Noradrenaline Usage and Dosage
Norepinephrine is the first-choice vasopressor for septic shock, initiated to target a mean arterial pressure (MAP) of 65 mmHg after adequate fluid resuscitation. 1
Initial Resuscitation and Timing
Before starting norepinephrine, administer at least 30 mL/kg of crystalloid fluids for initial resuscitation in patients with sepsis-induced hypotension 1. However, do not delay norepinephrine if severe hypotension persists - it can be started during fluid resuscitation as an emergency measure when diastolic blood pressure is critically low or when cerebral/coronary ischemia is threatened 2.
Recent evidence strongly supports early norepinephrine initiation (within 1 hour of shock recognition), which is associated with:
- Reduced mortality 3, 4
- Less fluid overload (502 mL less fluid at 6 hours) 4
- Faster achievement of MAP targets 4
- More mechanical ventilation-free days 4
For maternal sepsis specifically, start norepinephrine at 0.02 µg/kg/min if MAP remains <65 mmHg after fluid resuscitation 5.
Dosing Protocol
Adult Dosing (FDA-Approved) 6
Standard dilution: Add 4 mg norepinephrine to 1,000 mL of 5% dextrose solution (concentration: 4 mcg/mL)
Starting dose: 2-3 mL/min (8-12 mcg/min or approximately 0.05-0.1 mcg/kg/min)
Maintenance dose: 0.5-1 mL/min (2-4 mcg/min or approximately 0.02-0.05 mcg/kg/min)
Titration: Adjust to maintain MAP ≥65 mmHg (or 40 mmHg below pre-existing systolic pressure in previously hypertensive patients) 6
High-dose threshold: When doses exceed 0.25-0.5 mcg/kg/min, consider adding vasopressin rather than further increasing norepinephrine 1, 7
Pediatric Dosing 8
Starting dose: 0.5 ± 0.4 µg/kg/min
Maximum dose: May require up to 2.5 ± 2.2 µg/kg/min (higher than traditionally recommended)
First-line consideration: Pediatric guidelines suggest norepinephrine or epinephrine over dopamine 9. Recent data suggest norepinephrine may be associated with lower mortality than epinephrine in children without cardiac dysfunction 10.
Route of Administration
Central vs Peripheral Access
Preferred route: Large central vein (antecubital or femoral vein acceptable) 6
Peripheral administration is safe when central access is delayed:
- Can be administered peripherally for median duration of 3 hours without adverse effects 8
- In adults, peripheral norepinephrine avoided CVC placement in 51.6% of patients 11
- Extravasation rate: 75.8 events/1,000 catheter-days, mostly causing minimal injury 11
- No patient required surgical intervention for extravasation in recent large study 11
Practical approach: Start peripherally or via intraosseous route if central access not immediately available, particularly in pediatrics 9. Transition to central access when feasible for prolonged infusions.
Avoid: Leg veins in elderly patients or those with peripheral vascular disease due to increased gangrene risk 6
Escalation Strategy
When MAP target not achieved with norepinephrine alone:
Add vasopressin 0.03 units/min (not to exceed 0.04 units/min) to spare norepinephrine dose 1, 12
- Do NOT use vasopressin as sole initial agent 1
Add epinephrine if additional agent needed or substitute for norepinephrine 1
Consider low-dose corticosteroids (hydrocortisone 200 mg/day) if requiring norepinephrine >0.25 mcg/kg/min for ≥4 hours 5
Add dobutamine (up to 20 mcg/kg/min) if evidence of persistent hypoperfusion with cardiac dysfunction despite adequate preload and MAP 1
Special Considerations
Obesity
Obese patients (BMI ≥30) require lower weight-based doses but similar absolute doses compared to non-obese patients 13. Consider using non-weight-based dosing (absolute mcg/min) rather than mcg/kg/min in obese patients.
Monitoring Requirements
- Arterial catheter placement recommended as soon as practical for all patients on vasopressors 1
- Monitor for arrhythmias (particularly with cyclopropane/halothane anesthesia - contraindicated) 6
- Check infusion site frequently for blanching or extravasation 6
- Serial lactate measurements to guide resuscitation adequacy 1
Drug Interactions
Extreme caution with MAO inhibitors or tricyclic/imipramine antidepressants - may cause severe, prolonged hypertension 6
Common Pitfalls
- Delaying norepinephrine while pursuing aggressive fluid resuscitation - early initiation (within 1 hour) improves outcomes 3, 4
- Avoiding peripheral administration when central access delayed - peripheral use is safe for initial hours 8, 11
- Using dopamine instead - dopamine associated with higher mortality and more arrhythmias; reserve only for bradycardic patients 1, 2
- Inadequate fluid resuscitation first - always correct hypovolemia, but don't delay vasopressors in profound shock 2
- Infusing into leg veins in elderly - increases gangrene risk 6