What norepinephrine (noradrenaline) infusion rate should be used in a 70‑kg adult to achieve a mean arterial pressure ≥65 mm Hg?

Noradrenaline Infusion Rate for Septic Shock

For a 70-kg adult with septic shock, start norepinephrine at 0.02 µg/kg/min (approximately 1.4 µg/min or 8-12 µg/min non-weight-based), then titrate to maintain MAP ≥65 mmHg. 1

Initial Dosing Strategy

The most recent maternal sepsis guidelines from 2025 provide the clearest starting dose recommendation: 0.02 µg/kg/min 1. For a 70-kg patient, this translates to approximately 1.4 µg/min.

The FDA label provides alternative guidance: start with 8-12 µg/min (2-3 mL/min of a 4 µg/mL solution), which aligns closely with the weight-based calculation 2.

Titration and Maintenance

• Target MAP: 65-70 mmHg initially 3, 4, 5
• Average maintenance dose: 2-4 µg/min (0.5-1 mL/min of standard dilution) 2
• Titrate every 5 minutes based on blood pressure response
• Maximum doses can reach 68 mg/day (approximately 47 µg/min) in refractory cases, though this suggests occult volume depletion 2

Preparation and Administration

Standard dilution: Add 4 mg norepinephrine to 1000 mL of 5% dextrose to create a 4 µg/mL solution 2. This is the FDA-recommended concentration that balances safety with ease of titration.

• Administer through a large central vein when possible
• Peripheral administration is acceptable initially until central access established 1
• Use an infusion pump for precise control
• Place an arterial line as soon as practical 3, 4, 5

Weight-Based vs. Non-Weight-Based Dosing

Recent research demonstrates that obese patients require lower weight-based doses but similar absolute doses compared to non-obese patients 6. At 60 minutes, obese patients averaged 0.09 µg/kg/min versus 0.13 µg/kg/min in non-obese patients, but both groups received approximately 8-9 µg/min in absolute terms.

Clinical implication: For obese patients, consider using non-weight-based dosing (8-12 µg/min starting dose) rather than calculating based on actual body weight, which may lead to excessive dosing.

MAP Target Considerations

While 65 mmHg is the standard initial target 3, 4, 5, individualize based on:

• Chronic hypertension: Consider targeting higher MAP (75-85 mmHg) if the patient shows clinical improvement 3, 7. However, research shows this may not improve microcirculation in all patients 8, 9
• Elevated CVP: Higher MAP targets may be warranted 7
• Age and comorbidities: Older patients may benefit from avoiding excessive vasopressor doses 7

The 2019 study by Lamontagne showed that increasing MAP from 65 to 85 mmHg improved microcirculation in both hypertensive and non-hypertensive patients 9, but the 2009 study by Dubin found no microcirculatory benefit and potential harm 8. Start at 65 mmHg and only increase if there's clear evidence of inadequate perfusion despite adequate volume status.

Escalation Strategy

If MAP remains inadequate despite low-moderate dose norepinephrine (0.1-0.2 µg/kg/min or 7-14 µg/min):

1. Add vasopressin 0.03-0.04 units/min (not 0.04 as stated in one guideline - this appears to be an error; standard is 0.03 units/min) 3, 1
2. Add epinephrine if cardiac dysfunction present 3, 1
3. Consider hydrocortisone 200 mg/day if requiring ≥0.25 µg/kg/min for ≥4 hours 1

Critical Pitfalls to Avoid

• Never use norepinephrine before adequate fluid resuscitation (minimum 30 mL/kg crystalloid) 3, 4, 5
• Do not dilute in saline alone - use dextrose-containing solutions to prevent oxidation 2
• Avoid abrupt withdrawal - taper gradually 2
• Do not use dopamine for renal protection 3, 4, 5
• Suspect occult hypovolemia if requiring very high doses 2

Monitoring Requirements

• Continuous arterial pressure monitoring preferred 3, 4, 5
• Hourly MAP and urine output at minimum 1
• Lactate levels at baseline and 6 hours 1
• Cardiac output/stroke volume if available 1

The 2024 closed-loop study demonstrated that automated titration maintained MAP in target range 80% of time versus 42% with manual titration 10, highlighting the importance of frequent reassessment and adjustment.