Vasopressors & Inotropes

persistent hypotension, mean arterial pressure (MAP) <65 mmHg, or clinical hypoperfusion (mottling, cool extremities, rising lactate, falling urine output) during ongoing fluid resuscitation = vasopressor now, not another reflex bolus.

• reassess volume status quickly: passive leg raise or a POCUS look at the IVC; do not keep giving fluid on reflex if not fluid responsive.
• start early once hypotension or hypoperfusion persists and fluid responsiveness looks unlikely: vasopressor alongside ongoing fluid, not after a fixed volume finishes.
• start norepinephrine while access is sorted; a peripheral line is fine short term, do not wait for a central line.
• target MAP ≥65 mmHg by default; invasive arterial monitoring as soon as available; individualize lower in older adults or chronic hypertensives (below).

a vasopressor raises blood pressure mainly by increasing systemic vascular resistance (SVR); an inotrope raises cardiac output mainly by increasing myocardial contractility.

• vasodilation → vasopressor
• low cardiac output → inotrope
• mixed shock → targeted combination

• recheck MAP, lactate trend, capillary refill, and UOP every 30–60 min while titrating.
• a falling lactate and improving mentation matter more than the number on the monitor alone.
• re-image with POCUS if the dose keeps climbing, don’t just add another agent blind.

• norepinephrine-equivalent above 1 mcg/kg/min, or 2 or more vasoactive agents = refractory shock: look for a missed cause (undrained source, adrenal insufficiency, occult cardiogenic component), not just a higher dose.
• phenylephrine (peripheral bolus 50–200 mcg (8) or infusion up to 180 mcg/min): reserve for a tachyarrhythmia limiting norepinephrine / epinephrine, or salvage when norepinephrine + low-dose vasopressin fails
  • pure α1: drops cardiac output in preload-dependent patients
  • a push around norepinephrine initiation was independently associated with higher ICU mortality in a matched cohort (9): use briefly, reassess, do not repeat
• weaning: once MAP is stable off escalating support, taper the most recently added or highest-risk agent first, one at a time; reassess after each step.

• escalating norepinephrine with a full IVC and B-lines on POCUS → reassess for an occult cardiogenic component, add dobutamine rather than another vasopressor.
• digital mottling or cyanosis on vasopressin → reduce or stop it, do not push past 0.04 units/min.
• new tachyarrhythmia limiting epinephrine or norepinephrine titration → correct K+ and Mg2+, consider phenylephrine as a bridge.
• persistent hypotension despite 3 agents → reassess adrenal axis, source control, and volume status. this is an escalation trigger, not a fourth drug.
• extravasation or a line concern on a peripheral pressor → stop the infusion, aspirate, escalate access urgently.

• norepinephrine, not dopamine, is first line even in cardiogenic-predominant shock (SOAP-II subgroup) (4).
• no second vasopressor before reassessing volume and cardiac function on POCUS: an under-filled or failing heart needs fluid or an inotrope, not more vasoconstriction.
• starting a pressor too late is a classic error; so is reflexive large-volume fluid in a non-responder: check responsiveness, not a fixed volume script.
• milrinone vs dobutamine: no clear outcome difference head to head (DOREMI trial) (10); renal function is the practical tiebreaker, milrinone accumulates in kidney impairment.