What is the initial dose of norepinephrine (vasopressor) for treating hypotension?

Initial Norepinephrine Dosing for Hypotension

Start norepinephrine at 0.02 mcg/kg/min (approximately 8-12 mcg/min for a 70 kg adult) via continuous IV infusion, targeting a mean arterial pressure (MAP) of 65 mmHg. 1

Critical Pre-Administration Requirements

Before starting norepinephrine, administer at least 30 mL/kg crystalloid bolus (approximately 2 liters for a 70 kg adult) unless the patient has profound, life-threatening hypotension. 1, 2

• Use balanced crystalloids (lactated Ringer's or Plasma-Lyte) preferentially over normal saline for fluid resuscitation 3
• In cases of severe hypotension (systolic BP <70 mmHg) or diastolic BP ≤40 mmHg, start norepinephrine immediately while fluid resuscitation continues rather than waiting for complete volume repletion 2, 4
• Early norepinephrine administration (within 93 minutes of presentation) significantly increases shock control rates compared to delayed administration and reduces fluid overload complications 5

Preparation and Concentration

Standard dilution: Add 4 mg norepinephrine to 250 mL of D5W to yield 16 mcg/mL concentration. 6

• Alternative concentration: Add 4 mg to 1000 mL D5W for 4 mcg/mL if larger fluid volumes are needed 6
• Do not dilute in saline alone—dextrose-containing solutions protect against oxidation and loss of potency 6

Administration Route

Central venous access is strongly preferred to minimize extravasation risk and tissue necrosis. 1, 2, 3

• If central access is unavailable or delayed, peripheral IV administration can be used temporarily with strict monitoring 1, 2
• Place an arterial catheter as soon as practical for continuous blood pressure monitoring 2

Target Blood Pressure and Titration

Target MAP of 65 mmHg for most patients. 1, 2, 3

• In previously hypertensive patients, consider targeting MAP no more than 40 mmHg below their baseline systolic pressure 6
• In pregnant patients (20 weeks gestation to 3 days postpartum), use systolic BP <85 mmHg as the threshold for vasopressor initiation 1

Monitor blood pressure every 5-15 minutes during initial titration. 2, 3

• Assess tissue perfusion markers: lactate clearance, urine output >50 mL/h, mental status, capillary refill 2, 3
• Titrate dose to achieve both MAP target AND adequate tissue perfusion, not just blood pressure alone 2

Maintenance and Escalation

Typical maintenance dose ranges from 2-4 mcg/min (0.5-1 mL/min of standard dilution). 6

• Maximum doses can be much higher (up to 68 mg/day or 3 mg/h) if hypotension persists, but always suspect and correct occult hypovolemia first 6, 2

When norepinephrine reaches 0.1-0.25 mcg/kg/min and hypotension persists, add vasopressin 0.03-0.04 units/min as second-line therapy rather than continuing to escalate norepinephrine alone. 1, 2, 3

• Consider adding epinephrine 0.1-0.5 mcg/kg/min if persistent hypoperfusion despite adequate vasopressors 2
• For persistent hypoperfusion with myocardial dysfunction, add dobutamine up to 20 mcg/kg/min 2

Special Populations

Pregnant patients with septic shock: Start at 0.02 mcg/kg/min, consider more restrictive initial fluid boluses (1-2 L) due to lower colloid oncotic pressure and higher pulmonary edema risk. 1, 3

Pediatric patients: Start at 0.1 mcg/kg/min, titrate to effect, typical range 0.1-1.0 mcg/kg/min, maximum up to 5 mcg/kg/min may be necessary. 2

Critical Pitfalls to Avoid

• Never start norepinephrine without addressing hypovolemia first (except in life-threatening hypotension), as vasoconstriction in hypovolemic patients causes severe organ hypoperfusion despite "normal" blood pressure 2, 3
• Do not use dopamine as first-line agent—it is associated with higher mortality and more arrhythmias compared to norepinephrine 2, 7
• Avoid phenylephrine as first-line therapy—it may raise blood pressure while worsening tissue perfusion 2
• Monitor for extravasation continuously—if it occurs, immediately infiltrate 5-10 mg phentolamine diluted in 10-15 mL saline at the site to prevent tissue necrosis 2, 7, 6
• Do not mix with sodium bicarbonate or alkaline solutions—norepinephrine is inactivated in alkaline solutions 2

Evidence for Early Administration

Recent high-quality evidence demonstrates that early norepinephrine administration (simultaneously with fluid resuscitation) significantly improves outcomes in septic shock. 5 A 2019 randomized controlled trial showed that early norepinephrine at 0.05 mcg/kg/min increased shock control rates from 48.4% to 76.1% by 6 hours and reduced cardiogenic pulmonary edema (14.4% vs 27.7%) and new-onset arrhythmias (11% vs 20%). 5 Early administration increases cardiac output and preload, improves microcirculation, and avoids fluid overload. 8