedrine metabolism:

• Slow MAO metabolism + liver conjugation

Ephedrine elimination

Ephedrine elimination:

• Renal elimination; significant unchanged drug

Ephedrine cardiac side effects

Ephedrine cardiac side effects:

• Tachycardia/HTN → β stimulation + NE release

• Dysrhythmias/ischemia possible

Ephedrine respiratory side effects

Ephedrine respiratory side effects:

• Mild bronchodilation → β effect

Ephedrine other side effects

Ephedrine other side effects:

• Tachyphylaxis → repeated doses deplete NE stores

• CNS stimulation/mydriasis

Ephedrine contraindications/cautions

Ephedrine contraindications/cautions:

• MAOIs/TCAs/cocaine → exaggerated sympathomimetic response

• Catecholamine depletion → reduced effect

• CAD/tachyarrhythmia → HR/ischemia risk

Ephedrine dose

Ephedrine dose:

• IV: 5-25 mg

• IM: 10-50 mg

Ephedrine oral exam pearl

Ephedrine oral exam pearl:

• "Ephedrine is useful for hypotension with bradycardia because it supports HR and CO, but repeated doses can tachyphylax."

Epinephrine class

Epinephrine class:

• Vasopressor/inotrope

• Endogenous catecholamine

Epinephrine MOA

Epinephrine MOA:

• Direct α1/α2 + β1/β2 agonist

• Low dose favors β effects; higher dose adds more α vasoconstriction

Epinephrine onset

Epinephrine onset:

• IV onset 1-2 min

Epinephrine duration

Epinephrine duration:

• 5-10 min

Epinephrine half-life

Epinephrine half-life:

• ~1 min

Epinephrine metabolism

Epinephrine metabolism:

• COMT + MAO metabolism

Epinephrine elimination

Epinephrine elimination:

• Blood/liver/kidney clearance

Epinephrine cardiac side effects

Epinephrine cardiac side effects:

• Tachycardia, HTN, angina, dysrhythmias → β1/α effects

Epinephrine respiratory side effects

Epinephrine respiratory side effects:

• Bronchodilation → β2 stimulation

• ↓ mediator release → helps anaphylaxis

Epinephrine other side effects

Epinephrine other side effects:

• Anxiety/tremor if awake

• ↓ K⁺ possible → β2 intracellular shift

Epinephrine contraindications/cautions

Epinephrine contraindications/cautions:

• No absolute contraindication in anaphylaxis/arrest

• CAD/arrhythmias/pheochromocytoma → titrate carefully

Epinephrine dose

Epinephrine dose:

• Resuscitation bolus: 10 mcg/kg

• β2 range: 1-2 mcg/min

• β1 range: 4-5 mcg/min

• α/β range: 10-20 mcg/min

Epinephrine oral exam pearl

Epinephrine oral exam pearl:

• "Epinephrine is the key anaphylaxis drug because it supports BP, bronchodilates, and decreases mediator release."

Dopamine class

Dopamine class:

• Inotrope/vasopressor

• Endogenous catecholamine

Dopamine MOA

Dopamine MOA:

• Dose-dependent receptor activity

• Low dose: dopaminergic effects

• Moderate dose: β1 → ↑ HR/contractility

• High dose: α1 → vasoconstriction

Dopamine onset

Dopamine onset:

• ~1-5 min

Dopamine duration

Dopamine duration:

• Short duration → titratable infusion

Dopamine half-life

Dopamine half-life:

• ~2 min

Dopamine metabolism

Dopamine metabolism:

• MAO + COMT metabolism

Dopamine elimination

Dopamine elimination:

• Renal elimination of metabolites

Dopamine cardiac side effects

Dopamine cardiac side effects:

• Tachycardia/dysrhythmias → β1 stimulation

• ↑ myocardial O₂ demand

Dopamine respiratory side effects

Dopamine respiratory side effects:

• Minimal direct respiratory effect

Dopamine other side effects

Dopamine other side effects:

• Extravasation injury possible → vasoconstriction

Dopamine contraindications/cautions

Dopamine contraindications/cautions:

• Tachyarrhythmias/CAD → worsens HR and ischemia risk

• MAOIs/TCAs → exaggerated response

Dopamine dose

Dopamine dose:

• Infusion commonly 2-20 mcg/kg/min

• Titrate to desired β vs α effect

Dopamine oral exam pearl

Dopamine oral exam pearl:

• "Dopamine is dose-dependent: more β1 at moderate doses and more α at higher doses, but tachyarrhythmias limit its usefulness."

