What is the recommended starting dose and titration schedule for intravenous norepinephrine (noradrenaline) in an adult with hypotension to achieve a target mean arterial pressure?

Norepinephrine Dosing in Adult Hypotension

Start norepinephrine at 0.02 µg/kg/min (approximately 0.5 mg/h or 8–12 µg/min for a 70 kg adult) via central venous access, titrating every 5–10 minutes to achieve a mean arterial pressure (MAP) of 65 mmHg. 1, 2, 3

Pre-Administration Requirements

Before initiating norepinephrine, you must address hypovolemia first:

• Administer at least 30 mL/kg crystalloid bolus within the first 3 hours of septic shock recognition, either before or concurrent with vasopressor initiation 1, 3
• In pregnant patients, limit the initial bolus to 1–2 L to reduce pulmonary edema risk 1, 3
• Exception: In severe hypotension with critically low diastolic pressure (systolic <70 mmHg), start norepinephrine immediately as an emergency measure while fluid resuscitation continues 2, 3

Starting Dose and Titration Schedule

Initial Dosing

• Starting dose: 0.02–0.05 µg/kg/min (approximately 0.5 mg/h for a 70 kg adult) 1, 2, 3
• Alternative concentration: 0.5 mg/h equals approximately 8–12 µg/min 2, 3

Titration Protocol

• Increase by 0.02–0.05 µg/kg/min every 5–10 minutes until MAP ≥65 mmHg is achieved 3
• Alternative approach: Increase by 0.5 mg/h every 4 hours as needed, up to a maximum of 3 mg/h 2
• Monitor blood pressure and heart rate every 5–15 minutes during initial titration 1, 2, 3

Hemodynamic Targets

Standard MAP Target

• Target MAP of 65 mmHg for most patients 1, 2, 3
• This represents the minimum threshold for adequate organ perfusion; below this, tissue perfusion becomes linearly dependent on arterial pressure 1

Individualized Targets

• Chronic hypertension: Target MAP of 70–85 mmHg to reduce the need for renal replacement therapy 1, 2, 3
• A multicenter trial found no mortality difference between MAP targets of 65 mmHg (34% mortality) versus 85 mmHg (36.6% mortality) in the general population 1
• The subgroup with chronic hypertension had reduced RRT requirements at the higher MAP target 1

Administration Route and Monitoring

Vascular Access

• Central venous access is strongly preferred to minimize extravasation risk and tissue necrosis 1, 2, 3
• If central access is unavailable, peripheral IV or intraosseous administration can be used temporarily with strict monitoring 1, 2, 3

Continuous Monitoring

• Place an arterial catheter for continuous blood pressure monitoring as soon as practical 2, 3
• Monitor tissue perfusion markers beyond MAP alone 2, 3:
  • Lactate clearance: Repeat every 2–4 hours if elevated 2, 3
  • Urine output: Maintain ≥0.5 mL/kg/h 1, 2, 3
  • Mental status, capillary refill ≤2 seconds, and skin perfusion 2, 3

Escalation Strategy for Refractory Hypotension

When to Add a Second Agent

Add vasopressin when norepinephrine reaches 0.1–0.25 µg/kg/min and MAP remains <65 mmHg despite adequate fluid resuscitation 1, 2, 3

Vasopressin Dosing

• Fixed dose of 0.03 units/min (do not titrate) 1, 2, 3
• Never exceed 0.03–0.04 units/min except as salvage therapy; higher doses cause cardiac, digital, and splanchnic ischemia without additional benefit 1, 2, 3
• Vasopressin must always be combined with norepinephrine, never used as monotherapy 2, 3

Third-Line Options

• Epinephrine: Start at 0.05 µg/kg/min, titrate up to 0.3 µg/kg/min if MAP cannot be achieved with norepinephrine plus vasopressin 1, 3
• Dobutamine: Add 2.5–20 µg/kg/min when MAP is adequate (≥65 mmHg) but signs of tissue hypoperfusion persist, especially with myocardial dysfunction 1, 2, 3
• Hydrocortisone: 200 mg/day IV for refractory shock after ≥4 hours of high-dose vasopressor therapy 1, 2, 3

Critical Pitfalls to Avoid

Agents to Avoid

• Dopamine is strongly contraindicated as first-line therapy (Grade 1A); it increases mortality by 11% absolute risk and causes significantly more arrhythmias compared to norepinephrine 4, 3
• Low-dose dopamine for renal protection is contraindicated (Grade 1A); it provides no benefit 2, 4, 3
• Phenylephrine is not recommended except in three specific scenarios: norepinephrine-induced serious arrhythmias, documented high cardiac output with persistent hypotension, or salvage therapy 4, 3

Administration Errors

• Do not mix norepinephrine with sodium bicarbonate or alkaline solutions; this inactivates the drug 2, 3
• Do not delay norepinephrine while pursuing aggressive fluid resuscitation in profound hypotension 2, 3
• Do not focus solely on MAP; incorporate tissue perfusion markers (lactate, urine output, mental status) into therapeutic decisions 2, 3

Extravasation Management

If extravasation occurs, infiltrate phentolamine 5–10 mg diluted in 10–15 mL saline intradermally at the site immediately to prevent tissue necrosis 2, 3

Standard Concentration Preparation

• Add 4 mg norepinephrine to 250 mL D5W to yield 16 µg/mL concentration 2
• Alternative: Add 1 mg to 100 mL saline for 10 µg/mL concentration 2