One skill that distinguishes ICU nurses as critical care nurses is their working knowledge of adrenergic agonists and other IV cardiac/vasoactive medications. ICU nurses are handy in a crisis because they can make quick decisions about what is needed to hemodynamically stabilize a declining patient. Below are a list of common IV medications seen in the adult ICU.
Definitions
Dromotrope - A dromotrope affects AV node conduction. A positive dromotrope increases AV nodal conduction.
Inotrope - An inotrope alters the force or energy of muscular contractility. A positive inotrope increases strength of contraction.
Chronotropic - Chronotropic medications change the heart rate by affecting the nerves controlling the heart or by changing the rhythm produced by the sinoatrial node. Positive chronotropes increase HR.
Receptors
Adrenergic receptors are sensitive to epinephrine and norepinephrine. Adrenergic agonists such as isoprenaline and dobutamine, on the other hand, stimulate adrenergic receptors to produce a more profound effect.
Receptor | Site | Action | Examples |
Alpha 1 | Peripheral vascular smooth muscle | Vasoconstriction increases BP & Heart Rate | Epinephrine, norepinephrine, phenylephrine |
Alpha 2 | Brain and peripheral blood vessels | inhibits sympathetic activity to lower BP | Clonidine, Dexmedetomidine (Precedex) |
Beta 1 | Heart | Increases contractility/stroke volume and HR, which increases cardiac output | Epinephrine, norepinephrine, dobutamine |
Beta 2 | Lungs | Smooth muscle relaxation in airways resulting in bronchodilation | Epinephrine |
Dopamine | Renal Vasculature | Increases Urine Output | Dopamine |
Adrenergic Agonists
Dobutamine
Class: Inotrope
Indications: Commonly used in acute congestive heart failure, low cardiac output as in cardiogenic shock, and after cardiac procedures for sort-term recovery
MOA: Mostly a beta 1 agonist. However, it decreases systemic vascular resistance and afterload (vasodilation) (beta 2) while increasing contractility (inotropy), heart rate (chronotropy), and cardiac output (beta 1). It is weaker than milrinone and therefore is less prone to hypotension. Hypovolemia should be corrected before initiation of therapy.
Nursing Considerations: Central access is preferred. Monitor for hypokalemia and arrhythmia.
Dose:
Initiate at 0.5-1 mcg/kg/min
Maintain at 2.5-20 mcg/kg/min
Max dose is 40 mcg/kg/min
Vasopressin
Class: Antidiuretic hormone (ADH) and vasopressin receptor agonist
Indication: Commonly used as an adjunct to norepinephrine, as in septic shock. Used when hypotension is not responsive to volume resuscitation. Also used in cardiac arrest, GI hemorrhage, and diabetes insipidus.
MOA: alters reabsorption of water to increase volume and increase blood pressure. At higher than physiologic doses, vasopressin acts as a peripheral vasoconstrictor causing smooth muscle of the GI tract to contract increasing systemic vascular resistance and blood pressure.
Nursing Considerations:
Give via central line
May cause decreased cardiac output; monitor urine output
May cause angina, myocardial ischemia, and cardiac dysrhythmia
Use with caution in patients with heart failure as it can cause fluid overload.
Note: it is compatible with normal saline and D5W
Dose:
Cardiac arrest - 40 units
Septic shock adjunct - 0.01-0.04 units/min
Phenylephrine (NeoSynephrine)
Class: alpha adrenergic agonist
Indication: Commonly used for hypotension, septic shock after adequate volume resuscitation, or intraoperative/anesthesia related hypotension. Also used to treat priapism and congestion.
MOA: Constricts blood vessels by stimulating alpha adrenergic receptors. Increases systemic vascular resistance and BP. Does not increase HR cut can cause reflux bradycardia. Increases coronary perfusion, which can improve cardiac output.
Nursing Considerations: Central line administration preferred. Okay to use via peripheral IV as push-dose. May cause reflux bradycardia.
