Generic Name

Norepinephrine

Mechanism

• α₁‑adrenergic agonist → vasoconstriction of arterioles & venules → ↑ systemic vascular resistance (SVR) & blood pressure.
• α₂‑adrenergic agonist (minor) → central inhibition of norepinephrine release, producing modest baroreflex-mediated BP rise.
• β₁‑adrenergic agonist (low affinity) → ↑ cardiac contractility (inotropy) and heart rate, supporting cardiac output during shock.
• Net effect: Rapid restoration of mean arterial pressure (MAP) with minimal tachycardia compared to vasopressin or dopamine.

Pharmacokinetics

Indications

• Cardiogenic shock (post‑cardiac‑surgery, myocardial infarction)
• Septic shock or distributive shock when MAP < 65 mmHg despite fluids
• Hypotension during anesthesia or major surgery
• Resuscitation in advanced life support protocols (adult ACLS, Pediatric Advanced Life Support)
• Underlying arrhythmias secondary to low preload or aftershock

Contraindications

• Absolute: Hypersensitivity to norepinephrine or any excipients; severe coronary artery disease with impaired left ventricular function (risk of ischemia).
• Relative:
• Patients with uncontrolled hypertension or history of vasospastic disorders (e.g., Prinzmetal’s angina)
• Severe peripheral arterial disease (increased risk of digital ischemia)
• Severe intrathoracic pressure (e.g., tension pneumothorax) due to additive peak pressures
• Warnings:
• Use caution in patients with arrhythmic risk profiles (Brugada, QT prolongation);
• Avoid peripheral administration without a central line if dose > 1 µg/kg/min due to extravasation risk.

Dosing

• Loading dose: Generally not administered; immediate infusion preferred.
• Starting infusion: 0.01–0.03 µg/kg/min in ICU; titrate by 0.01 µg/kg/min increments every 5‑10 min until MAP 65‑70 mmHg.
• Maximum: 3 µg/kg/min (rarely exceeded in shock states).
• Route: Central venous line preferred; peripheral line acceptable for short duration (< 24 h) at < 2 µg/kg/min with needle aspiration.
• Concentration: 4 µg/mL (100 µg/mL) in 10‑mL diluted 0.9 % NaCl; adjust per institutional protocol.
• Adjuncts: Add vasopressin or epinephrine in refractory shock after adequate norepinephrine dosing.

Adverse Effects

• Common
• Local site pain / vasoconstriction (if extravasated)
• Reflex bradycardia
• Elevated systolic BP spikes
• Serious
• Arrhythmias (PVCs, SVT, VF) due to tachycardia/high BP
• Myocardial ischemia/infraction (especially in CAD)
• Transient ischemic attacks, gangrene from extravasation
• Hypersensitivity reactions (rare)

Monitoring

• Hemodynamics: Continuous MAP & HR; target MAP 65–70 mmHg (or individualized goal)
• Vascular access: Watch for extravasation and phlebitis; clamp if infiltration suspected.
• Laboratory:
• Serum lactate (shunt/ischemia indicator)
• Cardiac enzymes if ischemic symptoms develop
• Metabolic panel for kidney/liver function (metabolism)
• Fluid balance: Maintain euvolemia; avoid excessive fluid overload.
• Sedation & analgesia: Ensure adequate depth to prevent sympathetic surges.

Clinical Pearls

1. Start low, titrate fast – Norepinephrine’s potent vasoconstriction demands a *microdose approach*; small increases dramatically raise MAP.

2. Central line first – Even if peripheral infusion is used for short term, place a central line within the first hour “just in case” and move the infusion promptly.

3. Plate detection – A rising serum lactate ahead of MAP changes may predict impending shock; consider earlier norepinephrine even when MAP is near goal.

4. Avoid “bridging” to epinephrine – Norepinephrine is preferred for shock; only switch to epinephrine if tachyarrhythmias or septic arrest remains uncontrolled.

5. Layer of Support – Pair levitation patient [hospital standing positions & leg elevation] to reduce venous stasis while on vasopressors if feasible.

6. Extravasation – If leakage occurs, immediately aspirate waste fluid, apply warm compress & administer phentolamine 4 mg IV push; surgical consultation if skin ischemia persists.

7. Data-Driven – Adopt smart infusion pumps with built‑in alarm ranges (e.g., 0.01–3 µg/kg/min) to prevent overdosing, especially in mixed‑protocol stays.

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• Key pharmacology terms: vasopressor, α‑adrenergic agonist, mean arterial pressure, septic shock, catecholamine metabolism, tachyarrhythmia, extravasation.

Use this card as a quick reference when managing life‑threatening hypotension in acute care settings.