Vasopressin class

Vasopressin class:

• Non-catecholamine vasopressor

• Endogenous antidiuretic hormone analog

Vasopressin MOA

Vasopressin MOA:

• V1 receptor agonist → vasoconstriction → ↑ SVR/MAP

• V2 receptor effect → water retention

Vasopressin onset

Vasopressin onset:

• Rapid IV effect

Vasopressin duration

Vasopressin duration:

• Short clinical duration

Vasopressin half-life

Vasopressin half-life:

• Minutes

Vasopressin metabolism

Vasopressin metabolism:

• Metabolized by tissue/liver/kidney peptidases

Vasopressin elimination

Vasopressin elimination:

• Renal clearance of metabolites

Vasopressin cardiac side effects

Vasopressin cardiac side effects:

• Coronary/mesenteric ischemia possible → intense vasoconstriction

• Bradycardia possible

Vasopressin respiratory side effects

Vasopressin respiratory side effects:

• Minimal direct respiratory effect

Vasopressin other side effects

Vasopressin other side effects:

• Hyponatremia/water retention → V2 effect

• Peripheral ischemia

Vasopressin contraindications/cautions

Vasopressin contraindications/cautions:

• CAD/mesenteric ischemia/PVD → vasoconstriction risk

• Hyponatremia risk with prolonged/high dosing

Vasopressin dose

Vasopressin dose:

• Shock: 0.04 units/min

• Cardiac arrest: 40 units IV bolus

• Variceal bleed: 20 units IV over 5 min

Vasopressin oral exam pearl

Vasopressin oral exam pearl:

• "Vasopressin raises MAP through V1-mediated vasoconstriction and is useful in vasodilatory shock, especially when catecholamine response is poor."

Esmolol class

Esmolol class:

• Selective β1 blocker

• Ultra-short acting

Esmolol MOA

Esmolol MOA:

• β1 antagonism → ↓ SA/AV node conduction + ↓ contractility

• ↓ myocardial O₂ demand → blunts sympathetic response

Esmolol onset

Esmolol onset:

• Rapid onset

Esmolol duration

Esmolol duration:

• ~15 min → short because plasma esterases rapidly metabolize it

Esmolol half-life

Esmolol half-life:

• ~9 min

Esmolol metabolism

Esmolol metabolism:

• Rapid plasma esterase hydrolysis

Esmolol elimination

Esmolol elimination:

• Renal elimination of metabolites

Esmolol cardiac side effects

Esmolol cardiac side effects:

• Bradycardia, hypotension, heart block → β1 blockade

Esmolol respiratory side effects

Esmolol respiratory side effects:

• Bronchospasm possible in susceptible patients → β selectivity is not absolute

Esmolol other side effects

Esmolol other side effects:

• Masks hypoglycemia/tachycardia

Esmolol contraindications/cautions

Esmolol contraindications/cautions:

• Bradycardia/hypotension/heart block

• Asthma/CHF/vasospastic angina → caution

• Combined calcium-channel blocker therapy → brady/heart block risk

Esmolol dose

Esmolol dose:

• Bolus: 5-10 mg q5 min

• Max bolus: 80 mg

• Infusion: 5-300 mcg/kg/min

Esmolol oral exam pearl

Esmolol oral exam pearl:

• "Esmolol is ideal for short-lived tachycardia or intubation response because it is β1 selective and rapidly metabolized by esterases."

Metoprolol class

Metoprolol class:

• Selective β1 blocker

• Longer-acting than esmolol

Metoprolol MOA

Metoprolol MOA:

• β1 blockade → ↓ HR/contractility/AV conduction

• ↓ renin release → helps BP control

Metoprolol onset

Metoprolol onset:

• IV onset within minutes

Metoprolol duration

Metoprolol duration:

• Several hours → longer-lasting β blockade than esmolol

Metoprolol half-life

Metoprolol half-life:

• ~3-7 hr

Metoprolol metabolism

Metoprolol metabolism:

• Hepatic metabolism

Metoprolol elimination

Metoprolol elimination:

• Renal elimination of metabolites

Metoprolol cardiac side effects

Metoprolol cardiac side effects:

• Bradycardia, hypotension, heart block → β1 blockade

Metoprolol respiratory side effects

Metoprolol respiratory side effects:

• Bronchospasm possible at higher doses → β1 selectivity decreases

Metoprolol other side effects

Metoprolol other side effects:

• Fatigue/sedation possible

• Masks hypoglycemia

Metoprolol contraindications/cautions

Metoprolol contraindications/cautions:

• Bradycardia, hypotension, heart block

• Decompensated HF → negative inotropy

• Asthma/COPD → bronchospasm caution

Metoprolol dose

Metoprolol dose:

• IV: 1-5 mg increments, titrate to HR/BP

• Useful if patient missed home β-blocker

Metoprolol oral exam pearl

Metoprolol oral exam pearl:

• "Metoprolol is useful when I want longer β1 blockade, but unlike esmolol it does not have a quick off-switch."

Labetalol class

Labetalol class:

• α1 + β blocker

• Antihypertensive

Labetalol MOA

Labetalol MOA:

• β blockade → ↓ HR/contractility

• α1 blockade → ↓ SVR

• Combined effect lowers BP without as much reflex tachycardia

Labetalol onset

Labetalol onset:

• ~2-5 min IV

Labetalol duration

Labetalol duration:

• ~2-4 hr

Labetalol half-life

Labetalol half-life:

• ~5-8 hr

Labetalol metabolism

Labetalol metabolism:

• Hepatic metabolism

Labetalol elimination

Labetalol elimination:

• Biliary/fecal + renal metabolites

Labetalol cardiac side effects

Labetalol cardiac side effects:

• Bradycardia/hypotension → β + α blockade

• Heart block possible

Labetalol respiratory side effects

Labetalol respiratory side effects:

• Bronchospasm possible → β2 blockade