Dose: 20-200 mcg/min as IV drip. A push syringe has 10 mL (100 mcg/mL); administer 0.5-5mL at a time in emergency situations only at a rate of 1 mL per 20 seconds.
Norepinephrine (Levophed)
Class: Alpha and some beta adrenergic agonist
Receptors: α, β1
Indication: Hypotension. Common first line pressor for septic related cardiogenic shock or neurogenic shock.
MOA: Mostly vasoconstricts to increase SVR and BP (alpha 1). Increases HR and inotropic CO (beta 1). Oxygenation to organs (beta 2).
Nursing Considerations: Central line administration. Concurrent treatment of hypovolemia with IV bolus, hypoxemia, and acidosis is needed with initiation of therapy.
Dose: Comes in concentrations of 4-20mg per 250 mL in D5W, NS, or LR.
Epinephrine (Adrenaline)
Class: Alpha and beta adrenergic agonist (non-selective)
Receptor: α1, α2, β1, β2
Indication: Good in a crisis. Use for severe sepsis, shock, hypotension, in ACLS, or anaphylaxis.
MOA: Vasoconstriction increases SVR and BP (alpha 1). Increases inotropy, HR, and CO (beta 1). Bronchodilation (beta 2). Relaxes muscles of airways and tightens blood vessels.
Nursing Considerations: Central line administration. Has a short half life of 2-3 minutes. Can cause lactic acidosis, tachycardia, and ECG rhythm changes.
Side Effects: anxiety, headache, diaphoresis, N/V, palpitations, dizziness, weakness, SOB, tremors
Adverse Effects: tachycardia, HTN, arrhythmias (V-fib), stoke, cerebral hemorrhage (subarachnoid hemorrhage)
Dose:
Hypotension/Shock - continuous infusion starting at 0.1 mcg/kg/min of a 4 mg/250 mL concentrated drip.
Cardiac arrest - give 1 mg q3-5 min (the entire 1:10,000 syringe). If you are using a 1:1000 vial, DO NOT administer without first diluting in 10 mL normal saline.
Anaphylaxis - Give 0.3 mg IM (which is 0.3 mL of a 1:1000 solution vial). IM has delayed response. May be repeated if severe anaphylaxis persists. IV push or infusion loading dose of 0.2-0.5 mg (2-5 mL of 1:10,000 syringe) potentially followed by a continuous infusion at a rate of 0.8 mcg/min.
Laryngeal edema/stridor - Racemic epinephrine is administered as a 0.05 mL/kg dose of 2.25% concentration. Administer via nebulizer for inhalation. It is usually combined with dexamethasone to help with inflammation. If you are using a 1 mg/mL epinephrine vial, dilute in 4 mL 0.9% normal saline.
Dexmedetomidine (Precedex)
Class: nonbarbituate sedative, hypnotic
Receptor: α2
Indication:
MOA: Alpha 2 agonist providing sedation and analgesia without causing respiratory depression.
Nursing Considerations:
May potentiate effects of opioids, sedatives, and hypnotics, anesthetics, and other vasoactive agents
Monitor for bradycardia and hypotension
nausea
takes patients time to wake up after discontinuing
Dose:
Loading dose: 1 mcg/kg over 10 minutes
Maintenance dose: 0.2 to 0.7 mcg/kg/hr
Other IV Cardiogenic and Vasoactive Medications
Milrinone
Class: Phosphodiesterase (PDE) 3 inhibitor
Indications: Acute heart failure if there is BP room as it can cause hypotension
MOA: Inhibits PDE3 isoenzyme in vessels causing vasodilation and resulting in reduced systemic vascular resistance and afterload. Inhibition of PDE3 isoenzymes in the heart leading to increased contractility (inotropy); inhibition of PDE3 leads to an increase in intracellular concentrations of cAMP, which phosphorylates protein kinase to then activate cardiac calcium channels.
