Vasopressors raise blood pressure mainly by constricting arterioles (raising systemic vascular resistance). Inotropes raise cardiac output by making the heart contract more forcefully. Many drugs do both, and the balance changes with dose. Perfusion pressure is judged by mean arterial pressure (MAP); most adults with shock are started at a target of MAP 65 mmHg.

Receptor effects to know

Inotropes

• Dobutamine — mainly beta-1 (some beta-2): raises contractility and cardiac output; may lower BP through mild vasodilation.
• Milrinone — phosphodiesterase-3 inhibitor: raises cAMP in the heart and vessels → stronger contraction plus vasodilation ("inodilator"). Works even when beta receptors are blocked.

Vasopressors support pressure while the cause is treated. They do not replace volume, source control, bleeding control, or revascularization.

Choosing by shock type (current practice)

• Septic shock (Surviving Sepsis Campaign 2026): norepinephrine first; add vasopressin; add epinephrine if MAP remains low. With cardiac dysfunction, either norepinephrine or epinephrine may be the first-line vasopressor (norepinephrine with tachydysrhythmias, epinephrine with bradydysrhythmias). With persistent hypoperfusion from cardiac dysfunction, dobutamine is added to norepinephrine or epinephrine is used alone. Initial MAP target 65 mmHg (60–65 mmHg is suggested for adults aged 65 years or older). Vasopressors may be started through a peripheral IV rather than waiting for a central line. IV corticosteroids are suggested for adults with septic shock (commonly hydrocortisone 200 mg/day in divided doses; watch glucose).
• Cardiogenic shock: norepinephrine for hypotension; dobutamine or milrinone for low output once BP allows; mechanical support in selected clients.
• Hypovolemic / hemorrhagic shock: volume or blood first; vasopressors only as a short bridge.
• Neurogenic shock: fluids cautiously, then norepinephrine; atropine for symptomatic bradycardia.

Dopamine (and older norepinephrine) labels carry a boxed warning on extravasation, naming phentolamine as the antidote; current norepinephrine labels keep this as a warning. Adrenergic IV infusions are high-alert medications.

• Uncorrected hypovolemia — vasoconstriction on an empty tank worsens organ ischemia. Correct volume first unless BP is critically low (then give both at once).
• Peripheral vascular disease, mesenteric or peripheral thrombosis — higher risk of limb or gut ischemia.
• Sulfite sensitivity — some norepinephrine and dopamine products contain sodium metabisulfite.
• Dobutamine: avoid in hypertrophic obstructive cardiomyopathy (outflow obstruction worsens). Atrial fibrillation: can speed ventricular rate.
• Milrinone: caution in severe obstructive valve disease and kidney impairment.
• Pregnancy: vasopressors are used when the mother's life depends on them; vasoconstriction can reduce uterine blood flow, so fetal monitoring is added when viable. Phenylephrine and norepinephrine are commonly used for hypotension during spinal anesthesia.
• Interactions:
  • MAO inhibitors, tricyclic antidepressants, linezolid — exaggerated, prolonged hypertensive response to adrenergic drugs (dopamine needs a large dose reduction after MAOIs)
  • Beta blockers — blunt dobutamine and the beta effects of epinephrine; unopposed alpha effect can cause severe hypertension with epinephrine
  • Halogenated anesthetics — sensitize the heart to catecholamine dysrhythmias
  • IV phenytoin with dopamine — reports of severe hypotension and bradycardia
  • Never mix catecholamines with sodium bicarbonate or other alkaline solutions in the same line (inactivation)

Listed in priority order.

1. Perfusion and hemodynamics
   • Continuous ECG; arterial line as soon as practical; until then noninvasive BP every 5–15 minutes during titration
   • MAP against the ordered target (usually ≥ 65 mmHg); heart rate and rhythm
   • Perfusion markers: mental status, skin temperature, capillary refill, urine output ≥ 0.5 mL/kg/h, lactate trend (> 2 mmol/L [18 mg/dL] = hypoperfusion)
2. Safe infusion
   • Infusion pump, standard concentration, independent double check of drug, concentration, dose units (mcg/min vs. mcg/kg/min), and pump programming
   • Dedicated line or lumen; label the line; never flush or bolus through a vasopressor line
   • Titrate in small steps per protocol; wean gradually — never stop abruptly (rebound hypotension). Change syringes or bags before they run out
3. IV site and extravasation
   • Peripheral infusion: large vein in the upper arm or forearm (not hand or wrist), well-functioning catheter, site check at least hourly or per protocol, move to central access if infusion continues or doses rise
   • At the first sign (blanching, coolness, swelling, pain): stop the infusion, leave the catheter in place to aspirate if protocol allows, notify the provider, give phentolamine by local infiltration per protocol (alpha-agonists only), elevate the limb
4. Organ ischemia — check fingers, toes, nose, ears for color and warmth; report abdominal pain, distension, or GI bleeding (mesenteric ischemia)
5. Metabolic — glucose (epinephrine), potassium, magnesium; kidney function; platelets (milrinone)
6. Treat the cause alongside — fluids, antimicrobials, source control, blood, revascularization

Most clients are critically ill; teach the client if awake, and the family:

• Explain why continuous monitoring, frequent BP checks, and an arterial line are needed
• Report burning, pain, or swelling at the IV site right away
• Report chest pain, palpitations, shortness of breath, headache, or numb, cold, or discolored fingers and toes
• Explain that the dose is changed often and stopped slowly as the heart and blood pressure recover
• Clients sent home on continuous milrinone (advanced HF, bridge to transplant or palliation): keep the pump running, care for the central line, and report dizziness, palpitations, fever, or line problems

• Alpha-1 = vasoconstriction; beta-1 = heart rate and contractility; beta-2 = bronchodilation and vasodilation
• Norepinephrine is first-line in septic shock; add vasopressin, then epinephrine (Surviving Sepsis Campaign 2026)
• Initial MAP target 65 mmHg; urine output ≥ 0.5 mL/kg/h and falling lactate show improving perfusion
• Correct hypovolemia first — vasopressors are not a substitute for volume
• Dobutamine and milrinone are inotropes for low cardiac output; both can lower BP
• Phenylephrine → reflex bradycardia; dopamine → more dysrhythmias than norepinephrine
• Vasopressors can start peripherally in a large proximal vein with frequent site checks
• Extravasation of norepinephrine, epinephrine, phenylephrine, or dopamine → stop infusion, phentolamine
• Pump, dedicated line, never bolus or flush the line, wean gradually
• MAOIs and tricyclic antidepressants exaggerate the pressor response