What is the maximum infusion rate of norepinephrine (vasopressor)?

Maximum Infusion Rate of Norepinephrine

The maximum infusion rate of norepinephrine is 3 mg/h (approximately 0.6-1.0 mcg/kg/min in a 70 kg adult), though doses exceeding 1.0 mcg/kg/min are associated with mortality rates approaching 90% and should prompt consideration of additional vasopressor agents. 1, 2

Standard Dosing Parameters

Adult Dosing Range

• Initial rate: 0.5 mg/h (approximately 0.1-0.5 mcg/kg/min or 7-35 mcg/min in a 70 kg adult) 1, 3
• Titration: Increase by 0.5 mg/h every 4 hours as needed 1
• Maximum rate: 3 mg/h 1
• Weight-based maximum: 0.6-1.0 mcg/kg/min before adding second vasopressor 1, 3

Pediatric Dosing Range

• Starting dose: 0.1 mcg/kg/min 1
• Typical range: 0.1-1.0 mcg/kg/min 1
• Maximum: Up to 5 mcg/kg/min may be necessary in some children 1

Critical Thresholds and Clinical Implications

Mortality-Associated Dosing

• Doses >1.0 mcg/kg/min are associated with 90% ICU mortality and represent refractory septic shock 2
• Maximum dose within 24 hours ≥0.6 mcg/kg/min is significantly associated with 7-day mortality (sensitivity 47%, specificity 93%) 4
• When norepinephrine reaches 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

Practical Dosing Considerations

• Obese patients require lower weight-based doses (mean 0.09 mcg/kg/min) compared to non-obese patients (mean 0.13 mcg/kg/min), but similar total doses (approximately 8-9 mcg/min) 5
• Non-weight-based dosing may be more appropriate in obese patients to avoid underdosing 5

Preparation and Concentration

Standard Adult Concentration

• Add 4 mg norepinephrine to 250 mL D5W to yield 16 mcg/mL concentration 1
• Alternative: 1 mg in 100 mL saline creates 10 mcg/mL concentration (1:100,000 solution) 1

Pediatric Preparation ("Rule of 6")

• 0.6 × body weight (kg) = number of milligrams diluted to total 100 mL of saline 1
• Then 1 mL/h delivers 0.1 mcg/kg/min 1

Administration Requirements

Route and Monitoring

• Central venous access is strongly preferred to minimize extravasation risk 1, 3
• Peripheral administration is acceptable temporarily if central access is delayed, using ≥18 gauge IV at or above the antecubital fossa, with maximum dose 20 mcg/min 6
• Peripheral extravasation rate is approximately 4.5% when protocol is followed 6
• Monitor blood pressure and heart rate every 5-15 minutes during initial titration 1
• Place arterial catheter as soon as practical for continuous monitoring 3

Target Blood Pressure

• Mean arterial pressure (MAP) ≥65 mmHg is the standard target 1, 3
• Titrate to MAP and tissue perfusion markers (lactate clearance, urine output >50 mL/h, mental status, capillary refill) 1

Critical Precautions

Pre-Administration Requirements

• Address hypovolemia FIRST with minimum 30 mL/kg crystalloid bolus before or concurrent with norepinephrine initiation 1, 3
• In severe hypotension (systolic <70 mmHg), start norepinephrine as emergency measure while continuing fluid resuscitation 1

Extravasation Management

• If extravasation occurs, immediately infiltrate phentolamine 5-10 mg diluted in 10-15 mL saline into the site 1, 3
• Pediatric phentolamine dose: 0.1-0.2 mg/kg up to 10 mg 1

Drug Incompatibilities

• Never mix with sodium bicarbonate or alkaline solutions in the IV line, as norepinephrine is inactivated in alkaline solutions 1

Special Clinical Scenarios

Anaphylaxis

• Use only when epinephrine injections and volume resuscitation fail 1
• Alternative concentration: 1 mg in 100 mL saline at 30-100 mL/h (5-15 mcg/min) 1

Septic Shock

• Norepinephrine is the first-choice vasopressor over dopamine, epinephrine, or phenylephrine 3
• Target MAP 65 mmHg with adequate tissue perfusion markers 3

Cardiogenic Shock

• Use cautiously and transiently due to increased afterload risk 3
• Typical range: 0.2-1.0 mcg/kg/min 3