Nursing Considerations: Can cause hypotension and arrhythmias.
Dose - 0.125-0.75 mcg/kg/min
Dopamine
Class: Inotrope at medium dose, alpha 1 agonist at high dose; It is a natural catecholamine and the precursor to norepinephrine.
Indication: Decreased CO with bradycardia for medium dose; hypotension for high dose. Bradycardia refractory to atropine. Heart failure, septic shock, and hypotension unresponsive to fluids. No longer recommended for acute oliguric renal failure.
MOA: Neurotransmitter that acts through the CNS to increase HR and BP via vasoconstriction at high doses (alpha 1). Increases both HR and contractility at medium-range doses (beta 1). It increases perfusion to the renal system at low doses (dopamine receptors).
Nursing Considerations:
Before initiating, correct acidosis, hypercapnia, hypovolemia, and/or hypoxia.
Dopamine must be diluted prior to administering it as an IV injection.
Monitor BP, ECG, and HR continuously as it may cause tachy arrhythmias.
Monitor for hypokalemia
Monitor pulmonary wedge pressure and CO
Central access administration preferred.
Not a first-line drug and can actually increase mortality in cardiogenic shock.
May cause chest pain, palpitations, dyspnea, headache, nausea.
Wean off when discontinuing.
Low Dose: 0-5 mcg/kg/min (renovascular dilation)
Med Dose: 5-10 mcg/kg/min (inotropic effect increases CO and HR)
High Dose: 10-20 mcg/kg/min (alpha 1 agonist causes vasoconstriction, increase in BP and HR)
For Inotropic Support & Hypotension:
initiate at 2-5 mcg/kg/min
Increase by 5-10 mcg/kg/min increments
Max dose is 50 mcg/kg/min
Clevidipine (Cleviprex)
Class: Calcium channel blocker
MOA: Inhibits the influx of calcium into myocardial and smooth muscle cells
Indications: Hypertensive crisis
Nursing Considerations:
Can produce negative inotropic effects and exacerbate heart failure. Monitor HF patients carefully.
Monitor BP and HR continually during infusion.
Contraindicated in the presence of soy and egg allergies
hypotension
headache
short half life of less than 1 minute
Dose: Initial dose is 1-2 mg/hr (2-4 mL/hr). Can be doubled initially every 90 seconds. As BP approaches goal, increase dose by less than double and wait 5-10 minutes between dose adjustments. A approximate 1-2 mg/hr increase generally produces an additional 2-4 mmHg decrease in SBP.
Nitroprusside (Nipride)
Class: Nitrate
MOA: Potent vasodilator of arterioles and venules. Increases the release of nitric oxide, which relaxes smooth muscle and vasodilation of both arteries and veins
Indications: Acute hypertensive crisis, congestive heart failure
Nursing Considerations: Monitor BP continuously.
Hypotension
Headache/Dizziness
Cyanide toxicity in prolonged uses can be lethal. Therefore, infusion of the maximum dose rate of 10 mcg/kg/min should never last more than 10 minutes. Monitor acid-base balance and venous oxygen concentrations.
Dose: 0.3 mcg/kg/min. Titrate every few minutes to desired effect. Average dose is 3 mcg/kg/min. Maximum dose of 10 mcg/kg/min for no more than 10 minutes at max dose.
Nitroglycerin
Class: Nitrate
MOA: Increases release of nitric oxide, dilates coronary arteries, and smooth muscles of both veins and arteries
Indications: post-op CABG to maintain graft patency, acute MI, angina
Nursing Considerations:
Place only 1 tiny tablet under the tongue, sublingually
Can cause Hypotension
Side effects include headache and dizziness
CONTRAINDICATED in patients who have taken erectile dysfunction/pulmonary hypertension phosphodiesterase inhibitors, such as milrinone, sildenafil (Viagra), tadalafil (Cialis) within the past 24 hours
