What is the calculation for norepinephrine infusion rate using a 50 mL infusion pump?

Norepinephrine 50 mL Infusion Pump Calculation

For a 50 mL infusion pump, add 1 mg of norepinephrine to 50 mL of saline to create a concentration of 20 mcg/mL, then set the pump rate in mL/h to deliver the desired mcg/min dose using the formula: pump rate (mL/h) = desired dose (mcg/min) × 3. 1

Standard Concentration Preparation

The most practical approach for a 50 mL pump is to create a 20 mcg/mL concentration:

• Mix 1 mg (1 mL of 1:1000) norepinephrine in 50 mL total volume of normal saline or D5W 1
• This yields a final concentration of 20 mcg/mL 1

Dosing Calculations

Starting Dose

• Begin at 0.1-0.5 mcg/kg/min (approximately 7-35 mcg/min for a 70 kg adult) 1
• For the 20 mcg/mL concentration: pump rate (mL/h) = desired mcg/min × 3
• Example: For 10 mcg/min, set pump at 30 mL/h 1

Titration Protocol

• Increase by 0.5 mg/h (equivalent to approximately 167 mcg/min) every 4 hours as needed, up to maximum 3 mg/h 1
• Target mean arterial pressure of 65 mmHg or increase MAP by 10 mmHg 1
• Monitor blood pressure and heart rate every 5-15 minutes during initial titration 1

Alternative Concentration for Anaphylaxis

If using norepinephrine for refractory anaphylaxis (not responding to epinephrine):

• Add 1 mg norepinephrine to 100 mL saline (10 mcg/mL concentration) 2
• Start at 30-100 mL/h (5-15 mcg/min) and titrate based on clinical response 2
• This is only for anaphylaxis scenarios after epinephrine failure 1

Critical Safety Considerations

Volume Resuscitation First

• Administer minimum 30 mL/kg crystalloid bolus BEFORE or concurrent with norepinephrine initiation 1
• Vasoconstriction in hypovolemic patients causes severe organ hypoperfusion despite "normal" blood pressure 1

Infusion Pump Programming Hazards

• Never use the loading dose function on infusion pumps for norepinephrine 3
• A documented case showed inadvertent 1.8 mg bolus delivered in 2 minutes when pump reverted to historical rate of 999 mL/h, causing cardiac arrest 3
• Always verify pump settings and clear historical values before starting infusion 3

Access and Monitoring

• Central venous access is strongly preferred to minimize extravasation risk 1
• If peripheral IV must be used temporarily, monitor site continuously 1
• If extravasation occurs, immediately infiltrate phentolamine 5-10 mg diluted in 10-15 mL saline into the affected area 1

Drug Compatibility

• Never mix norepinephrine with sodium bicarbonate or alkaline solutions in the IV line 1
• These inactivate catecholamines 1

Pediatric Calculations

For children requiring norepinephrine:

• Use the "Rule of 6": 0.6 × body weight (kg) = mg of norepinephrine to add to 100 mL saline 2, 1
• Then 1 mL/h delivers 0.1 mcg/kg/min 2, 1
• Standard pediatric dosing ranges from 0.1-1.0 mcg/kg/min, starting at lowest dose 1
• Doses up to 5 mcg/kg/min may be necessary in some children 1

Infusion System Optimization

• Use low dead-space volume extension sets to minimize time to steady-state 4
• Double-syringe pump systems with constant saline flow at 5 mL/h provide most reliable delivery 4
• Standard extension sets can take up to 40 minutes to reach steady-state after onset 4
• At low flow rates (1 mL/h), start-up delays range from 89-1622 seconds depending on pump assembly 5