Vasopressors (artery and venous), Catecholamines (epinephrine, norepinephrine, dopamine, phenylephrine) these Stimulate α1 (↑ SVR/vasoconstriction) and/or β1 (↑ contractility/HR) receptors VS Non-catecholamines (vasopressin, angiotensin II): Cause vasoconstriction via non-adrenergic pathways.
spectrum= pure alpha 1--> mixed--> pure beta 1

  • Phenylephrine (Pure α1)

    • AE: Reflex bradycardia , not with AR

    • 0.25-3 mcg/kg/min (titreate by 0.25)

    • PIV Maximum dose: 0.5 mcg/kg/min

  • NoreEpi/Levophed (α1>>>β1)

    • AE: Peripheral ischemia (digits, gut), Extravasation → tissue necrosis

    • α1 → vasoconstriction → ↑ SVR and β1 → mild ↑ contractility

    • 0.05 - 1 mcg/kg/min (titrate by 0.03)

    • PIV Maximum dose: 0.2 mcg/kg/min

    • put central line if ≥0.1–0.2, PIV 18-20 gage ok, Maximum dose (PIV): 0.2 mcg/kg/min

    • also good place to add 2nd agent when 0.15-0.2

  • Epi (β1 (LD)> α1 (HD), also β2 )

    • AE: Tachyarrhythmias, ↑ lactate (β2 effect, not always hypoperfusion), Hyperglycemia, arrhythmia

    • 0.05-0.5 mcg/kg/min (titrate by o.02) (( 0.05-0.2 has more isotropy, up to 0.3 more vasoconstriction ))

    • Maximum dose (PIV): 0.1 mcg/kg/min

    • Watch: HR + lactate trend (can be misleading)

  • Dopamine (Mod-β1, High-α1 ) (X)

    • AE: Tachyarrhythmias (big one) arrhythmia

    • 2-20 mcg/kg/min (titrate by 2)

    • Medium (3–10 mcg/kg/min)→ β1 (contractility), High (>10 mcg/kg/min) → α1 (vasoconstriction)

    • Start 5 mcg/kg/min Titrate by 2–5 mcg/kg/min every few minutes , Usual range: 5–20 mcg/kg/min

    • PIV Max dose 10 mcg/kg/min

    • Watch: AFib, VT

  • -Vasopressin (add-on)

    • AE: Ischemia (skin, gut) Hyponatremia (V2 effect at higher doses)

    • V1 (vascular) Vasoconstriction

    • fixed dose 0.03 or 0.04, Always in CVC never PIV, Never alone it is add on

  • Methylene blue or hydroxocobalamin (vasodilator scavenger)

when 3rd vasopressor is added

  • methaleen blue turn urine bright green color ,

  • avoid in G6PD and on other seretonin syndrom increasing drugs

  • hydroxocobalamin another option makes urine dark red ( hard for hemodylaissi)

INOTROP

  • -Dobutamine (β1 → contractility >> β2 →vasodilation)

    • (Easier to titrate, less Hypotn)

    • AE: arrhythmias ,Hypotension (β2 vasodilation)

    • β1 → ↑ contractility and β2 → mild vasodilation, start NEPI first then add this

    • 5-40 mcg/kg/hr

    • Watch: BP drop while HR rises

  • Milrinone (Pulmonary HTN / RV failure, more HypoTn, renal Clarence) same add NEPI first

  • Methylene blue:

    • Causes blue-green urine discoloration

    • Avoid in G6PD deficiency

    • Use caution with serotonergic drugs (risk of serotonin syndrome)

      Hydroxocobalamin:

      • Causes dark red urine discoloration

      • Can interfere with hemodialysis machines and lab assays

Wean norepinephrine first, then discontinue vasopressin; consider midodrine 5–10 mg TID as an oral bridge (delayed onset over hours), and discontinue prior to discharge.

Shock → Vasopressor Approach

  • Undifferentiated / Septic shock →
    Norepinephrine ± vasopressin ± epinephrine

  • Cardiogenic shock →
    Norepinephrine ± dobutamine (± milrinone) ± epinephrine ± vasopressin (adjunct)
    → If low CI → add epinephrine/dobutamine
    → If low BP → add vasopressin

  • Obstructive shock →
    Treat cause + norepinephrine ± vasopressin ± epinephrine

  • Anaphylactic shock →
    Epinephrine (β2 + α1 effects)

  • Post-epidural hypotension →
    Phenylephrine

  • LV outflow tract obstruction →
    Phenylephrine ± vasopressin (avoid inotropes)

Perfusion Assessment

  • Lactate = only one data point

  • Always assess:

    • Urine output

    • Mentation

    • Liver function

    • Renal function

    • Skin perfusion

👉 Lactate = “check engine light,” not the whole picture

⚠️ Lactate may be falsely elevated with:

  • Albuterol / continuous nebs

  • Epinephrine

🧠 Push-Dose Pressors (Peri-intubation / crash)

  • Use when acute hypotension (e.g., intubation) BP<50

  • Intubation ↓ sympathetic tone + preload

Options:

  • Epinephrine: 20–50 mcg (esp bradycardia / low CI)

  • Phenylephrine: 100–200 mcg

  • ± Vasopressin (less common push)

👉 Always:

  • Have pressors + 500 mL LR ready

  • Start infusion ASAP (push is temporary)

🧠 General Pressor Safety

  • Vasopressin → requires central line (preferred)

  • Catecholamines at low dose can be given peripherally (with monitoring + antidote available)

Before intubation:

  • Prepare push-dose pressors (premixed syringes)

  • Cycle BP frequently (q1 min)

  • Consider A-line

🧠 Pearls

  • Dopamine in crash carts → stable at room temp (logistical reason, not clinical superiority)